[NEW] CSEC® Revision Guide Human and Social Biology.pdf

Macmillan Education 4 Crinan Street London N1 9XW A division of Macmillan Publishers Limited Companies and representatives throughout the world ISBN 9781-380-00702-5

AER

Text © Terry Hudson and Debbie Roberts 2016 Design and illustration © Macmillan Publishers Limited 2016 The authors have asserted their right to be identified as the authors of this work in accordance with the Copyright, Designs and Patents Act 1988. First published 2016 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publishers. Original design by Macmillan Publishers Limited Page make-up by Sparks – www.sparkspublishing.com Illustrated by Oxford Designers & Illustrators Cover design and illustration by Clare Webber These materials may contain links for third party websites. We have no control over, and are not responsible for, the contents of such third party websites. Please use care when accessing them.

a n d n a m u H y g o l o i B Social Terry Hudson & Debbie Roberts

Contents Introduction How to Use This Book Revision and Exam Tips

3 3 4

Section A The Organism and Its Environment Unit 1 Living Organisms in the Environment Test Questions for Section A

5 15

Section B Life Processes Unit 1 Nutrition Unit 2 The Respiratory System Unit 3 The Circulatory System Unit 4 The Skeletal System Unit 5 Excretion and Homeostasis Unit 6 Coordination and Control Unit 7 The Reproductive System Test Questions for Section B

16 30 37 45 52 59 67 75

Section C Heredity and Variation Unit 1 Heredity and Variation Test Questions for Section C

76 85

Section D Disease and Impact on Humans Unit 1 Disease and Impact on Humans Test Questions for Section D

86 100

Section E Impact of Health Pr actices on the Environment Unit 1 Impact of Health Practices on the Environment Test Questions for Section E

101 114

Paper 1 Practice Questions

115

Paper 2 Practice Questions

116

Answers to Test Yourself Questions

117

Glossary

125

Introduction Written by experienced teachers and authors, Macmillan Education’s CSEC® Revision Guides provide a clear route to exam success. Inside this book you’ll find complete, concise revision notes on all key syllabus topics, in addition to practical advice on how to approach your revision and tackle the exams themselves, helping you to prepare effectively for your examinations. Having reviewed the key points of each topic, you can refresh your knowledge and build your confidence with in-text practice questions, before moving on to sample practice exam papers at the end of the book. Questions are written in CXC examination style so that you will become familiar with exam wording and know exactly how to achieve your best possible grades. Answers to questions are available online at www.macmillan-caribbean.com.

How to Use This Book Self Check

Tick the box that shows how confident you feel

Yes

Maybe

Each section starts with a concept map showing key topics and, crucially, how they link together. Does X cause Y? Does X run in tandem with Y? Does X allow Y to happen?

No

Each section begins with a checklist so you can rate your confidence in each topic and prioritise your revision effectively.

At the end of each section you will have the opportunity to fill in your own blank Concept Map to check your understanding. It will also provide a useful summary for last-minute self-testing.

Reviewed

Test Yourself with these quick fire questions to monitor your progress.

Revised

Mastered

You’ll find these checkboxes for each topic so you can track your learning and be confident you’ve covered everything thoroughly. Review the topic and return to your Student’s Book if there’s anything you don’t understand, then come back and revise the topic in this revision guide – and tick ‘Mastered’ when all of your answers were correct!

Revision Tips provide you with interesting ways to make sure you retain all of this information. Whenever you find a keyword highlighted like this, you can find out its meaning in the glossary at the back of the book.

Remember boxes

contain handy nuggets of key information. If you don’t understand these, go back to your Student’s Book and refresh the topic.

Revision and Exam Tips The content in this revision guide has been carefully written to make sure you have all of the key information needed for CSEC success at your fingertips. It has already been broken down for you into manageable chunks, based on the official CXC syllabus and exam structure. Here are some tips to help you get the best out of this material: ■

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Start preparing ahead of the exams so you can give yourself enough time to get through all your work. Set long-term and short-term goals to help break up the work into manageable chunks. Write out a revision plan to help you stay on track; make sure to include breaks as learning is much more effective when spaced out over stretches of time. Remove all distractions from your study area. Make sure you have all the resources you need – this guide, a pen and extra paper. Use practical memory aids where you can; make flash cards, and use tables and mind maps like the ones in this guide. Try explaining all of the key words to another person without looking at the glossary. Test yourself and ask someone to test you. Recognise your revision milestones using the self-check boxes provided.

In the exam: ■

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Spend the first 10 minutes reading through the paper carefully, and work out a rough schedule to make sure you complete all the questions. Read each question before trying to answer it. Check your work and presentation carefully. Make sure you understand what the questions mean, so you can apply your knowledge properly: Analyse: study something in detail and identify characteristics of each piece of information Assess: make a judgement based on the facts provided Calculate: work out the value Comment: give your opinion Compare: give similarities Contrast: give differences Define: give the meaning Describe: give the characteristics ■

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Discuss: key points Estimate:give givethe a value based on rough working Explain: give reasons Identify: name/characterise Illustrate: give examples Justify: support your answer with evidence

The Organism and Its Environment

Section A

Unit

1

Living Organisms in the Environment

Concept Map Osmosis and active transport

Diffusion and cell membranes

OSMOSIS AND DIFFUSION

Photosynthesis: the process

Investigate effects of light and chlorophyll

The characteristics of living organisms

Unspecialised plant and animal cells

LIVING ORGANISMS IN THE ENVIRONMENT

Functions of cells

Principle of food chains Carbon and nitrogen cycle Food chains in habitat

Plants as producers

Cells of the human body The importance of cell specialisation in humans

Trophic levels

Self Check

Tick the box that shows how confident you feel

Yes

Maybe

No

I can describe the characteristics of living organisms. I can compare structure of unspecialised plant, animal and bacterial cells. I can state the functions of cell structures. I can identify selected cells which make up the human body. I can explain the importance of cell specialisation in humans. I can distinguish between osmosis and diffusion, and describe diffusion and cell membranes. I can explain the process of photosynthesis. I can investigate the effect of light and chlorophyll on starch production. I can explain the principles of food chains and construct food chains from selected habitats. 5

The Organism and Its Environment

Section A

The Characteristics of Living Organisms

Reviewed

Revised

Mastered

Living things have certain characteristics that are NOT common innon-living things.There are seven in total: 1. Nutrition: commonly thought of as food. In animals, digestion breaks nutrition down to release energy. Plants take in carbon dioxide, water and inorganic substances. 2. Growth: the increase of weight or size. 3. Excretion: the removal of waste matter produced by metabolism. TheRemember removal of undigested matter 4. Respiration: the release of energy from food in complex from the intestine is called egestion or elimination not excretion. chemical reactions. 5. Movement: movement of the whole body is locomotion or animals can move certain parts of their body. 6. Irritability: detection and reaction to changes or stimuli in the environment using nerves, brain and sense organs. 7. Reproduction: living things produce new individuals through sexual (fusion of sex cells) or asexual (no fusion of sex cells) reproduction. Non-living things have a chemical structure but do not have all of the characteristics listed above.

Test Yourself: Which of the seven characteristics would a machine, for example a car, possess?

The Structures of Unspecialised Plant, Animal and Bacterial Cells

Reviewed

Revised

Mastered

Test Yourself: Use the key words to label the plant cells. cell wall

1

2

cell membrane

3

nucleus

4

5

6

7

8

6

cytoplasm vacuoles mitochondria chloroplast starch grain

The Organism and Its Environment

Section A

Typical bacteria cell

HIV

Glycoprotein

Ring of plasmid DNA

Viral envelope

Large chromosomal ring of DNA

Cell wall

Cytoplasm

Capsid

Flagella

Bacteria have prokaryotic cells with no nucleus but they do have cytoplasm , a cell membrane and a cell wall. The genetic material, or nucleoid, floats in the cell. Some bacteria have whip-like structures called flagella to help them to move.

RNA (two identical strands)

Reverse transcripase

Viruses are often considered as non-living as Remember they can exist in a ‘Pro’ means before. ‘Karyon’ means nut or nucleus. Prokaryotic chemically inactive organisms evolved before state outside a cell. the nucleus evolved.

Structure of a fungus cell

Cell wall

Cell membrane

Amoeba

Clear ectoplasm

Cell membrane Nucleus

vacuole Contractile

Nucleus Pseudopodium Food vacuole

Cytoplasm

Food storage granule

Contractile vacuole Granular endoplasm

Eukaryotic organisms have cells with a membrane-bound nucleus. Some eukaryotes are singlecelled – such as amoeba. These have a typical animal cell structure.

Test Yourself: Describe TWO differences between a bacterial cell and an animal cell.

7

The Organism and Its Environment

Section A

The Functions of Cell Structures

Reviewed

Cell walls are rigid structures. In plants these are made of cellulose fibres. Cell membranes are flexible and allow some materials to pass through them. Mitochondria are found in animal and plant cells. They help the cells to break down sugars to produce energy. Chloroplasts are only found in plant cells. They help the cells to use energy from the sun in a process called photosynthesis.

1.

2. 3. 4.

of substances into and out of the cell?

Selected Cells in the Human Body

Nucleus

Where most of the cell’s chemical reactions occur

Cell membrane

Site where photosynthesis takes place

Cytoplasm

Prevents plant cells from bursting

Chloroplast

Contains the genetic material of the cell

Mitochondria

Controlsof exchange materials

Reviewed

Cilia

Microvilli

Apical surface Golgi apparatus Nucleus Basolateral surfaces

Mitochondria Basement membrane

3 Sperm cell Head Neck Middle piece Nucleus Acrosome Spiral shaped mitochondrion 8

Tail

Mastered

using the word bank below. List ONE key feature of each of the cells. 2 Egg cell

egg muscle sperm

Corona radiata Plasma membrane Nucleus (haploid) ZonaCytoplasm pellucida

nerve epithelial

4 Muscle cell Nerve

Plasma membrane

Revised

Test Yourself: Label each of the cell diagrams

These are some of the specialised cells of the human body: 1 Epithelial cell

Thick rigid wall Thin, flexible and partially permeable

Site where energy is produced during respiration

Prokaryotic cells such as bacteria do not have organelles.

Link each organelle to its function. One has been done for you. Which structures are found in BOTH animal and plant cells? Which organelles in cells are responsible for producing energy during respiration? Which organelle controls the movement

Mastered

Cell wall

The structures found inside eukaryotic cells are called organelles. The organelles of the cell work together to keep the cell alive. Each organelle has special functions. Remember

Test Yourself:

Revised

Striations Nerve end plate Nucleus Muscle cells

The Organism and Its Environment

Section A

The Importance of Cell Specialisation in Humans

Reviewed

Revised

Mastered

In single-celled organisms the cell carries out all of the functions needed for life. With multicellular organisms the individual cells are often specialised to carry out different jobs. Cells that divide or reproduce in organisms are unspecialised so they don’t have a special function or contain all of the organelles. They may develop and become differentiated cells that form tissues. There are four main tissues in the human body: epithelial, connective, nervous and muscle.

Test Yourself: 1.

Remember

Fill in the gaps in the table of tissue types and functions. Typeoftissue

Cells that are reproduced by the body are unspecialised.

Function Protects surfaces

Connective

Contract for movement

Nerve

2. What is the role of an unspecialised cell? 3. What is the importance of specialisation in humans?

Distinguish Between Osmosis and Diffusion

Reviewed

Revised

Mastered

This movement of substances happens in three main ways.

Diffusion: is the movement of particles from a region of high concentration to low concentration. The particles move down a concentration gradient – from high to low concentration.

Remember Cells have to allow substances to move in and out.

Osmosis: is a special example of diffusion. It is the diffusion of water molecules across a differentially permeable membrane such as a cell membrane. Water moves in both directions but there is a greater movement from high concentration to low concentration.

Active transport: this is when particles are moved across cell membranes against a concentration gradient. The cells need to use energy and the process involves carrier proteins in the membrane.

Test Yourself:

1. List ONE common feature in the three main ways that cells move substances in and out. 2. List any differences in the three main ways that substances can be transported. 9

Section A

The Organism and Its Environment

Diffusion and Cell Membranes

Reviewed

Revised Diffusion

The diagram shows the diffusion of gas particles. Diffusion is an important process in organisms as it allows vital substances in and out of cells. An important example of diffusion is gas High concentration exchange in the alveoli. Oxygen diffuses from the lungs into blood vessels and carbon dioxide diffuses in the Concentrated Dilute sugar sugar opposite direction. solution solution Diffusion can occur across permeable cell membranes. This allows gases and liquids to move from high concentration to low concentration. This is important as it allows: materials to enter and leave single-celled organisms such as amoeba products of digestion to enter the blood from the gut carbon dioxide to diffuse out of the blood and oxygen into the blood in the lungs.

Mastered

Low concentration Uniform distribution of water and sugar molecules

■

Diffusion

■

■

Osmosis and Active Transport

Sugar Permeable molecules membrane

Reviewed

Water molecules

Revised

Mastered

Osmosis is a very important process and special type of diffusion. It is the movement of water across cell membranes through a semi- or partially permeable membrane from a low to a high concentration. The tiny gaps in the membrane allow smaller water molecules to pass through but prevent larger molecules, for example sugar, from passing. It allows nutrients to be transported into cells and waste to be transported out of cells. It maintains the pressure within and outside cells It allows roots to absorb water It allows our bodies to keep the blood free from waste materials. ■

■

■

Active transport allows essential chemicals to enter cells against a concentration gradient. This is the opposite of diffusion and osmosis. Cells need to use energy to operate this process. Active transport is important in: root hairs where the concentration of minerals inside the cells is higher than in the soil the human gut where low concentrations of nutrients can be transported into the blood. ■

■

The root hair cell membranes contain carrier molecules. These transport mineral ions across the membrane into the cell. This is against the concentration gradient. Cell membrane with thin cell wall Vacuole

Test Yourself: 1.

2.

Describe ONE difference between osmosis and active transport. Why is active transport vital to living things? Soil particles

10

Minerals and water absorbed

The Organism and Its Environment

Section A

The Process of Photosynthesis

Reviewed

Revised

Mastered

Photosynthesis is the synthesis or making of glucose from carbon dioxide and water using light energy absorbed by chlorophyll. The chlorophyll is found in chloroplasts. The structure of chloroplasts maximises the amount of light energy hitting the chlorophyll molecules. Light energy is converted into chemical energy. The glucose made is used for energy in respiration or stored as starch in the plant.

Remember

Photosynthesis

6CO2

+ 6H2O

Carbon dioxide + Water

C6H12O6 +

6O2

Glucose + Oxygen

Chlorophyll is found in the chloroplasts in plant cells found in leaves.

Notice that the splitting of water produces oxygen. The carbon dioxide is reduced to carbohydrate. Carbon dioxide enters leaves through small holes called stomata. Water and minerals are absorbed through the roots. Photosynthesis also takes place in algae and in some bacteria. The bacteria do not use the same chemical process but they do use light energy. ■

■

Factors that increase the rate of photosynthesis are: light intensity, the carbon dioxide level and the temperature.

Test Yourself: 1.

Name the organelle that is the site of photosynthesis.

2. Explain why water and carbon dioxide are needed for photosynthesis.

3. Are organisms that use photosynthesis heterotrophic or autotrophic? 4. Name the products of photosynthesis.

11

The Organism and Its Environment

Section A

Investigating the Effect of Light and Chlorophyll on Starch Production

Reviewed

B. Plant lacks CO 2

Graphs showing factors increasing photosynthesis s i s e h t n y s o t o h p f o e t a R

Light intensity

C. Plant in dark lacks light

D. Variegated leaf, parts lack chlorophyll

Test Yourself: 1.

2. Carbon dioxide concentration

3. 4.

is s e h t n y s o t o h p f o e t a R

Chlorophyll absent

Potassium hydroxide

Glass sheet smeared with vaseline

R

When iodine is used to test for starch the colour will be blue/black.

Chlorophyll present

Bell jar

s i s e h t n y s o t o h p f o e t a

Mastered

Remember

Factors that increase the rate of photosynthesis are light intensity, carbon dioxide level and temperature. Box to keep light out

A. Normal plant

Revised

If the leaves are tested for starch, what do you predict the result will be for each plant A to D? How does increasing the temperature affect the rate of photosynthesis? Why do some farmers pump carbon dioxide into their greenhouses? Why does the rate of photosynthesis slow down towards night time?

Temperature

Plants as Producers:

Reviewed

How Other Living Organisms Depend on Plants

Revised

Mastered

Remember Green plants are the main source of food for living organisms.

Plants produce all of our food in the process of photosynthesis. Humans and other organisms depend on plants for food. Even if you are eating chicken, the energy has come from the plant that the chicken consumed. Food chains explain the relationship between living organisms. Green plants are always at the beginning of a food chain, to Explain how eating a beef show how all organisms in the food chain depend on burger is the result of photosynthesis. green plants carrying out photosynthesis.

Test Yourself:

12

Section A

The Organism and Its Environment

Explaining the Principles of Food Chains

Reviewed

Revised

Mastered

Test Yourself: Label the producer and consumers in this simple food chain.

Food chains always start with producers, which are usually green plants. The other organisms in the food chain get their energy and biomass by consuming (or eating) other organisms and are consumers. Food chains demonstrate the interdependence of organisms. Energy is lost at each step of a food chain and as a result they are short.

Test Yourself: 1.

2.

Label the producer and THREE consumers in this simple food web. Identify TWO other food chains in this web and draw them.

Other organisms will consume the organisms in this chain, creating food webs.

Test Yourself:

1. Explain why most food chains are usually short. 2. Explain why a producer is usually a green plant. 3. Explain the terms ‘omnivore’and ‘herbivore’.

Trophic Levels Trophic levels are the layers in a food web that include organisms that feed on the same type of food. This describes the position that an organism occupies in the food chain. The first trophic level are producers. The second areherbivores, the third contains first carnivores and the fourth contains second carnivores that have fed on first carnivores. There could be a fifth level of carnivores feeding on second carnivores. There is rarely a sixth trophic level because there would be insufficient energy passed on to support it.

Reviewed

Revised

Mastered

To Tert

Herbivores/ Primary consumers Photosynthesis/ Primary producers Soils/ Decomposers 13

The Organism and Its Environment

Section A

Carbon, Water and Nitrogen Cycles Carbon is one of the most important elements for living things. Humans and other organisms use a lot of carbon but we also put a lot back. This highlights the importance of the carbon cycle in the recycling of carbon and its compounds.

Reviewed

Revised

Mastered

The Carbon Cycle

Carbon dioxide in the atmosphere

1

2

Cellular respiration

Test Yourself: Look carefully at the diagrams on the right. Fill in the missing labels.

Food

Fossil fuels

Death and decomposition

The Nitrogen Cycle

The carbon cycle illustrates one of the continual reuses of materials in nature.

Excretion, urine, breathing, sweating

Test Yourself: Explain the role of decomposers in the carbon cycle.

Nitrogen is an essential element in all proteins. Air contains 79% nitrogen that most organisms cannot use.

1 in plant proteins

Ammonia in nitrates and soil

Egestion

Absorption by 2 The Water Cycle

Test Yourself: Explain how nitrogen is transferred from the soil to the atmosphere.

Precipitation

Condensation

Revision Tip: Draw the carbon and nitrogen cycle from memory. Check your drawings against the ones in the text. Then correct yours. Repeat this process until you can draw them from memory.

14

Decay by bacteria

Transpiration 1 Percolation

Run off

Groundwater flow

The Organism and Its Environment

Section A

Test Questions for Section A 1. All living organisms carry out certain activities, which make them different from inanimate objects. Which of the following lists shows three activities of all living organisms?

(a) growth, decay, movement (b) nutrition, movement, synthesis (c) exercise, metabolism, respiration (d) reproduction, growth, irritability 2. Which of the following cell organelles makes proteins for the cell? (a) nucleus (b) ribosome (c) mitochondria (d) cytoplasm 3. This should be found at the beginning of every food chain to show the initial energy: (a) water (b) chlorophyll (c) green plant (d) Sun 4. Food chains show: (a) the position of an organism in the environment (b) dependence of animals on each other (c) feeding relationships between living organisms (d) feeding relationships between animals 5. (a) Label the parts of the cells: 1

(8 marks) 2

3

4

5

6

7

8

(b) State the function of the chloroplast. (c) State the function of the cell membrane.

(2 marks) (2 marks)

15

Life Processes

Section B

Unit

1

Nutrition

Concept Map Deficiency diseases

Temperature

pH

Enzymes

Balanced diet

BMI

Teeth Dietary fibre

Human digestive system

NUTRITION

Major nutrients Absorption, egestion and excretion

Functions of water

Food tests

Self Check

Tick the box that shows how confident you feel

Yes

I can describe the major nutrients and their sources and functions. I can describe the symptoms and treatment of deficiency diseases. I can apply food tests and know the functions of water in the body. I can explain the role of dietary fibre in the body and the causes and effects of constipation and diarrhoea. I can explain the need for a balanced diet. I can describe the structure and function of different teeth and their care. I can identify the site of enzyme production, explain the role of enzymes and the effects of pH and temperature on enzyme activity. I can identify the various structures of the digestive system and explain their functions. I can describe the process of absorption in the alimentary canal and what happens to the products of digestion. I can distinguish between egestion and excretion.

16

Maybe

No

Life Processes

Section B

Major Nutrients and Their Sources

Reviewed

Revised

Mastered

The major nutrients are carbohydrates, proteins, fats, mineral salts, vitamins and water. Proteins are important for repair and growth and enzymes, haemoglobin, hormones and muscles are composed in large part of proteins. Carbohydrates supply much of the energy for the body. The simplest forms of carbohydrates are monosaccharides. These have the formula C6H12O6 and are reducing

Amino acids

sugars. This means they can reduce Benedict’s solution. Monosaccharides can combine to form disaccharides. These are non-reducing sugars. Polysaccharides are made up of very large chains of monosaccharides.

Protein

Carbohydrates

Monosaccharides

(one sugar molecule)

Disaccharides

Food

Polysaccharides

(two sugar molecules)

(ten or more sugar molecules)

Glucose

Sucrose

Starch

Fructose

Lactose

Glycogen

Galactose

Maltose

Cellulose

Grams of protein in 100 g of food

Fresh fruit Full-fat milk Skimmed milk Yoghurt Cereals Eggs Pulses Nuts Fish

0.8 3 4 5 12 12 13 17 18

Semi-cured cheese Meat

22 24

Fats provide energy and insulation. They also form part of cell membranes and a solvent for vitamins A and D. Rich sources of fats include butter, lard, pork and oils.

Remember

Test Yourself:

Proteins, fats and carbohydrates are macro-nutrients. Vitamins and mineral salts are micro-nutrients, as they are needed in such small quantities.

1. Name the monomers found in proteins. 2. Describe TWO uses of fats.

Classify Vitamins as Fat- or Water-Soluble Vitamins are complex organic substances needed in trace amounts to carry out and support vital body functions. They are grouped into water-soluble: those that dissolve in water; and fat-soluble: those that dissolve in fats.

Reviewed

Revised

Mastered

Test Yourself: Complete the table by placing ticks in the correct column. One has been done for you. Vitamin

Water soluble

Fat soluble

A B C D

✔

E K

17

Life Processes

Section B

The Main Functions and Sources of Some Vitamins and Minerals

Reviewed

Revised

Mastered

Vitamins are complicated organic substances. They are needed in small amounts for good health and growth. Mineral salts are simpler inorganic substances. They help the body to function and give strength. Daily requirement

Element C a l ciu m

0 .7 – 2 . 0 g

Deficiency results in

Use in the body f orm a tion of bon e s a n d te e t h ; a s s is ts

I r on

5–15 mg

blood clotting; muscle contraction f or m s h a e m og l ob i n i n r e d b l ood c e l l s

I o di n e

0.1 m g

f o r m s t h yr ox i n e i n t h e t h yr o i d g l a n d

P h o s p h or u s

1.0 g

Vitamin A B

C D E

K

Functions H e a l t h y t e e t h , s k i n a n d e ye s

g o i t re a n d reduced growth

Some good sources m ilk , ch e e se , g re e n vegetables g re e n ve g e ta b l e s , l i v e r, yeast, egg yolk, kidney sea fish, iodised table salt, cheese ch e e se , m e a t, fi s h , eggs, nuts

Sources E g g s , m e a t , m i l k , c h e e s e , d a rk g r e e n l e a f y v e g e t a b l e s , squash, carrots

He lp s body us e fo od en ergy, dige st prot ei ns ,Lean meats, eggs, fish, dairy products, soybeans, yeast, function of central nervous system, broccoli, lean beef, cabbage, whole grains digestion and metabolism *Note there is a variety of B vitamins; this is a summary H e l p s i m m u n e s ys t e m , h e l p s wou n d healing, helps absorption ‘ Su n s h i n e v i t a m i n ’ – h e l p s a b s or b c a l c i u m

Citrus fruits, green peppers, strawberries, tomatoes, broccoli, sweet and white potatoes, cantaloupe Dairy products, fish, oysters, sunshine!

(for healthy bones and teeth) P r o t e c t s b o d y a g a i n s t d a m a g e f ro m f r e e Wheat germ, corn, nuts, seeds, olives, spinach, green radicals, helps form red blood cells (to carry leafy vegetables, vegetable oils (sunflower oil, soybean oil) oxygen) B l o od c l o t t i n g , s t ro n g b on e s

C a b b a g e , c a u l i fl o we r, s p i n a c h , s oyb e a n s

Describe the role of calcium in the body.

2. Describe a source of vitamin A and its functions in the body.

18

a nae mia

f o r m a t i o n o f b o n e s a n d t e e t h ; n e e de d i n ri c k e t s the nucleus and as ATP for energy release

Test Yourself: 1.

ri c k e t s

Life Processes

Section B

Causes, Symptoms and Treatment of Deficiency Diseases

Reviewed

Revised

Mastered

The amount of food we eat depends on: age, gender, amount of exercise and employment. Males commonly require more energy each day than females and construction workers require much more energy than an office worker. Some people decide not to eat animals and prefer a vegetarian diet. These people replace animal protein with proteins from other sources such as pulses, nuts and mushrooms.

Vitamins Vi t a m i n A

Vitamin B 1

Deficiencydisease

P oo r v i s i on , l os s o f v i s i on i n da r k n e s s

B e ribe ri

Vi t a m i n C

Sc u rv y

Vi t a m i n D

Ri ck e ts

Ca lci u m

Symptoms

L os s o f v i s i on

We a k m u s c l e s a n d v e ry l i t t l e e n e r g y t o wo rk Ble eding u m s B o n ea srb ee n t

We a k b on e a n d t oo t h de c a y

We a k b o n e a n d t o ot h de c a y

I odi n e

G oi t r e

Iron

A na e m ia

We a k n e s s

P ro t e i n

K w a s h i o rk o r

G r o w t h s l ow s , s w ol l e n b od y a n d d i a rr h o e a

C a rb o h ydra t e

Ke t os i s

F a ts

P h ry n od e r m a

G l a nin d ne c k

B o dywe a k n e s sa n dl o s sofs t a m i n a H a i r l o s s , b ru i s i n g , c ol d i n t ol e r a n c e , l ow b o d y w e i g h t a n d low growth

Test Yourself: 1.

Name TWO diseases caused by vitamin deficiency.

2. Which TWO food groups are rich sources of energy?

Revision Tip: You can test yourself by looking at food labels and planning a healthy diet. This will help you to remember which food groups there are and which we need. You can also check that you do not eat too much sugar or fat.

Remember Eating too much sugary and fatty food can cause diabetes and obesity. Too much fat can also cause heart disease and high blood pressure (hypertension).

19

Life Processes

Section B

Food Tests

Reviewed

Revised

Mastered

It is possible to carry out some simple chemical tests to identify the different food substances. Testfor…

Description

St a rc h R e d u c i n g s u g a rs Non-reduc ing sug ars

Li p i ds

Result(colourchanges)

A ddaf e wdr op sofi o di n e s o l u t i on

O r a n g e t ob l u e - b l a c k

A dd B e n e di c t ’s s ol u t i o n , h e a t t o 8 0 ° C i n a wa t e r b a t h

B l u e t o o ra n g e - r e d

(If redu cing su gar test i s negat ive) bo il with hydrochlor Initially ic no change, repeated acid, cool and neutralise with sodium carbonate solution, Benedict’s test will turn blue to repeat Benedict’s test orange-red Add e th a no l , p ou r m i xt ur e i nt o wat e r i n a no th e r t es t t ub e

P ro t e i n s

W hi te em ul s ion f orms in wat er

A ddb i u re tre a g e n t

P a l eb l u et ol i l a c

Most lipids are insoluble because they have a long hydrocarbon chain. Proteins are soluble because of OH groups and other groups and charges.

Test Yourself:

Many carbohydrates are soluble because of the presence of OH groups, but solubility decreases with size. This is why starch is insoluble but glucose and sucrose are soluble.

2.

Functions of Water in the Body Approximately two thirds of the human body is composed of water. Water is an essential component of life. The chemical reactions in the body take place between substances dissolved in water. We also use water for cleaning and cooking.

Test Yourself: Why is the property of water as a solvent so important to life?

Regulates body temperature

Name the reagent you would use to distinguish between a reducing sugar and a non-reducing sugar. What colour does iodine form when mixed with starch?

Reviewed

Revised

Mastered

Moistens tissues such as those in the mouth, eyes and nose

Lubricates joints Protects body organs and tissues Helps prevent constipation Helps dissolve minerals and other nutrients to make them accessible to the body

20

1.

