Question

1. a. In both mitochondria and chloroplasts, ATP synthesis is coupled to electron transport. Which one of the following is likely to affect the coupling of electron transport to ATP synthesis in both of these systems? Explain.

A) the absence of light

B) the removal of oxygen

C) leucinostatin, an ATP synthase inhibitor

D)a photosystem II inhibitor

1.b. Explain why each of the other answer choices are not applicable to both of the systems.

Answer 1

Option B

Oxygen is required by mitochondria to carry out oxidative phosphorylation. Oxygen is the final electron acceptor in oxidative phosphorylation and gets reduced to form water which is the byproduct of oxidative phosphorylation.

In photophosphorylation, which takes place in chloroplast, oxygen is the byproduct of oxidation of water. Oxygen is released as a byproduct of photosynthesis.

Absence of light will affect only photophosphorylation because light is responsible for expectation of electrons located in photosystem 1 and photosystem 2.

Leucinostatin is a peptide molecule which inhibit oxidative phosphorylation. It does not affect photophosphorylation.

An inhibitor of photosystem II will affect only photophosphorylation because photosystem act as electron acceptor and electron donor in chloroplast. It has no role to play in oxidative phosphorylation.

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