Title: Factors affecting photosynthesis - Photosynthesis - OCR Gateway - GCSE Combined Science Revision - OCR Gateway - BBC Bitesize
Headings: Factors affecting photosynthesis
Photosynthesis
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Factors affecting photosynthesis
Light intensity
Carbon dioxide concentration
Temperature
Chlorophyll
The compensation point

Content: If oxygen production or carbon dioxide uptake is used as a measure of photosynthetic rate, the graphs are slightly different. The line does not go through the origin. This is because oxygen production and carbon dioxide uptake are affected by respiration as well as photosynthesis. Respiration uses oxygen and produces carbon dioxide. Below is a graph measuring the rate of photosynthesis plotted on carbon dioxide against light intensity: This graph shows that with no light, the carbon dioxide uptake is below zero (point A on the graph). With no light, there is no photosynthesis. So the rate of respiration is greater than the rate of photosynthesis. So this means there is an overall excess of carbon dioxide produced during respiration. An excess is the same as a negative uptake.