Lessens the burden on the kidneys and liver by flushing out waste products Carries nutrients and oxygen to cells

Life Processes

Section B

The Role of Dietary Fibre in the Body To prevent constipation

To cleanse the digestive system Why should we eat more fibre?

To prevent colon cancers

Eating foods high in fibre will help you feel fuller for longer

Reviewed

Revised

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The undigested fibre Remember stimulates the muscular Dietary fibre is also called roughage and it is not digested walls of the intestines to by the body. contract in waves to push the food through. This is called peristalsis. This movement of food is vital because if food stays in the large intestine for too long it can cause medical problems such as colon cancer. The cellulose in plant cells and tissues makes good fibre, as humans cannot digest it. Sources of this vegetable fibre are vegetables, fruit, nuts, wholegrain rice and bran.

Test Yourself:

1. Describe TWO functions of fibre in the diet. 2. Explain why easy-to-digest foods can cause constipation.

Causes and Effects of Constipation and Diarrhoea

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Mastered

As you have seen, lack of fibre can cause constipation. Other causes include: not drinking enough water eating too much sugary food Remember lack of exercise depression It is vital to practise proper hygiene when preparing and eating food. intestinal bacteria out of laxative abuse Microorganisms can pass from an infected balance taking too many calcium and person to the food and then on to another person. eating too much dairy magnesium supplements some medicines blocked intestines. ■

■

■

■

■

■

■

■

■

■

Diarrhoea is the continual passage of faeces. The faeces is often very liquid. Causes include diseases such as dysentery, typhoid, cholera and different forms of food poisoning. Health risks are caused by dehydration and so water and salts have to be given in serious cases.

Test Yourself:

1. Describe TWO causes of constipation. 2. How does proper food hygiene reduce the chances of diarrhoea?

Clean

Personal Hygiene

Kitchen

Wash hands in warm, soapy water. 20-second scrub.

Clean and sanitise all surfaces and utensils in hot, sudsy water.

Wash before and after preparing food in the kitchen.

Change dish towels often.

Cover coughs and sneezes.

Dispose of garbage promptly. 21

Life Processes

Section B

Explain What Is Meant by a Balanced Diet

Reviewed

Revised

Mastered

The six food groups in the Caribbean are: staples, legumes, food from animals, fruits, vegetables, and oils and fats. A balanced diet includes foods from each of these food groups. The foods provide the essential nutrients the body needs.

Test Yourself:

1. Name THREE food groups. 2. Explain the importance of vitamins. 3. Describe the importance of proteins in a healthy diet.

Typeofnutrient

Foodsources

C a r b oh ydr a t e Fat

Functions

C e r e a l s , s we e t e n e r s , r o ot c r o p s , p u l s e s , vegetables, fruit, dairy products

Fuel, energy storage, cell membrane, DNA, RNA

M e a t , m i l k , da i ry p ro du ct s, e g g s , fi s h o i l , vegetable seeds, nuts, vegetable oil

P r ot e i n

M e a t , fi s h , m i l k , d a i ry p r od u c t s , e g g s , p u l s e s , cereals

Fuel, energy storage, cell membrane, hormones Structure, transport, communication, enzymes, protection, fuel

Wa t e r

B e v e r a g e s , f ru i t s , v e g e t a b l e s

M e di u m f or b i o c h e m i c a l r e a c t i on s , transport, thermoregulation, excretion, lubrication

Vi t a m i n s

F ru i t s , v e g e t a b l e s , f a t t y fi s h

E n e rg y r e l e a s e f r o m m a c ro n u t r i e n t s , metabolism, bone health, blood health, immune function, eyesight

Minerals and trace Meat, fish, milk, dairy products, salt, cereals, Mineralisation of bones and teeth, blood elements fruits, vegetables, water oxygen transport, energy metabolism, muscle function, maintenance of acid–base balance and cellular fluid balance

Effects of Malnutrition on the Human Body

Reviewed

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Malnutrition is caused by a lack of balance in the diet. This can be through not having enough food or eating too much. Overeating animal fats can cause a blocking of arteries. This condition is known as atherosclerosis. This in turn can cause hypertension or high blood pressure. Diabetes is also linked to obesity and excess fat can produce bone and joint problems.

Remember

Low mood

Weight loss

Low energy

Reduced mobility Increased risk of falls

Muscle wasting Impact of malnutrition

Reduced independence

Increased risk of fractures Increased risk of hospital admissions

Infections

Confusion

Bulimia is a condition where

many vitamin and mineral people cannot stop themselves deficiency diseases. from consuming too much food. This addiction to food causes obesity.

Test Yourself:

1. Define ‘malnutrition’. 2. How can eating too much animal fat cause health problems?

22

Starvation is one form of malnutrition. So are the

Life Processes

Section B

Determining BMI =

BMI

Reviewed

Revised

Mastered

(weight in kilograms) (height in metres2 )

For example, if a 16-year-old person is 1.7 metres tall and their weight is 60 kilograms then their BMI would be: BMI =

60 (1.7 × 1.7)

=

60 2.89

Remember = 20.76

BMI stands for

body mass index.

This is then located on an age/BMI chart to determine whether this is a healthy BMI or not. 95th

Test Yourself:

ese Ob

A

I 22 M B 20

18 16 14 12 10

r k fo t ris

ese g ob bein

al N o rm e rang

1.

85th P e r

50th cne t il e

5th

2.

Use the chart to determine whether or not the person in the example is in the overweight, underweight or normal range. Calculate the BMI for a 15-year-old person who weighs 70 kilograms and is 1.5 metres tall. Which range does this person fall into?

2 3 4 5 6 7 8 9 10 1 1 12 13 14 15 16 17 18 19 20 Age (yrs)

Using Tables, Charts and Graphs to Represent Nutrition Data Serving Size 1/4 Cup (113 g) Nutritional data can be presented in many different ways. The key is to remember the major ideas: Different nutrients are used in the body for different functions We need a balance of these nutrients Too little of any nutrient can cause a ■

■

■

deficiency disease or even starvation ■

Too much food can result in obesity, diabetes, atherosclerosis and hypertension.

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Mastered

Nutrition Facts

Nutrition Facts

Serving Per Container 8

Serving Size 1 Cup (228 g) Serving Per Container 2

Amount per Serving Calories 100 Calories from Fat 20

Amount per Serving Calories 250 Calories from Fat 120

Total Fat 2 g Saturated Fat 1.5 g Trans Fat 0 g Cholesterol 10 mg Sodium 460 g Total Carbohydrate 4 g Dietary fibre 0 g

Total Fat 13 g Saturated Fat 5 g Trans Fat 2 g Cholesterol 30 mg Sodium 680 g Total Carbohydrate 31 g Dietary fibre 0 g

3% 7% 3% 19% 1% 0%

Sugars164gg Protein Vitamin A 0% Calcium 8%

20% 25% 10% 28% 10% 0%

Sugars5 5g g Protein Vitamin C 0% Iron 0%

* Percent Daily Values are based on a 2,000 calorie diet.

Test Yourself:

Revised

1. Which food label indicates the highest fat level? 2. Which food label shows a food that would be useful for muscle development? 3. Name any vitamins not included in either food.

Vitamin A 4% Calcium 15%

Vitamin C 2% Iron 4%

* Percent Daily Values are based on a 2,000 calorie diet. Your Daily Values may be higher or lower depending on your calorie needs Calories 2,000 2,500 Total Fat Less than 40 g 40 g Sat fat Less than 20 g 25 g Cholesterol Less than 200 mg 200 g Sodium Less than 2,400 mg 2400 mg Total Carbohydrate 350 g 375 g Dietary fibre 25 g 30 g

23

Life Processes

Section B

Types of Infant and Adult Teeth and Their Roles Incisors

Canine

Babies are born without teeth. The teeth develop over the first few years withthe incisors first, then canines and finally the molars.

Reviewed

Revised

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Primary Lower

Upper

Molars

At about age seven the baby teeth start to fall out and be replaced by permanent adult teeth. This starts with the incisors and then the canines and finally the molars. Most people have all of their adult teeth by the age of 21. Notice that there are more adult teeth.

Permanent Lower

Test Yourself:

1. Name the types of teeth found in baby and adult humans. 2. What happens to baby teeth after a person reaches about seven years old?

Importance of Teeth in Digestion

Reviewed

Upper

Remember Baby teeth and adult teeth are still shaped to carry out specific functions.

Revised

Mastered

Teeth play a vital role in the mechanical breakdown of food.

Remember The teeth cut, tear and grind up the food. This helps digestion in three ways: Chewing of food is called mastication. The food is formed into smaller pieces to make them easier to swallow The food is mixed in with saliva and this contains enzymes such as amylase to start the chemical digestive processes The surface area of the food is increased, so that later enzyme action will be more efficient. ■

■

■

Teeth have to be smooth and very hard to help them to perform their role.

Test Yourself: 1.

Describe how teeth are adapted to carry out their function.

2. Explain why chewing is so important for digestion.

24

Life Processes

Section B

Structure and Function of a Typical Tooth

Reviewed

Revised

Mastered

As you have seen, teeth are hard and smooth to help them to carry out their function. Their detailed structure is shown below.

Test Yourself: 1.

Complete the diagram of the tooth by labelling the main features. Use information from the table to help you.

En a m e l

De ntine Pulp cavity

1

Tooth anatomy

Tooth structure

Components

Function

N on - l i v i n g l a ye r of hard calcium salts

2

Protects dentine Forms a hard biting surface

So f t e r b on e - l i k e l a ye r

n w o r C

A c t s a s a s h oc k a b s or b e r

Contains tooth cells, Tooth cells divide to form dentine nerves and blood Supply food and oxygen to cells capillaries

C e m ent

T h i n l a ye r o f b on e like material

Root opening

Pathway for blood capillaries and nerves

Covers dentine of root Holds root in socket

3 Gums

Gums

Bone

Bone

Dentin

4

t o o R

Nerves and blood vessels

For blood supply, growth and replacement of tooth Nerves carry messages to and from brain

5

2. Explain the functions of enamel and dentine.

Relating Tooth Structure to Function Masticationis the process of chewing food to break it down into smaller pieces. This makes it easier to swallow and increases surface area to speed up digestion.

Reviewed

Revised

Mastered

Test Yourself:

1. Explain how molars are well adapted to their function. 2. Why do carnivores have large canine teeth?

Test Yourself: 1.

Label the diagram using the words listed below:

canine

incisors

pre-molar

molar

the table below to show the role of each type 2. Complete of tooth in digestion. Notice how the shape of each type of tooth makes it well designed for its function. Typ e s

F u nc tion Used to cut off food Used to rip and tear food Used to grind and chew food Used to crush and chew food

25

Life Processes

Section B

The Causes of Tooth Decay

Reviewed

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Tooth decay is caused by the production of acids by bacteria living in the plaque Remember of the mouth. The acid reacts with the enamel and holes are formed. The bacteria Plaque is a sticky substance containing bacteria. These break ferment sugars and so sugary food is a major cause tooth of decay. down sugar in your food and Some drinks are acidic. Look at what happens to teeth when they are left in soda.

produce acid. This acid makes holes in your teeth.

Time spent in soda

Test Yourself: 1. Which types of food and drinks should you 0hr

1hr

2days

3 days

4 days

5 days

Soda is dangerous to human teeth.

avoid to reduce tooth decay?

2. What is plaque and why is it harmful?

The Process of Tooth Decay

Reviewed

The acid produced by bacteria attacks teeth in a series of stages shown in the diagram opposite.

Bacteria ferment sugars in food to make an acid Acid erodes enamel and dentine Tartar or plaque Cavity accumulates food

Food accumulates in space Bleeding and inflamed gums

It is important to keep teeth clean. Regular brushing and a low sugar diet will stop plaque and cavities. You should eat hard, crispy foods and foods containing calcium, phosphorus and vitamins C and D. Every six months a dentist should check your teeth. Some areas add fluoride to of fibrous the water supply and this can help to prevent tooth decay. Fibres membrane destroyed

Test Yourself: Why is it important to clean teeth regularly?

up one reaction with one food. Enzymes hold the substrate in such a way that less energy is needed to break bonds.

Test Yourself:

Active site

Enzyme changes shape slightly as substrate binds

Revised

Mastered Products

Substrate entering Enzyme/substrate Enzyme/products Products leaving active site of complex complex active site of enzyme enzyme

1. Explain how enzymes help in the breakdown of substrates. 2. Are enzymes used up during this process?

26

Abscess may form Stimulated nerve ending induces severe toothache

Reviewed Substrate

Mastered

Bacteria enter bloodstream Tooth eventually dies

Tooth loosened

Role of Enzymes Enzymes are biological catalysts. They speed up the chemical reactions involved in breaking down food. Each enzyme is specific – it will only speed

Revised

Remember Digestion is a mixture of physical processes such as chewing and churning and chemical processes such as enzyme action.

Life Processes

Section B

The Production of Enzymes Enzyme

Produced in

Reviewed

Site of release

Revised

Mastered

pH level

Carbohydrate digestion: Sa l iva ry a m yla se

S a l i v a ry g l a n d s

P a n c re a t i c a m yl a s e

P a n c re a s

Ma lt a s e

Sm a ll i n te sti n e

M ou t h

Ne u t ra l

Sm a l l i n t e s t i n e

B a si c

Sm a l l i n t e s t i n e

B a si c

Remember

Protein digestion: P e p si n

G a s t r i cg l a n d s

St o m a ch

A c i di c

Try p s i n

P a n c re a s

Sm a l l i n t e s t i n e

B a si c

P e p t i da s e s

Sm a l l i n t e st i n e

Sm a l l i n t e s t i n e

Enzymes are biological catalysts. Digestive enzymes are produced at the most appropriate places in the digestive system.

Ba si c

Nucleic acid digestion: Nu c l e a se

P a n c re a s

Sm a l l i n t e s t i n e

B a si c

Nu c l e os i da s e s

P a n c re a s

Sm a l l i n t e s t i n e

B a si c

Fat digestion: Li p a s e

P a n c re a s

Sm a l li n t e s t i n e

Basic

Test Yourself:

1. Describe TWO enzymes that help to digest carbohydrates and name their site of production. 2. Which protease is produced in the pancreas?

Reviewed

Effects of pH and Temperature on Enzymes Different enzymes work best at different pH levels. This is related to where in the alimentary canal they are found. Enzymes found in the stomach have an optimal pH of 2 Enzymes found in the small intestine have an optimal pH of 7.5. ■

Salivary amylase y it v tic a e m y z n E

Pepsin

Arginase

56 7 891 0 pH

Mastered

y it itv c a

0

■

1 234 Acidic

e m y z n e g n si ea cr n I

Revised

Optimum temperature 10 20 30 40 50 60 7 0 Temperature (°C)

11 12 Basic

As temperature increases, so does the rate of enzyme action.

Remember

Optimum temperature is often body temperature (37°C).

At very high temperatures the protein will be denatured and the rate will drop to zero.

Test Yourself:

1. Describe the effect of temperature on the rate of enzyme activity. 2. Explain why the enzyme pepsin has an optimal pH of 2.

27

Life Processes

Section B

The Digestive System Digestion

Physical

Chemical

Reviewed

Revised

Mastered

Humans digest or break down their food by a combination of physical and chemical digestion. Each part of the digestive system is adapted to carry out different functions. This can be to mix foods, add enzymes, move the food along, absorb nutrients or excrete waste. Structure of alimentary canal

Alters the size and shape of foods so they can pass through the digestive system, e.g. teeth and stomach

Enzymes break down complex foods to simple molecules, e.g. starch maltose glucose

Test Yourself: 1.

2. 3.

Describe the functions of amylase and lipase. Name the substrate and products in each case. Explain the functions of the stomach. Describe the processes taking place inthe small intestine.

Mouth

Salivary glands

Oesophagus

Liver Gall bladder Pancreas Small intestine

Stomach Large intestine Rectum

Appendix

Anus

Reviewed

Revised

Mastered

The Process ofthrough Digestion : this means taken the wall of the small intestine. Folds called Absorption villi increase the surface area of the wall. Movement is through diffusion. This is the movement of a substance from an area of high concentration to an area of low concentration. The concentration Remember of nutrients in the small intestine is higher than in the blood and so the The shape of the villi increases nutrients pass through the lining and into the bloodstream. surface area so more absorption can take place.

Test Yourself: 1.

Structure of the villi

Small intestine

How does the shape of the villi help to increase absorption?

Villus

2. Explain how diffusion drives absorption.

Epithelial cells

Circular folds

Capillaries Villi

Lacteal

Vein Artery 28

Life Processes

Section B

Describe What Happens to the Products of Digestion

Reviewed

Revised

Mastered

Assimilation is the process of making use of the products of digestion that have been absorbed. These can either be stored or broken down for energy or used in repair and growth. Glucose is taken to the liver. There it is either: stored in the liver as glycogen sent to the body for energy stored under the skin and around organs as fat. ■

■

■

The hormone insulin, produced in the pancreas, controls the balance between glycogen and glucose. The liver detects insulin and more glucose is removed and stored as glycogen. This lowers blood sugar levels. If blood sugar levels are too low then the pancreas secretes glucagon. The liver detects the glucagon and glycogen is broken down to glucose. Blood sugar levels rise. The liver has many other important functions.

Test Yourself: 1.

Explain what happens if blood sugar levels are too high.

What is the function of the liver?

Blood-clotting Immunity to infections

Excretion of drugs, chemical substances and alcohol from the blood

Storage of excessive glucose in the form of glycogen

Synthesis of proteins and cholesterol Excretion of wastes in the bile juice

Excretion of bile juice for lipid digestion

2. Describe the role of glucagon.

Distinguishing Between Egestion and Excretion ■

■

Reviewed

Revised

Mastered

Excretion is the removal of materials from inside the body. Egestion is the removal of undigested foods that have not been absorbed by the body.

If materials consumed are not digested then they pass through the alimentary canal relatively unchanged. Some substances that are broken down in the body are passed out via the alimentary canal. An example is bilirubin. Bilirubin is formed when red blood cells are broken down. It is a yellow colour. In the faeces this turns to a brown colour – giving faeces its characteristic colour.

Test Yourself: 1.

Explain the difference between egestion and excretion.

Remember

2. Why is bilirubin in faeces an example of excretion?

The elimination of faeces through the anus is egestion – not excretion.

29

Life Processes

Section B

Unit

2

The Respiratory System

Concept Map Mechanism of breathing

Vital capacity

Structure and function

Respiratory tract

Smoking

Mouth-to-mouth resuscitation

RESPIRATORY SYSTEM

Anaerobic and aerobic respiration Equation for respiration

Role of ADP and ATP

Self Check

Tick the box that shows how confident you feel I can explain the importance of breathing in humans. I can describe the structure and function of the respiratory tract. I can explain the mechanism of breathing and factors that impact on breathing rate. I can explain vital capacity. I can distinguish between aerobic and anaerobic respiration. I can define the roles of ADP and ATP. I can explain the technique of mouth-tomouth resuscitation. I can explain the effects of smoking and interpret smoking data.

30

Yes

Maybe

No

Life Processes

Section B

Breathing in Humans

Reviewed

Respiration is the process of obtaining energy by the chemical breakdown of food molecules such as glucose in cells. Respiration takes place mainly in the mitochondria of cells. Glucose The process requires oxygen. This oxygen enters the body through the lungs in the process of breathing. C6H12O6 The main function of the respiratory system is to bring oxygen to the body and allow carbon dioxide to leave. The respiratory system has: exit and entry points to the atmosphere through the mouth, nose and trachea a cleaning system with tiny hairs or cilia a large surface area with alveoli in the lungs a thin permeable respiratory surface in the alveoli a rich blood supply from capillaries around the alveoli a breathing system involving the ribs, intercostal muscles and diaphragm. ■

Revised

Mastered

Energy stored in chemicals Oxygen

Carbon dioxide

Water

6O6

6CO6

6H2O

Test Yourself: Label the trachea, bronchiole and diaphragm on the diagram.

■

■

■

Alveoli

■

■

Right bronchus Heart

Test Yourself:

Ribs

1. Explain the role of alveoli in the lungs. 2. Why are cilia so important?

Intercostal muscles

Mechanism of Breathing Breathing is a mechanical process that allows air to be taken into the body so that gases can be exchanged.

Test Yourself: Does diagram A show inhalation or exhalation? Explain.

A

Y tube

B Chest expands Sternum Ribs Lung Diaphragm contracts

Reviewed

Chest contracts

Diaphragm relaxes

Revised

Mastered

(trachea and bronchi) Bell jar (chest cavity) Balloon (lung)

Volume decreases, pressure increases

Sheath (diaphragm) Volume increases, pressure decreases

Notice that when the diaphragm moves downwards the intercostal muscles move the rib cage upwards and out. This decreases the internal air pressure and so air from the outside moves into the lungs. The opposite happens during breathing out. There is still 16% oxygen in exhaled air. That is why CPR can be effective. Also, it is thought that the carbon dioxide being blown into a person’s lungs can trigger breathing.

Gases O x yg e n C a r b ondi o x i de Ni t r og e n

% composition in inhaled air 21 0.04 78

% composition in exhaled air 16 4 78

N ob l e g a s e s

A p p r ox i m a t e l y 1

A p p ro x i m a t e l y 1

Wa t e r v a p ou r

Sm a l l a m ou n t

La rg e r a m ou nt

31

Life Processes

Section B

Factors Affecting Rate of Breathing

Reviewed

Revised

Mastered

The medulla region of the brain automatically controls breathing rate. When the carbon dioxide concentration level in the blood increases, such as during exercise, this triggers chemoreceptors in the aorta and carotid arteries and a message is sent to the medulla. This then causes the breathing to become deeper and then faster to attempt to provide sufficient oxygen and reduce the build-up of carbon dioxide. Activity

Reason for increase

E x e rc i s e

B e c a u s e c a rb on d i o x i d e a n d l a c t i c a c i d a c c u m u l a t e i n t h e b l oo d

We i g h t Anxie ty

B e c a u s e m o r e w o rk h a s t o b e d on e w i t h a l a rg e r b od y A dr e n a l i n e r e l e a s e d i n c r e a s e s t h e m e t a b ol i c r a t e

D ru g s

St i m u l a n t si n c r e a s et h em e t a b ol i cra t e

Env ironme nta l factors

Poor vent ila tion a ccu mul ate s carb on dioxi de in ins pired air; a ir pollu tion by cars increases carbon dioxide in inspired air

C om b u s t i on

A l l f o rm s i n c r e a s e i n s p i r e d c a r b o n d i o x i d e

Al ti tu de

Th e low pres su re af fe ct s br ea th in g a nd mu sc le s work ha rder to comp en sa te ; th e la ck of oxygen above 3000 m causes carbon dioxide to accumulate in the blood

Smoki ng

C ar b on mono xi de i s conv erte d to ca rb on di ox i de a nd i ns p i re d; ca us es sh ort ne s s of breath; particles constrict bronchioles and induce wheezing

Il ln e ss

e .g . a s t h m a c a u s e s w h e e z i n g a s b r o n c h i ol e s c o n s t ri c t

Test Yourself:

1. Which part of the brain automatically controls breathing? 2. How is an increase in carbon dioxide concentration in the blood detected?

Remember Breathing is the mechanism through which oxygen enters the body and carbon dioxide is removed.

The Concept of Vital CapacityReviewed

Revised

Mastered

Vital capacity is the largest volume of air breathed out after fully breathing in. This can vary greatly depending on body size and fitness levels. Plastic or rubber tubing

Plastic container

Inspiratory reserve volume (IRV)

Vital capacity (VC) Tidal volume (TV)

Air pushes water out

Expiratory reserve volume (ERV)

Tank of water

Residual volume (RV)

Remember The inspiratory and expiratory reserve volumes are the additional volumes of air that can be breathed in or out above normal values.

32

Test Yourself:

1. Explain what tidal volume is. 2. Describe what residual air is.

Life Processes

Section B

Reviewed Revised Distinguishing Between Gaseous Exchange and Breathing The process of breathing is the taking of air into the lungs and expelling it out. During breathing in, the air pressure inside the chest cavity is reduced so that air at higher pressure in the atmosphere will enter. During breathing out, the air pressure inside the chest cavity is increased and so air is expelled into the atmosphere.

Gaseous exchange is NOT the same

Breathing in

Mastered

Breathing out

Chest contracts

Chest expands Ribs

Lung

Diaphragm Diaphragm contracts

as breathing. With gaseous exchange, the gases actually move across the respiratory surface and into or out of the blood.

Diaphragm relaxes

Test Yourself:

1. Explain how altering air pressure inside the chest cavity allows inhalation and exhalation. 2. Is oxygen passing through the alveoli to the blood anexample of breathing or gaseous exchange?

Gaseous Exchange Surfaces

Reviewed

Revised

Mastered

Gaseous exchange takes place by diffusion through surfaces. The larger the surface area, the greater will be the rate of diffusion. Also, exchange surfaces are thin, moist, and have a good Air in and out transport system (blood vessels or xylem) nearby. Blood out

Blood in Bronchiole

Capillary

Alveoli O2

CO2

Inside the lungs are very small air sacs called alveoli. These increase the surface area inside the lungs. The alveoli are covered with a network of small blood vessels. This allows air in the lungs to be brought close to the blood supply.

Remember Gas exchange by diffusion in lungs

Blood capillaries

Air space (alveolus)

Test Yourself:

Blood = low concentration of oxygen and high concentration of carbon dioxide; Air = higher concentration of oxygen and lower concentration of carbon dioxide; Diffusion = the movement of gases from a region of high concentration to a region of lower concentration.

1. How does diffusion help oxygen to move from the lungs to the blood? 2. How does diffusion help carbon dioxide to move from the blood to the lungs? 3. Use your knowledge of gaseous exchange to explain the structure of gills. 33

Life Processes

Section B

Aerobic and Anaerobic Respiration

Reviewed

Revised

Mastered

The respiration described above is called aerobic respiration. It needs a supply of oxygen. Glucose is broken down completely to carbon dioxide and water. If oxygen is not present then a form of respiration can still take place. This is anaerobic respiration.

Remember

Some microorganisms such as yeast can use anaerobic respiration. The glucose is not broken down fully so less energy is produced. During exercise, muscles may not get enough oxygen. They use anaerobic respiration

Anaerobic simply means ‘without air’.

to get some energy but lactic acid is made as a by-product. This causes cramp.

Test Yourself: 1.

Complete the table: Anaerobic respiration Glucose breakdown

Anaerobic respiration Aerobic respiration

Not complete

O x yg e n

Yeast

Energy

Glucose

Ethanol

Carbon dioxide

Ne e de d

E n e rg y r e l e a s e d

Sm a ll a m ou nts

En d p rodu ct s

An im al s = l ac ti c a ci d

Muscle

Plants = carbon dioxide and ethanol

Energy

Glucose

Lactic acid

2. Describe how anaerobic respiration can slow down athletes. 3. Explain how anaerobic respiration is important in brewing and baking. 4. Why is less energy obtained in anaerobic respiration than in aerobic?

Roles of ADP and ATP in Energy Transfer Adenosine diphosphate is a vitally important chemical. It can be changed to adenosine triphosphate by the addition of another phosphate group, and this requires energy. The phosphate group of ATP can be given up to reform ADP, and this makes the energy available for chemical reactions in cells where and when it is needed. You have seen how this takes place during respiration.

Reviewed

Revised ATP

P–

Adenine Adenosine

Adenine

Triphosphate

2. 34

P–

P–

Ribose

Adenosine

Diphosphate ADP

36 ADP + 36Pi

Test Yourself: What are the two requirements for converting ADP to ATP? What is the importance of the ADP=ATP cycle to living things?

P–

Energy

ATP is adenosine triphosphate.

1.

P–

Ribose

P–

Notice that each molecule of glucose can produce 36 molecules of ATP Remember during aerobic respiration. ADP is adenosine diphosphate and

Mastered

C6H12O6 +

6O2

Glucose + Oxygen

36 ATP 6CO2

+ 6H2O

Carbon dioxide + Water

Life Processes

Section B

Mouth-to-Mouth Resuscitation

Reviewed

Revised

Mastered

Revised

Mastered

The principle of mouth-to-mouth resuscitation depends on two factors: Exhaled air still contains 16% oxygen Adding carbon dioxide to another person’s lungs could trigger breathing. ■

■

1

1

2

3

2

3

Test Yourself:

1. Explain why step 1 is so important in mouth-to-mouth resuscitation. 2. What is the person doing in step 3 and why?

The Effects of Smoking Cigarettes contain over 4000 chemicals that might damage health. Three major ones are: tar

Reviewed

Chemical

Description

Ta r

O i l yb l a c k substance

■

■

nicotine

■

carbon monoxide.

These are drawn deep inside the lungs.

Ni c ot i n e

Carbon monoxide

Health impact Damages alveoli and cilia. Makes it difficult to breathe and gas exchange is reduced.

A ddi ct i v e Increases heart rate and blood colourless liquid pressure. May cause strokes that turns brown and heart attacks. Colourless and odourless gas

Bonds with haemoglobin in red blood cells. Causes breathlessness.

Being in smoky environments can also cause health problems – even if you are not smoking yourself. This is called second-hand smoking. That is why it is important to have smoke-free areas. Marijuana smoking and addiction can also damage health. It can cause acute chest illness and obstruction of airways. People using marijuana can also have problems with memory, coordination, increased heart rate, confusion and panic attacks.

Test Yourself:

1. Describe the health problems caused by cigarette tar. 2. What health problems can be caused by second-hand smoking? 3. How is smoking marijuana harmful to health? 35

Life Processes

Section B

Interpreting Smoking Data: Worldwide and Caribbean Test Yourself: 1.

