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Biology questions, chapter 9
Nama / NameKelas / ClassTarikh / Date

Nutrition and the Human Digestive System

46 marks. Use Practice to check each answer as you go, or Exam to answer everything against the clock first.

Section A: objective questions

12 marks
Choose the best answer for each question.
1

Question 1

Which organ is part of the digestive system but is NOT part of the alimentary canal?
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B
The pancreas, liver and gallbladder add digestive juices but food does not pass through them. The other three are parts of the alimentary canal.
For the teacher: Remembering, low difficulty, standard 9.1.1
Textbook p. 144
2

Question 2

Which process is an example of chemical digestion?
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C
Chemical digestion needs enzymes. Chewing, churning and peristalsis are physical digestion.
For the teacher: Understanding, low difficulty, standard 9.2.1
Textbook p. 144
3

Question 3

Which cells in the gastric glands secrete hydrochloric acid?
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D
Parietal cells secrete hydrochloric acid. Chief cells secrete pepsinogen and mucous cells secrete mucus.
For the teacher: Remembering, low difficulty, standard 9.2.3
Textbook p. 145
4

Question 4

Which is NOT a function of hydrochloric acid in the stomach?
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A
Emulsification of lipids is done by bile in the duodenum, not by hydrochloric acid.
For the teacher: Understanding, low difficulty, standard 9.2.3
Textbook p. 146
5

Question 5

Bile helps in the digestion of lipids because it
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C
Bile has no enzyme. It emulsifies lipids into tiny droplets and makes the medium alkaline, which helps lipase.
For the teacher: Understanding, low difficulty, standard 9.2.4
Textbook p. 146
6

Question 6

A patient has no pancreas. Which digestion is NOT affected, because the enzyme comes from another organ?
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D
Salivary amylase comes from the salivary glands. Pancreatic amylase, trypsin and lipase would be missing.
For the teacher: Applying, medium difficulty, standard 9.2.4
Textbook p. 147
7

Question 7

Starch is mixed with amylase in tube A and with distilled water in tube B at 37 °C for 10 minutes. Which result is expected with Benedict's solution?
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A
Amylase hydrolyses starch to maltose, a reducing sugar, so A gives a brick-red precipitate. Starch is not a reducing sugar, so B stays blue.
For the teacher: Applying, medium difficulty, standard 9.2.5
Textbook p. 148
8

Question 8

Which structure in a villus absorbs fatty acids and glycerol?
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B
Fatty acids and glycerol recombine to lipid droplets and enter the lacteal. Glucose and amino acids enter the blood capillaries.
For the teacher: Understanding, low difficulty, standard 9.3.2
Textbook p. 151
9

Question 9

Glucose in the ileum is absorbed into the epithelial cells against its concentration gradient. What is this process?
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D
Glucose and galactose are absorbed by active transport, which uses energy to move molecules against the gradient.
For the teacher: Understanding, low difficulty, standard 9.3.2
Textbook p. 152
10

Question 10

In the liver, excess amino acids are converted to urea. What is this process called?
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A
Deamination removes the amino group from excess amino acids to form urea.
For the teacher: Remembering, low difficulty, standard 9.4.2
Textbook p. 154
11

Question 11

0.50 g of groundnut is burnt and heats 20 g of water by 15 °C. What is the energy value of the groundnut? (1 g water needs 4.2 J per °C)
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C
(20 × 4.2 × 15) ÷ (0.50 × 1000) = 1260 ÷ 500 = 2.52 kJ g⁻¹.
For the teacher: Applying, medium difficulty, standard 9.6.1
Textbook p. 156
12

Question 12

A man often has a hard, dry stool and passes it with difficulty. Which advice is best?
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A
Fibre stimulates peristalsis and water keeps the faeces soft, so they move easily. This prevents constipation.
For the teacher: Evaluating, high difficulty, standard 9.7.2
Textbook p. 161

Section B: structured questions

34 marks
Answer all questions. Write your answers in the spaces provided.
13

Question 13

Salivary amylase acts on food in the mouth.
[2 marks] (a)State the substrate and the product of salivary amylase.
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[1 mark] (b)Saliva has pH 6.5 to 7.5. Why is this important?
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For the teacher: Understanding, low difficulty, standard 9.2.2
Textbook p. 145
14

Question 14

Explain how protein is digested in the stomach.
[2 marks] (a)Name the inactive enzyme and the cells that secrete it.
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[1 mark] (b)Explain how it becomes active.
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[1 mark] (c)State the product of protein digestion in the stomach.
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[1 mark] (d)Why does the stomach wall not get digested?
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For the teacher: Understanding, low difficulty, standard 9.2.3
Textbook p. 145
15

Question 15

A student mixes 5 ml of albumen suspension and 1 ml of 0.1 M hydrochloric acid in each of tubes A and B. He adds 1 ml of 1% pepsin to A and 1 ml of distilled water to B. Both tubes are kept at 37 °C for 20 minutes.
[1 mark] (a)State the manipulated variable.
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Tick each point you got.
[2 marks] (b)State the observation in each tube after 20 minutes.
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[2 marks] (c)Explain the result in A.
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For the teacher: Analysing, medium difficulty, standard 9.2.5
Textbook p. 149
16

Question 16

Diagram 1 shows a villus in the ileum.
Villus in the ileum with lacteal, epithelial cells, blood capillaries and lymph vessel labelled
Diagram 1
[1 mark] (a)The epithelium of the villus is one cell thick. Explain why this is an advantage.
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Tick each point you got.
[2 marks] (b)State two other adaptations of the ileum or villus for absorbing nutrients.
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Any 2 points
Tick each point you got.
[2 marks] (c)Name the two substances absorbed into the lacteal, and the vitamins carried by it.
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For the teacher: Understanding, low difficulty, standard 9.3.2
Textbook p. 151
17

Question 17

Blood from the small intestine flows to the liver.
[1 mark] (a)Name the blood vessel that carries blood from the small intestine to the liver.
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[3 marks] (b)State three functions of the liver in assimilation.
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Any 3 points
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For the teacher: Understanding, low difficulty, standard 9.4.2
Textbook p. 153
18

Question 18

A standard 0.1% ascorbic acid solution and three juices (P, Q and R) were each added drop by drop to 1 ml of DCPIP solution. The table shows the volume of each liquid needed to decolourise the DCPIP.
LiquidVolume needed (ml)
0.1% ascorbic acid2.0
Juice P5.0
Juice Q2.5
Juice R8.0
[2 marks] (a)Which juice has the highest vitamin C content? Give a reason.
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Tick each point you got.
[2 marks] (b)Calculate the percentage of vitamin C in juice P.
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[2 marks] (c)Juice Q is boiled for 30 minutes. Predict the volume needed afterwards and explain.
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For the teacher: Applying, high difficulty, standard 9.6.2
Textbook p. 158
19

Question 19

Siti eats mostly white rice and fried food with few vegetables. She often has constipation. She was also told her stomach lining is inflamed because she skips meals.
[2 marks] (a)Explain why her diet causes constipation.
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[2 marks] (b)Name the condition of her stomach lining and state its cause.
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[2 marks] (c)Suggest two changes to her habits.
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Any 2 points
Tick each point you got.
For the teacher: Evaluating, medium difficulty, standard 9.7.2
Textbook p. 161