NEET Biology: Photosynthesis questions with solutions

Q1. Which of the following is not true about photosynthesis?

1. In non-cyclic photophosphorylation, water is split and oxygen is released
2. Photosystem-II makes noncyclic photophosphorylation more efficient than does cyclic photophosphorylation
3. Cyclic system is used when there is insufficient \( N A D P^{+} \) present to absorb electrons in plant cells
4. More carbohydrate is produced during cyclic photophosphorylation than during non-cyclic photophosphorylation

Answer: More carbohydrate is produced during cyclic photophosphorylation than during non-cyclic photophosphorylation

Cyclic photophosphorylation produces ATP but no NADPH and no oxygen, so it cannot drive carbohydrate formation as effectively as non-cyclic photophosphorylation. Non-cyclic photophosphorylation provides both ATP and NADPH, which are needed for carbon fixation and sugar production.

Q2. Dark reaction of photosynthesis is called so, because

1. It can also occurin dark
2. It does not require light.
3. cannot occur during day time
4. It occurs more rapidly in night

Answer: It can also occurin dark

The dark reaction is called so because it does not directly require light energy. It can proceed in darkness as long as ATP and NADPH from the light reaction are available, so the correct idea is that it can also occur in dark.

Q3. ETC of photosynthesis process is

1. Bound to thylakoid membrane
2. Present in stroma
3. Bound to outer chloroplast membrane
4. Dispersed in cytosol

Answer: Bound to thylakoid membrane

The photosynthetic electron transport chain is embedded in the thylakoid membrane, where it can pass electrons between photosystems and pump protons to build the gradient needed for ATP synthesis. The stroma contains Calvin cycle enzymes, not the ETC.

Q4. The first stable product of Calvin cycle is

1. 3- phosphoglycerate.
2. 1,3- biphosphoglycerate.
3. Glyceraldehyde-3- phosphate.
4. Ribulose-5- phosphate.

Answer: 3- phosphoglycerate.

In the Calvin cycle, CO2 is first fixed to ribulose-1,5-bisphosphate by RuBisCO, forming an unstable 6-carbon intermediate. This immediately splits into two molecules of 3-phosphoglycerate, making it the first stable product.