2. 3. 4.

Reviewed

Revised

Males

Which country on the graph had the highest lung cancer mortality (death rate) in 1950? Which country on the graph had the highest lung cancer mortality (death rate) in 2006? How do the death rates for women compare with those for men in each country? Describe the trends in smoking deaths for each country.

Mastered

Females

90 80 70 0 0 60 0 , 0 50 0 1

90 80 70 0 0 60 0 , 0 50 0 1

r e p e t a R

r e p e t a R

40 30 20 10 0

5 5 5 5 5 50 5 60 6 70 7 80 8 90 9 00 06 19 19 19 19 19 19 19 19 19 19 20 20

United States Spain Japan Finland United Kingdom Hungary China (rural areas)

40 30 20 10 0

5 5 5 5 5 50 5 60 6 70 7 80 8 90 9 00 06 19 19 19 19 19 19 19 19 19 19 20 20

Year of death

Year of death

Source: WHO Mortality Database

Using Data and Charts to Represent Data on the Respiratory System

Reviewed

Revised

Mastered

Average number of Country A n t i g uaanBda r b u da

% of male deaths due to tobacco 1 .8

% of female deaths due to tobacco 3 .1

cigarettes smoked per person each year 375

B a r b a dos

4 .1

0 .1

D om i n i c a

8 .6

13.2

339

G re n a da

10.5

4 .8

229

Ja m a ic a L uScti a SV t i n c e nat n d t he G re n a di n e s Tr i n i d aadnTdob a g o

1 2 .5 3.9 9.5 9.7

344

5 .5 2 .5 8 .2 1 .4

283 249 351 11 06

Other countries in the world have much worse smoking figures. The highest average number of cigarettes smoked per person is in Serbia (2861), followed by Ukraine (2401) and Montenegro (2157).

Test Yourself: Which Caribbean country listed in the table has the highest average consumption of cigarettes

1. per person? 2. Which has the lowest? 3. How do the Caribbean countries compare with Serbia, Ukraine and Montenegro?

Revision Tip: To remember a diagram, try drawing it without looking at your notes or the book. Then look back in your notes and check what you have missed. Close your notes and try drawing the diagram again. This way you are revising the bits you don’t know, so it is more efficient. 36

Life Processes

Section B

Unit

3

The Circulatory System

Concept Map Clotting

Examples of materials

Bloodcells Composition and function

Need for a transport system

Blood

Lymphatic system

CIRCULATORY SYSTEM

Structure of circulatory system

Heart Double pump

Arteries, veins and capillaries

Blood pressure

Heart attacks

Self Check

Tick the box that shows how confident you feel

Yes

Maybe

No

I can explain the need for a transport system in humans and identify materials that need to be transported. I can relate the structures of the heart to their function. I can explain the concept of blood pressure. I can describe the structure and function of the circulatory system. I can relate the components of blood to their functions. I can relate the structure of arteries, veins and capillaries, and the structures of blood cells, to their functions. I can describe the process and importance of clotting. I can describe the causes and effect of heart attacks. I can use tables, charts and graphs to represent data on the circulatory system. I can describe the structure and function of the lymphatic system.

37

Life Processes

Section B

Need for Transport Systems in the Human Body

Reviewed

Centre a long way from outer surface

In multicellular organisms many of the cells will not be near the surface. Materials have to be transported around the organism. This allows vital materials to reach every cell in the organism.

Test Yourself: 1.

2.

Why do multicellular organisms need a transport system? Why is surface area to volume important in cells?

Test Yourself: Complete

Unicellular organisms have a limit to their size. If they grow too big the inside of the cell becomes too far from the surface to exchange materials.

Centre can be reached by materials Length of side = 3 Surface area = 3 2 x 6 = 54 Volume = 33 = 27

Length of sides = 2 Surface area = 22 x 6 = 24 Volume = 23 = 8

Length of sides = 1 Surface area = 12 x 6 = 6 Volume = 13 = 1

Surface/volume = 2

Surface/volume = 3

Surface/volume = 6

Materials That Need to Be Transported The substances that need to be transported in animals are shown in the table here.

Substance to be transported d i s s ol v e d f oo d

Reviewed

Transported from i l e u m w h e re i t i s a b s o rb e d

n i t r og e n ou sw a s t e

Revised

Mastered

Transported to c e l l s of t h e b ody – t o b e used for respiration, stored, converted to other materials, etc.

c e l l sw h e r e p r o d u c e d to be excreted

the table using these words:

carbon dioxide oxygen endocrine glands lungs kidneys

Mastered

Remember

Unicellular organisms can exchange materials with their environment. Each cell has a large surface area compared to its volume.

Revised

body cells to be used for respiration where it diffuses into the blood body cells where it is produced in respiration h or m on e s

lungs to be excreted organs where their effects are needed

where they are produced white blood cells marrow of bones where they where there are including antibodies are produced infections or invasions by microorganisms

In plants water must be transported from the soil to the leaves. The plant also needs dissolved minerals to be transported. Manufactured food is transported away from the leaves to be used and stored.

38

Test Yourself: 1.

2.

List THREE substances that must be transported in multicellular animals. Describe why plants need to transport water from the roots to the leaves.

Life Processes

Section B

Relating the Structures of the Heart to their Function

Reviewed

Revised

Mastered

The different parts of the heart have distinct functions and they are adapted to carry ret ur ns deo x yg e na te d b l ood f rom b ody t o these out efficiently.

Structure

Function

h e a rt

p u m p s b l oo d t o l u n g s a n d a l l b od y p a rt s

v en a c av a

right atrium ri gh t a tr iu m

re ce iv es de ox yg en at ed bl ood a nd pu mp s it to right ventricle

rig h t ve n tric l e pulmonary artery

carries deoxygenated blood to lungs

pulmonary vein

returns oxygenated blood from lungs

l ef t a tr iu m

Notice that atria always receive blood.

p u m p s b l o od t o l u n g s

re ce i ve s o xyge na te d b lood a nd p um p s i t to left ventricle

le f t ve n tric l e

p u m p s b l o od a ro u n d t h e b o d y

a or t a

c a r r i e s ox y g e n a t e d b l o od f r om h e a rt

c a rdi a c m u s c l e

The ventricles always send blood out of the heart. The right ventricle pumps blood to the lungs and the left ventricle pumps blood through the aorta to the body.

c o n t ra c t s w i t h ou t f a t i g u e

tr ic us p id va lv e

Test Yourself:

p re ve nt ba ck flow of b l ood i nt o a tr i a

1.

bicuspid valve v a l v et e n do n s

s u p p o rt v a l v e s

sem ilu nar val ves

Why are heart valves so important?

pre ven t ba ckfl ow of bl ood into ve ntr icl es

Remember

2. Where do the ventricles pump blood?

The main function of the heart is to pump blood around the body but it must separate oxygenated and deoxygenated blood.

The Structure and Function of the Heart: Double Pump

Reviewed

Revised

Mastered

The heart acts as a double pump. This means it has one pump that sends oxygen poor blood to the lungs to pick up oxygen and get rid of carbon dioxide and a second pump which delivers oxygenated blood to the rest of the body. How the heart pumps blood

Test Yourself: 1.

Name the FOUR chambers of the heart.

The heart is divided into 2 parts. Each part is a pump, so the heart is a double pump

From the body

To the lungs

To the body

From the lungs

2. Explain the importance of the heart being a double pump.

The right side pumps deoxygenated blood to the lungs to pick up oxygen.

The left side pumps oxygenated blood to the rest of the body for use. 39

Life Processes

Section B

The Concept of Blood Pressure

Reviewed

Revised

Mastered

Blood pressure is the measurement of force applied to artery walls

Blood pressure is linked to the force of blood being pumped around the body and the size and elasticity of the blood vessels – especially arteries. If the heart pumps weakly, or vessels are leaking, then blood pressure will be low. Imagine a hosepipe with leaks in it. The pressure of water reaching the end will be low. If you gently squeeze the hose, then the pressure increases. This happens if arteries are partly blocked – with cholesterol for example.

Remember Remember what causes atherosclerosis. This increases blood pressure.

Atherosclerosis

Artery narrowed by plaque

Normal artery

Test Yourself: 1.

Explain the factors that contribute to blood pressure.

2. How does atherosclerosis increase blood pressure?

Blood flow Atherosclerotic plaque

Relating Components of Blood to Their Function

Reviewed

Revised

Mastered

Blood is made up of: 55% blood plasma 45% blood cells. ■

■

The liquid plasma plays a vital role in transporting the cells and also important dissolved substances. It is 90% water and 10% solutes. Plasma carries nutrients from digestion and waste materials from cells. Hormones are also carried from glands to where they are required. The plasma also provides water for tissues and cells and carries heat around the body. The different blood cells are adapted to carry out different functions: red blood cells carry oxygen white blood cells help to fight infections and produce antibodies 1. Describe THREE important functions of plasma. platelets play a vital role in 2. List the different cells types found in blood. clotting. ■

■

■

40

Test Yourself:

Life Processes

Section B

Structure and Function of Circulatory System

Reviewed

Revised

Mastered

The pulmonary circuit involves the movement of blood from the heart to the lungs and back again. The systemic circuit involves the movement of blood from the heart to the rest of the body and back again. Pulmonary circuit External respiration Pulmonary artery

Lung alveoli CO 2

O2

Pulmonary vein Red blood cells

Systemic veins

Systemic arteries

Red blood cells CO 2 Internal respiration

Test Yourself:

1. Label the diagram. 2. Which blood vessels

Vessels to the heart are called

O2 Tissue cells Systemic circuit

1

2 . 3

take blood to and from the kidneys?

4

3. Explain the differences between pulmonary and systemic circuits. Vessels from the heart are called

5 .

6 8

7

41

Life Processes

Section B

Relating Structures of Arteries, Veins and Capillaries to Functions Veins contain one-way valves to prevent blood flowing backwards. Arteries have thicker walls as they have to withstand more

Reviewed

Revised

Mastered

Remember Arteries are thick-walled vessels that take blood away from the heart. Veins are thin-walled vessels that return blood to the heart. These two types of vessels are linked by tiny blood vessels called capillaries.

pressure from the heart. Capillaries are very narrow with thin walls to allow rapid exchange of materials across the walls and so they can reach all parts of the body.

Test Yourself: Describe TWO differences between arteries and veins.

Blood Cells and Their Function Our blood cells are adapted to carry out their function. Red blood cells: Thin and disk-like to increase surface area Contain haemoglobin to attach oxygen No nucleus.

Reviewed

Revised

Mastered

White blood cells help fight infection

■

■

■

Red blood cells carry oxygen to tissues throughout the body

White blood cells: ■

■

Phagocytes move like amoeba and ingest harmful organisms Lymphocytes produce antibodies.

Test Yourself: 1.

Describe the function of red blood cells.

2. Describe the function of white blood cells.

42

Platelets help form blood clots that control bleeding

Life Processes

Section B

The Process and Importance of Clotting The skin acts as a physical barrier and acts as the body’s first line of defence. If the skin is cut the platelets in the blood start the clotting mechanism.

A

Reviewed

Disease-causing organism may enter

Loss of blood

Test Yourself: Explain how clotting helps to protect the body from infections.

A cut vessel

Revised

Mastered

No more loss of blood, pathogens have a barrier once more Clot

The cut is sealed with a blood clot

B

Platelets exposed to air in damaged tissue Calcium ions Vitamin K Thrombin (active)

Prothrombin (inactive protein in the blood)

Fibrinogen (inactive protein in the blood)

Causes and Effects of Heart Attacks

Reviewed

Fibrin (insoluble fibres that trap red blood cells and form a clot)

Revised

Mastered

The human heart can beat up to 3 billion times in a lifetime. However, some diseases can seriously weaken the heart. Cardiovascular disease

Causes

Hypertension, or high blood pressure

Caused by a hardening of the arteries so they are not elastic. This can be the result of age or fatty deposits of cholesterol.

H ea rt a tt ac k

Ca u se d b y b lood ve s se l s i n t he he a rt be i ng b lock e d. Th i s c a n b e d ue to a b l ood c l ot that stops blood flowing. This is called a thrombosis. This can stop the heart beating.

St ro k e

C a u s e d b y a b l oo d c l ot i n a b l oo d v e s s e l i n t h e b ra i n . T h e p e r s on a f f e c t e d m a y b e unable to speak or move and may experience drooping on one side of the face.

Like all tissues and organs in your body, the heart needs a constant supply of oxygen-rich blood. When this supply is interrupted, heart muscles are damaged and begin to die. This damage can be irreversible and if too large a portion of the heart is damaged it will cause a cardiac arrest (the heart stops beating).

Test Yourself: 1.

What causes arteries to harden and possibly cause hypertension?

2. How can lifestyle increase the risk of a person having a heart attack?

43

Life Processes

Section B

Using Data and Charts to Represent Data on the Circulatory System

Reviewed

Revised

Mastered

Test Yourself: 1.

How has activity affected heart rate and breathing rate? Explain.

2. Describe TWO possible reasons for the heart and breathing rates of person 1 and person 2 being different.

in120 /m 100 te a R 80

60 40 20 0

Person 1 before activity Heart rate/min 104 Breathing rate/min 28

Person 1 after activity 172 56

Person 2 before activity 68 28

Reviewed

Revised

Person 2 after activity 128 35

Mastered

The Lymphatic System The functions of the lymphatic system are to: ■

■

■

■

transport fats from the digestive system drain excess liquids from cells and tissues remove debris from cells and tissues transport clean liquid back to the blood.

The lymphatic system has THREE parts: lymphatic vessels – the tubes along which lymph travels lymph – the actual fluid lymph nodes – to clean lymph.

Remember The lymphatic system is a one-way system from the body to the heart.

Venous system:

■

■

■

Test Yourself:

vessels, with valves

1. Describe TWO functions of lymph. 2. Explain the role of lymph nodes. Lymphatic capillary

Revision Tip: Write 10 key words from thecirculation unit. Place them onto cards. Try to define the words and then sketch diagrams that allow you to then use thekey words as labels.

44

Arterial system: Heart Lymphatic system: Lymph duct Lymph trunk Lymph node Collecting lymphatic

Blood capillaries

Life Processes

Section B

Unit

4

The Skeletal System

Concept Map Bone structure

Movement

Importance Major bones

Joints

Locomotion

Human skeleton

SKELETAL SYSTEM

Tendons and ligaments

Cartilage

Self Check

Tick the box that shows how confident you feel

Yes

Maybe

No

I can identify the major bones of the skeleton. I can describe the structure and function of the human skeleton. I can describe the structure of bone and distinguish between bone and cartilage. I can explain the importance of cartilage. I can describe the functions of tendons and ligaments. I can identify different types of joints and describe their movement. I can identify the biceps and triceps of the upper arm. I can describe how limbs move. I can explain the importance of locomotion in humans. I can evaluate the factors that adversely affect the skeletal system. 45

Life Processes

Section B

Major Bones of the Skeleton

Reviewed

Revised

Mastered

Reviewed

Revised

Mastered

Test Yourself: 1.

Which bone is which? Write in the correct letter for each bone.

cranium = ___ clavicle = ___ scapula = ___ vertebral column = ___ humerus = ___ radius = ___ ulna = ___ pelvic girdle = ___ femur = ___ tibia = ___ fibula = ___ patella = ___

2. Name the bones of the leg. 3. Name the bones of the arm.

Structure and Func tion of the Human Skeleton Protection

Shape

For vital organs

Holds your body in shape

The rigid ribs make sure the chest does not collapse onto the lungs. This would stop us breathing. Blood vessels are also protected by bone.

Support

Holds the vital organs in the correct place

Remember The skeleton plays a vital role in protection, locomotion, support and blood formation.

Movement

Muscles and joints allow the body to move

Blood production

Red and white blood cells are made in bone marrow

Test Yourself:

1. What are the functions of the ribs? 2. Which part ofthe skeleton protects the brain? 3. Explain how the skeleton helps us to maintain our shape.

46

Life Processes

Section B

Structure and Function of a Typical Bone Bone is made up of living cells and a matrix made from connective tissue and calcium phosphate and calcium carbonate. The cartilage covers the ends of the bones and stops them rubbing together. It also helps to absorb shocks. The epiphysis is another name for

Reviewed

Revised

Compact bone Periosteum Marrow cavity

Epiphysis

Diaphysis shaft

the head of the bone.

Mastered Epiphyseal Cartilage plate Cancellous bone

Epiphysis head

Cancellous bone is also known as spongy bone. This stores red marrow, where red blood cells are made. The epiphyseal plate is the area where bones grow and the diaphysis is the shaft. Compact bone is hard and dense. It gives the bone its strength. The periosteum is a protective layer where there is no cartilage. This is where tendons and ligaments are attached. The marrow cavity contains yellow bone marrow. This is where white blood cells are made.

Test Yourself: 1.

Remember

Describe the role of red and white bone marrow.

Bones have to be hard, strong and light.

2. Explain why calcium is needed in the diet.

Distinguishing Between Bone and Cartilage Flexible matrix Smooth, glossy outer surface

Epiphysis (region of growth)

Cartilage cells secreting the matrix Shaft Outer suppliedmembrane with blood vessels

Reviewed

Revised

Mastered

Ball Cartilage

Cartilage is made of a flexible connective tissue with a smooth Spongy bone appearance. It is made of a flexible (contains matrix of mainly protein. Within red marrow) Yellow bone marrow the matrix are cartilage cells that secrete the matrix. There is also a Compact bone Periosteum glossy outer surface with a supply Marrow cavity of blood vessels. Blood vessel

Test Yourself: 1.

Remember Cartilage is much softer and more flexible than bone.

Epiphysis (region of growth)

Name THREE places where cartilage is found in the skeleton.

2. Describe how cartilage differs from bone. 47

Life Processes

Section B

The Importance of Cartilage Cartilage acts as a shock absorber and as a cushion between bones. It is also slippery so it lubricates joints. Flexible cartilage forms the softer parts of the ears and nose.

Test Yourself: 1.

Locate THREE places where cartilage is providing flexible structure.

2. Locate TWO places where cartilage is providing lubrication. 3. Name TWO places where cartilage is acting as a shock absorber.

Reviewed

Revised

Mastered

Cartilage in nose Cartilage in external ear Larynx Articular cartilage of a joint Costal cartilage Cartilage in intervertebral disc Pubic symphysis Meniscus (pad-like cartilage in knee joint) Articular cartilage of a joint

Tendons and Ligaments

Reviewed

Revised

Mastered

Ligaments are connective tissue that supports joints. Elastin fibres make them flexible but strong.

Some ligaments and tendons of the knee joint

Tendon

Remember Tendons attach muscles to bones. They Ligaments attach bone to bone. Tendons attach muscles to bone. connect to the membranes of cells in the periosteum. Tendons are composed of collagen – which is a white fibrous protein. The collagen fibres do not stretch and this is important for tendons.

Test Yourself: 1.

Describe the difference between ligaments and tendons.

Ligament

2. Explain why ligaments need to be made from stretchy elastin fibres but tendons need to be made from non-stretch collagen fibres.

48

Life Processes

Section B

Different Types of Joints

Reviewed

Revised

Mastered

Bones are designed to be light and strong. They can flex slightly but they cannot bend. This is why joints are needed. Some joints are fixed. They are fused together. An example is the plates of the skull. Ball and socket

Hip

Hinge

Knee

Test Yourself: 1.

Explain how a ball and socket joint works.

2. Give TWO examples of hinge joints.

Slightly movable

The Biceps and Triceps

Reviewed

Lumbar spine

Revised

Mastered

of the Upper Arm Muscles are made from bundles of muscle fibres. These are like small cables. The muscle fibres can contract and relax. This means that muscles pull during contraction but they cannot push, as when they relax they cannot exert a force on the bone they are attached to. The muscles that move the lower arm from the elbow are the biceps and triceps muscles. These muscles can be felt if you bend your arm. You will feel them contracting and relaxing.

Test Yourself: 1.

Label the biceps and triceps on the diagram opposite. Explain why muscles can pull but NOT push bones.

2. 3. Is the biceps muscle on the top of the humerus or below?

49

Life Processes

Section B

How Skeletal Muscles Function in Limb Movement Muscles always work in pairs. These are called antagonistic pairs. The muscles are attached to bone with strong tendons. The biceps muscle lies above the humerus and this bulges when the arm is flexed.

Reviewed

Revised

Mastered

Remember Tendon of insertion means a tendon is attached to the bone that moves the most. The tendons of srcin are attached to a bone that does not move very much.

The biceps is joined to the radius by a single tendon of insertion and to the scapula by two tendons of origin. The triceps is joined to the ulna by a single tendon of insertion and to the humerus by two tendons of srcin and the scapula by one tendon of srcin. When the biceps contract the lower arm is flexed (bent). The triceps relax. When the triceps contract the lower arm extends (straightens). The biceps relax.

Test Yourself: Explain how the biceps and triceps muscles

Contracted biceps muscle

Relaxed triceps muscle

Lower arm moves up

must work together to bend and straighten the arm. Elbow joint

The Importance of Locomotion

Reviewed

Revised

Mastered

Many animals need to look for and capture or collect food. They also need to be able to avoid being eaten. Movement, or locomotion, provides an important survival ability. Humans also use locomotion for sports, work and recreation.

Remember Movement can cover leaves unfurling or an arm waving. Locomotion is the movement of the whole living organism from one place to another.

Test Yourself: 1.

List FOUR reasons for locomotion in animals.

to find food to avoid extreme environmental conditions, e.g. storms or volcanoes

to escape predators Reasons for animal locomotion

to move away from waste products to disperse offspring

2. Explain the difference between movement and locomotion.

to reduce competition to avoid danger

50

to find a mate

Life Processes

Section B

Factors that Adversely Affect the Skeletal System

Reviewed

Poor posture can be caused by poor muscle tone, wearing high heels, injury, tension, arthritis and obesity. Good posture can be helped through good muscle tone and this is achieved by healthy diet and exercise.

1.

Describe THREE causes of poor posture.

Good posture means that the body is held upright with only a slight tension in the muscles. This indicates good muscle tone and healthy bones and muscles.

Poor posture

Good posture

Head is forward Back is flat

Mastered

Remember

A factor that can adversely affect the skeleton is poor posture. This puts a strain on muscles and can impact on circulation, breathing and digestion.

Test Yourself:

Revised

Poor posture

Head is forward Balanced upright posture

Sway back

Round shoulders Weak ab muscles

2. Explain how exercise helps with good posture. Seating positions

Less than 70°

90°

135°

Other factors affecting the skeletal system include: Osteoporosis: a bone disease in which the bones become brittle Osteoarthritis: a condition characterised by the loss of joint cartilage and bone Dislocation: injury caused when the normal joint position is disturbed. ■

■

■

Revision Tip: Ask someone to lie down on a large sheet of paper or some A4 sheets of paper taped together. Draw round the outside of their body. Now try to draw their skeleton into the body shape. Label as many bones as you can and give their functions. Write protection, support, locomotion or blood formation.

51

Life Processes

Section B

Unit

5

Excretion and Homeostasis

Concept Map Kidneys

Materials excreted

Skin

Structure and function

Importance of excretion

EXCRETION AND HOMEOSTASIS

Feedback mechanisms

Water

Blood sugar Homeostasis Temperature

Self Check

Tick the box that shows how confident you feel I can explain the importance of excretion in human beings. I can explain the role of organs involved in excretion. I can describe the structure and function of the kidney. I can relate the structure of skin to its functions. I can explain the concept of homeostasis. I can explain the concept of feedback mechanisms. I can describe the regulation of blood sugar. I can explain the regulation of water. I can distinguish between heat and temperature. I can describe the regulation of temperature. 52

Yes

Maybe

No

Life Processes

Section B

Importance of Excretion in Human Beings

Reviewed

Revised

Mastered

Waste product

Many of the products of metabolism can be toxic. They can also slow down important chemical processes in cells. If allowed to build up in the body they would be harmful.

Heat

Test Yourself:

1. Complete the table by writing in the missing waste products. TWO reasons why waste products must be excreted 2. Describe from living things.

Oxygen Calcium oxalate Tannins

Reviewed Explain the Roles of the Organs Involved in Excretion

Revised

Mastered

Excretions can be toxic and must be removed before they cause damage to cells and tissues. The main organs of the body involved in the excretion of waste products are: kidney lungs skin. ■

■

■

Organ

Remember

Mucus, bile, salts and water are also excreted through the alimentary canal.

Excretory products u r e aw , a t e rs, a l t s

Lu n g s

Sk i n

Excretion u rin e

e x paiirre d

wa t e rs, a l t st,r a c e o su f re a

A l i m e n t acrayn a l

s we a t

fae ce s

Test Yourself:

1. Complete the table by adding the correct excretory organ or excretory product. 2. Name the organs involved in the excretion of water. 3. Which organs excrete urea?

53

Life Processes

Section B

Structure and Func tion of the Kidney

Reviewed

Revised

Mastered

The kidneys filter blood to remove excess water and urea. The filtering takes place in millions of tiny tubules called nephrons.

Test Yourself: Label the diagram using the words below. cortex

medulla

Bowman’s capsule

glomerulus

loop of Henle

Waste products leave the blood in the Bowman’s capsules. Only small molecules are removed so this is called ultrafiltration. Useful substances such as water, salts and glucose can be reabsorbed as they pass down the tubes of the nephrons. The rest pass eventually to the bladder as urine. If the kidneys fail this is called renal failure. This allows toxins to build up in the blood. People have to visit the hospital to have their blood filtered through a machine. This is called dialysis.

Test Yourself:

1. Describe the function of the kidneys. 2. Where does ultrafiltration take place? 3. Explain why renal failure is so harmful to health.

54

Revision Tip: Make a chart to show which substances need to be excreted from living things. Now draw one plant organ and one animal organ that fulfil this function. Label the parts and highlight which waste products are excreted.

Life Processes

Section B

The Structures of the Skin and their Functions 1 Sweat

Heat is carried away as sweat evaporates

2

Reviewed

Revised

Mastered

The skin has some important roles: temperature control (homeostasis) excretion (urea, water and salts). ■

Less blood flow close to the skin Sweat gland Arterioles constrict 3

4 which Layer of warm trapped keeps bodyairwarm

A lot of blood flow close to the skin – heat is lost from the blood Arterioles dilate Heat can be easily lost from the skin

5

Hair erector muscles relax

Hair erector muscles contract

■

To help to regulate body temperature at 37°C, the skin controls how much or how little heat is lost. It is very important to protect skin from the ultraviolet rays from the Sun. These rays can cause wrinkles, age spotsand increase the risks of skin cancer. You should: stay in the shade, wear protective clothing – including a hat– and use sunscreen. Also avoid strong soaps and detergents as these chemicals can damage skin. Not smoking and having a healthy diet will help skin to be healthy.

Melanin is a natural chemical produced by the

Remember Even a lot of melanin in the skin cannot completely protect from skin cancer. It is still important to protect skin from ultraviolet rays.

skin to help protect against the sun. Melanin cangive a sun protection factor (SPF) four times greater than no melanin. People with a lot ofmelanin have darker skin and this can reduce the riskof skin cancer.

Some people who want lighter-coloured skin carry out skin bleaching. Some of the products used can be harmful.

Test Yourself: 1.

Describe how the skin helps to regulate body temperature.

2. Describe THREE ways of protecting skin from ultraviolet rays. 3. Explain why skin bleaching may not be a healthy thing to do. arrows to connect the label with the correct part of 4. Draw the skin.

The evaporation of the water in sweat helps to cool the skin. This temperature control is very important, especially on very hot days.

Test Yourself:Explain how excretion through the skin also helps with controlling body temperature.

Remember The urea and salts that can collect on skin are broken down by bacteria and this irritates the skin and gives off unpleasant smells. That is why it is important to wash them off.

55

Life Processes

Section B

Homeostasis

Reviewed

The conditions inside the human body must be carefully controlled. Maintaining this constant internal environment is called homeostasis. Some factors that are regulated are: carbon dioxide concentration in the blood body temperature blood sugar levels water content. 3 Input: Information sent along afferent pathway to Any imbalance is detected and triggers aresponse from the body. This addresses the imbalance. Receptor (sensor)

Revised

Mastered

Remember The nervous system and hormones are responsible for homeostasis.

■

■

■

4 Output: Information sent along efferent pathway to

■

that need to be regulated and kept in balance.

Effector

2 Change detected by receptor

Test Yourself:

1. Define homeostasis. 2. List some examples of factors

Control centre

1

Imb alan

Stimulus: Produces change in variable

ce

Variable (in homeostasis) Imb alan c

Feedback Mechanisms

Reviewed

Most mechanisms for homeostasis involve negative feedback mechanisms. A detected change causes the body to bring it back to normal. Positive feedback mechanisms are less common. An example is the role of the hormone oxytocin in initiating childbirth. The stretching of the birth canal stimulates more oxytocin to be produced.

Response of effector feeds back to influence magnitude 5 of stimulus and returns variable to homeostasis

e

Revised

Mastered

Homeostasis through negative feedback

Negative feedback

Normal condition (norm)

Negative feedback

Corrective mechanism

Corrective mechanism

Stimulus Receptor (above normal)

Stimulus (below normal) Receptor

Test Yourself: 1.

Explain how a negative feedback mechanism would work to address a factor being too high.

2. Describe the difference between negative and positive feedback mechanisms.

56

Remember Homeostasis is controlled by selfregulating mechanisms in the body. Too much of one factor triggers a process to reduce it. Too little of a fac tor triggers a process to increase it.

