Question

What would happen to the concentrations of ATP, NADPH, and sugars if PSI stopped working?

Decrease
Stay the same
Increase

Answer 1

If Photosystem I stopped working, ATP and NADPH concentrations would decrease, leading to a reduction in sugar production during photosynthesis.

Step-by-step explanation:

If Photosystem I (PSI) stopped working, the consequences would significantly affect the photosynthetic process. The concentrations of ATP, NADPH, and sugars would decrease. This is because PSI is crucial in the light reactions of photosynthesis for the production of NADPH, and it also plays a role in establishing the proton gradient that drives the synthesis of ATP via chemiosmosis.

• The proton concentration of the intermembrane space would decrease, stopping the production of ATP, as the flow of protons through ATP synthase is essential for ATP formation.
• The concentration of NADPH would also decrease because PSI is responsible for reducing NADP+ to NADPH, which is utilized in the Calvin cycle to produce sugars.
• As a result, the production of sugars would decrease because the Calvin cycle depends on the availability of ATP and NADPH for the fixation of carbon dioxide.