Asserotion: `C_(4)` photosynthetic pathway is more efficient than the `C_(3)` pathway.
Reson : Photorespirationis suppressed in `C_(4)` plants.

Options

A. If both the asserition and the reasion are true and the reason is a correct explanation of the assertion
B. If both the assertion and reasoni s not a correct ecplanation of the assertio
C. If the assertion is true but the reason is false
D. If both the asseertion and reason are false

Answer

A

Explanation

`C_(4)` photosynthetic pathway is more efficient than `C_(3)` pathway as `C_(4)` plants can pick up `CO_(2)` even when it is found in low concentration. PEP enymes shows high affinity for `CO_(2)`. `C_(4)` plants contain two types of chloroplast (Kranz anatomy): Bundle sheath chloroplast and mesophyll chloroplast. Bundle sheath cells contain calvin cycle enzymes. Due to high concentration of `CO_(2)` in bundle sheath cells, RuBP carboxylase works only for calvin cycle and not for photorespiration.
Photorespiration is a wasteful process as it works to undo the act of photosynthesis in `C_(4)` plants. No energy rich compound is produced in this process. When temperature increase more and more photosynthetically fixed carbon is lost by photorespiration thus reducing the efficiency of `C_(3)` plants.