What are the main components of the membrane system in chloroplasts...

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 (Figure 11.6). The cyclic flow hence, results only in the synthesis of ATP, but not of NADPH + H⁺ . Cyclic photophosphorylation also occurs when only light of wavelengths beyond 680 nm are available for excitation.