Life Processes

Section B

The Regulation of Blood Sugar

Reviewed

Mastered

High blood sugar Stimulates glycogen breakdown Glucagon

Raises blood sugar

When the glucose concentration in the blood is too high, a hormone called insulin is produced in the pancreas. Insulin causes the liver to convert glucose to glycogen. This removes glucose from the blood to be stored in the liver.

Revised

Liver Glycogen Glucose

Pancreas

Stimulates glycogen formation

When the glucose concentration in the blood is too low, a hormone called glucagon is produced in the pancreas. Glucagon causes the liver to convert glycogen back to glucose. This returns glucose to the blood to increase blood sugar concentrations.

Insulin

Tissue cells

Lowers blood sugar

Promotes insulin release

Stimulates Stimulates glucose uptake glucagon from blood release

Low blood sugar

Test Yourself: 1.

Explain the role of hormone insulin.

Remember The site in the pancreas that detects high blood sugar and secretes insulin is known as the Islets of Langerhans. Glucagon is also produced here.

2. Explain the role of hormone glucagon.

The Regulation of Water Water content of the blood LOW

The kidneys play a vital role in osmoregulation. ADH (anti-diuretic hormone) controls the process. This is produced in the pituitary gland in the brain.

Test Yourself: 1.

Describe the role of ADH in osmoregulation.

2. When water content in the blood is too

Reviewed

Too much salt or sweating Brain produces more ADH

Revised

Mastered

Water content of the blood HIGH Too much water drunk Brain produces less ADH

Water content of the blood NORMAL

High volume of water reabsorbed by kidney

Low volume of water reabsorbed by kidney

Urine output LOW

Urine output HIGH

(small volume of concentrated urine)

(large volume of dilute urine)

low does this trigger more orless ADH?

57

Life Processes

Section B

The Regulation of Temperature

Reviewed

When body temperature rises: Sweat glands release more sweat. The evaporation of sweat has a cooling effect Blood vessels in the skin dilate. More blood reaches the skin and can be cooled. ■

Revised

Mastered

Remember The human body functions most efficiently at 37°C. This is known as body temperature.

■

When body temperature falls: Muscles contract rapidly and cause shivering. This warms the muscles Blood vessels in the skin constrict. This allows less blood to the surface of the skin so less heat is lost Hairs on the skin become erect to trap and warm air.

Hypothalamus

■

Nerve impulses sent to skin

■

Thermoreceptors

Increased sweating: vasodilation

Increase in body temperature

Decrease in body temperature

■

Body temperature is regulated by the hypothalamus in the brain. The hypothalamus receives stimuli from receptors in the skin and circulatory system. This triggers nerve impulses to be sent back to effectors to maintain body temperature.

Normal body temperature (37°C)

No change

Normal body temperature (37°C)

Decrease in body temperature

Increase in body temperature

Thermoreceptors

Shivering, vasoconstriction

Test Yourself: TWO responses that occur when body 1. Describe temperature increases.

Nerve impulses sent to skin Hypothalamus

2. Which part of the body regulates body temperature?

Remember The urea and salts that can collect on skin are broken down by bacteria. This irritates the skin and gives off unpleasant smells. This is why it’s important to wash

Revision Tip: The flow charts showing the various examples of homeostasis are very useful summaries. Try drawing them from memory, then check for any parts you have missed. Keep doing this until you can draw and label them all with ease.

58

them off regularly.

Life Processes

Section B

Unit

6

Coordination and Control

Concept Map Accommodation

Stimuli Sense organs Eye

Sight defects

Brain COORDINATION AND CONTROL

Nervous system Endocrine system

Nerves and neurones Reflex action

Sites of hormone production

Roles of hormones

Self Check

Tick the box that shows how confident you feel

Yes

Maybe

No

I can describe the main divisions of the nervous system. I can describe the main functions of the brain. I can distinguish between a neuron and a nerve. I can describe the functions of motor and sensory neurons and spinal synapses. I can explain the mechanism of the reflex action and the process of voluntary actions. I can explain the response of sense organs to stimuli. I can relate the structure of the eye to its functions. I can explain how images form in the eye, including accommodation and sight defects. I can distinguish between endocrine and nervous control. I can identify the sites of hormone production and explain the roles of selected hormones in the human body. 59

Life Processes

Section B

The Main Divisions of the Nervous System C e n t r a l n e r vo u s s y s t e m

Reviewed

Revised

Mastered

The nervous system transmits information from our senses around our body. The brain interprets the stimuli and coordinates the body’s response.

P e r i p h e r a l n e r ve s y s t e m

Nerve fibres

Damage to the nervous system through injury or disease can result in physical disabilities and even paralysis.

Test Yourself: How can damage to the spinal cord cause paralysis?

Functions of the Main Regions of the Brain

Reviewed

The brain coordinates the central nervous system. It allows humans to think, reason, learn and solve problems. outside: grey matter inside: white matter

Cerebrum

The brain is protected inside the skull and has a tough membrane (meninges). The cerebrospinal fluid surrounding the brain helps to cushion it.

Hypothalamus controls the body’s

■

■

The brain can be divided into different areas and each has different functions.

Test Yourself:

Mastered

Motor areas Foot Leg Skin and Intellectual Trunk areas muscle (thought) Arm Hearing Face Sight

internal environment – homeostasis Pituitary gland endocrine gland secretes several hormones

1. Describe how the brain is protected. 2. Explain the functions of the cerebrum, cerebellum and medulla.

60

Revised

Sensory areas receive impulses from receptors via sensory neurones Cerebellum controls balance by coordinating muscular activity

Medulla oblongata controls involuntary muscular actions, e.g. heartbeat, breathing, swallowing, peristalsis, blood pressure

Life Processes

Section B

Neurons and Nerves

Reviewed

Revised

Mastered

The nerves of the body look like thin threads. These are bundles of fibres inside a protective sheath. Inside the fibres are elongated nerve cells called neurons. Neurons are made up of three parts: Nerve cell body: contains typical animal cell components Dendrites: tiny branching projections found at the neuron’s receiving end. These act to pick up signals from other cells Single nerve Dendrite fibre (neuron) Axon: a long, thin fibre with branches at the end. The ends form Cell body synaptic terminals. Nerve ■

■

■

Nerve

The fatty myelin sheath acts as an insulator and can increase nerve impulses as they jump from node to node. The Schwann cells produce the myelin sheath.

Bundle of nerve fibres Neurilemma Axon

Test Yourself:

Axon

1. Describe the difference between nerves and neurons. 2. What is the function of dendrites?

Myelin

Neuron

Node of Ranvier

Motor and Sensory Neurons and Spinal Synapses Test Yourself:Label the

Reviewed

Schwann cell nucleus

Revised

Mastered

Remember

A

diagram using the words given.

A motor (effector) neuron has the cell body at one end. Sensory neurons have the cell body in the middle.

motor neuron B

sensory neuron interneuron. C

Sensory neurons conduct incoming impulses from sense organs to the central nervous system. Motor neurons conduct impulses outwards from the central nervous system to the effector, e.g. muscle. Interneurons, sometimes called mixed or connector

Axon terminal Synaptic vesicles

neurons, connect sensory and motor neurons.

Synapses are gaps between neurons. When the nerve impulse arrives it causes the release of neurotransmitters. These cross the gap and are detected by receptor sites. These then make impulses to travel along the other neuron.

Receptor site

Neurotransmitter

Synaptic space

Dendrite or cell body

Test Yourself:Explain how nerve impulses pass between neurons. 61

Life Processes

Section B

Mechanism of Reflex Action

Reviewed

Revised

Mastered

If you put your thumb on a sharp pin, you pull it away really quickly. This is a reflex action. The stimulus does not have to travel to the brain, be processed and then a response coordinated. This is like a shortcut and is called the reflex arc.

Test Yourself: 1.

Explain how reflex actions are important protection mechanisms.

2

the pathway that an impulse 2. Describe travels along in the reflex action. 3. Fill in the labels on the diagram.

receptor spinal cord synapse effector (muscle) sensory neuron motor neuron relay neuron

7 3

6

4 5

4. Explain how reflex actions are 5.

Remember

important protection mechanisms. Describe the pathway that an impulse travels along in the reflex action.

Other examples of reflex action are changes in pupil size in different light intensities and the knee jerk reaction.

Voluntary Actions

Reviewed

Revised

Mastered

Voluntary actionsare actions that the person decided to do, such as a person standing up or deciding to run along a beach. The process starts with the brain. The person decides to undertake an action or is stimulated to do so by an outside factor such as a friend asking them to do something. Once the brain decides to act, the signal is sent down the white matter of the spinal cord. It then moves along a motor neuron to the effector muscle. This then contracts and brings about the action wanted. Numerous impulses are sent to coordinate complicated movements such as walking.

Test Yourself: 1.

Voluntary and involuntary (reflex) actions

Which of the pictures show voluntary actions?

2. Explain how voluntary actions are undertaken. Drinking

62

Sneezing

Blowing bubbles

Life Processes

Section B

Voluntary and Involuntary Actions Voluntary

Involuntary

Person sits on an uncomfortable chair

Person sits on a pin

Reviewed

Revised

Mastered

Voluntary actions are those actions that require thought. Involuntary actions are reflex actions and occur quickly and without thought. Damage to the nervous system through injury or disease can result in physical disabilities Remember and even paralysis.

Blinking and sneezing are involuntary or reflex actions.

Nerves stimulus messagesend to the brain

Nerves send stimulus to spinal cord

Test Yourself: 1.

Brain interprets the message

Nerves transmit response from spinal cord to leg muscles

Nerves transmit response from brain to leg muscles

Person jumps up

Explain the differences between voluntary and involuntary actions.

2. Why are involuntary actions so important to us?

Person stands up to find a better chair

The Response of the Sense Organs to Stimuli

Reviewed

Revised

Mastered

Living organisms react to changes in the environment. A stimulus is a change in the environment that an organism reacts or responds to. This can be: light textures moisture. Remember temperature chemicals ■

■

■

■

■

Specialised cells in the sense organs called receptors detect the stimulus. The plural of stimulus is stimuli.

Test Yourself: 1.

Complete the table by adding the name of the sense organs. Senseorgan

Stimulusdetected Chemicals in the air Chemicals in food Touch, temperature, pain, pressure Light Sound and changes in position

2. List the stimuli detected by the skin. 3. Name the specialised cells that detect stimuli. 63

Life Processes

Section B

The Structure of the Eye

Reviewed

Revised

Mastered

Reviewed

Revised

Mastered

Rods are light-sensitive cells that allow us to see black and white. Cones are light-sensitive cells that allow us to see colour.

Test Yourself: the parts of the eye with 1. Link their specific functions. 2. Why is it important to control the amount of light entering the eye?

3. Describe the functions of rods and cones.

4. Explain how the lens alters shape to focus on near and far objects.

How Images Are Formed in the Eye

When light passes through the pupil it is refracted by the lens. When the light hits Remember the retina it is detected by rod and cone cells. This triggers neurons to fire. The stimuli from the retina travel along the optic nerve to the brain, where they are interpreted. This is done for each eye. The image on the retina is inverted.

The fovea is a place in the centre of the retina that only contains cones. These are very close together and give good resolution.

Rod Lens Pupil Cornea

Synaptic endings

Iris

to brain Retina

Test Yourself:

1. What is the fovea? 2. What is the blind spot?

64

Discs

Optic nerve -sends messages

Light Object

Nuclei

Cone Inner segment

Outer segment

Life Processes

Section B

Accommodation in the Eye

Reviewed

Revised

Mastered

How the eye focuses light

Accommodation is a reflex action. It is a response to looking at objects that are near or far away. The action causes the lens to change shape.

Contracted muscle Distance focus

Suspensory ligaments hold the lens in place. The ciliary muscles form a ring around the suspensory ligament. When these relax the ligaments become tight and this causes the lens to become thinner. When the ciliary muscles contract, the ligaments become slack

Relaxed muscle

Close focus

and the lens, which is elastic, becomes fatter.

Test Yourself:

1. Explain why accommodation is defined as a reflex action. 2. Is the lens thin or fat when looking at objects at a distance?

Sight Defects and CorrectionReviewed The two most common eye defects are: myopia (short-sightedness): corrected by glasses with concave lenses ■

■

Revised

Mastered

Test Yourself: Label the diagram that shows myopia. 1

2

hypermetropia (longsightedness): corrected by glasses with convex lenses.

Very bright light can damage the cells of the retina or the optic nerve. This is why you should never look directly at the sun and welders must be very careful. Physical injury can also damage the eyes. Eye protection during science experiments and activities such as cutting wood and metalis essential. Damage to the optic nerve can result in vision problems and blindness. With early detection, glaucomacan be treated.

Normaleye

P

R

E

S

S

U R

E

Build-up of aqueous humour fluid

Cataracts are caused when the lens becomes cloudy so vision is impaired. This can be the result of age, injury, diabetes or life choices such as smoking and heavy alcohol drinking.

Eyewithglaucoma

Damage to the optic nerve

Test Yourself:

1. How can myopia be treated? 2. List THREE possible causes of cataracts. 3. Why is it important to have regular eye tests?

65

Life Processes

Section B

Endocrine (Hormonal) and Nervous Control

Reviewed

Revised

Mastered

As well as nervous control the body has a chemical control system. This is endocrine the or hormonal system. This system uses chemical messengers produced in glands. Nervous system Mode Messengers Release Target cells

Blood borne

Describe TWO differences between the nervous system and

H or m on e s

C l os e t o c e l l o f i n fl u e n c e

D i s t a n t t o c e l l of i n fl u e n c e

Sp ec i fic loca ti on (o nl y a t n er v e s up p ly)

Speed Duration

Test Yourself:

Endocrine system

Electrical→ chemical Ne u r ot r a n s m i t t e r s

Fast Sh o rt

More wides p rea d

the endocrine system.

S l ow L on g

The endocrine systemis a collection of glands. These secrete specific hormones into the bloodstream.

Test Yourself: Label the endocrine glands.

1 6

2

3

7 8

9 10

4

11 5

Reviewed The Roles of Selected Hormones in the Human Body Hormone

Source

ADH

P i t u i t a ry gland (in brain) A dre n a l glands P a n c re a s

A dre n a l i n e Insu li n

Role Controls the water content of the blood Prepares the body for physical action L ow e r s b l o od g l u c os e

Mastered

Effect Conserves body water by reducing the loss of water in urine Increases heart rate

R e g u l a t e s c a rb o h ydra t e and fat metabolism in the body Te s t o s t e r o n e Te s t e s C o n t ro l s d e v e l o p m e n t of Regulates muscle male secondary sexual development, skin, and characteristics penile turgor P ro g e s t e r on e O v a ri e s R e g u l a t e s m e n s t ru a l Maintains secretory cycle endometrium (uterus lining) O e strog e n O va ri e s C on t ro l s d e v e l o p m e n t o f Tissue growth and cell female secondary sexual proliferation in specific characteristics areas in the body FSH Pituitary Pr oduc ti on of eg gs H e lp s eg gs ma tu re in th e Follicle stimulating gland ovaries. Starts production hormone of oestrogen LH Pituitary Release of eggs when Starts the release of the Luteinising gland mature mature eggs from the hormone ovaries

66

Revised

Test Yourself: 1.

What is the function of the hormone insulin?

TWO 2. Name hormones

3.

produced by the pituitary gland. Why is the pituitary gland often called the master gland?

Life Processes

Section B

Unit

7

The Reproductive System

Concept Map Birth control

AIDS

Menstrual cycle Sexually transmitted diseases

Male and female reproductive systems

Birth process

REPRODUCTIVE SYSTEM

Asexual and sexual

Family planning

Advantages and disadvantages

Abortion

Birth control

Self Check

Tick the box that shows how confident you feel

Yes

Maybe

No

I can distinguish between sexual and asexual reproduction. I can describe the structure and function of male and female reproductive systems. I can describe the menstrual cycle and explain ovulation, fertilisation, implantation and development of the embryo. I can describe the birth process. I can outline the importance of pre-natal care – ante- and post-natal. I can explain how birth control methods prevent pregnancy, and discuss advantages and disadvantages of birth control methods. I can describe the transmission and control of AIDS and gonorrhoea. I can discuss the issues related to abortion. I can explain the importance of family planning. I can use tables and charts to represent data. 67

Life Processes

Section B

Sexual and Asexual Reproduction

Reviewed

Mastered

Binary fission in amoeba

Reproduction is the process where new individuals (offspring) are produced from parents. Asexual reproduction only needs one parent. The offspring are genetically identical copies of the parent. They are clones. Unicellular organisms reproduce by asexual reproduction. They do this by splitting Cell in half through a process called binary fission. Plants can also grows reproduce using asexual reproduction.

Nucleus divides

Cytoplasm splits

Asexual reproduction only needs one parent but does not produce unique offspring so t here are no chances for new and improved organisms.

the genetic material needed for a new organism. Male gametes: pollen or sperm Reproduction Female gametes: eggs As e xu a l ■

Advantages

■

Disadvantages

R a p i d p o p u l a t i on increase No partner needed I n t ro d u c e s v a ri e t y into a species

Se x u a l

Two identical offspring

Remember

Sexual reproductionneeds two parents. Each parent produces sex cells orgametes. Each gamete contains half of

The male and female gametes fuse together during fertilisation and the cell that forms has the full amount of genetic material. This is a mixture of the genetic material from the two parents. This leads to variation in the offspring.

Revised

No genetic variation

Time and energy needed to find a mate

Test Yourself: Describe ONE advantage and ONE disadvantage of asexual reproduction.

Structure and Func tion of Reproductive Systems in Male Humans

Reviewed

Revised

Mastered

The human male gametes are called sperm. They are formed inside the testes. The testes hang below the body in the scrotum to keep the temperature 2°C below body temperature. Sperm cells are stored in the epididymis and during sexual intercourse are mixed with a fluid from the prostate gland and seminal vesicles to produce semen. 1

Test Yourself: 1.

9

Where are sperm cells made?

2 8

2. What is semen?

3

3. Explain the role of erectile tissue.

7

4

6

5

4. Label the diagram with the words below. bladder penis rectum ureter 68

urethra testes epididymis prostate gland seminal vesicles

Life Processes

Section B

The Reproductive System in Female Humans

Reviewed

Revised

Mastered

The female reproductive system is located in the pelvic region. The human female gametes are called ova or eggs. These are produced in the ovaries. The ova travel along the oviduct, or fallopian tube, by the movement of tiny hairs called cilia. During sexual intercourse semen is sent into the vagina and sperm cells swim to meet the egg in one of the fallopian tubes and one sperm fertilises the egg.

Remember The uterus will develop during pregnancy to protect and feed the fetus.

Test Yourself:

1. Where are ova produced? 2. How do the ova travel to the uterus? 3. Where does fertilisation take place?

The Menstrual Cycle

Reviewed

Revised

Mastered

The menstrual cycle is controlled by hormones and takes place so that a female’s body is prepared for reproduction. During menstruation many changes take place to the uterus and ovaries.The broken-down lining of the uterus, which contains blood, mucus and the unfertilised egg, passes out of the vagina. This is known as menstrual bleeding or the period. Oestrogen Progesterone

Developing eggs inside the follicles One emerges as ‘dominant’ and grows alone

The menstrual cycle involves ovulation, hormone production, build-up of the uterus lining, breast development and (if the egg is not fertilised) menstrual bleeding. The cycle usually takes approximately 28 days.

The egg bursting out of the follicle at the moment of The follicle left ovulation behind turns into the corpus luteum (yellow body)

Uterus lining is shed

New egg and Egg released Uterus lining Unfertilised egg uterus lining thickens further passes through begins to thicken uterus 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 192 02 12 22 32 42 52 62 72 8

Menopause is when the menstrual cycle and periods stop and a woman is no longer able to become pregnant. This happens between the ages of 45 and 55.

Test Yourself:

1. What is the purpose of the menstrual cycle? 2. What is the role of progesterone during the menstrual cycle? 3. What is the menopause? 69

Life Processes

Section B

Fertilisation

Reviewed

Revised

Mastered

The process of mating or sexual intercourse allows the male gametes (sperm) to meet the female gamete (ova or egg). The erectile tissue of the penis fills with blood during arousal and the penis becomes erect. In females arousal causes the vagina to become lubricated. The penis is then inserted into the vagina and sperm cells are ejaculated below the cervix and swim up to the oviduct. Fertilisation is when one of the millions of sperm cells that have swum up the fallopian tube meets the egg and penetrates the egg’s surface.

Sperm cells compete to enter the ovum

One sperm enters the Only one sperm egg. The fertilisation cell has been membrane lifts able to enter

Only the head of the sperm enters the ovum and then other sperm are prevented from entering. It is during fertilisation that the genetic material from the male meets that of the female.

Test Yourself:

1. Define fertilisation. 2. Explain why it is important that only one sperm cell

Remember During pregnancy menstruation stops. This is sometimes the first sign for a woman that she is pregnant.

fertilises the ovum.

Reviewed

Development of the Human Embryo

Revised

Mastered

Hormonal levels during pregnancy

The fertilised ovum is called a zygote. This starts to 120 Oestrogen undergo cell division as each cell divides in two. This Progesterone sl 100 e continues until a ball of cells called an embryo is formed. v le 80 l a 60 Approximately seven days after fertilisation the embryo n o m 40 becomes embedded in the lining of the uterus. After this r o H 20 implantation the placenta begins to form. This is the link 0 between the baby and the mother that allows exchange 4 6 8 10 12 14 16 18 20 2 2 of materials. Oestrogen and progesterone continue to Week of pregnancy be produced. A membrane called the amnion surrounds the embryo so it develops in a fluid-filled sac to protect it. The fluid is called amniotic fluid. In here the embryo develops into a foetus (fetus) and continues to develop for nine months until birth.

Test Yourself:

1. Explain how the ovum moves from the ovary to the uterus. 2. What is a zygote? 3. Describe the role of oestrogen.

70

Remember The blood of the mother and baby do not mix at the placenta.

Life Processes

Section B

The Birth Process Stage 1

Muscle contractions begin in the uterus. The baby stimulates the mother’s pituitary gland to secrete oxytocin. The rhythmic contractions break the amnion and fluid passes out.

Stage 2

Increasingly strong contractions push the baby through the cervix and out through

Reviewed Initial (latent) phase

Fetus

Uterus

Uterus Vagina

Umbilical cord Fetus Stag2e

Effaced cervix

Stag3e

Uterus

Cervix Umbilical clamp

Stage 3

The baby is born head first. The mother helps by pushing. After the birth the umbilical cord is cut and tied or clamped. The placenta and Umbilical membranes are shed from the mother. These are cord called afterbirth.

Mastered

Active phase

Cervix Vagina

Umbilical cord Fetus

the vagina.

Stage 1

Revised

Crowning of the head

Placenta

Umbilical cord Vagina

Remember

Test Yourself:

1. At which stage of labour is oxytocin first produced? 2. At what stage of labour is the baby pushed through the cervix and vagina? 3. What is afterbirth?

Pre- and Post-Natal Care Ultrasound transducer

Non-harmful soundwaves

Reviewed

The contractions lead to more oxytocin being produced. This is an example of a positive feedback mechanism.

Revised

Mastered

Pre-natal care is especially important in the first four months of pregnancy. Mothers visit the doctor Remember regularly for checks. An ultrasound may be Pre-natal means ‘before birth’. Post-natal means ‘after birth’. used to check the growth of the baby. Other tests that are done are: Mother’s blood is checked for Rhesus factor, iron level and immunity to diseases such as rubella Mother’s urine is checked for diabetes and kidney or bladder infections Mother’s weight is checked to see if she is eating properly and the baby is developing well. ■

■

■

Post-natal care involves providing the baby with: food, warmth and comfort, emotional development, and protection from disease. Breast-feeding helps with food and protection against disease as the milk contains essential nutrients and antibodies against diseases. Babies are also given vaccinations to protect against diphtheria, whooping cough, tetanus, meningitis, hepatitis and polio.

Test Yourself:

1. How does breast milk protect babies from diseases? 2. Describe TWO examples of pre-natal care. 71

Life Processes

Section B

Methods of Birth Control

Reviewed

Revised

Mastered

Birth control methods can be natural, barrier, hormonal or surgical. All involve stopping sperm reaching the ovum inside the female. Type of birth control method

Example

Natural

Abstinence

100% safe and no risk of pregnancy

No opportunity for sexual intercourse

Rh yt hm me th od

Na tu ra l wi th no si de e ff e ct s; approved by many religions

Can be complicated; no protection against disease

Wi t h d r a w a l

Na t u ra l wi t h n o s i de e f f e c t s ;

No protection against disease;

Condoms – worn by the man

free Best barrier against diseases; cheap

not very effective Condoms can break; some people allergic to latex

Barrier

Advantages

Disadvantages

Diaphragm – used by Easy to use; protection for up No protection against diseases; the woman to 6 hours messy as have to use spermicide; may be allergic to latex Intrauterine devices (IUDs) – worn by the woman

Very effective in preventing pregnancy; once fitted stays in place

No protection against diseases; risk of infection after fitting

Hormonal

Oral contraceptive (the pill) – taken by the woman

Very effective in preventing pregnancy; constant protection

No protection against diseases; need to take regularly; some side effects

Surgical

Male tubal ligation (vasectomy)

Very effective in preventing pregnancy; life-long

May not be reversible; no protection against diseases

Fe ma le t ub e li ga ti on

Ver y ef fe ct iv e in p re ve nt in g pregnancy

Is not reversible; no protection against diseases

Test Yourself: than abstinence, which birth control method gives the most protection against diseases? 1. Other 2. Why must people be sure they do not want children before having a tubal ligation?

Reviewed Revised Transmission and Control of Sexually Transmitted Diseases Bacteria

Symptoms

• Burning when urinating •• Sores, and rashes Testiclebumps pain (men) • Abdominal pain (women) • Discharge • Itching Prevention

• Abstinence • One regular partner • Condoms • Avoid contact with body uids 72

• Gonorrhoea • Syphilis • Chlamydia Virus

• Genital herpes • Hepatitis • AIDS (HIV) Fungi

• Candida

Treatment Antibiotics Antibiotics Antibiotics

Mastered

Sexually transmitted diseases (STDs) are diseases passed on during sex. You CANNOT catch STDs from money, books, shaking hands, insect bites, plates, cups Remember

Treatment

No known cure No known cure Antiretroviral drugs Treatment

Antifungals such as uconazole or diucan

or toilet seats.

STDs can only be caught by sexual activity. Condoms can prevent the transmission of STDs.

Test Yourself: 1.

2.

List THREE ways that sexually transmitted diseases can be prevented. How are bacterial diseases treated?

Life Processes

Section B

Abortion

Reviewed

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Abortion can be used as a form of birth control but this is very controversial. Abortion can involve: suction to remove young fetus lining of the uterus being scraped drugs such as oxytocin surgery.

Remember

■

This is an issue that you will be expected to have your own opinions about but consider both sides of the debate.

■

■

■

Some arguments in favour of abortion

Some arguments against abortion

Economicbaby or social mean Some people consider it as murder wouldreasons be verycan difficul t having a Mothers may have psychological problems Health reasons if the mother’s health is at risk Mothers may have physical problems from The fetus may be deformed and would suffer the procedure and could become infertile In some countries it is illegal

Test Yourself: 1.

How can oxytocin be used for abortions?

2. What health arguments are there in favour of abortion?

The Importance of Family Planning

Reviewed

Revised

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Family planning is important for the health of mothers and children and the well being of the family. It is also important to control populations to reduce problems such as energy use and waste production. Having children more than five years or less than two years apart can cause serious health issues for mothers and children. Women could be fertile for up to 35 years and in theory could have 14 babies. This would be very risky for health and it would be difficult to support so many children. Family planning allows a small family, so: parents can provide more time, care and education for each child parents may have more financial security and more money ■

■

■

■

parents may decide to have children later in life to allow them to develop a career parents may decide to have children earlier so that they are nearer in age to their grown-up children.

Older mothers have a greater chance of having babies with birth defects such as Down’s syndrome.

Remember Family planning can involve having fewer children and spacing them so they are not born too close together.

Test Yourself:

1. Describe why family planning is especially important for women. 2. How can family planning help countries? 73

Life Processes

Section B

Using Tables and Charts to Represent Data

Reviewed

Revised

Mastered

The Total Fertility Rate (TFR) is the average number of children that would be born to a woman over her lifetime.

Test Yourself: 1.

Which country in the chart has the highest TFR?

2. Which country in the chart has the smallest TFR?

3. How might the populations of these countries develop over the next 30 years if the TFR does not change?

Total fertility rates for select countries, 2010

Poland Russia Latvia Bulgaria China Sweden USA Qatar Peru India Philippines Rwanda Zambia 01

23456 Total fertility rate

The situation isn’t static though. Trends in total fertility rate by region, 1950–2050

Test Yourself: 1.

What is happening to world Total Fertility Rates?

2. What advantages might this give to families?

3. What will this do to the world’s population growth?

8 7 ) R F T ( e t a r y t lii t r e f l a t o T

6 5

World More developed regions Africa Asia Latin America/Caribbean

4 3 2 1 0

5 15 75 85 95 25 55 65 45 35 0 0 0 0 19 0 19 19 19 19 20 0–2 0–2 0–2 70– 0–2 10– 80– 90– 50– 60 – 2 4 9 3 9 9 9 9 0 0 1 1 1 1 1 2 20 20 20 20

Revision Tip: When using charts, look for patterns and trends. Try to pick out specific issues to comment on – don’t just give general ideas. For example, in the chart above you could say: ‘The TFR in Africa has gone down’. It would be better to say: ‘The TFR in the Africa region declined from 6.8 in 1955 to 4.2 in 2015 and is predicted to fall to 3 by 2035.’

