Describe an experiment to show that carbon dioxide is necessary for photosynthesis. State expected results and explain them.

a) The aim of the experiment is to investigate whether carbon dioxide is necessary for photosynthesis.

b)

i) Leaf A: The leaf will turn blue-black when tested for starch.

ii) Leaf B: The leaf will remain brown/yellow (the color of iodine) when tested for starch.

c) Leaf A was exposed to carbon dioxide, light, and water, which are all essential requirements for photosynthesis. As a result, photosynthesis occurred in leaf A, producing glucose that was stored as starch. The presence of starch is indicated by the positive iodine test, which turns the leaf blue-black.

d) Three other factors that affect the rate of photosynthesis are:

• Light intensity
• Temperature
• Water availability