8. What does an increase in temperature have an effect on, that controls the rate of photosynthesis?

An increase in temperature can have a significant effect on the rate of photosynthesis, which is the process by which green plants, algae, and some bacteria convert light energy, usually from the sun, into chemical energy in the form of glucose.

Here are the steps to understand this:

1. Photosynthesis is a chemical reaction that is catalyzed by enzymes. Enzymes are proteins that speed up chemical reactions in living organisms.

2. Like all enzymes, the enzymes involved in photosynthesis are sensitive to temperature. They have an optimal temperature at which they work most efficiently.

3. If the temperature increases beyond this optimal point, the structure of the enzymes begins to break down, or denature. This means they can no longer catalyze the photosynthesis reaction effectively, and the rate of photosynthesis decreases.

4. Additionally, higher temperatures can cause the plant to lose water through transpiration. If the plant loses too much water, it may close its stomata (the tiny pores on the surface of leaves where gas exchange occurs). This prevents the plant from taking in more carbon dioxide, which is needed for photosynthesis, thus slowing the rate of photosynthesis.

5. However, up to a certain point, an increase in temperature can actually increase the rate of photosynthesis. This is because as temperature increases, so does the kinetic energy of the molecules involved in the reaction. This means they are more likely to collide and react, speeding up the rate of photosynthesis.

So, in summary, an increase in temperature can both increase and decrease the rate of photosynthesis, depending on the specific temperature and the plant's adaptations to heat and water loss.