74

Life Processes

Section B

Test Questions for Section B 1. Which of the following foods does not contribute (a) (b) (c) (d)

to obesity even if eaten in large quantities? fibre protein fat carbohydrate

2. Which of the following formulae is used to (a) (b) (c) (d)

calculate body mass index (BMI)? weight/height height × height × weight height/weight weight/height × height

3. Name the hard, smooth surface layer of teeth. (a) dentine (b) enamel (c) pulp cavity (d) cement

4. The bones of the lower arm are: (a) femur and humerus (b) tibia and fibula (c) radius and ulna (d) scapula and clavicle 5. Which of the following substances increases blood sugar concentration?

(a) insulin (b) glycogen (c) oxytocin (d) glucagon 6. The short, branched extension of a nerve cell that receives impulses from other cells is called the:

(a) dendrite (b) axon (c) synapse (d) neuron

7. The diagram shows the reflex action.

A

B C

D

(a) Name the stimulus. (b) Name the effector. (c) Add the correct names to each letter:

(1 mark) (1 mark)

A=

(1 mark)

B=

(1 mark)

C=

(1 mark)

D=

(1 mark)

(d) Describe the reflex action.

(1 mark) (1 mark) (1 mark) [9 marks] 75

Heredity and Variation

Section C

Unit

1

Heredity and Variation

Concept Map I can use tables and graphs to represent data

Genetic engineering

Process of mitosis and meiosis

Meiosis and genetic characteristics

HEREDITY AND VARIATION

Importance of genetic variation Advantages and disadvantages of genetic engineering

Inheritance of a single pair of characteristics

Inheritance of sex in human beings

Self Check

Tick the box that shows how confident you feel I can describe the processes of mitosis and meiosis. I can explain the importance of meiosis in the transmission of genetic characteristics. I can explain why genetic variation is important. I can distinguish between genetic and environmental variation. I can explain the inheritance of a single pair of characteristics. I can describe the inheritance of sex in human beings. I can explain the concept of genetic engineering. I can discuss the advantages and disadvantages of genetic engineering. I can use tables, charts and graphs to represent data.

76

Yes

Maybe

No

Section C

The Process of Mitosis

Heredity and Variation

Reviewed

In order for animals and plants to grow and repair, cell division has to take place in a process Remember called mitosis. The cell starts by copying A chromosome is a long length or duplicating everything so that when it of coiled DNA. The human cell contains 23 pairs. divides there is the right amount of material in each new cell. The diagram shows how each chromosome is split into two chromatids. The chromatids separate and form new chromosomes. New nuclear membranes form, resulting in two nuclei with identical chromosomes. Then the cell splits in two.

Test Yourself: 1.

How many pairs of chromosomes does a general cell have?

2. What is a chromatid?

The Importance of Mitosis

Revised

Mastered

Chromosomes in nucleus are copied

Chromatids pulled apart and moved towards poles

Chromosomes separate

Cell divides

Reviewed

Revised

Mastered

Mitosis produces identical daughter cells with the same number and type of chromosomes as the parent cell and are described as diploid. The daughter cells can be described as clones of the parent. The cells produced in mitosis can be used to repair the tissues of the body or in the process of growth. They are NOT specialised cells. Asexual reproduction requires only one parent. The parent divides into two or part of the parent separates and develops into offspring. Binary fission is an example of asexual reproduction and occurs in unicellular organisms, for example bacteria. Vegetative propagation is also an example of asexual reproduction in plants.

Test Yourself: 1.

Explain why the daughter cells can be described as clones.

2. Why is mitosis important to living organisms?

Remember Haploid (n) is a single set of unpaired chromosomes. Diploid (2n) contains two sets of paired chromosomes.

77

Heredity and Variation

Section C

Meiosis

Reviewed Gametes

Meiosis in humans only occurs in male testes and female ovary tissue. Cells of the reproductive system divide by a process called meiosis to form sperm or egg cells known as gametes. One chromosome of each homologous pair comes from the mother (called a maternal chromosome) and one comes from the father (paternal chromosome).

Sperm nucleus

Revised

Mastered

Egg nucleus

Paternal chromosomes

Maternal chromosomes Fertilisation Zygote with maternal and paternal chromosomes

New individual Meiosis

maternalover Crossing and paternal chromosomes exchange lengths/genes

Homologous chromosomes are similar but not identical. Each carries the same genes in the same order, but the alleles for each trait may not be the Remember same. During meiosis there Meiosis produces cells which are two divisions. have half the normal number

Meiosis complete

of chromosomes.

Test Yourself: Identify where the two divisions

Meiosis produces 4 gametes, different complements of genes on the chromosomes

take place on the diagram.

Reviewed

Revised

Mastered

Importance Meiosis Meiosis serves TWO purposes: itof keeps the number of chromosomes from doubling each generation, and it provides genetic diversity in offspring. It differs from mitosis, which is the process of cell division that occurs in all other or somatic cells. Gametes have half the number of chromosomes of other cells or somatic cells. During sexual reproduction an egg and a sperm combine to form a zygote. In a human cell there are two sets of 23 chromosomes (46 in total), known as the diploid number. Gametes have one set of 23 chromosomes, known as the haploid number. When the egg and sperm combine, the zygote has a set of 23 from each parent (46 in total). If gametes divided by mitosis then the number of chromosomes would double every time.

Test Yourself: 1.

How many chromosomes does

gamete have? does meiosis take place 2. aWhere

Mitosis

Passes on the normal diploid number of chromosomes

in humans?

Nuclei have genes mixed by crossing over

3. Complete the table to check

Provides variation

your understanding of mitosis and meiosis.

For fertilisation to restore diploid number Genetic continuity

78

Meiosis

Occurs in normal body cells

Heredity and Variation

Section C

Why Genetic Variation Is Important Test Yourself: Sort the following statements into the advantages and disadvantages of sexual reproduction:

1. variety 2. chance of not finding a mate 3. sexually transmitted diseases easily contracted 4. leads to continuous evolution 5. reduces the chance of offspring inheriting genetic disease 6. no guarantee of offspring being produced

Reviewed

Revised

Mastered

Sexual reproduction happens when a male gamete and a female gamete fuse and is called fertilisation. Some of the genetic information from each parent mixes, producing offspring that resemble their parents but are not identical to them. Sexual reproduction leads to variety in the offspring. Both animals and plants can reproduce using sexual reproduction.

Remember

Variation can be organised into continuous and discontinuous.

Variation makes it less likely that a change in environmental conditions will wipe out an entire species. This includes height, weight, gender, blood type, tongue rolling. Some bacteria have become resistant to antibiotics as a result of variation.

Variation is a result of inherited genes and the impact of the environment on a species.

Genetic Variation and

Reviewed

Revised

Mastered

Environmental Variation Genetic variationis a result of inheritance and controlled by genes. This controls the blood group of an individual. Other examples are eye colour, natural hair colour and gender. Genes can also control the height of an individual but this can be affected by environmental factors such as diet and exercise. The average height of the population is increasing over generations because of the environmental impact of diet and nutrition. Smoking and poor health choices impact on characteristics and are purely environmental. Gene mutation is a change in part of theDNA that can alter the characteristic that it controls. Sickle cell anaemia is an Normal division Non-disjunction example of this. This occurs when Human chromosomes the whole chromosome is mutated. no.21 (44 others not shown) The evolution of organisms Two in one gamete Normal haploid is dependent on mutations responsible for changes that Meiosis gametes promote survival. Dies

Test Yourself: List TWO

Fertilisation

Ovum

examples of genetic variation. Sperm Zygote Normal 2 chromosomes no.21 + 44 others = 46

Extra chromosome Down’s syndrome 3 chromosomes no.21 + 44 others = 47 79

Heredity and Variation

Section C

The Inheritance of a Single Pair of Characteristics

Reviewed

Revised

Mastered

Test Yourself: Fill in the missing definitions and terms in the table. Term

Definition Deoxyribonucleic acid, the hereditary material in humans Ribonucleic acid, used to send the genetic code into the cells and to identify amino acids

I n h e rit a n c e Made up of DNA and are instructions to make proteins P h e n ot yp e Genetic makeup of a cell that determines a specific characteristic (phenotype) H om ol og o u s A lle l es Carry two different alleles for a gene H o m o z yg ou s Controls the characteristic in the phenotype The allele is not expressed in the phenotype Mutation Gene mutation

Affecting a small part of the chromosome, e.g.

Ch romoso m al m ut at ion

A ff e ct s th e who l e ch romosome re s ul ti ng i n ma j or ch a ng es , e .g .

M on oh y b r iidn h e r i t a n c e

Characteristics can be determined through crosses or punnet squares: Parent’sphenotype

Normal

Parent’sgenotype

X

Gamete’sgenotype

XH

Zygote’s genotype

X HX H

Carrier

HY

X HX h Y

X

H

Xh

X HY

X HX h

X hY

Zygote’s phenotype Normal Normal Carrier Haemophiliac female male female male A a Key A AA Aa 25% will have albinism 25% will not have albinism 50% will not be carriers a

80

Aa

aa

Heredity and Variation

Section C

The Inheritance of Sex in Human Beings

Reviewed

Revised

Mastered

Males have a genotype XY. The Y determines male characteristics. Females have XX. The lack of a Y chromosome determines female characteristics. Female carrier X CX c X

C

X

Chromosomes

c

Normal male X CY –

Alleles in gametes

XC X CX C Normal female

Xc X CX c Carrier female

X CY – Normal male

X cY – Colour-blind male

X

C

Y

–

Gametes XC

Test Yourself: 1.

Draw a punnet square diagram to determine the sex of offspring from these genotypes. What are the percentages of female and male offspring?

Y–

C = dominant normal allele c = recessive allele for red/green colour blindness

Remember Chromosomes determine the sex of an individual.

2. What is the ratio of females to males?

1

1 3

4

5

6

2 7

8

9 10

Female with black hair Male with black hair Female with red hair Male with red hair

11 12 13 14 151 6 17 18 The allele for black hair B is dominant to the allele for red hair b. What are the genotypes of all the individuals? The males and females with red hair would have to be bb. bb 1

B? 2

To have a bb offspring, individual 2 would

Bb 2

Bb B? Bb 4 5 6

to beblack-haired Bb. B? have All their 9 children are Bb. To have a bb offspring, individual 5 would have to be Bb. bb bb Bb bb 7 8 9

bb

bb bb Bb bb

2 bb 3

B? 4

B? 6 bb 1

bb 3

bb 7

The sex chromosomes also carry genes for other characteristics. These include haemophilia and colour blindness. The second diagram shows the genetic crosses for the sex linked characteristic of colour blindness. Pedigree charts can also be used to show the occurrence of characteristics in a family tree. The first chart is generic. The second shows a pedigree chart for the disease haemophilia.

81

Section C

Explaining the Concept of Genetic Engineering

Heredity and Variation

Reviewed

Revised

Mastered

Genetic engineeringchanges the traits of one organism by inserting genetic material from a different organism. An organism that has had genes added from another is known as a transgenic organism. Examples of uses of genetic engineering are crop resistance to insects, maize and potato resistant to fungi, increased growth in salmon and chicken, pork with less fat content, milk and dairy products with increased protein, increased protein in soya milk, wheat and maize crops that can fix nitrogen and medical uses, for example the production of insulin. Genes from daffodils are injected into rice so that it contains Vitamin A.

Test Yourself: Look at the diagram of a medical use of genetic engineering to make insulin from bacteria. Label as many stages as you can and make notes on each stage.

Remember Cloning produces exact copies within the same species. Genetic engineering can involve swapping genes across a species.

82

Heredity and Variation

Section C

Advantages and Disadvantages of Genetic Engineering Genetic engineering has many advantages. Producing crops resistant to insects reduces the use of Remember pesticides. A crop that Cystic fibrosis is a recessive grows well and produces genetic disorder.

Reviewed

Revised

Mastered

Cow Sperm is taken from a bull from a highyield dairy herd Cow is artificially inseminated with sperm Zygotes develop into embryos in cow and then removed from the uterus

an increased yield reduces the need for fertiliser use. The process is also used to increase protein in Embryos are split into several smaller soya milk and dairy products, resulting in a healthier embryos, each of diet. Crops, for example tomatoes, are genetically which can grow into a new calf modified to produce nutritious fruit. Reducing the Embryos placed in fat content in pork also reduces the amount of fat the uteruses of consumed. Genetic engineering also increases the foster mothers shelf life of some foods, so less is wasted. Productive breeds of livestock have been developed in temperate climates, but they do not thrive in tropical climates such as the Caribbean. The grass they feed on is less nutritious and they often suffer heat stress. The use of genetic engineering has resulted in tropical breeds which cope in the heat. Gene therapy is also being used to treat genetic disorders, for example cystic fibrosis.

Extending records for treated and untreated yields

40 s g k 30 in led i y 20 k il M

Actual yield with rbSTH treatment Predicted yield with treatment Actual yield untreated Predicted yield untreated

The effects of using genetically modified organisms in food production are not really known. Bovine somatotrophin Treatment begins (BST) is a hormone produced by bacteria. This is injected into cows and doesn’t 10 10 30 50 70 90 110 130 15 0 170 190 210 2 30 250 270 290 appear to have a negative impact when Days in lactation humans consume the meat or milk. The concern is that we don’t know what impact there could be in the future. There are discussions about whether, if we do not know the implications, we should use it. DNA fingerprinting is also viewed as an Remember invasion of privacy. DNA contains all the genetic information for an organism

Other implications are that selectively bred plants and animals will all share as a genetic code. very similar genes. Some diseases would be more dangerous as all the organisms would be affected. Also, there is an increased risk of genetic disease caused by recessive alleles. Inbreeding 1. List TWO advantages of genetic engineering. can lead to the loss of alleles from the gene 2. List TWO disadvantages of genetic engineering. pool, affecting new varieties in the future.

Test Yourself:

83

Heredity and Variation

Section C

Using Tables, Charts and Graphs to Represent Data

Reviewed

Revised

Mastered

Test Yourself: Parent’s genotype Gamete’sgenotype

Zygote’s genotype Zygote’s phenotype

1.

Ss S

SS

Test Yourself:

Ss s

S

Ss

Normal Carrier

Ss

s

F is the cystic Mother fibrosis allele

ss

Carrier Sickle cell sufferer

Father

1.

F

F

F

FF

FF

f

Ff

Ff

Explain the use of the chart.

Explain the use of the chart.

2. What does this tell us? 2. What does this tell us?

Revision Tip: Practise drawing cross diagrams and punnetsquares for different genotypes. Write key words and definitions on sticky notes and stick them in places where you will look regularly, for example on your mirror.

Test Yourself: Interpret the data from this graph. Extending records for treated and untreated yields

Actual yield untreated Predicted yield untreated Actual yield with rbSTH treatment Predicted yield with treatment

40

s 30 g n ik d le i y lik 20 M

10

84

Remember Tables and charts are used to display data. Charts are usually easier to use than t ables.

Treatment begins

10 30 60 70 90 110 130 160 170 190 210 230 260 270 290 Days in lactation

Heredity and Variation

Section C

Test Questions for Section C 1. Which of the following processes occur during

(a) (b) (c) (d)

meiosis? I two cell divisions II production of four diploid cells III movement of chromosomes IV creation of spindle I and II only II and III only I, III and IV only I, II, III and IV

2. If an albino offspring has two normally pigmented

(a) (b) (c) (d)

parents, what could be the genotype of the parents if ‘A’ represents the normal skin pigment and ‘a’ represents the albino condition? aa × aa AA × Aa AA × AA Aa × Aa

3. Different forms of the same gene are called: (a) DNA (b) allele (c) heterozygous (d) homozygous 4. This is an environmental trait: (a) eye colour (b) earlobe shape (c) nose shape (d) height 5. Which of the traits in the question above could be environmental and/or inherited?

6. (a) Explain what is meant by the following genetic terms: (i) phenotype (ii) homozygous (iii) sex-linked genes (iv) monohybrid cross (b) Use a punnet square to determine the likelihood of two heterozygous parents producing a child

(1 mark) (1 mark) (1 mark) (1 mark)

with cystic fibrosis.

(2 marks) (c) Draw a punnet square to determine the gender of offspring in humans.

(3 marks) (d) What are the chances of a male offspring? (1 mark) [10 marks]

85

Disease and Impact on Humans

Section D

Unit

1

Disease and Impact on Humans

Concept Map Life cycle of the mosquito

Disinfectant and antiseptic

Vectors and control methods

Impact of disease on human population

Methods to control microorganisms Malaria and dengue fever

Antibiotics; antifungal

Define good health and disease

Personal hygiene

Issues of lifestyle diseases

DISEASE AND IMPACT ON HUMANS

Signs and symptoms

I can use data tables and charts

Misuse of drugs Immunity and vaccination

Causative agents; signs; symptoms; prevention and control; HIV/AIDS

Effect of asthma on respiratory system

Self Check

Tick the box that shows how confident you feel I can define the terms ‘good health’ and ‘disease’. I can classify diseases and differentiate between ‘signs’ and ‘symptoms’. I can explain how asthma affects the respiratory system. I can discuss issues related to lifestyle diseases and discuss the impact of disease on the human population. I can discuss the causative agents, signs, symptoms, prevention and control of diseases, including HIV/AIDS. I can explain the effects of vectors on human health and methods of controlling them. I can explain how and why personal hygiene is maintained. I can explain the methods used to control the growth of microorganisms. I can distinguish between disinfectants and antiseptics.

86

Yes

Maybe

No

Disease and Impact on Humans

Section D

‘Good Health’ and ‘Disease’

Reviewed

Revised

Mastered

Health is a state of complete physical, mental and social well being. To be healthy a person needs to be normal in all three aspects. (WHO). Being healthy is not just being free from disease. Disease is the lack of health because of an interaction with a disease agent, for example a pathogen.

Test Yourself: Join the THREE aspects of health with the definition, example and control method in the table. Aspect

Definition

Example

Control

Free from signs injuryofor physical disease

Broken bone or spots on the skin

Balanced diet and exercise

Free from depression or worry

Feelings of sadness, loneliness, helplessness and anxiety

Avoid worry and be positive

Good relationships with others and a positive outlook

No concern or interest in Show an interest in the others. Negative outlook on well being of others. Be life in general friendly and positive.

Classifying Diseases Fill in the blanks in the table. Test Yourself: Typeofdisease Namedexample

Reviewed

Cause

Revised

Mastered

Symptoms

Pathogenic Caused by parasitic organisms (pathogens) like viruses, bacteria, fungi, protozoa and worms. Examples: malaria, TB, cholera, influenza

Virus (pathogen) invades the Headache, body by contact with infected sore throat, person. It is airborne or muscular pains, droplet-borne fever

Deficiency Caused by a shortage of a nutrient (e.g. vitamin, mineral) in diet. Examples: kwashiorkor, nightblindness, iron deficiency anaemia

Deficiency of ironcauses a Weakness, fatigue, reduction in the number of shortness of breath, red blood cells which reducesincreased heartbeat, the oxygen-carrying capacity pale appearance of the blood. This is because iron is an integral part of the structure of haemoglobin in red blood cells

Hereditary Caused by genes passed on from one generation to the next.

Gene for the disease is passed to the offspring . The gene causes the red blood cells to be sickle shaped

Weakness, tiredness, weight loss, may lead to kidney failure,

Examples: haemophilia, cystic fibrosis, sickle cell anaemia

which reduces oxygencarrying ability

heart failure

Physiological Caused by a malfunction of body’s organ. Examples: asthma, hypertension, diabetes, glaucoma, stroke

Inability of the islet of Langerhans to produce insulin. Body cells are unable to absorb glucose which stays in the blood

Tiredness, continual thirst, weight loss, increased urination, coma

87

Disease and Impact on Humans

Section D

Reviewed Differentiate Between the Terms ‘Signs’ and ‘Symptoms’

Revised

Mastered

Symptomsand signs are used to detect the presence of a disease. Symptoms are felt by the sufferer. A symptom is not always obvious or visible to the observer. Examples include feeling dizzy or nauseous, pain or headache. Signs are visible to the Remember observer and include swellings, weight, tiredness, fever and high temperature. Infectious diseases can be spread between organisms.

Test Yourself:What would be the signs and symptoms for the following diseases? Complete the table. Disease

Sign

Symptom

Kwa s h i or k o r C old Malaria

Causes, Symptoms and Treatment of Asthma Cause Spread/vector Signs Control Treatment

Reviewed

Revised

Mastered

Remember

inducers – allergens triggers – airborne irritants, stress, exercise may be inherited airborne particles

Allergens that can cause asthma could be house dust mites, pet’s fur or feathers, fungal spores, smoke, air pollutants and pollen.

wheezing, coughing and shortness of breath inflammation of bronchiole tubes avoid source, e.g. allergens or triggers

Test Yourself: What impact could increased stress have on an asthma sufferer?

use of inhaler – corticosteroids antihistamines to reduce inflammation

Explain How Asthma Affects Reviewed the Respiratory System Air enters the respiratory system from the nose and mouth and travels through the bronchial tubes

In a non-asthmatic person, the muscles around the bronchial tubes are relaxed and the tissue thin,airflow allowing for easy

In an asthmatic person, the muscles of the bronchial tubes tighten and thicken, and the air passages become inflamed and mucus-filled, difficult for airmaking to moveit

Revised

Mastered

The diagram shows the Remember causes of asthma. The airways Asthma can be inherited but environmental factors can become swollen as a result of trigger an attack. an immune response to an irritant. This restricts the airway.

Test Yourself: Explain why an asthma sufferer might feel short of breath.

Normal bronchial tube

Inflamed bronchial tube of an asthmatic

Why asthma makes it hard to breathe

88

Disease and Impact on Humans

Section D

Issues Related to Lifestyle Diseases

Reviewed

Revised

Mastered

The diagram below shows the key differences between type 1 and 2 diabetes. Type 1

Test Yourself: Describe the issues that

Often diagnosed in childhood Not associated with excess body weight Often associated with higher than normal ketone levels Treated with insulin injections or insulin pump Cannot be controlled without taking insulin

someone suffering from type 1 diabetes would have.

DIABETES What’s the difference?

Type 2

Usually diagnosed in over 30 year olds Often associated with excess body weight Often associated with high blood pressure and cholesterol levels Is usually treated initially without medication or with tablets Sometimes possible to come off diabetes medication

Remember Obesity is a serious form of malnutrition.

The human heart can beat up to 3 billion times in a lifetime. However, some diseases can seriously weaken the heart. Cardiovascular disease

Causes

Hypertension, or Caused by a hardening of the arteries so high blood pressure they are not elastic. This can be the result of age or fatty deposits of cholesterol. H ea rt a tt a ck

Ca us ed by b lood ve ss el s i n t he he ar t b e in g blocked. This can be due to a blood clot that stops blood flowing. This is called a thrombosis. This can stop the heart beating.

St r ok e

C a u s e d b y a b l oo d c l ot i n a b l o od v e s s e l in the brain. The person affected may be unable to speak or move and may experience drooping on one side of the face.

The Importance of Diet and Exercise

to harden and possibly cause hypertension?

Reviewed

Revised

Mastered

The physiological effects of exercise

To provide energy for exercise your body breaks down carbohydrates and fats. This helps to balance energy input and energy output. Some of this energy is used in exercise. People who do regular activity have a lower risk of many chronic diseases. Research shows that physical activity can also boost self-esteem, mood, sleep quality and energy.

Test Yourself: A well-balanced diet is essential for good health. The charts gives an example of this. List examples of sources of the nutrients in the chart.

Test Yourself: What causes arteries

Fats 30%

Protein 15%

Carbohydrates 55%

Lung capacity increases

Muscle tone improves Posture better Body shape Less fat Muscle size

Heart and circulation improve Heart stronger Less cholesterol

increases Digestion better as muscles in the abdomen mix food better

Remember Exercise results in more sweating, so more water is needed.

89

Disease and Impact on Humans

Section D

Reviewed Revised Causes, Signs, Symptoms, Prevention and Control of Diseases The main means of entry of disease organisms

Means of infection t le p o r , d r i A

n o tic fe n i

r et a w d n a d o o F

l a u ex S

se r u co r et n i

cet s In

tc ta n o c in k S

l a s e im it n b A

Pathogen

Disease

virus

colds

Natural opening

virus (rubella) German measles bacterium

TB

bacterium

diphtheria

bacterium

food poisoning

bacterium

typhoid cholera

protozoan

amoebic dysentery

worm

tapeworm

bacterium

syphilis

bacterium

gonorrhoea

virus

AIDS

virus

dengue

bacterium

tetanus

fungus

ringworm

mite

scabies

worm

hookworm

virus

rabies

nose

mouth

reproductive and anal passages insect bites

cuts and skin surface

skin puncture

Test Yourself: Suggest ONE method of control for each of the infections.

90

Mastered

Disease and Impact on Humans

Section D

Prevention/Control of HIV/AIDS

Reviewed

Revised

Mastered

AIDS is caused by the human immunodeficiency virus. It destroys the T lymphocytes, which results in a weakening of the immune system. This means that death of a patient is the result of other infections, for example pneumonia or tuberculosis. The infection is usually passed on through sexual intercourse with a person infected by the virus. In the past people could also become infected after a contaminated blood transfusion. Now blood is screened for HIV before blood is transfused. Infected mothers can pass the virus to a child during birth. Combinations of drugs are taken to treat HIV/AIDS, including: non-nucleoside reverse transcriptase inhibitors (NNRTIs) nucleoside or nucleotide reverse transcriptase inhibitors (NRTIs) protease inhibitors (PIs) entry or fusion inhibitors integrase inhibitors.

Test Yourself: How

■

■

could the spread of HIV/AIDS be controlled?

■

■

■

The side effects can be problematic and include: nausea, vomiting or diarrhoea, heart disease, weakened bones or bone loss, breakdown of muscle tissue (rhabdomyolysis), abnormal cholesterol levels and higher blood sugar levels.

Effects of STIs on Pregnant Mother and Foetus

Reviewed

Revised

Mastered

Sexually transmitted infections (STIs) are serious for all women, as they can have damaging effects on their health and fertility. If an infected woman is pregnant, STIs can cause complications such as early labour, uterine infections and many more. Some of the negative effects on the baby may not be noticed until later in its development.

Test Yourself: Read through the statements. Identify each as true or false.

STIs can be passed on from a pregnant woman

HIV-positive women can transmit the virus that causes AIDS through the placenta during pregnancy to the foetus

to the baby Sexually transmitted diseases, for example gonorrhoea, chlamydia, hepatitis B and genital herpes, can be transmitted to the baby during vaginal delivery

Women who are HIV-positive can pass the virus that causes AIDS to the baby during the process of breastfeeding

Women who are HIV-positive can pass the virus that causes AIDS to the baby during the process of birth

STDs can be passed to a baby during pregnancy, birth and breastfeeding

Some STIs – syphilis for example – can cross the placenta and infect the foetus. This could potentially impact negatively on foetal development

91

Disease and Impact on Humans

Section D

Impact of Disease on Human Population

Reviewed

Revised

Mastered

Disease has an impact on society and the economy of a country. People suffering from degenerative diseases, for example cancer, place a massive drain on resources. The cost of people being off work due to ill health also affects the economy. Humans are also affected economically by disease in plants and animal livestock that are grown for food. Disease canreduce the numbers or wipe out a cropor livestock quickly. Mealy bug in the Caribbean is an example o f this. BSE, commonly known as mad cow disease, has resulted in the death of many cattle. This results in the loss of income for the farmer and a shortage of food. We live in a world where food stocks are moved easily. Disease control is very important but difficult to manage.

Test Yourself:

Remember

1. Describe how disease can impact on the economy of a society. 2. Explain why diseases move around the world.

Diseases are often spread by pathogens that cannot be seen by the human eye.

Reviewed Revised Effects of Malaria and Dengue Fever on the Human Body What are the side effects of malaria?

Fever Fatigue and pain

Enlargement of the spleen Back pain

Headaches Symptomsofmalaria usually occur around 10–15 days after being Chills bitten. You may get a and severe case of malaria. sweating This is called Falciparum malaria. Dry If untreated this can cough cause severe illness. This may include seizures, breathing Vomiting problems, confusion, mental kidney and failure, coma and nausea even death.

Symptoms of dengue fever Fertile phase Sudden-onset fever

Headache Mouth and nose bleeding Muscle and joint pains Vomiting Rash Diarrhoea

Test Yourself:

Critical phase

Hypotension Pleural effusion Ascites Gastrointestinal bleeding Recovery phase

Altered level of consciousness Seizures Slow heart rate Itching

1. List TWO effects of malaria on the human body. 2. If you were a doctor, how would you distinguish between malaria and dengue fever?

92

Mastered

Disease and Impact on Humans

Section D

Vectors of Disease

Reviewed

Revised

Mastered

Vector-borne transmission involves an animal such as an insect. For example, dysentery is caused by houseflies and plague by fleas. Malaria is transmitted by mosquitoes, one of the region’s most common vectors. Anopheles mosquitoes carry the malarial parasite. Aedes mosquitoes carry the parasites that cause dengue fever and yellow fever. The Culex mosquito carries the parasite for elephantiasis. Very little is known about the incubation period of the Zika virus, but it is spread by daytime-active Aedes mosquitoes, such as A. aegypti and A. albopictus.

at the table.Fill in the missing words of the name of the vector and the diseases they spread. Test Yourself: Look Vector Examplesofdiseasesspread Yellow fever, malaria,

fever gastroenteritis plague

Rat

Stages in the Life Cycle of the Mosquito and Housefly

Reviewed

Revised

Mastered

Mosquitoes are parasites.

