Question

Read the assertion and reason carefully to mark the correct option in question.

Assertion: Stroma lamellae have both $PSI$ and $PSII$ but the membrane of grana lack $PSII$ as well as $NADP$ reductase.

Reason: Cyclic photo-phosphorylation also occurs when only light of wavelength below $680nm$ is available for excitation.

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

Answer 1

The correct option is A If both assertion and reason are false.

Assertion-Reason relation

Photosynthesis occurs in the chloroplasts which have photosynthetic pigment, chlorophyll. Grana and stroma are the main parts of chloroplast.

Granal lamellae have both $PSI$ and $PSII$ while stroma lamellae lack $PSII$ and $NADP$ reductase used to produce $NADPH$.

Hence, the assertion statement is false.

Assertion-Reason relation

The type of phosphorylation where the electrons are returned to their source i.e., photosystem is termed as cyclic phosphorylation.

$PSI$ is involved in photo-phosphorylation which ideally absorbs wavelength of $700nm$.

Hence, the reason statement is false.

Final answer

(D) If both assertion and reason are false.