NEETBotanyPhotosynthesis in Higher Plants
Under what condition does cyclic photophosphorylation occur?
Options
- AWhen only light of wavelengths below 680 nm are available
- BWhen only light of wavelengths beyond 680 nm are available
- CIn the absence of light
- DIn the presence of darkness
Correct answer
B. When only light of wavelengths beyond 680 nm are available
Step-by-step solution
When only PS I is functional, the electron is circulated within the photosystem and the phosphorylation occurs due to cyclic flow of electrons. A possible location where this could be happening is in the stroma lamellae. While the membrane or lamellae of the grana have both PS I and PS II the stroma lamellae membranes lack PS II as well as NADP reductase enzyme. The excited electron does not pass on to NADP+ but is cycled back to the PS I complex through the electron transport chain. The cyclic flow hence, results