Adult

Eggs

Adult emerges Mosquito life cycle

Pupa

Larva Adult

Pupae

They feed on the blood of other animals, including humans. This animal or human is called the host.

Remember

Pathogens are usually microscopic organisms, for example viruses, bacteria and protozoans, that are capable of causing disease.

Houseflies lay their eggs in moist, dark piles of trash or rotting carcasses or manure. The process from laying the egg to adulthood takes about 10 days. Houseflies mechanically transmit at least 65 diseases to humans. They excrete or regurgitate wherever they land. These diseases can include Remember cholera, leprosy, TB, polio, Houseflies are vectors. typhoid and dysentery.

Test Yourself:

1. Explain the term ‘vector’. 2. Explain how removing water or covering it with oil

Housefly life cycle

reduces the numbers of mosquitoes.

Eggs Larvae (maggots) 93

Disease and Impact on Humans

Section D

Importance and Methods of Controlling Vectors

Reviewed

Revised

Controlling mosquitoes involves: What attracts mosquitoes? Removing puddles of water or standing water around your home to reduce breeding sites Removing garbage such as unusable tires from the yard to prevent pools of water from forming inside them Maintaining any local swimming pools to prevent Moisture Heat (standing water sources) (exhaled gases) mosquito breeding, and reporting any abandoned pools to your local health department Keeping windows and door screens in good working order Considering the use of pesticides and insect repellent.

Mastered

■

■

■

■

Smells

(perfumes, scented soaps and lotions)

■

■

Test Yourself: 1.

2.

Look at what attracts mosquitoes and consider thelife cycle of the mosquito. Suggest appropriate methods of control at each stage. Suggest methods of controlling houseflies.

Personal and Community Hygiene Test Yourself: 1.

2.

Which of these examples prevent the growth and spread of microorganisms? Mark them with a large M. Which of these examples prevent body odours? Mark them with a large BO.

2

3

1

Reviewed

Revised

Mastered

Hygiene means more than keeping clean. It includes anything we do to stay healthy and prevent microorganisms causing diseases. How we wash our hands, look after animals and dispose of waste materials are all aspects of hygiene. It is important that communities work together to ensure good hygiene. This includes sewage and other waste disposal.

Test Yourself: is personal hygiene so 1. Why 4

5

6

important?

2. Why is it important that whole communities work together to improve hygiene standards?

94

Disease and Impact on Humans

Section D

Controlling the Growth of Microorganisms Microorganisms need food and water just like other living things. Different microorganisms can live in very hot conditions or very cold conditions. Those that cause diseases in humans often grow well at body temperature. Many microorganisms reproduce by binary fission. They grow and then divide in two. This means that every time the microorganisms reproduce, the population doubles. This is known as exponential growth. A bacterium called E. coli causes food poisoning. The number ofE. coli cells growing in food can double every 17 minutes. Over a few days a few hundred cells can result in a population of many billions.

Reviewed

so ture is peratops the m e e t it s nism Th low roorga g c mi rowin e g th ration il ige k efr s ism

rg

m

G

ic m

m a

o

g

o

g

r

o

w

o

D

g

t

g

w

ii n g

r

o

u

t

ry

a

f

i

S

r u

it

p

e

r

w

d

o

r

o

ing

ia

o

ic r

m

o

M ca ic r ith nn oo r

Heat

ro

a t

a

n

is

w

m

e

r

Ir t

m fr

r

i sm

n tio

o

Mastered

K micro ills orga n

R

y n ra a

a

Revised

in

a a

n

n

d

T

s

b

d h

is e

c

s

to

i

o

x

id

u

g

lp

h

e

u

r

m ps

o

Bacteria

Ad d s ug in g ar T he co high n su g ce n fr o m a r r tr a t i on e of or m g a fo o d o v e s n is . T h w a t e r ms e c an m icrono t g r ow

s in m to g g s ps is

Preserving food means stopping microorganisms from growing. Microorganisms can grow on our food and spoil it. They may produce toxins – which are poisons – that can make us ill if we eat the food. Washing hands before handling food, cooking food well, storing it in a refrigerator or freezer and keeping it sealed are important ways to prevent food from spoiling and being contaminated. Raising or 1. reducing the temperature will control the growth 2. of microorganisms. Changing their environment by making it acidic through pickling or salting will prevent the microorganisms from reproducing.

k c Pi

S a lti

li

n

ng

er i s o m W at r ed f sis. o r e m v o s m o is m y b d o o f rg a n i c r o o gr o w The m t o n n ca

st

p

o

s

is

a

m

n

d g c i o r in g a e icro ow

Th m e th

gr

Test Yourself:

Disinfectants and Antiseptics

Describe THREE ways of reducing the chance of microorganisms spoiling food. Explain why microorganisms can be harmful if they are allowed to grow in food.

Reviewed

Revised

Mastered

Disinfectants are chemicals that kill or inhibit the growth of microorganisms on inanimate or nonliving objects, for example work surfaces, toilets and sinks. They are more toxic to humans. High-level disinfectants, for example lyso and chloro, kill viruses and spores. Carboxylic acid has been used in drains and on humans in a dilute state. Antiseptics are chemicals that kill or inhibit the growth of microorganisms on animate objects or living tissue. They are useful in keeping wounds clean but can cause irritation and slow the healing process. Surgery in medicine is now carried out in aseptic conditions where the area is sterile and so microorganisms are removed before they can contaminate tissues.

Test Yourself: Explain why disinfectants should not be applied to a skin wound.

Remember Microorganisms multiply exponentially.

95

Disease and Impact on Humans

Section D

Defence Against Disease Antibiotics are chemicals that work by either killing or stopping bacteria from multiplying. The first antibiotic, penicillin, was discovered in the 1930s. Bacterial infections were commonly fatal before this. There are also two main kinds of white blood cells (leucocytes) that are part of the body’s defence system. Lymphocytes are part of the lymphatic system. They recognise the antigens on the pathogens.

Reviewed

Revised

Mastered

Pathogens (organisms causing disease) Bacteria

Toxins Gain entry to body

Viruses Bacterium 1 Antigen on surface stimulates 2 Lymphocyte

An antigen is a large molecule, often a protein. Each lymphocyte carries a type of antibody or protein that chemically fits specific antigens. The lymphocyte reproduces quickly, making many antibodies, when in contact with the antigen. Antibodies are large protein molecules that destroy pathogens.

3 Divide to make many lymphocytes

The antibodies neutralise the antigen by binding to them and destroying them or clumping them together to allow the phagocytes to ingest them easily. They also bind to the pathogen and release chemical signals that attract more phagocytes. Antitoxin can also be released, that binds to the toxins and prevents them damaging the body. Phagocytes engulf microorganisms as shown in the diagram.

7 Destroys the bacterium

Test Yourself: Define the terms antibiotic, antigen,

4 Some remain in ‘memory’ 5 Antibody made 6 Joins with antigen

1

Phagocyte 2 Lobed nucleus

antibody and anti-toxin. Term

Bacteria

Finger-like process

Definition

Antibiotic

3 Enzymes for digestion

Antigen

Ingested bacteria in food vacuole

Bacteria destroyed

Antibody

Remember Anti-toxin

96

Antifungal creams and powders are used to treat fungal infections, for example ringworm and scabies. Benzyl benzoate ointment is the main treatment for scabies.

Disease and Impact on Humans

Section D

Types of Immunity

Reviewed

The immune system protects the body from diseases.

Revised

Mastered

Remember

Antibodies either burst the cells or attract white blood cells (phagocytes) that engulf and destroy the microorganisms.

The microorganisms causing the disease have antigens on their surfaces. When these unknown antigens enter the body then antibodies are produced.

Artificial immunity is when we fool the body into thinking we have an infection and it produces antibodies. This is done through vaccination. A vaccine contains weakened or killed pathogens. The body recognises the antigens on the pathogens and produces antibodies. This prepares the body in case How the body responds to infections – natural immunity a person is infected later with the actual disease. Some viruses, such as the HIV (AIDS) virus, attack the immune system. This opens the infected person up to many secondary diseases, commonly pneumonia.

Test Yourself: 1.

2.

Explain how antibodies protect the body from infections. Explain artificial immunity.

m u r se y d o ib t n A

Secondary

Primary 0

10

20

100 1 10 1 20

New pathogen

Previously encountered pathogen

Days

Reviewed Revised Mastered Immunity/Immunisation; Vaccine/Vaccination Immunity is the body’s resistance to Artificial passive immunity is a result of antibodies being injected directly into a person suffering from a disease. The fluid injected is called the antiserum. The body is not stimulated to Remember produce its own antibodies. Most vaccines are weak The action is almost cultures that can cause a mild immediate but short-lived. form of the disease.

Test Yourself: Compare the vaccine against antiserum injections. Give ONE advantage and ONE disadvantage of each.

suffering from disease

1. Natural innate active immunity

inborn immunity

2. Natural innate passive immunity

passed from mother to fetus and baby

3. Natural acquired active immunity

antibodies produced by a natural infection, e.g. TB

4. Artificial active acquired immunity

antibodies produced by a vaccine, e.g. TB vaccine

5. Artificial passive serum injection contains acquired immunity antibody, e.g. antiserum to snake bites and tetanus

Vaccine g iv es a ctiv e i mm u nity few wee ks be for e an tib ody le vel is hi gh long l a s ti ng , e .g . a nt i T B

Antiserum g i ve s p a s si ve im m u n i ty imm ediat e hi gh le vel of an tib ody s h o rt l a s t i n g , e . g . a n t i t e t a n u s

cultures of organisms made non-toxic extracted from blood plasma after by heat or antiseptics immunisation

97

Disease and Impact on Humans

Section D

Use and Misuse of Drugs A drug is a substance that affects the way the body or mind works.

alcohol

non-prescription Drugs including painkillers can drugs improve the quality of life of people who are ill. Prescription hormone injections drugs include sedatives and antibiotics and save lives or prevent serious damage to the body tissues.

Reviewed

Revised

Mastered

prescription drugs steroids

Types of drugs

diet pills illegal drugs

Some people take drugs – for example, cocaine, LSD, heroin, ecstasy, alcohol or marijuana – to make them feel better, but these often act as depressants and make the user feel worse. Often these people become dependent or addicted to these drugs. Drugs can improve athletic performance and this List THREE categories of drug. is one reason why they are banned in sport. Drugs can also act as stimulants or cause hallucinations. A person taking drugs can suffer from depression, heart disease and liver failure.

Test Yourself:

Social Effects of Drug Misuse

Reviewed

Revised

Mastered

Using illegal or non-prescription drugs can lead to addiction. Drug use also leads to breakdown of families, inability to work and increases in crime. To help them to cheat, athletes sometimes also use blood doping illegally. This is when blood is taken from an athlete and stored. It is later added before a competition so that the athlete has more red blood cells.

Test Yourself:The graph shows the harm out of 100 that individual recreational or non-prescription drugs cause. Which of the drugs causes the most harm? Can you explain this?

98

Harm caused by drugs

*With a maximum possible harm rating of 100 0 10 20 30 40 50 60 70 Alcohol Heroin Crack cocaine Methamphetamine Cocaine Tobacco Amphetamine Cannabis GHB Benzodiazepenes Ketamine Methadone Mephedrone Butane Qat/Khat Anabolic steroids Ecstasy LSD Buprenorphine Mushrooms

Harm to others Harm to users

80

Disease and Impact on Humans

Section D

Use Tables, Charts and Graphs to Represent Data on Disease

Reviewed

Revised

Mastered

Test Yourself: 1.

Global asthma rates

What does this information tell us about the distribution of asthma sufferers?

2. Why might this

Percentage of the population affected 10.1+ 7.6–10.0 5.1–7.5 2.5–5.0 0–2.5 No standardised data available

be the case?

Test Yourself: Interpret the data in Test Yourself: The graph shows three antibiotic resistant

the graph. Antibody concentration after two injections of antiserum – passive immunity

diseases. Explain the patterns or trends in the graph. Increase in antibiotic resistance d o lo b e h t

60% 50% ce n a st si e R %

MRSA VRE FQRP

40%

n i s e i d o ib t n a a i r e h t h p i d f o

30% 20% 10% 0%

n io t a r t

1981

1985

1989

1993

1997

−10% Source: Centers for Disease Control and Prevention

2001

n e c n o C

0 10 1st injection

20 30 40 2nd injection Days

50

Revision Tip: Make revision cards with the key words and terms for this unit. Write a definition on a sticky note from memory. Check the definition in your notes or textbook. Write a correct definition on the revision card.

99

Disease and Impact on Humans

Section D

Test Questions for Section D 1. Which of the following symptoms occur during an (a) (b) (c) (d)

asthmatic attack? shortness of breath, wheezing, fainting sneezing, coughing, vomiting shock, coughing, shortness of breath too breathless to eat, sleep or speak

2. Which of the following vectors causes malaria? (a) Anopheles mosquito (b) bats (c) rats (d) Aedes aegypti mosquito 3. This is NOT a factor to define good health according to the World Health Organization:

(a) physical wellbeing (b) mental wellbeing (c) the absence of disease (d) social wellbeing

4. Mosquitoes can be controlled using the following method:

(a) washing surfaces (b) opening windows (c) removing standing water (d) personal hygiene 5. The definition for antigens is: (a) substances that kill or prevent the growth of bacteria

(b) large molecules – often protein but some can be carbohydrate – that stimulate the lymphocytes to make and release antibodies (c) large protein molecules that destroy pathogens (d) antibodies to control specific toxins that act as antigens.

6. (a) (i) Define the term ‘antibiotic’ as used in the pharmaceutical industry (ii) Give one example of an antibiotic.

(1 mark) (1 mark)

(b) Explain why antibiotics should be prescribed by a physician. (2 marks) (c) Explain why a physician would not prescribe antibiotics for the flu. (2 marks) 7. (a) Dengue fever is a common disease. Name the vector. (1 mark) (b) What type of infection is this? (1 mark) (c) Explain how the disease can be controlled. (2 marks) [10 marks]

100

Impact of Health Practices on the Environment

Section E

Unit

1

Impact of Health Practices on the Environment

Concept Map Causes of air and water pollution

The effects of pollutants on humans and the environment

Methods of controlling pollution Pollutants

IMPACT OF HEALTH PRACTICES ON THE ENVIRONMENT

Solid waste

Testing for bacteria in water

Water cycle

The impact of humans on water supplies

Large-scale water purification

Proper and improper sewage disposal Pit latrines

Self Check

Tick the box that shows how confident you feel

Yes

Maybe

No

I can identify pollutants in the environment, and discuss the causes of air and water pollution. I know the effects of pollutants on human beings and the environment. I can explain the methods of controlling pollution. I can describe the water cycle. I know how to test for bacteria in water. I can describe simple and large-scale methods of purifying water. I can discuss the impact human beings have on water supplies. I can distinguish between proper and improper sewage disposal. I can explain why the siting of pit latrines is important in the Caribbean. I can evaluate the impact of solid waste on the environment. 101

Impact of Health Practices on the Environment

Section E

Identifying Pollutants in the Environment

Reviewed

Revised

Mastered

Pollution is the introduction of a contaminant or pollutant to the environment that can cause harm or discomfort to humans or other organisms living in it. One of the major causes of pollution on Earth is the burning of fossil fuels. We also burn fuels to power cars and other vehicles, which can cause lead pollution. Factories can also burn fossil fuels to produce electricity or run machinery, which can result in the production of industrial pollutants. In addition, smoke particles and asbestos can pollute the air. Smogs occur when high concentrations of smoke and sulphur dioxide are present in the atmosphere. Photochemical smog occurs when sunlight causes chemical reactions with pollutants from exhaust fumes, resulting in ozone (O 3).

Test Yourself: List the gases produced as a result of burning fossil fuels.

Air and Water Pollution

Reviewed

Revised

Mastered

We pollute the water supply with gases and solid particles. When fuels burn, the gases dissolve and produce acid rain. Farming can pollute the water when chemicals that become agricultural pollutants are spread on the land to make crops grow. Bacteria can pollute the water from sewage and the disposal of refuge in landfill sites.

Test Yourself: Review your learning by completing the table below. Pollutant

Example 1

Example 2

Affecting water or air or both

A g r i c u l t u ra l D om e s tic I n du s t ri a l

The Effects of Pollutants on Human Beings and the Environment The effects of pollution on human beings

Reviewed

Revised

Mastered

Health effects

Premature deaths due to PM10’NO2 Premature deaths due to CO and the environment are increasing annually. Bronchitis and related conditions Acute respiratory hospitalisations Acute cardiac hospitalisations Cancer Restricted activity days Analyse the data. Can 0 you see any trends or relationships between them?

Test Yourself:

102

20

40 60 Percentage

80

Household

Vehicle

Industrial

100

Impact of Health Practices on the Environment

Section E

Methods of Controlling Pollution

Reviewed

Revised

Mastered

We could reduce our carbon footprint by using public transport and walking rather than driving places in cars. To reduce agricultural pollutants, farmers would have to change their methods of farming. Organic farmers claim that they do not use chemicals in the growing of their products.

Test Yourself: 1.

Fill in the blanks in the table. Pollutant

Origin

Damage

Prevention

1 Particles – smoke, domestic fires, industrial lung damage, silicosis, block plantsmokeless fuel, Clean Air e.g. soot and asbestos combustion, mining, brake stomata, bronchitis Acts, better chimneys linings 2 Sul ph ur diox ide 3 C a rb on m on ox i d e

fu el comb us ti on , e .g . c oa l, oil, petrol ca r e x h a u s t cigarette smoking

4 C a r b o n di ox i de

a l l f o rm s o f c o m b u s t i o n

5 H ydr oc a r b o n s

c a r e x h a u st , i n du s t ri a l waste

6 Ox ides of ni tr og en 7 O zon e

‘reducing smog’ lung damage, bronchitis, forms acid rain

remove sulphur from fuels and flue gases

forms carboxyhaemoglobin catalysts or heat reactors preventing oxygen uptake by blood, in car exhausts loss of consciousness and death ‘ g r e e n h o u s e e f f e c t ’ of o v e rh e a t i n g

fi n d ot h e r s o u rc e s of energy

photochemical smog damages catalysts or heat reactors plants, rubber, clothing, in car exhausts, modify eye irritation, reduces visibility car engines

ca r ex ha us t, in du st ri al combustion c om b i n a t i o n of h y d r o c a rb on s with nitrogen dioxide

8 Le a d

p e t ro l – c a r e x h a u s t

9 Ta r a n d s m ok e

c i g a r e t t e s m ok i n g

10 Pathogens, e.g. virus, bacteria

infected person sneeze droplets

t o x i c t o t h e n e rv o u s s yst e m de a t h – l u n g c a n c e r, b r on c h i t i s , coronary disease, etc. respiratory system, influenza – mucous membrane

l e a d - f r e e p e t r ol a n d modify engines no smoking good ventilation

2. Discuss the impact of people using cars less.

The Water Cycle

Reviewed

Revised

Mastered

The Water Cycle

Test Yourself: Label the diagram of the water cycle. Try to add the labels

2 1

from memory first and then check if they are correct.

Remember

3

Water is a natural resource

4 Percolation

Run off

Groundwater flow

In total, 97% of the that is recycled. Earth’s water makes up the oceans and seas and 2% exists as ice. Only 1% is fresh water on land or in air. The water is continuously recycled in a natural process known as the water cycle.

103

Section E

Impact of Health Practices on the Environment

Simple Ways of Purifying Water in the Home

Reviewed

Revised

Mastered

About two thirds of the Earth is covered in water. The majority of this cannot be drunk because it is contaminated with salts and microbes. Water can be purified in the home. Simply boiling water can prevent the growth of bacteria that are polluting the water. Filtration systems can be constructed from cones of leaves or bark. These can be lined with sand, charcoal, grass or gravel. When the water soaks through, pollutants can be absorbed, leaving purer water to drip out of the bottom. Filtering systems can be purchased. These can include silver particles that break down pesticides and prevent bacteria growing, carbon or charcoal absorb contaminants like chlorine. Distillation can make saltwater pure. Salt water is heated and the vapour condensed to produce pure water. Adding chlorine or bleach to water can kill microorganisms. ■

■

■

■

Remember Microorganisms prefer similar conditions to humans and other living things.

Test Yourself: Explain why this method of purifying water would cause pollution.

Testing Water for Bacteria

Reviewed

Revised

Mastered

Most bacteria can only be seen using a microscope, but they can make humans and other living organisms ill or even result in death. Therefore it is very important to test water for bacteria. Agar plates are also used to test for bacteria. Water is mixed with the agar and put on a plate. The agar provides a good environment to encourage any bacteria present to grow. The agar plate will be incubated to provide a constant ideal temperature. The agar plate is then examined to see if any colonies of bacteria are present. It is possible to see colonies of bacteria without a microscope as they are clustered together.

Test Yourself: Explain why bacteria are grown on agar plates.

104

Remember The microorganisms have perfect conditions to grow on the agar plate.

Impact of Health Practices on the Environment

Section E

Large-scale Water Purification Screening

Reviewed

1.

Sewer pipes 2

Inlet

Effluent

3 Grit pit: slow passage of sewage allows grit to settle

Sludge pump Outlet

Sedimentation

Aeration

Biological filter: stones covered with aerobic bacteria and protozoa which feed on the organic matter Effluent in

4

4

either

or Percolating Aeration filter tank

Sprinkler

Sludge removed to sludge digester making methane

5

Remember Only 1% of water on Earth is pure enough to drink. We have to reuse it constantly.

or activated sludge Side view aeration tank Mixing paddle

5 Air

Coke bed with microorganism film Effluent disposal

3.

What is the purpose of adding oxygen? Why is the sludge fermented? What is the function of the chlorine?

Sedimentation tank: solid material settles as sludge

Sludge: fermented to make methane gas or dried for fertiliser Either biological filter Side view percolating filter

2.

2 Screen traps paper, sticks and other large objects

3

Side view sedimentation tank

Mastered

Test Yourself:

1 Mechanical scraper removes material for burning

Revised

Effluent out Further settling until water is pure

Compressed air supplies oxygen 6

6

for aerobic organic bacteria matter which rapidly decompose

Reviewed The Impact of Human Activities on Water Supplies

Revised

Mastered

If you compare this with other people you will see that the human activities that impact on water usage vary considerably. We pollute the water with contaminants and we waste water. Dripping taps and leaky pipes waste water at an alarming rate. The table below shows annual household usage of water. Number of people in the home

Annual water usage in cubic metres Low

Average

High

1

45

66

100

2

55

110

136

3

82

136

175

4

110

165

210

5

136

182

245

6

155

206

265

Test Yourself: 1.

2. 3.

What do you use water for? List as many uses as you know. As the number of people doubles, does the usage of water double? Can you explain this?

105

Section E

Impact of Health Practices on the Environment

Contaminated Water

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Many infections are carried by water and are known as water-borne diseases. They can infect humans and other organisms directly when the water is ingested or carried by flies and insects. The water-borne diseases are highly infectious and often life-threatening. Food prepared in contaminated water can also lead to the ingestion of pathogens. Bacterial diseases include typhoid, paratyphoid dysentery, hepatitis and cholera Viral diseases include poliomyelitis Protozoal infections include amoebic dysentery These contaminate the water supply through faecal matter. ■

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Deaths from unsafe water, sanitation and hygiene

WSH deaths/million 0–10 10–50 50–100 100–200 200–500 500–1050 No data

The map shows the number of deaths from contaminated water.

Test Yourself: Why are there more deaths in some countries than others?

106

Impact of Health Practices on the Environment

Section E

Proper and Improper Sewage Disposal

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Sewage is water-carried waste. This can be from industry, domestic settings or agriculture. As the population increases, there is a greater demand to treat sewage effectively. In the Caribbean between 1995 and 2004 there was a bigger improvement in sanitation than anywhere else in the world, according to the World Health Organization. However, according to a 2004 study, in Saint Lucia, for example, only 13% of the population is connected to the sewage system. There is an increased need to dispose of sewage quickly and efficiently. These images are of examples of improper and proper sewage disposal. Sewage inlet

Concrete cover

Mosquito gauze

Concrete cover Ground level

Scum

Broken stones

Sludge

Decomposition by anaerobic bacteria

2 m minimum

Soakaway pit

Decomposition by aerobic bacteria

Test Yourself: 1.

Consider each producer of sewage and then think about how it is generated and how it gets into the water table. Complete the table. Examples

How does it combine with water?

D om e s tic Ag ric u lt u re In du stry

2. Explain the impact of improper sewage disposal practices. 3. The increase in nutrients from improperly treated sewage can also cause ‘blooms’ of seaweed. In June 2015, Barbados witnessed a bloom of sargassum seaweed and this was termed a natural disaster. Explain how improper sewage disposal resulted in the sargassum seaweed disaster. 107

Section E

Impact of Health Practices on the Environment

Treatment of Sewage: Biological Filters/ Activated Sludge There are many methods for the proper treatment of sewage. Biological filters can be used in the treatment of some forms of sewage. One is settled wastewater that has gone through a process of sedimentation and screened raw sewage. The picture demonstrates the process. Activated sludge is another method of treating sewage, where microorganisms are used to break down sewage. The microorganisms are kept in suspension and aerated. They come into contact with the sewage in a reactor and form activated sludge. Solid waste is then separated from the sludge. The sludge is Waste recycled and used at the beginning of the process. water This outlines the basic activated sludge process, but the steps can vary. There are activated sludge treatment works in the Caribbean where there can be a demand to remove waste, but they are not always efficient.

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Distributor Filter media Treated effluent Sludge draw off point

Settlement zone for wastewater

Activated sludge process

Clarifier Aeration tank/reactor Treated effluent Air Recycled solids/bacteria

Test Yourself: Explain the purpose of the excavated soil.

Microorganisms need warmth, food and water to reproduce.

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Revised

Tight-fitting lid Latrine slab of wood or concrete at least 0.15 m above ground level with hole, preferably covered when not in use

Soil residue decomposes and accumulates

Mastered Latrine shelter designed and built with appropriate local materials

Air vent

Pit lining extends at least 1.0 m below ground level (deeper if soil is unstable)

108

Waste solids

Remember

Pit Latrine

these can contaminate the soil and water table over time.

Mastered

Package BF plant

Test Yourself: Why is the sludge aerated?

The pit latrine is another method of disposing of human faeces. It consists of a hole in the ground. The faeces are excreted into the hole and left to decompose over time. This works most efficiently if water is not used in the process. Disinfectants and chemicals should NOT be used as

Revised

Mound of excavated soil to seal pit lining and to prevent flooding of pit by surface water Foot-rest Gas escapes into the atmosphere

Pit should be at least 2 m deep and 1 to 1.5 m round or square Liquids percolate into the soil

Impact of Health Practices on the Environment

Section E

Why the Siting of Pit Latrines Is Important

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Pit latrines can cause health hazards if they are not sited correctly. If they are constructed correctly they can last a family of six up to five years. There are several recommendations for the siting of the latrine. They should be constructed at least 30 metres from the nearest water source. Water sources include wells, rivers and streams. They should be at least 6 metres from any houses. This means that residents can use the latrine easily in bad weather or when it is dark.

Test Yourself: far should the pit latrine be sited from the home? 1. How 2. Explain why this is recommended.

It is essential that flies be controlled. Covering the hole in the pit after use and keeping the door of the latrine closed can do this. Cleaning products can help to control the flies but they must be kept away from the waste in the bottom of the pit.

The Use of Pit Latrines in the Caribbean

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It is estimated by the World Health Organization that 1.77 billion pit latrines are used throughout the world. As the population increases, the number of pit latrines is likely to increase also. They continue to be the cheapest and easiest method of disposing of human excrement to date.

Test Yourself: 1.

Look at the data in the table below. These data were collected in 1981. Do you think this information is reliable? Island G re n a da SLtu c i a SV t i n ce n t B a rb a do s

% of total households using pit latrines 6 1 .8 2 5 1 .4 0 6 8 .6 6 5 2 .2 2

2. Using your knowledge and experience, do you think the data will be different now? 3. Suggest why the pit latrine should be constructed at least 30 metres from a water supply. 4. Why is it important to control flies? 5. Why is the use of pit latrines an indicator of poverty?

Remember A pathogen is a microorganism that can cause disease.

109

Impact of Health Practices on the Environment

Section E

Methods of Domestic Refuse Disposal

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Americans produce more waste per year than any other country: 220 million tons of it. The removal of waste is the removal of garbage and sewage safely. This includes transporting it efficiently and safely from the place of production to the destination of disposal. Landfill is still the main source of disposal throughout the world. This is the cheapest method of disposal but it has many disadvantages. These include the production of methane gas. Incineration is also very common. By burning the waste, the volume is reduced to 20% of the srcinal. The end product, mostly ash, is disposed of in landfills. Gases are produced in this process and are released into the atmosphere. Recycling is another method of disposing of waste. Waste is made into new products. This can result in toxic chemicals and gases and is sometimes expensive to manage.

