Biology Characteristics of living organism Identification of a living organism An organism is an individual living thing that can react to stimuli, reproduce, grow, and maintain homeostasis. It can be a virus, bacterium, protist, fungus, plant or an animal. All living organisms do the seven following: 1. Movement. All living organisms show movement of one kind or another. All living organisms have internal movement, which means that they have the ability of moving substances from one part of their body to another. Some living organisms show external movement as well they can move from place to place. 2. Respiration. All living things exchange gases with their environment. 3. Sensitivity. Ability to sense and respond to changes in its surrounding 4. Growth. An increase in size, mass, complexity of an organism 5. Reproduction. Producing offspring similar to the parent 6. Excretion. Excretion is the removal of waste from the body. If this waste was allowed to remain in the body it could be poisonous. 7. Nutrition. All living organisms need to take substances from their environment to obtain energy, to grow and to stay healthy. An organism is considered “living” when it does all of these seven characteristics.
Cells Definition: The basic structure of organisms. All cells are made by other cells. a part of the cell containing DNA and RNA and responsible for growth and reproduction All organisms are made up of units called cells joined together. Very small living things like bacteria are made up of only one cell. Types of cell Animal cells Plant cells Specialised cells o Xylem cells o Leaf palisade cells o Root hair cells o Red blood cells o Nerve cells o Muscle cells o Bone cells Single cells o Amoeba
Many cells o Spirogyra Animal cells
Cell part Cell membrane
Cytoplasm
Definition A thin semi-permeable membrane that surrounds the cytoplasm of a cell, enclosing its contents.
Function
Gives shape the cell. Cell membrane anchors the cytoskeleton (a cellular 'skeleton' made of protein and contained in the cytoplasm). Attaching cells together to form tissue. Cell membrane is responsible for attaching the cell to the extracellular matrix (non-living material that is found outside the cells). Transportation of materials. This is needed for the functioning of the cell organelles. Cell membrane is semi permeable and controls the in and out movements of substances. Such movement of substances may be either at the expense of cellular energy or passive, without using cellular energy. Receive signals from other cells or the outside environment. They convert the signals to messages that are passed to the organelles inside the cell. Group together to form enzymes. These carry out metabolic reactions near the inner surface of the cell membrane. Proteins in the cell membrane. also help very small molecules to get themselves transported through the cell membrane, provided, the molecules are traveling from a region with lots of molecules to a region with less number of molecules. The contents outside of Fills the interior of the cell. The cytoplasm forms
Nucleus
Mitochondria
the nucleus and enclosed within the cell membrane of a cell. A part of the cell containing DNA and RNA and responsible for growth and reproduction An organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur
the ground substance of the cell. Hold cell organelles. Cell organelles control all of the cell’s activities. These keep the cell alive. Regulates all cell activity. It does this by controlling the enzymes present. Hold the DNA needed for reproduction.
Definition A space within a cell that is empty of cytoplasm, lined with a membrane, and filled with fluid.
Function
Provide energy for the cell through respiration. Location of ATP (adenosine tri-phosphate)
Plant cell
Cell part Vacuole
Removing unwanted structural debris Isolating materials that might be harmful to the cell Containment of waste products Maintaining internal hydrostatic pressure or turgor within the cell Maintaining an acidic internal pH Containing small molecules
Chloroplasts
Cell wall
Plant sap
An organelle found in plant cells that conduct photosynthesis
Exporting unwanted substances from the cell. Enabling the cell to change shape. Capture light energy. Store it in the energy storage molecules ATP and NADPH Use it in photosynthesis. It makes organic molecules and free oxygen from carbon dioxide and water. The rigid outermost cell Provides support. layer found in plants Bonds with other cell walls. This forms the and certain algae, structure of the plant. bacteria, and fungi but characteristically absent from animal cells Watery fluid of plants. Store important substances Cell sap is a fluid found Support the plant. The pressure of water filling in the vacuoles (small the cell vacuole pushes out against the cell wall. cavities) of the living This gives the wall enough strength to hold up cell fairly large green plants.
Animal vs. Plant cells Plasma membrane Nucleus Shape Chloroplast Cytoplasm* Mitochondria Vacuole Storage
Animal cell Only cell membrane Present Round (irregular shape) Animal cells don't have chloroplasts
Plant cell Cell wall and membrane Present Rectangular (fixed shape) Plant cells have chloroplasts because they make their own food (photosynthesis) Present Present Present Present One or more small vacuoles One, large central vacuole (much smaller than plant taking up 90% of cell volume. cells). Store energy as granules of Store energy as starch glycogen
*Plant and animal cells have many smaller structures in the cytoplasm.
