Question

The $C_4$ plants are photosynthically more efficient than $C_3$ plants because

• A. The CO${}_2$ efflux is not prevented.
• B. They have more chloroplasts.
• C. The CO${}_2$ compensation point is more.
• D. CO2 generated during photorespiration is trapped and recycled through PEP carboxylase.

Answer 1

The correct option is B They have more chloroplasts.

$C_4$ plants are photosynthetically more efficient than $C_3$ plants. They have lower compensation points and do not show photorespiration. They have more chloroplasts as compared to $C_3$ plants. They have chloroplasts both in the spongy mesophyll cells and in the bundle sheath cells. The chloroplasts are usually absent from bundle sheath cells but in $C_4$ plants bundle sheath cells are rich in chloroplast and have unusual type of chloroplasts. These chloroplasts are agranal and have RUBISCO enzyme.