Test Yourself: Evaluate the methods of waste management in the table. Methodofwastemanagement

Benefits

Drawbacks

Landfill Incineration Recycling

The Operation of Landfill

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Look at the image of the landfill site. The process shown is bullet pointed below. The waste is collected by a refuse truck The truck transports the refuse to the landfill site. This is often several miles away The landfill site is prepared by using industrial machines to dig out the ground The refuse truck deposits the waste. Destruction of habitats. Water and soil is polluted ■

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■

■

■

■

■

■

The industrial machines compact the waste The truck returns to collect more waste The landfill site is covered over Another landfill site is dug out.

Test Yourself: For each of these steps, consider the impact this has on human health and the environment.

110

Mastered

Section E

Impact of Health Practices on the Environment

Function of Landfill

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Landfills use vast areas of land. This land could be used for other purposes, for example agriculture, building homes, recreation and conservation. When the land is used as landfill sites it is likely that habitats are damaged and often destroyed permanently.

Remember

The Caribbean islands depend on their beauty to attract over 20 million tourists every year. This produces additional waste.

Most of the waste that goes to landfill could be recycled.

It was estimated that 27 000 to 945 000 tons of waste was generated in the Caribbean in 2005. At the fourth annual coastal clean-up conference held in Jamaica in 2008 it was suggested that 6 781 537 items of garbage were collected on coastal areas. Landfill usage has reduced in the USA and most of Europe. In 1970 there were approximately 20 000 sites in the USA. In 1998 this had reduced to 2000. It is estimated that in the Caribbean landfill continues to be the most common form of waste management. Open dumps where the waste is left uncovered are less common and managed upgraded sites have replaced them. Waste reduction is the most effective method of managing waste and protecting the environment.

Test Yourself: Why is it important for the Caribbean to maintain its aesthetic appeal?

The Impact of Solid Waste on the Environment

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Solid waste has a negative impact on the environment and health. This is summarised in the table below. Impact linked to solid waste Hum an hea lth

Neu rologi cal d ise ase , canc er, ast hma a nd oth er related lung disease, chemical poisoning, low birth weight, congenital malformations, nausea, vomiting, mercury toxicity, diarrhoea, intestinal disorders, plague

Aqu atic

In c r e a s e d l e v e l of m e r c u ry i n fi s h , p l a s ti c s trapping and injuring wildlife, degraded soil quality, degraded water quality, increased algal populations

Environment

Flooding due to obstructed run-off, methane gas, greenhouse gases, change in climate, depletion of the ozone layer

Test Yourself: List ONE negative

impact of solid waste on human health.

111

Impact of Health Practices on the Environment

Section E

Reduce, Reuse and Recycle

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You should be familiar with the phrase ‘reduce, reuse and recycle materials’. Think about all the items that you can reuse. The difficulty is in reducing materials. Reduce Reuse, feed, compost

Over the next few days think about any materials that you could avoid using or at least reduce their use. Use the triangle on the left to help you.

Recycle Recover

Test Yourself:

Remember

Dispose

What materials do you recycle? 1. 2. How could you reduce your use of plastic?

Composting is a method of reusing materials.

Biodegradable and Non-Biodegradable Biodegradable means that a material is

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Mastered

Biodegradable materials:

capable of decaying with the action of living organisms. As you have learned, plastic is a major component of solid waste in the world. This impacts on the Caribbean environment when it is not disposed of properly. The introduction of

Fruits Hair biodegradable plastics is a positive movement to reduce this problem. The plastics degrade NON-BIODEGRADABLE over time, reducing the amount of plastic at a given time. The United Nations claims that biodegradable plastics will still have a negative impact on the environment as the volume will remain the same. It also argues that temperatures must remain high for a considerable length of time for the plastics to fully degrade and not cause Plastic bags Hardware a threat to the environment. It is arguable that they are still better for the environment than nonbiodegradable materials that do not degrade over time.

Papers MATERIALS:

Bottles

Test Yourself: Give ONE reason why the United Nations does NOT think biodegradable carrier bags will have an impact on the environment.

112

Section E

Impact of Health Practices on the Environment

Use Table, Charts and Graphs to Represent Data

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Deaths from urban air pollution

UAP deaths/million 0–30 30–60 60–100 100–150 150–200 200–230 No data

Test Yourself: you find any patterns or trends between the data? 1. Can Why do you think this is? 2. 3. What can we do to change these data? 4. Look at the data in the table.Which would be the most appropriate method of displaying this data? Display the data in your method of choice in the space below.

Island G re n a da

% of total households using pit latrines 6 1 .8 2

StL u c i a

5 1 .4 0

S tVi n c e n t

6 8 .6 6

B a rb a do s

5 2 .2 2

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Section E

Impact of Health Practices on the Environment

Test Questions for Section E 1. Which of the following could lead to (a) (b) (c) (d)

eutrophication? Releasing disinfectant into the water table Releasing pesticide into the water table Releasing fertiliser into the water table Releasing antiseptic into the water table

2. Which of the following statements is not true (a) (b) (c) (d)

about pit latrines? They should be placed 30 metres from the nearest water source They should be placed 10 metres from the nearest water source They should be placed 3 metres from the nearest water source They should be placed 1 metre from the nearest water source

3. Which of the following statements is TRUE about pit latrines?

(a) They should be placed 13 metres from the home (b) They should be placed 16 metres from the home (c) They should be placed 6 metres from the home (d) They should be placed 3 metres from the home 4. Which of the following is NOT a result of inappropriate disposal of solid waste?

(a) greenhouse gases (b) smog (c) climate change (d) flooding due to obstructed run-off 5. Water vapour is changed into water by the process of: (a) condensation (b) precipitation (c) evaporation (d) transpiration

6. (a) Define the terms: (i) sewage (ii) biodegradable

(1 mark) (1 mark)

(b) Choose the correct term for each of the following actions: reuse, recycle, reduce. (i) Using a fabric shopping bag every time you shop is an example of (ii) Placing empty bottles in a bottle bank

(1 mark) (1 mark)

7. Describe how a landfill is made and comment on the impact this has on the environment.

(6 marks) [10 marks]

114

Paper 1 Practice Questions

Paper 1 Practice Questions 1. A major advantage of sexual reproduction is that it: (a) only requires one parent (b) requires less energy (c) produces useful clones of the parents (d) produces genetically different offspring

2. An example of a genetically inherited disease is: (a) AIDS (b) measles sickle cell anaemia (c) (d) tuberculosis

6. An enzyme that catalyses the breakdown of starch to maltose is called:

(a) pepsin (b) amylase (c) maltase (d) lipase

7. Muscle pairs working together to move limbs are known as: heterozygous (a) (b) alleles (c) antagonistic (d) allotropic

3. In a food chain comprising grass, cows and humans, the grass is the:

(a) producer (b) primary consumer (c) secondary consumer (d) tertiary consumer

4. The organelles within which the biochemical processes of respiration and energy production take place are known as the: (a) chloroplasts nucleus (b) cell membranes (c) (d) mitochondria

8. The process of cell division that results in a halving (a) (b) (c) (d)

of the chromosome number and the production of gametes is known as: mitosis germination sex determination meiosis

9. Other than abstinence, the most effective protection against sexually transmitted disease is: pill (a) the (b) wear a condom (c) rhythm method (d) tubal ligation

5. The movement of water from a less concentrated (a) (b) (c) (d)

solution to a more concentrated solution across a partially permeable membrane is called: active transport osmosis diffusion transpiration

10. It is important to locate a pit latrine: (a) as near to the house as possible (b) near a river so waste can wash away (c) downhill from a water source (d) uphill from a water source

115

Paper 2 Practice Questions

Paper 2 Practice Questions 1. (a) The diagram shows a picture of the heart. Complete the table by naming

A

the parts labelled A, B ,C, D and E. Describe the function of each. Label

Name

B

Function

A B E

C D

C

D

E

(5 marks)

(b) Describe the role of blood in protecting the body from disease.

(3 marks)

2. (a) Use the equation to calculate the BMI for the four people in the table. BMI =

weight in kilograms (height in metres)2

Person

Height(metres)

Weight(kg)

A

1 .6

55

B

1 .2

50

C

1 .5

65

D

1 .7

50

BMI

(4 marks)

(b) Use the chart below to determine which category each person falls into. BMI less than 18.50

Underweight

BMI 18.50–24.99

Healthy weight

BMI 25.00–29.99

Overweight

BMI 30 or more

Obese

Person A = (1 mark) Person B = (1 mark) Person C = (1 mark) Person D = (1 mark)

(c) Write down TWO health problems that can be caused by obesity. (1 mark) (1 mark) 116

Answers to Test Yourself Questions

Answers to Test Yourself Questions Section A The Characteristics of Living Organisms:Nutrition – petrol; excretion – exhaust gases; irritability – voice from satnav; respiration – air intake; movement – kinetic energy. The Structures of Unspecialised Plant, Animal and Bacterial Cells:Bacterial cells have a cell membrane, flagella, rings of chromosomal DNA and plasmid DNA. The Functions of Cell Structures: 1. nucleus: contains the genetic material of the cell; cell membrane: controls exchange of materials;cytoplasm: where most of the cell’s chemical reactions occur;chloroplast: site where photosynthesis takes place;mitochondria: site where energy is produced during respiration.2. Nucleus, cytoplasm, cell membrane, mitochondria.3. Mitochondria, cytoplasm.4. Cell membrane. Selected Cells in the Human Body:1. Epithelial cell: cilia create a large surface area. 2. Egg cell: haploid number of chromosomes. 3. Sperm cell: tail helps it to move to the egg. 4. Muscle cell: long cell to make contact with others around the body.

Osmosis and Active Transport:1. Active transport allows essential chemicals to enter cells against a concentration gradient. 2. Keeps our blood clean and helps plants to absorb water in the root hairs. The Process of Photosynthesis:1. Chloroplast. 2. Water is split and produces oxygen; the carbon dioxide is

reduced to carbohydrate.3. Autotrophic. Investigating the Effect of Light and Chlorophyll on Starch Production:1. Increasing the temperature will increase the rate of photosynthesis until it reaches a maximum and then the rate will fall. 2. Increasing the rate of carbon dioxide increases photosynthesis so that the plants will be bigger and the yield of crop will be greater. 3. There is a decreasing intensity of light. Plants as Producers:Green plants fix the energy from the sun in a process of photosynthesis. When other animals eat the plants, they consume the energy. When the meat from that animal is consumed, it is the energy from photosynthesis.

The Importance of Cell Specialisation in Humans: 1. (Top to bottom) epithelial, connects body organs, muscle, conducts impulses. 2. They have no special function but may develop organelles for a particular function later. 3. Humans are multicellular so individual cells carry out

Food Chains: TY#1: Producer – flower; consumer – grasshopper, mouse and owl. TY#2: 1. Producer – flower, consumer – three from caterpillar, grasshopper, ladybug, mouse, dragonfly, bird, owl. 2. E.g. flower-aphid-ladybug-owl, flower-grasshopper-bird-owl. TY#3: 1. Energy is lost at each

different jobs and are specialised to do this.

step of a food chain and as a result they are short. 2. They can photosynthesise. 3. An omnivore eats both plants and animals; a herbivore eats plants.

Distinguish Between Osmosis and Diffusion:1. They all move across a membrane. 2. The concentration gradient is different and energy is needed in active transport. Diffusion and Cell Membranes:The gas particles carrying the scent move from the highconcentration when it issprayed into the lower concentration of scent in the room or space.

Carbon, Water and Nitrogen Cycles:TY#1: 1, combustion; 2, photosyntheis. TY#2: When organisms die they are broken down into smaller compounds or decomposed by microorganisms known as decomposers. TY#3: Nitrates in the soil are absorbed by the roots of plants.

Section B Major Nutrients and Their Sources:1. Amino acids. 2. Insulation, energy, cell membranes, solvent for vitamins A and D.

The Role of Dietary Fibre in the Body:1. Prevent constipation, stimulate peristalsis, reduce the risk of colon cancer. 2. These foods do not stimulate peristalsis.

Classify Vitamins as Fat- or Water-Soluble:B, C – water-soluble, A, D, E, K – fat-soluble.

Causes and Effects of Constipation and Diarrhoea: 1. Any two from the bullet points. 2. It reduces the chances of microorganisms being passed from one person to another.

The Main Functions and Sources of Some Vitamins and Minerals:1. Formation of bones and teeth, muscle contraction and blood clotting. 2. Eggs, meat, milk, cheese, vegetables, squash and carrots. Important for healthy teeth, eyes and skin. Cause, Symptoms and Treatment of Deficiency Diseases: 1. Night blindness, beriberi, scurvy, rickets. 2. Fats and carbohydrates. Food Tests: 1. Biuret’s reagent.2. Blue-black. Functions of Water in the Body:Chemical reactions take place in solution and materials can be transported when dissolved.

Explain What Is Meant by a Balanced Diet:1. Any 3 from staples, legumes, food from animals, fruits, vegetables, and oils and fats. Also accept any 3 from carbohydrates, fats, protein, vitamins, water, and minerals and trace elements. 2. Needed for energy release, metabolism, bone health, blood health, immune function and eyesight. 3. Structure (including muscle) , transport, communication, enzymes, protection and fuel. Effects of Malnutrition on the Human Body:1. An unbalanced diet caused by either eating too little or too much food. 2. Arteries can be blocked and increase blood pressure.

117

Answers to Test Yourself Questions

Determining BMI:1. Normal range. 2. 31.1 and obese.

increase the surface area and have a permeable respiratory surface to allow gases to be in close proximity to the blood Using Tables, Charts and Graphs to Represent supply.2. They keep dirt and other particles out of the lungs. Nutrition Data:1. Label 2. 2. Label 1. 3. Vitamins B, D, E and K. Mechanism of Breathing:TY#1: Inhalation: diaphragm Types of Infant and Adult Teeth and Their and ribs expand so air pressure in lungs decreases; TY#2: 1. Roles: 1. Incisors, canines and molars. 2. They start to fall By moving up and down it increases/decrease air pressure out and be replaced by adult teeth. in the chest cavity; 2. Inhaled air has more O 2 and less water Importance of Teeth in Digestion:1. They are hard vapour and CO2 than exhaled air. and smooth. 2. It forms food into smaller pieces so it is easier Factors Affecting Rate of Breathing:1. The medulla to swallow, can be mixed with salivary enzymes and increases region. 2. Chemoreceptors in the aorta and carotid arteries. the surface area so that enzymes can act more efficiently. The Concept of Vital Capacity: 1. The amount of air Structure and Functionof a Typical Tooth:1. (Top to bottom) enamel, dentine, pulp, cementum and root end breathed in and out during quiet, normal breathing.2. The air left in the lungs that cannot be removed by expiration. opening.2. Enamel is hard and smooth to protect the tooth and form a hard biting surface. Dentine acts as a shock absorber. Distinguishing Between Gaseous Exchange and Breathing: 1. Air will move from a region of high pressure to a Relating Tooth Structure to Function:1. They have region of low pressure. If the chest cavity has lower pressure than a large flat surface with ridges for grinding. 2. These pointed the atmosphere, air will enter thelungs.2. Gaseous exchange. teeth are adapted for gripping and tearing flesh. Gaseous Exchange Surfaces:1. Moves from higher The Causes of Tooth Decay:1. Sugary foods and acidic concentration in lungs to lower concentration in the blood drinks. 2. A sticky substance on teeth that contains bacteria. along a concentration gradient; 2. Opposite of the above: The bacteria break down sugars to make acids. concentration in blood higher than the lungs; 3. Gills have a The Process of Tooth Decay:To remove plaque and large surface area and a rich blood supply. food particles to reduce tooth decay. Aerobic and Anaerobic Respiration:1. Role of Enzymes:1. The enzyme holds the substrate in such Aerobic Anaerobic respiration respiration a way that the bonds are more easily broken. 2. No, enzymes act as catalysts and are notused up during the reactions. Glucose N otc o mpl e te C o m pl e t e The Production of Enzymes:1. Salivary amylase in

breakdown Oxyg en

the salivary glands of the mouth, amylase in the pancreas and maltase in the smallpancreatic intestine. 2. Trypsin.

Energ y relea s ed

N o tn e e d e d S m a ll a m ounts

Need ed L a r g e a mou n t s

E nd pr od uc ts An im al s = la ct ic ac id ; CO2 + H2O Effects of Temperature and pH on Enzymes:1. Plants = carbon dioxide Enzymes have an optimal temperature. Enzyme action and ethanol increases as temperature increases but the enzymes denature if the temperature is too high;2. It is effective in the stomach 2. Lactic acid causes cramps; 3. CO2 (rising) as alcohol and is therefore able to catalyse well at the pH of the stomach. produced; 4. The process is not complete: some C-C bonds are not broken. The Digestive System:1. Amylase: breaks down starch, Roles of ADP and ATP in Energy Transfer:1. Lipase breaks down lipids (fattyacids);2. Churns food, adds Energy and phosphate. 2. Energy can be captured, digestive enzymes, adds acid, some substance are absorbed here; 3. Addition of digestive enzymes, bile’s added to split fats,.transported and used when and where it is needed.

Further down in the small intestine, the nutrients are absorbed Mouth-to-Mouth Resuscitation: 1. It clears the airway if Process of Digestion:1. They increase surface area. 2. Nutrients in the small intestine are in a higher concentration than in the blood and so the nutrients pass through the lining and into the bloodstream. Describe What Happens to the Products of Digestion:1. The hormone insulin is produced. The liver detects this and more glucose is removed and stored as glycogen.2. It is used to prevent low blood sugar levels. The liver detects glucagon and breaksglycogen down into glucose. Distinguishing Between Egestion and Excretion: 1. Egestion is the removal of undigested food. Excretion involves the removal of material from inside the body. 2. It must be a material from inside the body as it is formed by the breakdown of red blood cells. The Importance of Breathing in Humans:TY#1: (Top to bottom) trachea, bronchiole, diaphragm.TY#2: 1. They 118

the tongue is blocking it.2. Checking for breathing. The mouthto-mouth should be stopped if the person starts to breathe. Also taking fresh air is important if the process is being continued. The Effects of Smoking:1. Damages the alveoli and cilia in the respiratory tract causing breathing problems; 2.

The same as smoking: cancer and other lung diseases; 3. Chest problems, memory and coordination loss, increase heart rate, confusion, panic attacks. Interpreting Smoking Data: Worldwide and Caribbean:1.UK; 2. Hungary;3. Lower; 4. All increased 19501970s, then decrease in 2006. Rise in Hungaryis later than other countries and reduction also later (1995 rather thanthe more typical 1975). Using Data and Charts to Represent Data on the Respiratory System:1. Trinidad & Tobago;2. Grenada;3. Rates in the Caribbean are muchlower – almost half therate.

Answers to Test Yourself Questions

Need for Transport Systems in the Human Body: 1. Materials cannot otherwise reach every cell; 2. If a cell has a large surface area to volume ratio materials will not enter sufficiently to reach the centre.

Major Bones of the Skeleton:1. A: cranium, B: scapula, C: humerus, D: clavicle, E: vertebral column, F: pelvic girdle, G: radius; H:ulna, I: femur, J: patella, K: fibula; 2. Femur, tibia, fibia; 3. Humerus, radius, ulna.

Materials That Need to Be Transported:TY#1: working across the table, left to right: kidneys, oxygen, lungs, carbon dioxide, endocrine glands; TY#2: 1. Any of: nutrients, glucose, oxygen, carbon dioxide, nitrogenous waster, hormones, blood cells; 2,. Required for photosynthesis and to maintain cell rigidity (prevent wilting).

Structure and Function of the Human Skeleton:1. Protect heart and lungs; 2. Skull/cranium; 3. It is a rigid framework.

Relating the Structures of the Heart to their Function: 1. They prevent blood from passing the wrong way through the heart. They are all one-way valves. 2. The right ventricle pumps blood to the lungs and the left ventricle pumps blood to the body. The Structure and Function of the Heart:Double Pump: 1. Left and right auricles and left and right ventricles. 2. It allows oxygenated and deoxygenated blood to be pumped to different parts of the body without them mixing. The Concept of Blood Pressure:1. The force of the blood being pumped around the body and the size and elasticity of the blood vessels. 2. The narrowing of the tube reduces flow as more blood is trying to pass through the narrow tube. This builds up pressure. Relating Components of Blood to Their Function: 1. Carries dissolved nutrients and waste, transports hormones, provides water for cells and carry heat. 2. Red blood cells, white cells and platelets.

Structure and Function of a Typical Bone:1. Manufacture of red blood cells and white blood cells. 2. Bones contain calcium phosphate and calcium carbonate. Distinguishing Between Bone and Cartilage:1.

Nose, ear lobes and end of bones. 2. Cartilage is softer and more flexible. The Importance of Cartilage:1. Nose, ear and costal cartilage. 2. Knee joint or elbow joint. 3. Knee joint and intervertebral discs. Tendons and Ligaments:1. Ligaments are made from elastin fibres and join bone to bone. Tendons are made from collagen and join muscles to bone. 2. Ligaments need to stretch as joints will move. Tendons must not stretch asotherwise they would not pull on boneas efficiently as muscles contract. Different Types of Joints:1. The ball and socket joint is also known as a spheroidal joint. This is a type of synovial joint where the ball-shaped surface of a rounded bone fits into the cup-like shape of another bone.2. Ankle, elbow or knee. The Biceps and Triceps of the Upper Arm:1. (Top to bottom) biceps, triceps. 2. Muscles work by contracting but when relaxed they cannot exert a force on bone. 3. On top.

Structure and Function of Circulatory System: 1. 1 veins, 2 brain, 3 lung, 4 heart, 5 arteries, 6 stomach, 7 body, 8 How Skeletal Muscles Function in Limb liver. 2. Renal vein and renal artery. 3. The pulmonary system Movement: 1. The triceps and biceps control the links the heart and the lungs. The systemic circuits link the heartmovement of the elbow. The bicep shortens or contracts. This with the rest of the body. pulls the lower arm up and the elbow bends. The tricep then relaxes or lengthens. When the tricep contracts, the lower Relating Structures of Arteries, Veins and arm is pulled back down and the bicep relaxes. Capillaries to Function:Arteries have thicker walls and no valves. The Importance of Locomotion:2. Movement is the motion of any part of an organism, locomotion is the Blood Cells and Their Function:1. Transport oxygen; movement of the whole organism. 2. Ingest pathogens and produce antibodies. Factors that Adversely Affect the Skeletal The Process and Importance of Clotting:It seals the System: 1. Poor muscle tone, wearing high heels, injury, wound against infection. tension, arthritis and obesity. 2. It increases muscle tone and Causes and Effects of Heart Attacks:1. Age or fatty reduces obesity. deposits of cholesterol. 2. Smoking, poor diet, stress, lack of Importance of Excretion in Human Beings:1. exercise can increase the risk. carbon dioxide, urea, water.2. If waste products accumulate Using Data and Charts to Represent Data on the in living organisms they can cause poisoning and slow down Circulatory System:1. Both the breathing rate and heart vital chemical reactions. rate increase after exercise. The action of muscle contraction Explain the Roles of the Organs Involved in requires oxygen and glucose and also produces waste carbon Excretion: 1. dioxide. The heart and breathing rates increase in order to O r g an E x c r e t or yp r o du c t s meet this increased demand for oxygen and glucose and Ki d ney u r e a ,w a t e r,s a l t s remove carbon dioxide.2. Person 1 could be much fitter than Lung s c a r b o n d i o x i d e , w a t e r v a po u r person 2. Person 2 could have a heart or lung illness or be overweight. Person 1 may naturally have agreater lung capacity. Sk i n wa t e r, s a l t s , t r a c e s o f u r e a Al im en ta ry c an al wa te r (m et ab ol ic ), b il e, m uc us , sa lt s The Lymphatic System:1. Transport fats, remove debris, drain excess fluids and transport clean water back to the blood. 2. Kidneys, lungs, skin and alimentary canal. 3. Kidneys and 2. The nodes clean the lymph before it is returned to the blood. skin.

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Answers to Test Yourself Questions

Structure and Function of the Kidney: TY#1: 1. cortex 2. Bowman’s capsule3. glomerulus 4. loop of Henle 5. medulla. TY#2: 1. Remove nitrogenous waste (urea) and help with osmoregulation; 2. In the Bowman’s capsule;3. Toxic nitrogenous waster builds up in the blood. The Structures of Skin and their Function:TY#1: 1. Producing sweat for evaporation and through the dilation/ contraction of capillaries. Hairs are raised to trap air when cold; 2. Seek shade, wear protective clothingand sunscreen;3. Harmful chemicals are used in the manufacture in these products. 4.

Neurons and Nerves:1. Neurons are individual nerve cells. Nerves are made up of bundles of neurons inside a sheath.2. They act as antennae to pick up signals from other cells. Motor and Sensory Neurons and Spinal Synapses: TY#1: A – sensory neuron, B – interneuron, C – motor neuron. TY#2: 1. They are neurons that link sensory and motor neurons. 2. The impulses cross synapses via neurotransmitter chemicals. Mechanism of Reflex Action:1. They allow rapid response to danger and control of regular features, e.g. breathing. 2. Receptor detects stimulus and this passes along the sensory nevron to the spinal cord. It crosses the relay neuron and synapses ten travels along the motor neuron to the effector.3. 1 receptor, 2 spinal cord, 3 relay neuron, 4 synapse, 5 motor neuron, 6 effector, 7 sensory neuron. Voluntary Actions:1. Drinking and blowing bubbles. 2. The brain sends a signal down the white matter of the spinal cord. It then moves along a motor neuron to the effector muscle. This causes the action wanted. Voluntary and Involuntary Actions:1. Voluntary actions require thought and involuntary actions occur quickly and without thought. 2. They can mean we react quickly when in danger. The Response of the Sense Organs to Stimuli:1. (Top to bottom) nose, tongue, skin, eyes, ears. 2. Touch, temperature, pain and pressure. 3. Receptors.

TY#2: Sweating draws heat from the skin.

The Structure of the Eye:1. Cornea, conjunctiva and sclera linked to protection. Pupil, iris and lens linked to

Homeostasis: 1. The maintenance of a constant internal environment. 2. blood pH, carbon dioxide concentration, body temperature, blood sugar level, water content.

controlling light. 2. Too much light could damage the eye and too little would make it difficult to see. 3. Rods allow black and white vision and cones allow colour vision. 4. The lens narrows (becomes thin) to see far-away objects and thickens (becomes fat) to see nearer objects.

Feedback Mechanisms:1. This would be detected by a receptor and this would trigger a corrective mechanism. This would return the body to normal and stimulation of the receptor would stop.2. In negative feedback, over- or under-production of a factor triggers a corrective mechanism to address this. With positive feedback, the factor triggers the production of more of that factor.

How Images Are Formed in the Eye:1. A patch in the middle of the retina that only contains cones. It provides good resolution of images. 2. This is the point at which nerves pass out of the eye at the optic nerve. There is no retina here and therefore no vision.

The Regulation of Blood Sugar: 1. Acts on liver cells to Accommodation in the Eye:1. It requires no thought promote the storage of glucose as glycogen. 2. Acts on liver cells and happens without the person having to make a decision. to promote the breakdown of glycogen to glucose. 2. Thin. The Regulation of Water:1. ADH causes the kidneys to reabsorb more water and thus less water is excreted from the body in urine. 2. More. The Regulation Temperature: 1. More sweat is produced and bloodofcapillaries dilate. 2. Hypothalamus. The Main Divisions of the Nervous System:The nerve impulses from the brain which control movement cannot be sent to the body’s muscles via the peripheral nervous system. Functions of the Main Regions of the Brain:1. Tough membrane (meninges), cerebrospinal fluid, skull; 2. Cerebrum: intellectual (thought processes and motor/ sensory areas; cerebellum: balance through muscular coordination; medulla oblongata: involuntary muscle action e.g. breathing and heartbeat. 120

Sight Defects and Correction:TY#1: Top right.TY#2: 1. Have glasses with concave lenses.2. Age, injury, diabetes or life choices such as smoking and heavy alcohol drinking. 3. Eye defects such as glaucoma can be detected and treated early. Endocrine (Hormonal) and Nervous Control:TY#1: The nervous system uses nerves and is a mixture of electrical and chemical. The endocrine system uses chemical messengers carried in blood. The nervous system is faster, works in specific locations and is of short duration.TY#2: 1, hypothalamus; 2, pituitary gland; 3, parathyroid gland; 4, kidney; 5, testis (in male); 6, pineal gland; 7, thyroid gland; 8, thymus; 9, adrenal gland; 10, pancreas; 11, ovary (in female). The Roles of Selected Hormones in the Human Body: 1. Lowers blood sugar concentrations. 2. Antidiuretic hormone (ADH), follicle stimulating hormone (FSH),

Answers to Test Yourself Questions

luteinising hormone (LH). 3. Its hormones control other parts of the endocrine system. Sexual and Asexual Reproduction:Asexual reproduction only requires one parent and is quick. It does not allow any variation or chance to evolve or adapt. Structure and Function of Reproductive Systems in Male Humans: 1. Testes. 2. Fluid with sperm, fluid from the prostate and seminal vesicles. 3. It fills with blood to make the penis stiff.4. 1 ureter, 2 seminal vesicle, 3 rectum, 4 epididymis, 5 testes, 6 penis, 7 urethra, 8 prostate, 9 bladder.

Pre- and Post-Natal Care:1. The milk contains essential nutrients and antibodies against disease. 2. Ultrasound scans, blood tests for Rhesus factor, urine checked for diabetes and infections, weight checks. Methods of Birth Control:1. A condom worn by the man. 2. The procedure may not be reversible. Transmission and Control of Sexually Transmitted Diseases:1. Abstinence, use condoms, one regular partner. 2. Antibiotics.

The Reproductive System in Female Humans:1.

