Question

The exceptional difference between $C_3$ and $C_4$ plants is exhibited by phenomenon

• A. Photosynthesis
• B. Photorespiration
• C. Transpiration
• D. Crassulacean metabolism

Answer 1

The correct option is B Photorespiration

In $C_3$ plants, $C{O}_2$ is pumped directly into the Calvin cycle, leaving rubisco exposed to $O_2$. Rubisco in a $C_3$ will take up $O_2$ rather than $C{O}_2$ to undergo photorespiration. Photorespiration occurs under low concentrations of $C{O}_2$ and high concentrations of $O_2$. $C_4$ plants capture carbon dioxide in their mesophyll cells forming oxaloacetate. This oxaloacetate is then converted to malate and is transported into the bundle sheath cells, where oxygen concentration is low to avoid photorespiration.
Photosynthesis and transpiration occurs in both $C_3$ and $C_4$ plants. Crassulacean metabolism does not occur in both $C_3$ and $C_4$ plants.

So, the correct answer is option B.