Question

With reference to factors affecting the rate of photosynthesis, which of the following statements is not correct ?

• A. Increasing atmospheric $CO_2$ concentration up to $0.05\%$ can enhance $CO_2$ fixation rate
• B. $C_3$ plants respond to higher temperatures with enhanced photosynthesis while $C_4$ plants have much lower temperature optimum
• C. Tomato is a greenhouse crop which can be grown in $CO_2 -$ enriched atmosphere for higher yield
• D. Light saturation for $CO_2$fixation occurs at $10\%$ of full sunlight

Answer 1

Answer: (B)

$C_3$ plants respond to higher temperatures with enhanced photosynthesis while $C_4$ plants have much lower temperature optimum

Answer 2

In $C _{3}$ plants photosynthesis is decreased at higher temperature due to increased photorespiration.
$C _{4}$ plants have higher temperature optimum because of the presence of pyruvate phosphate dikinase enzyme, which is sensitive to low temperature.