Question

Why are bacteria required in the nitrogen cycle?

Answer 1

Answer:
            The correct option is d ( nitrogen needs to be fixed before it is used by plants).

Reason:
             Nitrogen fixing bacteria play a key role in nitrogen cycle, because they may a connection for the flow of nitrogen between atmosphere and the soil. Air contain 78% N, but it can not be taken by living organisms in its free form. Nitrogen fixing bacteria live in the roots of plants capture this free N and convert it into nitrogenous compounds which are then easily taken by plants.