Assertion: Plants photosynthesise during the day, whereas they respire at night.
Reason: Photosynthesis can occur in the presence of sunlight whereas respiration cannot.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Assertion: Mutant plants that are not able to carry out cyclic electron flow do not grow well in intense light conditions.
Reason: Cyclic electron flow may be photoprotective.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Heme and iron-sulfur complexes in photosynthesis:
1. act as reducing agents
2. act as oxidizing agents
3. both oxidize and reduce during electron transport
4. are needed only in respiration but not in photosynthesis