Question

In noncyclic electron transport system, the path of electron is
a) PS – I – > PS - II –> NADP
b) PS – II – > PS - I –> NADP
c) NADP – > PS - II –> PS – I
d) NADP – > PS - I –> PS – II

Answer 1

Hint:- Light reaction of photosynthesis contains two pathways such as cyclic and noncyclic systems. In both pathways, these reactions occur in the thylakoid membrane and ATP is produced during photosynthesis. In the non-cyclic electron transport system, NADP is also produced along with ATP.

Complete Answer:-
In the non-cyclic electron transport chain, both of the photosystems, PS I and PS II are required. This pathway is embedded in the thylakoid membrane. This photosystem contains electron acceptors and pigment complexes such as chlorophyll a and chlorophyll b.
In PS II, Solar (Light) energy is absorbed by pigment complexes from sun light and this energy is transferred to reach the higher concentration of core pigment known as chlorophyll a.
The electrons in the system are excited by the transferred energy and supply them to P680​. Break down of four electrons from the two water molecules, Oxygen​ is released. The splitting of water molecules and flow of electrons through cytochrome b6-f complex add protons to the thylakoid membrane.
Thus flow of electrons from PSII through quinone, cytochrome b6-f complex and plastocyanin to NADPH via PS I constitutes the process of Non-cyclic photophosphorylation.
Thus, the right option is B.

Note:- The electron transport chain or the Cytochrome oxidase system is also called a Respiratory chain because it is the most important and final step of cellular respiration. The major events of the electron transport chain include NADH and FADH which have the highest transfer potential and act as electron transporters to produce ATP.