Unidirectional flow of electrons to photophospherylation takes place in
A cyclic
B non-cyclic
C pseudocyclic
D all of the above
Answers
Answer:
B non cyclic is the correct answer
Answer:
B) Non cyclic photophosphorylation
Explanation:
⮕ In non cyclic photophosphorylation the flow of electrons are always unidirectional, that is the electrons are not cycled back to PS II (P₆₈₀)
⮕ Electrons are used in the reduction of NADPH to NADPH₂. It also utilizes water for the process of photolysis which produce oxygen and hydrogen.
⮕At the reaction centre, the elctrons are emitted which are accepted by plastoquionone which is an electron acceptor.
⮕ The electrons are then transferred through various electron carriers like cytochrome, plastocyanin and plastoquinone.
⮕ From plastocynic electrons are then transferred to the reaction centre of PS I (P₇₀₀)
⮕ The PSI becomes photoexcited and expels electrons that enter the electron transport system which are received by the NADP⁺ present in stroma.
⮕ It also receives electrons via photolysis of water and hence gets reduced into NADPH + H⁺
⮕ Here energy is released due to the transfer of electrons and is utilized to form ATP by the process of chemiosmosis.
⮕ In cyclic photophosphorylation, there is a cyclic flow of electrons to form ATP from ADP and iP.
⮕ Here the donor and the final acceptor is P₇₀₀ and occurs in low light intensity.
⮕ The electrons are accepted by the primary electron acceptor and move to ferrodoxin.
⮕ From here, electrons are transferred to cytochrome b and then cyctochrome f and finally to plastocyanin.
⮕ From plastocyanin, the electrons return back to the reaction centre of PS I.
⮕ Here 2 molecules of ATP are synthesised and no reduction of NADP takes place.