Diffusion Diffusion: The spread of particles through random motion from regions of higher concentration to regions of lower concentration.
Parts of solution Solute: A substance that is dissolved in a solvent to form a solution Solvent: A liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution A solute is dissolved in a solvent. Types of solutions Concentrated solution: Has a large amount of solute in the solvent. Diluted solution: Has a small amount of solute in the solvent.
Osmosis Osmosis: A special kind of diffusion. It is the net movement of solvent molecules through a partially permeable membrane (such as a cell membrane) into a region of higher solute concentration from a low solute concentration down a concentration gradient. How does it work? Partially permeable membrane – The cell membrane is selectively permeable because it allows certain molecules to pass through and no others. Water can pass through but dissolved substances cannot. Different concentration of solution on each side of the membrane – water will move from the weak solution (high concentration of water) to the strong solution (low concentration of water). Water potential gradient – when the number of molecules of water in the solution becomes less and the concentration of the solute becomes more, the water molecules move to the place where there is low concentration of water molecules.
Enzymes Enzyme: Biological catalysts that are produced in all living organisms and control all the chemical reactions that occur. Enzymes are present in all cells not just in the digestive systems. They are protein molecules that have particular shape which are held together by weak hydrogen bonds. Catalysts: Substance which increases the rate of reaction Substrate: The chemical compound on which the enzyme works. Active site: Part of an enzyme where substrates bind and undergo a chemical reaction. Two types of enzymes Breakers – Break large molecules into smaller simpler ones for the cells to use. This is especially important to digestion as some of the nutrients we get from foods are large molecules. Some examples are amylase to break down starch to form glucose molecules, protease to break down protein and lipase to lipids/fats.
Builders – Combine smaller ones to make large molecules inside our cell. These are important in plants to be used in photosynthesis, the opposite of respiration, because in photosynthesis, oxygen and water are combined together to form carbon dioxide and sugars.
Specific enzymes Carbohydreases break down carbohydrates to form polysaccharides Proteases break down proteins to form amino acids Lipases break down fats/lipids to form fatty acids and glycerol Amylase break down starch to form glucose and maltose Properties of enzyme 1. They are all proteins 2. Each enzyme controls one particular reaction 3. They can be used again. 4. They are affected by temperature 5. They are affected by PH 6. They are held together by weak hydrogen bonds. How do enzymes work? Enzymes work by lowering the activation energy (Ea or ΔG‡) for a reaction, thus dramatically increasing the rate of the reaction. Denaturation Enzymes are proteins that are bonded with weak hydrogen bonds. When heat or acidity is applied to the enzyme, the hydrogen bonds break and the active site no longer fits the particular substrate. The enzyme is said to be denatured. Sample questions 1. An enzyme has an ‘active site’ on its surface on which the reaction takes place. Use the idea of an active site to explain: a. Why an enzyme is specific for a particular substrate. An enzyme is described to be ‘specific’ when it only catalyzes on particular substrate. The hydrogen bonds in the enzyme create the shape that is specific to the substrate. An enzyme is specific for that particular substrate because each enzyme’s active site has a certain shape to fit a particular substrate. b. Why an enzyme denature at a high temperature. An enzyme ‘denatures’ when its shape does not fit its substrate because the hydrogen bonds are broken. Hydrogen bonds are weak bonds and connot stand the movement and energy created by the heat. Enzymes are denatured at high temperature due to the heat breaking the hydrogen bonds and the active site no longer is in its original shape to fit the substrate.
c. Why an enzyme can be used again and again. The enzyme isn’t broken down in the reaction but it is involved in the reaction. 2. How does amylase enzyme work? Amylase enzymes have an active site designed to break down the complex molecule of starch into the smaller globules of glucose to be absorbed into the body
Food and Digestion Purpose of food For energy For growth For repair Nutrition: Obtaining organic substances and mineral ions from which organisms obtain their energy and their raw materials for growth and tissue repair. Nutritional Requirements For plants – need carbon dioxide, carbon diozide, water, sunlight, and chlorophyll to make their own food. Also known as photosynthesis For animals – need seven essential nutrients: carbohydrates, proteins, fats, minerals, vitamins, water and roughage. Balanced Diet Definition: The intake of correct amounts of food substances Food substance Protein Fats
Vitamin A Vitamin C
Vitamin D
Iron
Function in body
Examples
Growth/repair Making enzymes Store of energy
Meat, fish, Amino acids soyabean Dairy, nuts, 3 fatty acids meat, fish
To make light Cod liver oil sensitive chemical To make Citrus fruit connective tissue
Composition
Retinyl palmitate Ascorbic acid
Deficiency Disease/Symptoms Kwashiorkor: loss of hair, swollen abdomen Lack of certain fatty acids may cause various diseases Poor night vision Scurvy: poor healing of wounds and bleeding gums Rickets: weak bones
To absorb enough Dairy Cholecalciferol calcium from the produce/sunlight or ergocalciferol intestines To produce Liver, egg yolk N/A Anaemia: lack of red haemoglobin for blood cells red blood cells
Calcium Fibre
Carbohydrate
Strengthening bones and teeth To allow correct rate of peristalsis
Supply of energy
Bread, dairy N/A produce Wholemeal Arabinoxylans, bread, fruit cellulose, dextrins, inulin, lignin, waxes, chitins, pectins, beta-glucans, and oligosaccharides Bread, rice, Glycogen potatoes
Rickets and poorly developed teeth Constipation, appendicitis, bowel cancer.
