Question

In the absence of $NADP^{+}$, electrons of photosynthetic electron transport system pass to
A. Cyt. F
B. Cyt b6
C. Plastocyanin
D. Quinine

Answer 1

We have to know that the electron cycle is a sequence of complexes which relocate electrons from electron donors to electron acceptors via redox reactions. This couples this transfer of electrons with the transfer of protons across a membrane. Peptides, enzymes, and other molecules are made up in the electron transport chain.

Complete answer:
We have to know that in cyclic electron transport the following process are obtained and which are listed below as,
-Solar energy is absorbed by the P700 pigment complex. Their energy is transferred to the PS I reaction centre-P700. The excited P700’s outer valence electron is lifted to a higher degree of energy that is absorbed by PS I’s primary acceptor. The primary acceptor passes electrons to ferredoxin.
-The electron returns to PS I through cytochrome b6, plastoquinone (PQ), cytochrome-f and plastocyanin with reduced ferredoxin, unable to decrease $NADP^{+}$.
-Since the electron released from PS I returns to PS I through multiple intermediate carriers, the electron transport is called cyclic.
We have to remember that the electron transport chain is a series of electron transporters in which shuttle electrons from NADH and $FADH_{2}$ to molecular oxygen embedded in the inner mitochondrial membrane.
So, the correct answer is “Option B”.

Note:
We must remember that the cytochrome b6f complex is an enzyme which is found in the thylakoid membrane and cytochrome $b_{6f}$ that catalyses the flow of electrons from plastoquinol to plastocyanin in plant chloroplasts, cyanobacteria, and green algae. The cytochrome $b_{6f}$ complex is one step along the chain during photosynthesis that moves electrons from Photosystem II to Photosystem I. Around the same time; protons are pumped into the thylakoid space to help create an electrochemical (energy) gradient that is later used to synthesize ATP from ADP.