Question

How many photons does it take to fully reduce one molecule of NADP+ to NADPH? a. 1

b. 2

c. 4

d. 8

Short answer

To fully convert one molecule of NADP+ to NADPH, 8 photons are required (4 at PSII and 4 at PSI). As a result, option (d) 8 is the proper response.

Step-by-step solution

Step:1 Definition 

Photosynthesis is defined as a process that occurs primarily in chloroplasts and is mediated by photosynthetic pigments such as chlorophyll a, chlorophyll b, carotene, and xanthophyll. Photosynthesis is a process that uses carbon dioxide, water, and sunshine to synthesis nutrition in green plants and a few other autotrophic organisms.

Step:2 Justification of the answer

Option (d) requires photons to convert 1 molecule of $\mathrm{NDAP}+$to$\mathrm{NDAPH}$. The electron proceeds from PS Il to PSI by absorbing four photons and passing through the cytochrome complex. Because it is a natural event for energy to be lost when travelling from a higher to a lower energy level, the electrons must raise their energy to travel to the lower energy level. As a result, at PSI, four photons are absorbed to excite electrons to continue their journey to, where they are reduced to. As a result, option is the proper response.

Step:2 Explanation of Incorrect answers

Option (a)1.1 photon is insufficient to separate the two water molecules at PSII and release an electron. As a result, this is a bad choice.

Option (b) 2.2 photons cannot also break 2 water molecules at PSII to release electrons, preventing the non-cyclic light process from continuing. As a result, this is a bad choice.

Option (c) 4: It is sometimes stated that 4 photons are required to decrease 1 molecule of NADP+ to NADPH, but since the photons lose energy as they travel down to PSI, they must be excited at PSI again by absorbing 4 photons for 2 electrons to travel further to convert NADP+ to NADPH. As a result, this is likewise a bad choice.