Question 1: Define the overall chemical reaction of photosynthesis.

Answer: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Question 2: Explain the role of chlorophyll in the reaction.

Answer: Chlorophyll absorbs light energy, which drives the process of photosynthesis.

Question 3: Describe where in the plant cell photosynthesis primarily occurs.

Answer: In the chloroplasts, mainly within the thylakoid membranes.

Question 1: If 12 molecules of carbon dioxide are used in a reaction, how many molecules of water are required? (Hint: the balanced equation shows a 1:1 ratio)

Answer: 12 molecules of water

Question 2: Calculate the amount of glucose produced if 36 molecules of carbon dioxide are used. (Assuming complete reaction, 6 molecules of CO₂ produce 1 molecule of glucose).

Answer: 6 molecules of glucose

Question 1: Describe a simple experiment to test the effect of light intensity on the rate of photosynthesis.

Answer: Use pondweed in water under different light intensities; measure the oxygen bubbles produced over time.

Question 2: Identify two variables that should be controlled in the above experiment.

Answer: Temperature and carbon dioxide concentration.

Question 3: State one safety precaution when conducting experiments involving aquatic plants and light sources.

Answer: Ensure electrical equipment is kept away from water to prevent electrical hazards.

Question 1: In an experiment, the rate of oxygen production was measured under three different light intensities: low, medium, and high. The data shows oxygen bubbles per minute as 2, 5, and 8 respectively. Explain what this data suggests about the effect of light intensity on photosynthesis.

Answer: The data indicates that increasing light intensity increases the rate of photosynthesis, as more oxygen bubbles are produced.

Question 1: Explain how light energy is converted into chemical energy during photosynthesis. (6 marks)

Answer: Light energy is absorbed by chlorophyll, exciting electrons. These high-energy electrons are transferred through the electron transport chain, leading to the formation of ATP and NADPH. These energy carriers are then used in the Calvin cycle to convert carbon dioxide into glucose.

Question 1: Describe one way that knowledge of photosynthesis reactions can be used to improve agricultural productivity.

Answer: By enhancing light conditions or using supplements like CO₂ enrichment to increase the rate of photosynthesis in crops.