Nutrition in Animals

26 Grade 9 Integrated Science questions on Nutrition in Animals, with worked marking schemes. 26 questions are available on this topic in full.

1. Question 1

   1 mark

   A learner eats a meal of ugali and sukuma wiki. In which part of the alimentary canal does the chemical digestion of the ugali (starch) begin?

   A. Small intestine

   B. Mouth

   C. Stomach

   D. Large intestine

   (1 mark)

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2. Question 2

   5 marks

   A learner draws the human alimentary canal. (a) Arrange the following parts in the correct order that food passes through: small intestine, mouth, stomach, oesophagus, large intestine. (3 marks) (b) State the function of the oesophagus. (2 marks)

   (5 marks)

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3. Question 3

   1 mark

   A goat is described as a herbivore while a lion is a carnivore. Which feature of the lion's teeth is best adapted for tearing flesh?

   A. Sharp, pointed canines

   B. Broad, flat molars

   C. Ridged premolars for grinding

   D. Chisel-shaped incisors only

   (1 mark)

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4. Question 4

   1 mark

   The wave-like muscular contractions that push food along the alimentary canal are called:

   A. Absorption

   B. Peristalsis

   C. Assimilation

   D. Digestion

   (1 mark)

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5. Question 5

   3 marks

   State the functions of the following parts of the digestive system:

   (a) Mouth

   (b) Stomach

   (c) Small intestine

   (3 marks)

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6. Question 6

   1 mark

   Hydrochloric acid is produced in the stomach during digestion. One important function of this acid is to:

   A. Emulsify fats

   B. Absorb vitamins

   C. Digest starch

   D. Kill germs in food

   (1 mark)

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7. Question 7

   4 marks

   (a) State the function of each of the following in digestion in humans:

   (i) saliva (ii) bile. (2 marks)

   (b) Explain why food must be digested before it can be used by the body cells. (2 marks)

   (4 marks)

   Marking scheme

   (a) (i) Saliva moistens and softens food to ease swallowing and contains the enzyme (salivary amylase/ptyalin) that begins the digestion of starch into maltose/sugars. (ii) Bile emulsifies fats, breaking large fat droplets into smaller droplets to increase the surface area for fat-digesting enzymes (it also neutralises the acidic food from the stomach). (b) Food is made of large, insoluble molecules that cannot pass through the walls of the gut into the blood; digestion breaks them down into small, soluble molecules that can be absorbed into the blood and used by body cells.

8. Question 8

   1 mark

   A herbivore such as a cow has broad, flat back teeth used for grinding plant material. These teeth are known as:

   A. Diastema

   B. Canines

   C. Molars

   D. Incisors

   (1 mark)

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9. Question 9

   3 marks

   A nurse advised a Grade 9 learner to include foods rich in roughage (dietary fibre) in the diet.

   (a) State two functions of roughage in the human digestive system. (2 marks)

   (b) Name one food substance that is a good source of roughage. (1 mark)

   (3 marks)

   Marking scheme

   (a) Any two of: roughage adds bulk to the food, which stimulates the muscles of the gut wall to move food along (peristalsis); it helps prevent constipation by keeping food and waste moving smoothly; it helps the gut absorb water properly / prevents digestive disorders. (2 marks) (b) Any one of: vegetables, fruits, whole-grain cereals (e.g. brown bread, maize bran), legumes/beans. (1 mark)

10. Question 10

    1 mark

    Proteins in a chapati-and-beans meal are digested into their end products before absorption. The end products of protein digestion are:

    A. Amino acids

    B. Maltose

    C. Fatty acids and glycerol

    D. Glucose

    (1 mark)

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11. Question 11

    1 mark

    Proteins are mainly digested in the

    A. stomach

    B. mouth

    C. large intestine

    D. liver

    (1 mark)

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12. Question 12

    1 mark

    The process of breaking down food into simpler substances that can be absorbed is called

    A. digestion

    B. absorption

    C. excretion

    D. respiration

    (1 mark)

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13. Question 13

    1 mark

    Vitamins and minerals are important in the diet because they

    A. help the body function properly and prevent deficiency diseases

    B. provide energy for the body

    C. build muscles only

    D. are not needed by the body

    (1 mark)

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14. Question 14

    1 mark

    During digestion in humans, the enzyme amylase in saliva acts on starch. The product formed when amylase digests starch is:

