What is the function of the structure identified by the red arrow?

The image shows bacteria with thick cell walls. The red arrow points to these cell walls.

Food capture

Mobility

DNA transfer

Protection

The cell wall is used as protection (other functions include support and structure)

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.

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