Question

Which of the following statements regarding cyclic flow of electrons during light reactions is false?

• A. This process takes place in the stromal lamella
• B. ATP synthesis takes place
• C. $NADPH+H^{+}$ is synthesized
• D. Takes place only when light of wavelength beyond 680 nm is available for excitation
• E. PS II is not involved in the process

Answer 1

Answer: (C)

The process through which $ATP$ is synthesised by cells is named phosphorylation. Photophosphorylation is formation of $ATP$ in presence of light. It may be of two types cyclic and non cyclic.
Non cyclic photophosphorylation involves both $PSI$ and $PSII$. Cyclic photophosphorylation involves $PSI$ only and occurs in stromal lamellae which lack both $PSII$ and $NADP$ reductase enzyme. Photocentre of $PSI$ is excited by wavelength o f $700nm$ (beyond $680nm)$. The excited electron does not pass onto $NAD{P}^{+}$ but is cycled back to $PSI$ through electron transport chain hence only $ATP$ is synthesised but not $NADPH+H^{+}$