Lack of carbohydrates is linked to lack of food (e.g. starvation)
Plant Nutrition Photosynthesis – The fundamental process by which plants manufacture carbohydrates from raw materials using energy from light.
Formula for photosynthesis] Formula for respiration in plants
Process of photosynthesis 1. Green plants take in CO2 through the stomata in the leaves by diffusion 2. Water is obtained through the root hair by osmosis from the soil and this is transported through the xylem to leaves. 3. Chloroplasts present in the leaf, trap light energy which is used to break down water molecules into hydrogen and oxygen ions 4. Hydrogen and CO2 combine to form glucose 5. Glucose usually changes into sucrose for transport and is stored as starch 6. Oxygen is released as a waste product or is used for respiration.
Respiration Definition Respiration: Chemical reactions that break down nutrient molecules in living cells to release energy. Aerobic Respiration: The release of a relatively large amount of energy in cells by the breakdown of food substances in the presence of oxygen. It mainly occurs when there is sufficient oxygen Anaerobic respiration: The release of a relatively small amount of energy by the breakdown of food substances in the absence of oxygen. Equation of aerobic and anaerobic exercise Aerobic respiration
Anaerobic respiration
Difference between aerobic and aneaerobic respiration Aerobic Takes place in the presence of oxygen Glucose is broken down into CO2 and H2O 38 ATPs are produced Takes place in the cytoplasm and mitochondria
Anaerobic Oxygen not required CO2 and C2H5OH 2 ATPs are produced Only in the cytoplasm
Oxygen Debt What is it? When your cells don't receive enough oxygen during exercise they start respiring without it, creating lactic acid as a result. Debt is simply breathing in the required amount of oxygen needed to get rid of the lactic acid that built up.
Gas exchange The respiratory system
Alveoli and gas exchange
Function of the alveoli The basic function of the alveoli is gas exchange. The alveoli structure is the site where the gaseous exchange during respiration takes place. These structures are surrounded by capillaries carrying blood. The exchange of carbon dioxide in the blood from these capillaries occurs through the walls of alveolus. The alveoli begins to function when we breathe in air through our nostrils. The air passes through a long route consisting of various organs of the respiratory system. These organs include the nasal
passages, pharynx, larynx, trachea, main bronchi, small bronchial tubes, bronchioles and finally reaching the alveolus through tiny air sacs. The air contains oxygen that is absorbed by the blood flowing through the capillaries. This oxygen is then passed on to the circulatory system, thus completing the gaseous exchange cycle. How gas exchanges take place in the alveoli? The pulmonary gaseous exchange takes place by passive diffusion. During this gas exchange, no energy is required to be burned by the cells. The gases move through a concentration gradient that is high concentration to low concentration. This means that oxygen in the alveolus is in the high oxygen concentration gradient. It diffuses into the blood that is in the low oxygen concentration gradient. This is because of the continuous oxygen consumption in the body. The same thing happens in case of carbon dioxide. Blood contains high carbon dioxide concentration and alveoli contains low carbon dioxide concentration. Thus, the gaseous exchange takes place through passive diffusion as a part of respiratory system function.
The circulatory system Heart Chambers The internal cavity of the heart is divided into four chambers: Right atrium Right ventricle Left atrium Left ventricle The two atria are thin-walled chambers that receive blood from the veins. The two ventricles are thick-walled chambers that forcefully pump blood out of the heart. Differences in thickness of the heart chamber walls are due to variations in the amount of myocardium present, which reflects the amount of force each chamber is required to generate. The right atrium receives deoxygenated blood from systemic veins; the left atrium receives oxygenated blood from the pulmonary veins. Valves of the Heart The right atrioventricular valve is the tricuspid valve. The left atrioventricular valve is the bicuspid valve. The valve between the right ventricle and pulmonary trunk is the pulmonary semilunar valve. The valve between the left ventricle and the aorta is the aortic semilunar valve. When the ventricles contract, atrioventricular valves close to prevent blood from flowing back into the atria. When the ventricles relax, semilunar valves close to prevent blood from flowing back into the ventricles.
