Question

Complete the following cycle given as figure by filling the boxes (a), (b), (c), (d).

Answer 1

The cycle given above represents the nitrogen cycle occurring in the environment.

The atmospheric nitrogen cannot be taken up by plants and animals as such, this is corrected by some bacteria and blue-green algae present in the soil. These microbes fix the atmospheric nitrogen into usable components which are utilised by other living organisms.

Nitrogen cycle checks the percentage of nitrogen in the atmosphere and maintains it at a constant level.

1. Lightning fixes nitrogen.
2. Nitrogen-fixing bacteria and blue-green algae fix atmospheric nitrogen.
3. Nitrogenous waste from excretion and death.
4. Bacteria turn compounds of nitrogen into gaseous nitrogen.