Abortion: 1. Large doses will encourage large contractions and this can pass the fetus out of the uterus. 2. The mother’s

The ovaries. 2. Moved by tiny cilia down the fallopian tubes. 3. In the fallopian tubes.

health could be at risk and a fetus may develop into a baby that would suffer.

The Menstrual Cycle:1. To prepare the lining of the uterus for implant of fertilised ovum. 2. It maintains the lining of the uterus during pregnancy.

The Importance of Family Planning:1. Having too many children, children too close together or children in later life has health risks for women. 2. The population will not continue to grow quickly so resources and waste can be managed better.

Fertilisation:1. This is the fusion of male and female gametes to produce a zygote.2. To reduce the risk of having additional generic material added to the ovum. Development of the Embryo:1. The cell resulting from the fusion of male and female gametes.2. It is the link between the mother and embryo through which gases and nutrients are exchanged. Describe the Birth Process:1. Stage 1. 2. Stage 2. 3. The placenta and membranes shed from the mother.

Using Tables and Charts to Represent Data:TY#1: 1. Zambia. 2. Poland. 3. The population of Zambia would increase greatly and the population of Poland would decline. TY#2: 1. They are declining. 2. Smaller families would have more resources to spend on education and health and parents could have time to develop careers. 3. The growth might slow or even stop, so populations could remain steady.

Section C The Process of Mitosis:1. 46. 2. A chromosome split into two.

Genetic Variation and Environmental Variation: Blood group, eye colour, natural hair colour and gender.

The Importance of Mitosis:1. The daughter cells have identical chromosomes to the parent cell. 2. growth and repair of the body, asexual reproduction.

The Inheritance of a Single Pair of Characteristics:

Meiosis:

Pairs of chromosomes divide

Term

De ox yr ib on uc le ic ac id , th e he re di ta ry ma te ri al in humans

RNA

Ri bo nu cl ei c a ci d, us ed to se nd th e ge ne ti c co de into the cells and to identify amino acids

Inh eri tan ce

Chromosomes divide

Ge ne Phenotype

Importance of Meiosis:1. 23. 2. Cells of the reproductive system, e.g. testes and ovary. 3. (Top row to bottom row) Occurs in the formation of gametes, Halves the

chromosome number to the haploid number, Nuclei have identical genes, Produces identical cells (clones), For body growth and development, Ensures variation. Why Genetic Variation is Important:TY#1: Advantages: variety, leads to continuous evolution, reduces the chance of offspring inheriting genetic disease. Disadvantages: chance of not finding a mate, sexually transmitted diseases easily contracted, no guarantee of offspring being produced. TY#2: The long-haired wolves would not survive and the numbers of shorter-haired wolves would increase.

Definition

DNA

Ge no ty pe

Tran smi ssi on o f gen eti c in form atio n fro m on e generation to the next M ad e u p o f D NA an d a re in st ru ct io ns to ma ke proteins Observable characteristics Gene ti c mak eup of a cell tha t det ermi nes a specific characteristic (phenotype)

Ho mo l o g o u s

A pa i r o f m a t c h i n g c h r o m o s o m e s

Alleles

D i f f e r e n t ve r s i on s o f th e s a me g e n e

Heterozygous

Carry two different alleles for a gene

Homozygous

Carry two copies of the same allele for a gene

Dominant

Controls the characteristic in the phenotype

Recessive

The allele is not expressed in the phenotype

Mutation

DNA is altered so that the characteristic is changed

Gene mutation

Affecting a small part of the chromosome, e.g. … sickle cell anaemia, haemophilia

Chromosomal mutation

Affects the whole chromosome resulting in major changes, e.g. … Down’s syndrome

Monohybrid inheritance

The study of inheritance of one characteristic

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Answers to Test Yourself Questions

The Inheritance of Sex in Human Beings:1. 50%. 2. 1:1. x

x

x

xx

xx

y

xy

xy

Explaining the Concept of Genetic Engineering: Human cells

Bacterium Plasmid (circular DNA found in bacteria) Plasmid cut using enzymes

Human DNA (insulin gene)

Human DNA inserted into bacterial plasmid and joined back up again

DNA extracted from human pancreatic cells

Recombinant DNA – DNA from two different species

Bacterial DNA Plasmid (recombinant DNA) introduced into a bacterium

As bacteria multiply, the genes are expressed to make their different parts. The insulin gene which was inserted will also be expressed

The plasmids are mass produced as the bacteria multiply. The insulin gene is also being mass produced and insulin is produced when the gene is expressed

Advantages and Disadvantages of Genetic Engineering: 1. Insect-resistant crops, increased crop yield, increased protein, nutritious fruit, reduced fat in meat, increased shelf life of food. 2. Impact on health is not really understood, invasive DNA usage, genetic disease will affect all organisms that share identical or similar genes, inbreeding leads to the loss of alleles. Using Tables, Charts and Graphs to Represent Data: TY#1: 1. This is a cross chart. It is used to determine the phenotype from the genotype of two heterozygous parents. 2. In this cross the offspring would have a 1:4 chance of being normal, 2:4 chance of being a carrier for the disease

and a 1:4 being that a sufferer ofto the disease. TY#2: 1. This is achance punnetofsquare is used determine the characteristics in offspring. 2. The likelihood of the offspring from two heterozygous parents for cystic fibrosis would be: 1:1 chance of inheriting or being a sufferer of cystic fibrosis or being a carrier.TY#3: 1. The milk yield increases dramatically at the start of lactation, untreated cattle yield then slowly declines. On treatment the yield also declines but is still higher.The treated cattle have ahigher yield than untreated cattle. Days of lactation are not affected.

Human insulin is separated and purified Insulin used in diabetic patients

Section D ‘Good Health’ and ‘Disease’: (Top to bottom) Physical health, Mental health, Social wellbeing. Classifying Diseases:Influenza; iron deficiency anaemia; sickle cell anaemia; diabetes. Differentiate Between the Terms ‘Signs’ and ‘Symptoms’: D i s ea se Kwas hi or ko r

S i gn

S ym p t o m

Sw ol le n abd om en , thi n Hunger, tiredness, limbs, sparse hair, sleepy, no interest underweight

Co ld

R unny nos e, co ug h

Cong es ti on, headache, sore throat

Malaria

Shaking, profuse sweating, vomiting, high fever, diarrhoea, anaemia

Headache, nausea

Causes, Symptoms and Treatment of Asthma:This could cause an asthma attack. Explain How Asthma Affects the Respiratory System: The air is not able to flow freely because the bronchial tubes become inflamed and mucus-filled. Discuss Issues Related to Lifestyle Diseases:1. The person would be dependent on insulin injections. They would have diabetes from birth. 2. Age or fatty deposits of cholesterol. The Importance of Diet and Exercise:fats – fatty 122

meats and fish, cheese, chocolate, oils, cheese, avocado; protein – eggs, milk, cheese, fish, nuts; carbohydrate – rice, corn, bread, cookies, cake. Causes, Signs, Symptoms, Prevention and Control of Diseases:From top to bottom: sneeze and cough into a tissue, avoid contact with infectious person, avoid contact with infectious person, immunisation and education, clean food, surfaces and hands, drink clean water and avoid eating or drinking food prepared with contaminated water, drink clean water and avoid eating or drinking food prepared with contaminated water, drink clean water and avoid eating or drinking food prepared with contaminated water, wear protection for all three STIs, useappropriate anti-insect bite treatment, avoid all skin contact, avoid contact with infected person, vaccine and/or avoid contact. Prevention/Control of HIV/AIDS:Avoid sexual contact with an infected individual or use protection during sexual intercourse. Effects of STIs on Pregnant Mother and Foetus: All are true. Impact of Disease on Human Population:1. People who are unable to work have to be supported. Treatment can be expensive and has to be paid for by family or the government. 2. Travel is much easier and cheaper now. This means that people travel more and may visit areas that have problems with diseases.

Answers to Test Yourself Questions

Effects of Malaria and Dengue Fever on the Human Body: 1. Two from fever, headache, fatigue, chills and sweating, dry cough, vomiting, back pain, enlargement of the spleen. 2. Dengue – mouth and nose bleeding, rash, diarrhoea, itching, hypotension, gastrointestinal bleeding.

Defence Against Disease: Te r m

Su bs tan ce s t hat ki ll or pre ven t t he g ro wt h of bacteria

An ti ge n

Lar ge mo le cule , ofte n pr ot ei n but som e can be carbohydrate. Stimulate the lymphocytes to make and release antibodies

Antibod y

Lar ge prote in mol ecu le tha t destr oys pat hog ens

Ant i-t oxin

Ant ibo die s to con trol spe cifi c to xin s th at a ct a s antigens

Vectors of Disease: Ve c to r

E xa m p l e s o f d i s e a s e s s p r e a d

m os q ui to

y e ll o w f e v er, m a l a r i a , d e n g u e f e v e r, elephantiasis

fli es , flea s a nd t icks

g a s t roenteri ti s

flea s rat

pl a g u e leptospirosis or Weil’s disease

D e fi n i t i on

Anti bio ti c

Types of Immunity:1. Antibodies either burst the cells or attract white blood cells (phagocytes) which engulf and destroy the microorganisms. 2. Artificial immunity is when we fool the body into thinking we have an infection and it produces antibodies. This is done through vaccination.

Stages in the Life Cycle of the Mosquito and Housefly: 1. An organism that carries a parasite or pathogen from one host to another.2. The mosquitoes lay their eggs on Immunity/Immunisation; Vaccine/Vaccination: or in standing water. The oil prevents this and also stops oxygenVaccine gives long-term active immunity but the result is getting to the larvaejust under the surface ofthe water. slower. Antiserum gives immediate results but it is shortImportance and Methods of Controlling Vectors: 1. Clearing bushes near homes, so that adults have nowhere to rest. Removing stagnant water so that the mosquito will have nowhere to lay eggs and the larvae will not grow. Covering water with oil will prevent oxygen getting to the larvae and the adult will not want to lay eggs there. Covering windows with mesh and spraying insect repellent will prevent the mosquito entering homes. 2. Keep the area clean and dispose of garbage and food correctly. Remove any rotting leaves or vegetation. Personal and Community Hygiene:TY#1: 1. 1, 3, 4 and 5. 2. 1. TY#2: 1. It prevents body odours and supports social acceptance. Caring for teeth prevents dental problems. It also removes pathogens and so prevents the transmission of infections. 2. Hygiene makes an area aesthetically pleasing but also prevents the transmission of infections. The removal of garbage, for example, controls vectors, for example the housefly. Controlling the Growth of Microorganisms:1. Any method of sterilisation including ultra high temperature, pasteurisation, autoclaving, boiling and canning. 2. They can spoil food and produce toxins that are harmful if ingested. Disinfectants and Antiseptics:They are more toxic to humans and will damage the tissues if contact is made. Disinfectants are designed to control microorganisms on inanimate objects.

lasting and is extracted from blood plasma, which could carry risk. Use and Misuse of Drugs:Any three from the following: alcohol, prescription drugs, non-prescription drugs, illegal drugs, steroids, diet pills, and hormonal injections (HCG). Social Effects of Drug Misuse:Alcohol causes the most harm to others and the user. This might be because it is easy to purchase in most countries. As a result more people use this more regularly than other drugs. Use Tables, Charts and Graphs to Represent Data on Disease:TY#1: 1. There are high rates of asthma cases in some countries compared to others. 2. Industrialised countries pollute the air. This could trigger asthma attacks. People may smoke more in these countries. TY#2: The graph shows that between 1981 and 2001 antibiotic resistance increased. MRSA has the most resistance but seems to have reached its maximum as the graph is levelling at 60%. FQRP is increasing the most and is currently at 25%. TY#3: When the first injection of antiserum was administered, the antibody levels rose immediately but began to fall straight away. At day 20 the antibody level had dropped. When the second injection was administered, the levels of antibodies rose again but dropped by day 50. This shows that the antiserum has an immediate effect but it does not last long.

Section E Identifying Pollutants in the Environment:Carbon dioxide, sulphur dioxide, carbon monoxide. Air and Water Pollution:

P oll ut ant

Exam p le 1

Examp le 2

Agr ic ul tu ral

Fe rt il is er

Pe st ic id e

D om es ti c

D eterg ents

S e wag e

Ind us tri a l

D eterg ents

Bu r n i n g o f fossil fuels

Affecting water or air or both bo th wa ter both

The Effects of Pollutants on Human Beings and the Environment:The biggest contributor to negative impact on health is created by household. Industrial has the least impact on health. Vehicle is close to the amounts created from household. Methods of Controlling Pollution:If people did not use cars as much, there would be less of these types of pollution: particles, sulphur dioxide, carbon monoxide, carbon dioxide, hydrocarbons and lead. The Water Cycle:1, condensation; 2, precipitation; 3, transpiration; 4, evaporation. 123

Answers to Test Yourself Questions

Simple Ways of Purifying Water in the Home: Heating the water would use energy from the burning of fossil fuels. Testing Water for Bacteria:It is not possible to see single microorganisms with the naked eye. Using agar plates in the right temperature encourages the microorganisms to grow into visible colonies. Large-scale Water Purification:1. Aerobic bacteria use the oxygen and rapidly decompose the organic matter. 2. To make methane gas or to be dried and used as a fertiliser. 3. Chlorine acts as a disinfectant and kills pathogens.

and carry pathogens. 5. It means that people are not connected to up-to-date sanitation. Methods of Domestic Refuse Disposal: Method of waste m a na g e m e n t

Benefit s

D r a wb a c k s

Landfill

Cheap

Production of methane, pollution, destruction of habitats

Incineration

Recycling

The Impact of Human Activities on Water Supplies: TY#1: Drinking, showering, cooking, watering plants, brushing teeth, washing clothes. TY#2: 1. No. 2. Some of the water will be used if there is one person or more in the house, for example in the air conditioning unit. Contaminated Water:Some countries do not have water treatment plants or good sanitation. Proper and Improper Sewage Disposal:TY#1 Examples Do me st ic

Ag ri cu lt ur e In du st ry

How does it combine with water?

Excreti on, water f rom Poor sanitation and bathing, water used for disposal washing clothes and food Fe rt il is er s, pe st ic id es , Water runs off into effluent the water table Ch em ic al s, so li d w as te , Poor sanitation and excretion from workers disposal

TY#2: Improper sewage disposal is much cheaper than proper sewage disposal but the costs can be great over time. Factories dispose of water from different processes by delivering it back into the water systems, which contaminate the other water. Improper sewage disposal contaminates the soil and water table. This has a massive impact on marine life and causes disease and illness in humans by ingesting the contaminated water directly or by eating food that has been washed in contaminated water. Bathers at the coast are at risk of ingesting sewage from seawater. TY#3: The sewage in the water provided excessive nutrients for the seaweed. This grew out of control and destroyed other organisms and plants that could not compete with it. Treatment of Sewage: Biological Filters/ Activated Sludge:To provide oxygen for aerobic respiration of the microorganisms. Pit Latrine: To seal the pit lining and prevent flooding of the pit by sur face water. The content could then overflow. Why the Siting of Pit Latrines Is Important:1. At least 6 metres. 2. They have to be close enough to be used in the dark, but fumes escape, which would be unpleasant for the people living in the home if it was too close. The Use of Pit Latrines in the Caribbean:TY#1: 1. No, many years out of date. 2. Yes, fewer houses using pit latrines. 3. To avoid contamination. 4. Flies can be vectors

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Cheap and easy

Product goes to landfill, gases and smoke are released into the atmosphere

New products are Expensive, can be made from waste difficult to manage, can cause pollution

The Operation of Landfill: ■ The waste is collected by a refuse truck. – Noise pollution and air pollution ■ The truck transports the refuse to the landfill site. This is often several miles away. – Noise pollution and air pollution ■ The landfill site is prepared by using industrial machines to dig out the ground. – Noise pollution and air pollution ■ The refuse truck deposits the waste. – Destruction of habitats. Water and soil are polluted ■ The industrial machines compact the waste. – Noise pollution and air pollution ■ The truck returns to collect more waste. – Noise pollution and air pollution ■ The landfill site is covered over. – Destruction of habitats. Water and soil are polluted ■ Another landfill site is dug out. – Noise pollution and air pollution Function of Landfill:The islands’ beauty attracts over 20 million tourists every year. The Impact of Solid Waste on the Environment:Any one from neurological disease, cancer, asthma and other related lung disease, chemical poisoning, low birth weight, congenital malformations, nausea, vomiting, mercury toxicity, diarrhoea, intestinal disorders, plague. Reduce, Reuse and Recycle: TY#1: Any from glass, paper, cardboard, cans, plastic.TY#2: Use reusable shopping bags and drinks containers. Biodegradable/Non-Biodegradable:The amount in use will be the same, temperatures will have to be constantly

highdegrade. for them to degrade. It will still take time for them to fully Use Table, Charts and Graphs to Represent Data: TY#1: 1. Some countries have an increased number of deaths due to air pollution. 2. These could be industrialised countries. 3. Educate people about air pollution. Place restrictions on factories and the use of vehicles. TY#2: 1. Bar chart.

Glossary

Glossary Abortion Termination or ending of pregnancy by

Capillary One of the tiny branching blood vessels that

removing the foetus or embryo before it can survive outside the uterus.

link arteries and veins.

Absorption The process where one substance is taken

of the atmosphere and then recycled back in.

up by another through tiny pores or holes.

Accommodation The reflex action of the eye

Carbon cycle The process of carbon being taken out Cardiovascular disease When the blood vessels

responding to the need to focus on near and far objects.

to the heart become narrower or blocked, putting the heart under stress.

Active transport The process by which molecules

Carnivore An animal that feeds on other animals.

move across a cell membrane against a concentration gradient. This requires energy.

Cartilage A connective tissue used to reduce friction

The process that releases Aerobic energy from respiration glucose in the presence of oxygen.

and act as shock absorber in the skeleton. Also used in soft

down from your mouth to your anus.

structures such as the ear. Cataracts When the proteins in the cells of your eyes become damaged and lose transparency, resulting in blurred vision.

Allele A type of gene.

Cell (biological) The smallest unit of living things.

Alveoli During breathing, gas is exchanged in these tiny

Cell membrane The membrane that forms the outer

air sacs within the lungs.

surface of cells. The cell membrane regulates the passage of materials into and out of the cell.

Alimentary canal The digestive track that runs

Anaerobic respiration The process that releases energy from glucose without the need for oxygen. Antagonistic pairs The movement of muscles

Cell wall A rigid layer lying outside the cell membrane of plants, fungi and bacteria.

that work in pairs. As one muscle contracts the other relaxes, resulting in contraction to move a bone.

Central nervous system The brain and the

Antibiotic A substance that kills bacteria and prevents

Chlorophyll A green pigment responsible for the

them from growing.

absorption of light in photosynthesis.

Antibody A protein produced by the body’s immune

Chloroplast An organelle in green plants containing

system to attack foreign organisms that get into the body.

chlorophyll.

Antigens Chemicals found in pathogens that are

Chromosomes Molecules of DNA that carry genetic

foreign to the body.

information in the nucleus.

Artery A muscle-lined vessel that carries blood from the

Cilia Tiny hair-like structures.

heart to other parts of the body.

Artificial selection Human intervention

spinal cord.

Circulation The movement of blood around the body, pumped by the heart.

to selectively breed plants or animals with desired characteristics.

Clones Identical cells produced from the same cell.

Asexual reproduction A type of reproduction

Co-dominance The relationship between two versions

where offspring are produced from one individual parent.

of a gene.

Assimilation The absorption of nutrients into the

Cones Photoreceptors that produce colour vision.

body.

Consumer Organisms that need to eat or consume

Autotrophic An organism that can synthesise its own

food as they cannot make their own.

food through photosynthesis or chemosynthesis.

Continuous variation Variation with no limit on

Balanced diet A diet that contains a healthy

the value that occurs in a population.

proportion of all of the food groups (carbohydrates, fats, proteins, vitamins, minerals and water).

Cytoplasm The jelly-like material within a cell.

Biodegradable A substance capable of being decomposed by bacteria or other living organisms.

Birth control Taking steps to prevent pregnancy. Blood The mixture of liquid and cells that circulates in

Decomposers Organisms that break down dead and decaying materials for food.

Deficiency disease When people do not get enough of the right nutrients in their diet it can make them ill.

many animals to transport oxygen and nutrients to cells and waste products away.

Diaphragm Large muscle that is used during

Body mass index (BMI) A person’s weight in

Dietary fibre Fibrous vegetable material that cannot

kilograms divided by their height in metres squared.

breathing.

Breathing The process of taking air into and out of the

be digested and aids the passage of food and waste through the alimentary canal.

lungs.

Diffusion The movement of atoms or molecules

Canine A pointed tooth next to the incisors that is

from an area of high concentration to an area of low concentration.

enlarged in carnivores.

125

Glossary

Digestion The mechanical and chemical breakdown of food molecules into smaller molecules.

Diploid Two complete sets of chromosomes within a cell. Discontinuous variation Variation with a limit on the value that occurs in a population.

DNA Deoxyribose nucleic acid, carries the genetic codes used to determine the characteristics of a living being.

Dominant trait A genetic feature inherited from the dominant allele.

Drug A substance that when taken into the body can cause chemical reactions. Any part of the body that responds to Effector impulses from stimuli.

Egestion The process of discharging undigested food and waste from the body.

Embryo A living organism in the early stages of development.

Endocrine system The collection of glands that produce hormones that help to regulate body functions.

Enzyme A protein that speeds up chemical reactions. Eukaryote DNA group that has a membrane-bound nucleus and linear chromosomes. Eukaryotes include animals, plants and fungi.

Eutrophication Fertilisers cause blooms of green plants, which use up oxygen.

Excretion The process of removing waste materials

Heart A muscular organ that pumps blood to help it circulate around the body.

Herbivores Animals that feeds on plants. Hereditary disease When a disease is biologically passed down the generations through DNA.

Heterozygous Individual that carries two different alleles for a certain characteristic.

Homeostasis The maintenance of constant internal environment.

Homozygous Individual that carries two of the same alleles for a certain characteristic. Hormone A chemical substance secreted through glands used to regulate the body’s activities.

Hypermetropia Long-sightedness. Immune response When the body defends itself in response to a foreign substance inside the body.

Immunisation A way of protecting the body from harmful pathogens through vaccination.

Incisor A narrow-edged tooth at the front of the mouth adapted for cutting.

Insulin Produced by the pancreas, this is a hormone that regulates the amount of sugar in the blood.

Involuntary (actions) An automatic response to a stimulus that is not controlled by the individual.

from the body.

Joints A structure where two or more parts of the

Fertilisation to produce a zygote. The fusion of male and female gametes

Landfill The disposal of waste material by burying it.

Fertiliser Chemicals that can be added to plants to

Lipids Fats and oils.

help them grow.

Lymph The fluid of the lymphatic system.

Foetus A developing embryo, usually eight weeks after

Lymphocytes White blood cells that produce specific

conception.

Food chains A series of organisms, each dependent on the next as a source of energy and nutrients.

skeleton come together. Some allow bending of the limbs.

antibodies.

Malnutrition The lack of proper nutrition caused

Food group A collection of foods that share the same

by not having enough to eat, not eating the right things or eating too much.

nutritional properties.

Mastication The first step of the digestive process,

Food web When all the food chains within a habitat

chewing and crushing food down using the teeth.

become joined up to form a web.

Meiosis Cell division that is used to produce male and

Gametes The male and female sex cells.

female gametes.

Gaseous exchange The movement of oxygen and

Melanin Human skin, hair and eyes get their colour from

carbon dioxide across a membrane in opposite directions.

this pigment.

Gene A small section of DNA that has codes for the

Menstrual cycle When the lining of the uterus is

production of certain proteins.

Microorganism A microscopic organism that can

selected genes from one living organism to another living organism to produce new varieties.

only be seen under a microscope. This includes bacteria, viruses and fungi.

Genetic variation A combination of characteristics

Minerals A naturally occurring inorganic substance

Genetic engineering Artificially transferring

prepared for pregnancy each month.

from two parents.

essential for the body.

Genotype The genetic make-up of an organism.

Mitochondria A structure within the cytoplasm of a

Glaucoma An eye disease caused by the pressure the

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Haploid One set of chromosomes found in a gamete.

cell that is responsible for aerobic respiration.

fluid of the eye puts on the lining of the eyeball, which can lead to permanent loss of vision.

Mitosis When two identical cells are formed as a result

Glycogen Glucose that has been stored.

Molar A broad, ridged tooth in adult mammals.

of a single cell dividing.

Glossary

Multicellular Having more than one cell. Muscles A tissue consisting of muscle fibres. Movement or tension in the body is caused by muscle contraction.

Myopia Short-sightedness caused by the refraction of the lens.

Nephron Microscopic filter found within the kidneys

Prokaryote A single-celled organism that does not have a nucleus or specialised organelles.

Proteins Molecules made up of chains of amino acids that build, maintain and repair tissues.

Psychological disease Psychiatric disorder (mental illness) that causes suffering.

responsible for cleaning the blood.

Pulmonary circulation The portion of the

Neuron A specialised cell transmitting nerve impulses. Nicotine A harmful, addictive substance found in

circulatory system that carries deoxygenated blood from the heart to the lungs and returns oxygenated blood to the heart.

tobacco smoke.

Receptor This responds to a stimulus and sends

Nucleus (cell) Large body in cytoplasm of plants and

impulses to the central nervous system.

animals that contains genetic material of DNA. Nutrients Nourishment found in food that is essential to animals and plants for growth, repair and to maintain health. Includes proteins, fats, carbohydrates, vitamins and minerals.

Recessive trait Characteristics carried in genes that

Omnivore An animal that eats both animals and plants. Organelles Structures in eukaryotic cells, for example the nucleus and mitochondria.

Osmoregulation The control of the water content

are not expressed.

Recycle Convert (waste) into reusable material. Red blood cells Cells in the blood that contain haemoglobin and carry oxygen.

Reflex (action) Rapid responses that do not involve the brain.

Renal failure A medical condition in which the

and concentration of salts.

kidneys fail to adequately filter waste products from the blood.

Osmosis Movement of a solvent through a semi-

Respiration Release of energy for cells from glucose.

permeable membrane separating two solutions of different concentrations.

Ova Female reproductive cell or gamete. Ovulation The release of one or more eggs from the

Response A reaction by the central nervous system to a stimulus.

Rods Photoreceptors in the eye responding to light.

ovary.

Roughage Fibrous vegetable material that cannot be

The that produces insulin and digestive Pancreas enzymes, located ingland the abdomen.

Pathogen Microorganisms that cause disease.

digested and aids the passage of food and waste through the alimentary canal. Sense organs Organs that contain receptors that are sensitive to stimulus, for example the eye, ear and nose.

Phagocytes A type of white blood cell that moves

Sewage Waste, for example excretion and urea, that is

towards pathogens and toxins and ingests them or releases enzymes to destroy them.

Phenotype The characteristics that are shown in

often mixed with water.

Sexual reproduction The joining of a male and

offspring.

female gamete. The offspring are similar but not identical to the parents.

Photosynthesis A chemical process where green

Signs (disease) Something that can be seen and

plants synthesise starch from carbon dioxide and water in sunlight.

Pit latrine A type of toilet that collects human faeces

measured such as temperature or heart rate.

Skeleton All the bones of the human body.

in a hole in the ground.

Sperm Male sex cell or gamete.

Placenta A temporary organ that joins the mother

Starch Type of carbohydrate.

to the foetus and transfers nutrients and oxygen as well as taking carbon dioxide and waste.

Plant A living organism that can photosynthesise.

STIs (sexually transmitted infections) Diseases generally contracted through sexual contact.

Plaque A sticky substance on teeth that attracts bacteria.

Stimulus Something that causes an action.

Platelets Cell fragments in the blood that are part of

Symptoms (disease) Something felt by a patient,

the process of clotting.

Pollution A substance in the environment that is harmful or poisonous.

Premolar Broad, ridged tooth in mammals. Situated behind the canine teeth.

Producer An organism as the source of energy in a food chain, for example a green plant.

such as pain or tiredness.

Synapses A junction between two nerve cells across which impulses pass by diffusion of a neurotransmitter.

Systemic circulation The portion of the circulatory system that carries oxygenated blood from the heart to the body and returns deoxygenated blood to the heart.

Tendons Strong fibrous collagen tissue attaching the muscle to a bone. 127

Glossary

Tooth decay The decay of the outer surface of a tooth

Vector An organism, often a biting insect or tick, that

as a result of acid produced by bacteria.

transmits a disease or parasite from one animal or plant to another.

Transpiration The movement of water up a plant through the xylem.

Unicellular Having or consisting of a single cell, for

the wall of the small intestine.

example protozoans, certain algae and spores, etc.

Vital capacity The greatest volume of air that can

Urea The major end product of nitrogen excretion in

be expelled from the lungs after taking the deepest possible breath.

mammals.

Urine An aqueous fluid produced by the excretory organs

Vitamins Compounds which are essential for normal

in animals for the removal of waste products.

growth and nutrition and are required in small quantities in the diet.

Vaccination A biological preparation used to improve

Voluntary action An action which the person

immunity to a particular disease. pathogen used in vaccination.

initiates by their own decision. White blood cells Also known as leucocytes, these cells are part of the immune system.

Vacuole A fluid-filled pocket in the cytoplasm of animal

Zygote A fertilised ovum (diploid cell), the result of the

Vaccine An inactive form of a pathogen or dead

and plant cells.

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Villi Folds that increase the surface area of the inside of

fusion of two haploid gametes.