Question

Which one of the following is limiting rate of photosynthesis in nature

• A. Light
• B. $C{O}_2$
• C. $O_2$
• D. Chlorophyll

Answer 1

The correct option is B $C{O}_2$

Carbon dioxide is a major limiting factor influencing the rate of photosynthesis. The concentration of $C{O}_2$ is very low in the atmosphere (between 0.03 percent and 0.04 percent). This level of carbon dioxide is far below the requirement for optimum photosynthesis. Increase in concentration up to 0.05 percent can cause an increase in the rate of photosynthesis but beyond this level, it becomes damaging over longer periods.