Question

Cyclic photophosphorylation produces

• A. ATP + NADPH + O_2​
• B. ATP
• C. NADPH
• D. ATP + NADPH

Answer 1

The correct option is B

ATP

The correct option is B.

Explanation for correct option:

1. Cyclic photophosphorylation refers to a process in which electrons move in a cyclic way to produce ATP.
2. It is a light-dependent process.
3. When photosystem-I absorbs the light, the electrons become excited and released from the photosystem.
4. After releasing, the electrons get into the electron transport chain to produce ATP.

Explanation for incorrect option:

Option A:

1. The cyclic phosphorylation only involves PS-I.
2. It lacks PS-II and NADP reductase enzymes.
3. So, only ATP is synthesized in the entire pathway of cyclic photophosphorylation.
4. On the other hand, O₂ is a leftover in non-cyclic photophosphorylation( PS-II), it is not produced in PS-I.
5. Nor NADPH neither O₂ is produced.

Option C:

1. The cyclic phosphorylation lacks PS-II.
2. During non-cyclic photophosphorylation, when the electrons are combined with H+ ions then the NADP is reduced to NADPH.
3. In cyclic photophosphorylation, the combination between electrons and protons does not occur.
4. NADPH is not produced in cyclic photophosphorylation.

Option D:

1. During cyclic photophosphorylation, ATP is synthesized in presence of light as the PS-I absorbs the light and the electrons are excited and released from the photosystem.
2. Cyclic photophosphorylation does not involve PS-II which produces NADPH from the NADP molecule.
3. NADPH is not produced.

Final answer: Cyclic photophosphorylation produces ATP.