Nitrogen fixation is done mostly by

Nitrogen fixation occurs between some termites and fungi. It occurs naturally in the air by means of NO x production by lightning. All biological nitrogen fixation is effected by enzymes called nitrogenases. These enzymes contain iron, often with a second metal, usually molybdenum but sometimes vanadium.

Explanation:

Rhizobium and blue green algae

a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.

answer: grassland biomes are closer to the equator and receive more rain.

grasslands are biomes that are dominated by grasses rather shrubs and trees. savanna are biomes that exhibit grasses, shrubs and small tree as vegetation. grasslands are located near the equator of the earth. these are found in north america. savanna biomes are found in africa, south america, australia and india. grassland exhibit moderate climatic conditions, it receives   amount of rainfall higher than savanna.   therefore, savanna exhibit dry and hot climatic conditions.