Emerson's enhancement effect and red drop have been instrumental in the discovery of
1. two photosystems operating simultaneously
2. photophosphorylation and cyclic electron transport
3. Oxidative phosphorylation
4. photophosphorylation and non-cyclic electron transport

During photorespiration, the oxygen consuming reaction(s) occur in :
1. stroma of chloroplasts and mitochondria
2. stroma of chloroplasts and peroxisomes
3. grana of chloroplasts and peroxisomes
4. stroma of chloroplasts

Assertion: Transfer of electrons from the split water molecule to P${680}^{+}$ is easy.
Reason: P${680}^{+}$ is the strongest biological oxidizing agent known.

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.

Assertion: The enzyme phosphoglycerate kinase[PGK] is present in all living organisms.
Reason: In the Calvin cycle, PGK catalyzes the phosphorylation of 3-PG, producing 1,3-BPG and ADP, as part of the reactions that regenerate ribulose-1,5-bisphosphate.

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: Photorespiration is considered as an evolutionary relic.
Reason: Unlike normal cellular respiration it uses ATP rather than generating it and unlike photosynthesis it produces no sugar.

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: Cyclic electron flow is the only photosynthetic mode of generating ATP for bundle sheath cells.
Reason: Bundle sheath cells contain PS I but no PS II.

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: When simultaneously exposed to light of both red and far red wavelengths, the rate of photosynthesis is far higher than the sum of the red light and far red light photosynthesis rates.
Reason: Two photosystems, processing different wavelengths, cooperate in photosynthesis.

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: A reduction in photorespiration by genetic engineering or because of increasing atmospheric carbon dioxide (due to fossil fuel burning) may not benefit plants as has been proposed.
Reason: Photorespiration may be necessary for the assimilation of nitrate from soil.

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: 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.