    A. Maltose

    B. Amino acids

    C. Fatty acids

    D. Glucose

    (1 mark)

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15. Question 15

    4 marks

    The human digestive system contains several enzymes. (a) State what an enzyme is. (2 marks) (b) Name the enzyme that digests proteins in the stomach and state its product. (2 marks)

    (4 marks)

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16. Question 16

    6 marks

    The small intestine is highly adapted for the absorption of digested food. State three adaptations of the small intestine that make it efficient for absorption, giving how each helps. (6 marks)

    (6 marks)

    Marking scheme

    Any three: It is very long (1) providing a large surface area/more time for absorption (1); it has many villi/microvilli (1) that increase the surface area for absorption (1); the villi have thin/one-cell-thick walls (1) allowing quick diffusion of food into blood (1); it has a rich network of blood capillaries (1) that carry away absorbed food maintaining a concentration gradient (1). (Max 6)

17. Question 17

    1 mark

    The absorption of digested food into the bloodstream takes place mainly in the small intestine. The finger-like projections that increase the surface area for absorption are called:

    A. Villi

    B. Cilia

    C. Alveoli

    D. Nephrons

    (1 mark)

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18. Question 18

    4 marks

    (a) Distinguish between mechanical digestion and chemical digestion. (2 marks)

    (b) Name the enzyme present in saliva and state the food substance it acts on. (2 marks)

    (4 marks)

    Marking scheme

    (a) Mechanical digestion is the physical breakdown of food into smaller pieces without changing its chemical nature (e.g. chewing/grinding by teeth), while chemical digestion is the breakdown of large insoluble food molecules into smaller soluble molecules by enzymes (a chemical change). (b) The enzyme is salivary amylase (ptyalin); it acts on starch, breaking it down into maltose (a sugar).

19. Question 19

    1 mark

    Digestion of starch begins in the

    A. mouth

    B. large intestine

    C. small intestine

    D. stomach

    (1 mark)

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20. Question 20

    1 mark

    Bile is a substance that helps in the digestion of fats. Bile is produced by the:

    A. Pancreas

    B. Gall bladder

    C. Stomach

    D. Liver

    (1 mark)

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21. Question 21

    1 mark

    The main role of the large intestine in the human digestive system is to:

    A. Absorb glucose into the blood

    B. Digest proteins

    C. Absorb water from undigested food

    D. Produce bile

    (1 mark)

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22. Question 22

    1 mark

    A ruminant such as a cow returns food from the stomach to the mouth to chew it again. This process is known as:

    A. Rumination (chewing the cud)

    B. Ingestion

    C. Egestion

    D. Peristalsis

    (1 mark)

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23. Question 23

    6 marks

    Herbivores and carnivores have differently adapted teeth. (a) State two differences between the teeth of a herbivore and those of a carnivore. (4 marks) (b) Give one reason why herbivores have large, ridged molars. (2 marks)

    (6 marks)

    Marking scheme

    (a) Any two contrasts, e.g. Herbivores have broad flat/ridged molars for grinding whereas carnivores have pointed/sharp molars (carnassials) for shearing (2); herbivores have small/blunt or no canines whereas carnivores have large sharp canines for tearing flesh (2); herbivores have sharp chisel-like incisors for cutting/biting plants whereas carnivores have smaller incisors (2). (Max 4) (b) The large ridged molars grind/crush tough plant material/cellulose (1) into small pieces to increase surface area for digestion (1).

24. Question 24

    1 mark

    The function of bile in digestion is to

    A. emulsify fats into smaller droplets

    B. digest proteins

    C. absorb water

    D. kill bacteria

    (1 mark)

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25. Question 25

    4 marks

    (a) State the meaning of the term balanced diet. (2 marks)

    (b) Name the food test used to identify the presence of starch and state the colour change observed when starch is present. (2 marks)

    (4 marks)

    Marking scheme

    (a) A balanced diet is a diet (meal) that contains all the required classes of food (carbohydrates, proteins, fats/lipids, vitamins, mineral salts, water and fibre/roughage) in the correct proportions/amounts needed by the body. (b) The test is the iodine test: a few drops of iodine solution are added to the food sample. When starch is present, the brown/yellow iodine solution turns blue-black.

26. Question 26

    1 mark

    Absorption of digested food mainly takes place in the

    A. small intestine

    B. stomach

    C. large intestine

    D. mouth

    (1 mark)

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