Form 4 Biology Chapter 6
Nutrition
Objective Questions 1
Table 1 shows the observations that are made during food tests carried out on food samples. Type of food test
Observation
Biuret test
Purple colour
Benedict solution
Light blue colour
Iodine solution
Dark blue colour Table 1
Based on the results above, which of the following conclusions about the food samples is correct? Protein Reducing sugar Starch A Not present Not present Present B Not present Present Not present C Present Not present Present D Present Present Not present 2
The product of urea defecation is formed from A fat B cellulose C glycerol D protein
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Soya bean and milk are considered as a type of food that are similar in quality because both A consist of the same elements B are balanced food C contain similar energy levels D contain all the required types of amino acid
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Which of the following enzymes requires an acidic medium for its reaction? A Trypsin B Erepsin C Pepsin D Lipase
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Which of the following graphs shows how the photosynthetic rate changes with the surrounding temperature? A
B
C
D
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Ascorbic acid is required by humans to help prevent contracting A scurvy B beriberi C rickets D pellagra
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Which of the following organic substances is first produced in the photosynthetic process? A Starch B Glucose C Sucrose D Maltose
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In an experiment that is carried out to study photosynthesis, some sodium hydrogen carbonate is added into a flask containing Chlorella to supply A oxygen B carbon dioxide C mineral salts D hydrogen
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How does the symbiosis between bacteria and protozoa, which is found in the herbivore digestive system, help in the animals’ digestion? A Hydrolyse the cellulose content in the animals’ diet B Synthesise amino acids that are not found in the animals’ diet C Catalyse the digestion of the animals’ diet that is incomplete D Hydrolyses the starch content in the animals’ diet
10 In the starch test, a green leaf is put into boiling water and then boiled in ethanol. Then, the leaf is washed with water before iodine solution is dropped on it. What is the effect if the leaf is not boiled in ethanol? A The leaf cells are still alive B The iodine does not react with the starch C The starch spots in the leaf cell is not hydrolysed D The colour change that is produced from the starch test is not clear 11
In an experiment to determine the energy value of groundnuts, the following readings are obtained: Mass of water in the test tube = 20.0 g Mass of burnt groundnuts = 0.5 g Temperature of water before the groundnuts are burnt = 30°C Temperature of water after the groundnuts are burnt = 80°C What is the energy value of the groundnuts? [Specific heat capacity of water = 4.2 Jg-10C-1] A 0.1 kJ B 2.0 kJ C 8.4 kJ D 13.4 kJ
12 In an experiment, 1 cm3 of human saliva is put into a test tube containing 2 cm3 of 0.1% starch solution. This mixture is allowed to react completely for 30 minutes. Then, an iodine solution is dripped into the mixture. After the test tube is shaken, the contents of the test tube will show the colour of A purple B brown C yellow D dark blue 13 Which of the following sequences of enzymes and digestive juices is the correct sequence relating to the digestion of egg white in the human digestive tract? A Saliva, pepsin, pancreatic juice, bile and intestinal juice B Saliva, pancreatic juice, bile and intestinal juice C Pepsin, pancreatic juice, bile and intestinal juice D Pepsin, pancreatic juice and intestinal juice 3
14 Table 2 shows the result that is obtained in an experiment to determine the vitamin C content in a sample of pineapple juice. Volume that is needed to discolour 1.0 cm3 of 0.1% DCPIP solution (cm3) 0.4 1.6
Sample Ascorbic acid 0.1% Pineapple juice
Table 2 What is the vitamin C content in the pineapple juice? A 0.25 mg cm-3 B 0.4 mg cm-3 C 0.6 mg cm-3 D 4.0 mg cm-3 15 All the following structures are part of the human digestive system except A ileum B larynx C liver D oesophagus 16 What causes a person to suffer from a disease such as anorexia nervosa? A Absorption of mercury substances through food B Self defence against taking sufficient food C Eating food that is high in cholesterol D Nerve damage during birth 17 A student heats a mixture of Benedict solution and urine from a patient suffering from diabetes mellitus. Which of the following can be observed? A White precipitate changes to a brick red precipitate B An orange precipitate is formed C Solution colour changes to blue D Mixture colour disappears 18 The purpose of preserving food is to A kill all the bacteria found in food B increase the quality of food C maintain the original form and taste of the food D enrich the food with nutrients
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19 Which combination of nutrients is required for the healthy formation of bones? A Calcium and vitamin C B Calcium and vitamin D C Iron and phosphate D Iron and vitamin D 20 What happens to the oxygen atom from the carbon dioxide molecule that is absorbed by green plants during the photosynthetic process? I Used to form a simple sugar substance II Channelled for oxidation in tissue respiration III Released as water molecule IV Released as oxygen gas A I and III only B II and IV only C I, II and III only D I, II, III and IV 21 In the assimilation process, excess amino acid in the liver is converted to substance X. What is substance X? A Urea B Nitrogen C Protein D Glucose 22 Which of the following conditions can cause the stoma to open? I Guard cell becomes turgid II Guard cell carries out photosynthesis III There is a high osmotic pressure in the guard cell IV Sugar is converted to starch in the guard cell A I and III only B I, II and III only C I, III and IV only D I, II and IV only 23 Constipation, teeth damage and obesity are caused by unhealthy eating habits such as I diet that supplies a high calorie value II not eating roughage III taking excess sugar IV drinking too much water when eating A I, II and III only B I and IV only C II and III only D I, II and III only 24 Which of the following statements about the basic human metabolic rate is true? 5
I The basic metabolic rate is not influenced by sex II The basic metabolic rate is influenced by weather III The basic metabolic rate of children is higher than the rate of the elderly IV The basic metabolic rate is not influenced by the size of the body A I, II and III only B I, II and IV only C I and IV only D II and III only 25 Oxygen that is released during photosynthesis is produced from the decomposition of I carbon dioxide II glucose III starch IV water A IV only B II only C I and III only D I, II and III only
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Structured Questions 1
An analysis of a box of milk shows the following nutrient contents: Protein Carbohydrate Fat
62.4% 7.0% 11.0%
(a) (i) Which nutrient content is used for growth and tissue repair? (ii) Which nutrient content contains the possible presence of any sugar? (iii) Calculate the percentage of nutrient content that is not shown in the list above. (b) Explain how roughage helps a person that is suffering from constipation. A student carries out an experiment to confirm the fat content of the milk. Figure 1 shows the sequence of the student’s experiment procedure. The pH indicator used is colourless when the ph value is 7 or less, and is purple in colour when the pH value exceeds 7.