Flow of Blood It is important to realize that both atria and ventricles contract at the same time. Blood flows from the right atrium to the right ventricle, and then is pumped to the lungs to receive oxygen. From the lungs, the blood flows to the left atrium, then to the left ventricle. From there it is pumped to the systemic circulation. How does the heart circulate blood around the body? Coronary circulation 1. Waste-rich blood fills the right atrium 2. It then contracts and pushes the blood into the right ventricle. 3. From the right ventricle, the blood is pumped into the lungs via the pulmonary artery. Pulmonary circulation 1. Waste-rich blood enters the lung 2. It fills the lung capillaries. It is within these capillaries that the carbon dioxide in the blood is exchanged for oxygen. 3. The new, oxygen-enriched blood continues its journey through the pulmonary veins in the lungs and returns to the heart through the left atrium. 4. From the left atrium, the blood is pumped to the left ventricle and then leaves the heart by way of the aorta. 5. Valves keep the blood flowing in the proper direction, preventing any blood from flowing backward and causing problems. Systemic circulation 1. Oxygenated blood is pumped through the aorta 2. Blood is forced through the arteries, which forces the blood through smaller arteries called arterioles. 3. The arterioles carry the blood and nutrients to the even smaller capillaries, where the blood makes contact with the cells in the body. 4. Oxygen is delivered and waste cells are picked up to make the journey back to the heart. 5. The waste-rich blood is pumped through the veins. 6. The veins reach the heart, where the waste-filled blood flows into the right atrium Veins, Arteries, Capillaries Veins
Structure Wide lumen Thin endothelium (single layer of cells) Has valves Smooth muscles Elastic tissue
Adaptation takes blood back to the heart so a high pressure is not required. It also allows ease of flow. reduces friction of the flowing blood keeps blood flowing towards the
Arteries
Capillaries
Receive blood under high pressure from the ventricles of the heart. The walls of arteries consist of three layers, namely an outer layer, a thick middle layer and an inner layer. Outer layer consist of white fibrous connective tissue which merges to the outside with the loose connective tissue in which artery is found. thick middle layer consist of elastic connective tissue and involuntary muscle tissue. this layer is supplied with two sets of nerves, one stimulating the muscles to relax so that the artery is allowed to widen, and the other one causing the circular muscles to contract, making the artery become narrower. The inner layer of endothelium consists of flat epithelial cells which are packed closely together and which is continuous with the endocardium of the heart. The flat cells make the inside lining of the arteries smooth. Very small Thin walls (one-two cells thick) Microscopic holes (in kidney/liver capillaries)
heart and prevents backflow. can constrict to improve exchange of gas at the alveoli works as the smooth muscles relaxes to return the vessel to its orignal size and shape Outer layer helps to anchor the arteries because the heart pumps the blood through the arteries at a great pressure. Flat cells limit friction between the blood and the lining to a minimum. Must be able to stretch each time the heart beats, without collapsing under the increased pressure.
Allows diffusion to occur Microscopic holes allow proteins and nutrients to be excreted.
Blood Structure Red blood cell (Erythrocytes)
Function To carry oxygen/carbon dioxide to cells o Concave shape allows large surface area in order for large amounts of oxygen per cell Contains hemoglobin which stick onto oxygen gas
Lymphocytes
Neutrophils granulocytes
Platelets
Makeup of Blood
Responsible for immune responses Two main: B cells and T cells o B cells: make antibodies that attack bacteria and toxins o T cells: attack body cells themselves when they have been taken over by viruses or have become cancerous Secrete lymphokines that modulate the functional activities of many other types of cells Present at sites of chronic inflammation First immune cells to arrive at a site of infection o Arrived through a process called chemotaxis Ingest pathogens Protect the body against pathogens Prevent excessive internal/external bleeding by clotting after an injury Maintenance of homeostasis (process which causes bleeding to stop)
Nervous System Definition Central Nervous System: Often abbreviated as CNS. It comprises of the brain and spinal cord. The CNS receives sensory information from the nervous system and controls the body's responses. Peripheral Nervous System: Often abbreviated as PNS. It is the division of the nervous system containing all the nerves that lie outside of the CNS Receptors: A sensory nerve ending that responds to a stimulus in the internal or external environment of an organism. Sense organ: A group of receptor cells responding to a specific stimulus, such as light, sound, touch, temperature, chemicals
