Question

All of these are associated with Photosystem II except
A. Electron transport chain
B. A reaction centre
C. ATP
D. NADPH
E. Water

Answer 1

Hint: Photosystem II is a protein complex in the light-dependent reactions of photosynthesis. It is present in the thylakoid membrane of the chloroplast. It consists of enzymes that capture photons of light. Photosystem II provides electrons for the whole photosynthesis process to occur.

Complete answer: Photosystem II is an important protein complex located inside the grana of the thylakoid membrane of the chloroplast. It is a photosynthetic pigment that has electron carriers, chlorophyll b, and few forms of chlorophyll a. Photosystem II is involved in non-cyclic photophosphorylation that produces ATP and NADPH. The photosystem II picks up electrons released by the photolysis of water. Electrons are forced out as photosystem II absorbs light energy. It consists of various pigment molecules like Chl-a, which is a one -molecule reaction centre. The Chl-a 670 is a 200 molecule pigment that acts as antenna chlorophyll. Chl-b is another 200 molecules pigment that is an accessory pigment. Carotenoids of up to 50 molecules are also present as accessory pigments.
Thus, we can conclude that Chl-a is a reaction centre in Photosystem II. ATP and NADPH are produced as end products of non-cyclic photophosphorylation which is performed by photosystem II. Water provides electrons to photosystem II. The electron transport chain, also known as ETC, is present in the inner mitochondrial membrane. It contains various enzymes and coenzymes that act as hydrogen and electron carriers forming a chain system. Electron transport Chain is not associated with photosystem II. It is usually associated with cellular respiration and energy production reactions.
Therefore, option A is the correct answer.

Note: The photosynthetic water splitting that occurs in photosystem II to provide electrons is an important reaction in plants. It is the source of nearly all of the oxygen present in the earth’s atmosphere. The reaction site for oxygen evolution in photosystem II is called the oxygen-evolving complex.