What Will Happen to a Cyanobacterium That Has Its Photosystem

Question

What will happen to a cyanobacterium that has its photosystem II (PSII) blocked?
A) Additional electron acceptors, such as NADP⁺, will be required to oxidize oxygen and overcome the lost PSII process.
B) Anoxygenic photosynthesis only using photosystem I (PSI) could occur by using cyclic photophosphorylation and an alternative electron donor such as H₂S.
C) It will die from being unable to obtain energy for photosynthesis.
D) Photons will generate excessive reactive oxygen species and the cyanobacterium will die as a consequence.

Accepted Answer

If the PSII is blocked, the cyanobacterium could potentially use PSI with cyclic photophosphorylation while using an alternative electron donor, such as H₂S, to undergo anoxygenic photosynthesis. However, this method would not produce oxygen as a byproduct. Therefore, the cyanobacterium would not be able to perform oxygenic photosynthesis and would not obtain as much energy as it could have with both PSII and PSI. But it would not necessarily die.