How do some cyanobacteria fix nitrogen while growing aerobically?
A) They don't, because nitrogenase is destroyed by oxygen.
B) They use special cells called heterocysts that protect the enzyme.
C) They use cysts that protect the enzyme.
D) They do it using no special structures or mechanisms.
E) They live symbiotically with other organisms that protect the enzyme.

Question

Quizplus · Accepted Answer

Some cyanobacteria have specialized cells called heterocysts that can fix nitrogen in anaerobic conditions. Heterocysts have a thick cell wall that limits the diffusion of oxygen from the atmosphere, creating an anaerobic environment that allows nitrogenase to function. However, because heterocysts lack photosystem II, they cannot perform photosynthesis, so the rest of the colony continues to carry out oxygen-producing photosynthesis in aerobic conditions.

How Do Some Cyanobacteria Fix Nitrogen While Growing Aerobically