CIE iGCSE Co-Ordinated Science B7.3 Digestion Exam Style Questions Paper 2
Question
When the phenol molecules in apples are exposed to air, they react with oxygen and the fruit turns brown. This is an enzyme-controlled reaction.
The graph shows the effect of pH on the time taken for pieces of apple to turn brown.
Which statements are correct?
1 The optimum pH for this enzyme is between 5 and 6.
2 As the pH increases from 3 to 5, the phenol molecules and the enzyme move faster.
3 As the pH becomes higher than 6, the shape of the active site changes.
(A) 1, 2 and 3
(B) 1 and 2 only
(C) 1 and 3 only
(D) 2 and 3 only
▶️Answer/Explanation
Ans : C
Question
The diagram shows a villus.
What are structures P and Q and which substances do they absorb?
▶️Answer/Explanation
Ans: D
Question
A student investigates the effect of size of gelatine cubes on the rate of digestion by protease. The student places a cube of gelatine with a volume of 8 cm3 into a beaker of protease. The time taken for the cube to be digested is recorded. A second 8 cm3 cube of gelatine is cut up into eight 1 cm3 cubes to represent mechanical digestion and the experiment is repeated.
The results are shown.
Which statements are correct?
1. Cutting up the 8 cm3 cube increases the surface area exposed to the enzyme.
2. Chemical digestion cannot occur unless mechanical digestion also occurs.
3. Mechanical digestion increases the rate of chemical digestion.
(A) 1, 2 and 3 (B) 1 and 2 only (C) 1 and 3 only (D) 2 and 3 only
▶️Answer/Explanation
Ans: C
Question
Which row about secretions in the alimentary canal is correct?
▶️Answer/Explanation
Ans: D