Question

In photosystem-I, the first electron acceptor is

• A. ferredoxin
• B. cytochrome
• C. plastocyanin
• D. an iron-sulphur protein

Answer 1

Answer: (D)

In photogystem-l, the primary electron acceptor is probably a Fe-S protein. The reduced primary acceptor transfers the electrons to secondary electron acceptor (most probably $P_{430}$ ). The sequence of electron transfer is as follows $\underset{Chlrophyll-aPhylloquinone\text{ (}Fe-s)Protein}{P_{700}\stackrel{e^{-}}{\to }{A}_1\stackrel{e^{-}}{\to }{A}_2}\stackrel{e^{-}}{\to }\underset{P_{430.}}{A_3}$ The reduced $P_{430}$ passes its electrons to ferridoxin (Fd) present at outer surface of thylakoid membrane.