Photosynthesis In Higher Plants Question 34
Question: Assertion : $ C_4 $ photosynthetic pathway is more efficient than the $ C_3 $ pathway. Reason : Photorespiration is suppressed in $ C_4 $ plants.
Options:
A) If both the assertion and the reason are true and the reason is a correct explanation of the assertion
B) If both the assertion and reason are true but the reason is not a correct explanation of the assertion
C) If the assertion is true but the reason is false
D) If both the assertion and reason are false
Show Answer
Answer:
Correct Answer: A
Solution:
$ 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 enzymes 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.
BETA
