Question

Which one of the following organisms does not have the ability to fix atmospheric nitrogen?

Options

• Nostoc

• Ulothrix

• Rhizobium

• Azotobacter

Answer 1

Ulothrix

Explanation:

• Nostoc, Rhizobium, and Azotobacter are well-known nitrogen-fixing organisms. Nostoc is a cyanobacterium that fixes nitrogen. Rhizobium is a symbiotic nitrogen-fixing bacterium found in legume root nodules. Azotobacter is a free-living nitrogen-fixing bacterium.
• Ulothrix, on the other hand, is a green alga and does not have the ability to fix atmospheric nitrogen.