🧬 QUESTION 1 — CHAPTER 1 [10 MARKS]
A student investigates the effect of pH on the activity of an enzyme. Three test tubes containing the same volume and concentration of enzyme solution are prepared at different pH values. The student measures the amount of product formed after 5 minutes.
(a) Identify the manipulated variable and responding variable. [2 marks]
(b) State two variables that must be kept constant and explain why each must be controlled. [4 marks]
(c) The student predicts that enzyme activity will increase continuously as pH increases. However, the results show that enzyme activity increases up to pH 7 and then decreases.
Explain why the results do not necessarily mean that the experiment is unsuccessful. [2 marks]
(d) State two characteristics of a good hypothesis. [2 marks]
🧬 QUESTION 2 — CHAPTER 2 [10 MARKS]
A student examines two cells under a light microscope.
Cell P has a cell wall, chloroplasts, a large central vacuole and a nucleus.
Cell Q has a cell membrane, cytoplasm and nucleus but no cell wall or chloroplasts.
The student places both cells in a solution with a lower water potential than the cell sap.
(a) Identify Cell P and Cell Q. [2 marks]
(b) Explain what happens to Cell P when it is placed in the solution. [3 marks]
(c) Explain what happens to Cell Q when it is placed in the solution. [3 marks]
(d) Explain why Cell P is less likely to burst compared with Cell Q. [2 marks]
TOTAL: 20 MARKS
2September 3, 2026 1.3K 19 10
