Rate of Photosynthesis
Science: KS3, topic 1.5.4
The Rate of Photosynthesis
The four key factors affecting the rate of photosynthesis are:
Temperature
- Increasing the temperature increases the rate of photosynthesis because more energy is provided.
- However, if the temperature is increased to above about 45°C, the enzymes that catalyse (speed-up) the reaction begin to denature (not work anymore).
- This causes the rate of the reaction to drop sharply until it stops altogether.
Light intensity
- Increasing light intensity increases the rate of photosynthesis because more energy is provided.
- However, if the light intensity is increased above a certain threshold, the rate of photosynthesis will not increase because another factor (such as temperature) is limiting the rate of the reaction.
Carbon dioxide concentration
- Increasing the carbon dioxide concentration increases the rate of photosynthesis because carbon dioxide is a reactant in photosynthesis.
- However, above a certain threshold, further increases in the carbon dioxide concentration do not increase the rate of photosynthesis because another factor (such as light intensity) is limiting the rate of reaction.
Chlorophyll concentration
- High chlorophyll concentration gives a high rate of photosynthesis.
Test yourself on Rate of Photosynthesis
What are the key factors affecting the rate of photosynthesis?
Select the correct statement about photosynthesis in each pair
What happens to the rate of photosynthesis once the temperature rises past about 45°C?
A plant is grown at a temperature of 50°C. What is most likely to happen to its rate of photosynthesis?