Microbiology of Soils
Nitrogen fixation

especially changes nitrogen compounds, mostly amines such as NH2
both (a) and (b)
changes the free nitrogen (N2) to a form usable by plants
fix the free nitrogen (N2) by which it should not be usable by plants

ANSWER DOWNLOAD EXAMIANS APP

Microbiology of Soils
A heterocyst is

a type of spore
a terminally differentiated cell that fixes nitrogen
a cell that carries out oxygenic photosynthesis
the progenitor of cyanobacterial vegetative cells

ANSWER DOWNLOAD EXAMIANS APP