Question

This question consist of two statements, assertion and reason. While answering this question you are required to choose any one of the following five responses.

Assertion: Dark reaction is purely enzymatic reaction.

Reason: It occurs only in absence of light.

• A. If assertion is false but the reason is true.
• B. If assertion is true but the reason is false.
• C. If both assertion and reason are true but the reason is not the correct explanation of the assertion.
• D. If both assertion and reason are false.
• E. If both assertion and reason are true and the reason is the correct explanation of the assertion.

Answer 1

The correct option is B If assertion is true but the reason is false.

Assertion-Reason relation

Photosynthesis proceeds through two phases- light reaction and dark reaction. The light reaction is involved in the synthesis of assimilatory powers such as ATP and NADPH. These energy molecules are further utilised in the dark reaction to reduce $C{O}_2$ into sugar. This reaction is independent of light. So, it can happen both in the absence or presence of light. It involves the Calvin cycle that is catalysed by the RuBisCO enzyme.

Hence, the assertion statement is correct but the reason statement is incorrect.

Final answer

(C) If assertion is true but the reason is false.