Question

As a research scientist, you measure the amount of ATP and NADPH consumed by the Calvin cycle in 1 hour. You find 30,000 molecules of ATP consumed, but only 20,000 molecules of NADPH. What is the source of the extra ATP?

Answer 1

Cyclic electron flow

Step-by-step explanation:

→The objective of this process is to synthesize ATP, so that proportion of ATP and NADPH could be met

→to prevent photo-inhibition of PS 1 and 11.

It involved only Photosystem 1 .(PS1) The process begins with the photo activation of chlorophyll molecule. The excited electrons at higher energy levels, emitted from the chlorophyll molecule is captured by electron acceptors and return to the chlorophyll molecule ( rather than the usual PS) by chains of electron carriers .

Therefore these electrons did not lose their energy as thermal energy. Instead large quantity of energy is conserved for ATP synthesis , via chemosomosisWith the resultant ATPs used in Calvin cycle for glucose, Amino acids and fatty acid production in light independent stage.

The continuous cyclic flow of these electron carriers(instead of non -cyclc flow or non cyclic photophosphorylation) ensures large quantity of energy conservation for the production of ATPs in chemosomosis.

This explains the reasons for 30,000 molecules of ATPs consumed.