Question

In $C_4$ plants photorespiration does not occur due to

• A. presence of Rubisco enzyme
• B. presence of high light intensity
• C. increased concentration of $C{O}_2$ at enzyme site
• D. presence of bundle sheath cells

Answer 1

The correct option is C increased concentration of $C{O}_2$ at enzyme site

In $C_4$ plants, photorespiration does not occur because they have a mechanism that increases the concentration of $C{O}_2$ at the enzyme site. This takes place when the $C_4$ acid from the mesophyll is broken down in the bundle sheath cells to release $C{O}_2$. This results in an increase in the intracellular concentration of $C{O}_2$. This ensures that the RuBisCO functions as a carboxylase, thus, minimising the oxygenase activity.