Question

Assertion: In C3 cycle, the first stable compound is 3C compound
Reason: In C4 plants, Calvin cycle is absent

• A. Both assertion and reason are true and reason is the correct explanation of assertion
• B. Both assertion and reason are true but reason is not the correct explanation of assertion
• C. Assertion is true but reason is false
• D. Both assertion and reason are false

Answer 1

The correct option is C Assertion is true but reason is false

In the C3 cycle, the first step involves the carboxylation of RuBP in the presence of enzyme RuBP carboxylase to form two molecule of 3- phosphoglyceric acid, a 3 carbon compound.

C4 fixation is an elaboration of the C3 carbon fixation which also involves Calvin cycle. It overcomes the tendency of the enzyme RuBisCO to wastefully fix oxygen rather than carbon dioxide in the process of photorespiration by ensuring that RuBisCO works in an environment where there is a lot of carbon dioxide and very little oxygen.