Photosynthesis In Higher Plants Question 195
Question: Assertion : One molecule of $ CO_2 $ is fixed to give 686 kcal in photosynthesis. Reason : To form a hexose, six molecules of $ CO_2 $ are fixed.
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 the assertion is false but reason is true
Show Answer
Answer:
Correct Answer: D
Solution:
The overall equation of photosynthesis is $ CO_2+2H_2O+n(h\nu )\to (CH_2O)+H_2O+O_2.
$ The standard free-energy change for the synthesis of hexose from $ CO_2 $ and $ H_2O $ is $ \Delta G{}^\circ =+686\ kcal.
$ As six molecules of $ CO_2 $ is involved to form one molecule of hexose, the energy input per $ CO_2 $ molecule will be 114 kcal.
BETA
