Unlike purple and green phototrophic bacteria, cyanobacteria
a. produce oxygen during photosynthesis.
b. do not require light.
c. use H₂S as an electron donor.
d. have a membrane-enclosed nucleus.
e. all of the above
Photosynthetic bacteria that also fix nitrogen are __________ .
a. mycoplasmas
b. spirilla
c. bacteroids
d. cyanobacteria