Practice Questions

1.Why does the rate of photosynthesis increase as light intensity increases?

Light provides energy for photosynthesis. As light intensity increases, more energy is available, so the rate of photosynthesis increases.

2.Why does the rate eventually level off?

At high light intensity, another factor becomes limiting, such as carbon dioxide concentration or temperature. This prevents the rate from increasing further.

3.Why is sodium hydrogencarbonate used?

Sodium hydrogencarbonate releases carbon dioxide in solution, providing a constant supply of CO₂ for photosynthesis.

4.Which variable must be kept constant to ensure a fair test?

Variables such as temperature, carbon dioxide concentration, type/length of pondweed, and light colour must be kept constant to ensure a fair test.