Title: Factors affecting the rate of photosynthesis - Pass My Exams: Easy exam revision notes for GSCE Biology
Headings: Factors affecting the rate of photosynthesis
Factors affecting the rate of photosynthesis
3. Carbon Dioxide

Content: Factors affecting the rate of photosynthesis - Pass My Exams: Easy exam revision notes for GSCE Biology
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Factors affecting the rate of photosynthesis
3. Carbon Dioxide
Carbon dioxide is used to make sugar in the photosynthesis reaction. The concentration of carbon dioxide in the Earth’s atmosphere varies between 0.03% and 0.04%. An increase in the concentration of carbon dioxide gives an increase in the rate of photosynthesis. It is difficult to do this out in the open air but is possible in a greenhouse. The rate of photosynthesis increases linearly with increasing carbon dioxide concentration (from point A to B on the graph). Gradually the rate falls of and at a certain carbon dioxide concentration the rate of photosynthesis stays constant (from point B to C on the graph). Here a rise in carbon dioxide levels has no affect on the rate of photosynthesis as the other factors such as light intensity become limiting. Many crops such as tomatoes and lettuce give higher yield when grown in greenhouses.