Question

Blue green algae fix _________ directly from air to enhance fertility of soil.

Answer 1

Blue green algae fix atmospheric nitrogen directly from air to enhance fertility of soil.

Explanation:

Plants and animals cannot take atmospheric nitrogen directly. Certain bacteria and blue-green algae present in the soil fix nitrogen from the atmosphere and convert it into compounds. Once nitrogen is converted into these usable compounds, it can be utilised by plants from the soil through their root systems.