As light intensity increases in photosynthesis so does the rate of photosynthesis. The more light there is the more photosynthesis in the thylakoid membrane is activated. However, the light intensity can only increase up to a certain point before the rate of photosynthesis no longer increases. Once there is a sufficient intensity of light, the ATP and NADPH that come from the light reactions will be in abundance. For the remaining part of photosynthesis to occur (the Calvin cycle), carbon dioxide is needed.
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