Figure 1 (c) Give two reasons why the bile salt is added to milk at the start of the experiment? (d) Explain why the action of the lipase enzyme causes the pH indicator solution to lose its purple colour. (e) When the same experiment is carried out using goat milk, the time taken for the pH indicator solution to lose its purple colour is 7 minutes. Based on the experiment’s data, which milk contains less fat? Explain your answer.
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Table 1 shows the daily nutrient requirements according to the individual. Individual
Mass of body/kg
Energy/ kg
Protein/g
Vitamin D/ug
Iron/mg
Children (1 year old)
7.3
3 200
20
10
6
Female (18 years old)
56.0
9 200
58
2.5
12
Male (18 years old)
60.0
12 000
80
2.5
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Table 1 (a) Based on Table 1, why do teenage boys require (i) only one fourth of the vitamin D requirements compared with the vitamin D requirements of children? (ii) almost two times the iron requirements compared with the iron requirements of children? (iii) less iron compared with teenage girls? (b) Calculate the daily requirement value of protein per kg of body mass for (i) children (ii) teenage boys (c) (i) (ii)
Based on the body’s protein requirement in (b), explain the difference in protein requirements between children and teenage boys. Explain why the body’s protein requirement can be met by eating meat or soya bean rather than by eating only one type of vegetable.
(d) State two food classes that is required for a balanced diet other than that found in Table 1.
Essay Question (a) Explain the meaning of food digestion and absorption in humans. (b) Describe the role of the pancreas in food digestion in our body. (c) Other than sterilisation and pasteurisation, describe five methods to prevent microbial growth or enzyme activity during the preservation of food. State how these methods can prevent the growth of microorganisms or their enzyme activity.
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Answers Objective Questions 1C 2D 3D 4C 5D 6C 7B 8B 9A 10 D 11 C 12 C 13 D
14 15 16 17 18 19 20 21 22 23 24 25
A B B B C B A A B D D A
Structured Questions 1 (a) (i) Protein (ii) Carbohydrate (iii) 100% - (62.4 + 7 + 11.0)% = 100% - 80.4% = 19.6% (b) Roughage The roughage stimulates peristalsis and prevents the stool from becoming hard. (c) 1 Alkaline characteristics – prepares a medium that is suitable for enzymatic action 2 Acts as the fat emulsifying agent (d) The action of the lipase produces fatty acid, which has acidic characteristics to neutralise the alkaline condition of the mixture in the test tube (e) Packaged milk because its digested products take a longer time to neutralise the contents of the test tube 2
(a) (i) Teenage boys are nearly at the end of their bone and teeth growth compared with children who need more vitamin D to help in calcium absorption for the formation of strong bone and teeth. (ii)
Teenage boys are more active compared with children; as such teenage boys need more iron nutrients to build haemoglobin for oxygen transport to the muscle for energy release.
(iii) Teenage girls experience menstruation every month. As such, they require more iron nutrients than teenage boys, to replace the loss of blood. (b)(i) Daily protein requirement per kg of body mass = 20 g = (2.7 g/kg)/(7.3 kg) (ii) Daily protein requirement per kg of body mass = 80 = (1.3 g/kg)/(60) 9
(c) (i) Children require twice the amount of protein compared with teenage boys because children are in the a stage of active growth, where protein is required to build new cells, while teenage boys only require protein to repair damaged tissues only. (ii) Meat/soya bean contains all the required amino acids. Eating one type of vegetable will not provide all the required amino acids. (d) 1 Roughage 2 Water Essay Question (a) The meaning of food digestion – Break up / hydrolyse big and complex food molecules into small and simple molecules through the action of enzymes. The meaning of food absorption – Small and digested food molecules diffuse from inside the intestine into the blood vessels (b)
Pancreas secretes pancreatic juice that has alkaline properties in order to prepare a suitable medium for enzymatic action. Pancreatic juice contains (i) amylase enzyme that acts on the starch to produce maltose, (ii) lipase enzyme that acts on the fat to produce fatty acids and glycerol, (iii) trypsin enzyme that hydrolyses peptone and polypeptide into peptides.
(c)
Hypothesis: Young mice is given vitamins in their milk grow faster than young mice that are not given this nutrition. Plan of experiment: Number of mice: 25 – 30 mice per group Create two groups. Group 1: Given milk containing vitamins Group 2: Given milk without vitamins Variable that: is manipulated – vitamin content in the milk; responds – increase in the growth rate (measured in mass); are kept constant – species, age, sex, surroundings, and milk quality
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