iGCSE Biology (0610)-7.2 Digestive system - iGCSE Style Questions Paper 3

Question

(a) Fig. 7.1 is a diagram of the human digestive system.

State the letter in Fig. 7.1 that identifies:

the gall bladder
the organ that secretes salivary amylase
where egestion occurs
where most absorption occurs
where physical digestion occurs
where the pH is acidic.

(b) The boxes on the left show some examples of nutrients. The boxes on the right show some examples of molecules. Draw lines to link each nutrient to a molecule found in that nutrient. Draw two lines.

(c) State the vitamin deficiency that causes rickets.

(d) Describe the dietary importance of the mineral ions calcium and iron.

(e) Fat, protein, vitamins and mineral ions are all required for a balanced diet. State the names of two other components of a balanced diet.

▶️ Answer/Explanation

Solution

Ans:

(a) H (gall bladder), A (salivary amylase secretion), F (egestion), G (absorption), C (physical digestion & acidic pH).

(b) Protein → Amino acids, Fat → Fatty acids & glycerol (as shown in the diagram).

(c) Vitamin D deficiency causes rickets, leading to weak bones.

(d) Calcium strengthens bones/teeth; iron is essential for haemoglobin in red blood cells.

(e) Two other components: Carbohydrates and water/fibre.

Question

(a) Fig. 1.1 is a diagram of the digestive system.

(i) State the letter from Fig. 1.1 that represents:

where salivary amylase is produced
where insulin is produced
the liver
where protease acts.

(ii) State one function of the hydrochloric acid in the stomach.

(b) Amylase is an enzyme.

(i) Describe the function of amylase.

(ii) Define the term enzyme.

▶️ Answer/Explanation

Solution

(a)(i)

1. A (where salivary amylase is produced – the salivary glands)

2. C (where insulin is produced – the pancreas)

3. G (the liver)

4. E (where protease acts – the stomach)

Explanation: The digestive system diagram would show these structures clearly. Salivary amylase is produced in the salivary glands (A), insulin is produced in the pancreas (C), the liver (G) is a large organ with multiple functions, and protease enzymes act in the stomach (E) to break down proteins.

(a)(ii)

Kills/destroys harmful microorganisms OR provides an optimum acidic pH for pepsin/protease enzyme activity.

Explanation: Hydrochloric acid in the stomach serves two main purposes. First, it creates a highly acidic environment that kills most pathogens entering with food. Second, it provides the ideal pH (around pH 2) for pepsin, the protease enzyme that breaks down proteins, to function most effectively.

(b)(i)

Amylase breaks down starch into simpler sugars (like maltose).

Explanation: Amylase is a digestive enzyme that specifically targets starch molecules. It catalyzes the hydrolysis of starch (a polysaccharide) into smaller carbohydrate units, primarily maltose (a disaccharide). This process begins in the mouth (salivary amylase) and continues in the small intestine (pancreatic amylase).

(b)(ii)

An enzyme is a protein that acts as a biological catalyst, speeding up chemical reactions without being used up in the process.

Explanation: Enzymes are protein molecules that play crucial roles in biological systems. They work by lowering the activation energy needed for chemical reactions to occur, thereby accelerating these reactions. Importantly, they remain unchanged after the reaction, allowing them to be reused. Each enzyme is specific to particular substrates and reactions.

iGCSE Biology (0610)-7.2 Digestive system – iGCSE Style Questions Paper 3

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