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

Answer 1

The Correct Option is C

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