Question

A plant is exposed to an optimum amount of light intensity, with a limited supply of CO${}_2$. As the carbon dioxide, concentration increases the rate of photosynthesis increases. Which of the following act as limiting factor in above-given case?

• A. Carbon dioxide
• B. Light
• C. Temperature
• D. Both A and B

Answer 1

The correct option is A Carbon dioxide

Blackman's law of limiting factors are the various factors which affect the rate of photosynthesis. It is considered that when the other factors are constant, the factor which is least or minimum has the direct effect on the rate of photosynthesis. When the light intensity is maintained at the optimum level, the other factor which is CO${}_2$ supply is reduced. This causes the rate of reaction to completely depend on CO${}_2$. When the carbon dioxide concentration increases, the rate of reaction increases. This explains that the limiting factor is carbon dioxide.

Thus, the correct answer is option A.