Question

In a non-cyclic electron transport system the path of the electron is
a. PSI - PSII - NADP
b. PS II - PS I - NADP
c. NADP – PSII - PS I
d. NADP -PS -I PS – II

Answer 1

Hint: Light reaction of photosynthesis consists of 2 pathways, they are cyclic and noncyclic, where they occur in the thylakoid membrane, In both pathways ATP is produced, and the formation of ATP during photosynthesis is termed as photophosphorylation, so this is called as cyclic and non-cyclic photophosphorylation. In the noncyclic pathway, along with ATP, NADP is also produced.

Complete answer:
- In the noncyclic photophosphorylation pathway, it requires both of the photosystems, which are PSI and PSII.
- This pathway occurs in the thylakoid membrane.
- This photosystem consists of pigment complexes and electron acceptors.
- The pigment complex consists of chlorophyll a and chlorophyll b and other pigment complexes.
- Solar energy is absorbed by the pigment complex and this energy is transferred from one complex to another until it reaches a higher concentration in chlorophyll a.
- Because of this energy abortion, the electrons present here are excited and these electrons are entered into the electron acceptor complex.
- The pathway begins in PSII where the electrons in this system are excited by the solar energy and they escape.
- Then electrons are taken by splitting the water molecule. And release the oxygen molecule.
- In the noncyclic pathway, the electron transport starts with PSII and it enters the PSI and finally to NADP.

Hence, the correct answer is option (B).

Note: In this pathway first, it begins in PSII where energy absorbed, electrons excited and leaves the reaction center, later this PSII replace the electrons from water splitting and again PSI absorb the energy and electrons are excited and leave the center and all these electrons go to an electron acceptor, and these electrons are given to NADP and it forms the NADPH and ATP.