Question

Assume a thylakoid which is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will have the most direct effect on which of the following processes?
A. Splitting of water
B. Absorption of light
C. Flow of electrons from photosystem II to photosystem I
D. Synthesis of ATP

Answer 1

Hint: Thylakoids are membrane-bound compartments inside chloroplasts and cyanobacteria. They are the site of the light-dependent reactions of photosynthesis. Thylakoids consist of a thylakoid membrane surrounding a thylakoid lumen.

Complete Answer:
- The thylakoid membrane of chloroplast is an internal system of interconnected membranes, they carry out the light reactions of photosynthesis. They are arranged into stacked and unstacked regions called grana and stroma thylakoids, respectively, that are differentially enriched in photosystem I and II complexes.
- It is the site that contains the chlorophyll used to absorb light and use it for biochemical reactions. In the thylakoid membrane, there are two photosystems I and II, the electrons which are excited leave and give off the energy to be used later in the process of photosynthesis. The energy created here is ATP and NADPH.
- The punctured thylakoid will not be able to have thylakoid lumen intact, so the $H^+ $concentration ions will not be developed. As a result, the ATP synthase will not work and ATP will not be synthesized.
- The thylakoids are the site of the light-dependent reactions of photosynthesis. These consist of light-driven water oxidation and oxygen evolution, the pumping of protons across the thylakoid membranes coupled with the electron transport chain of the photosystems and cytochrome complex, and ATP synthesis by the ATP synthase utilizing the generated proton gradient.

Hence, the correct answer is option (D). Synthesis of ATP.

Note: Thylakoids are the photosynthetic membranes of the chloroplasts in green leaves. They are majorly found to promote satiety when added to food, both in animal experiments and in humans.