Question

Atmospheric nitrogen gas is always fixed by nitrogen-fixing micro-organisms. Decomposers release nitrogen gas from dead bodies of plants and animals.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (D)

If both assertion and reason are false

Answer 2

Biologically nitrogen is fixed by certain free living and symbiotic bacteria and cyanobacteria. $70\%$ of nitrogen fixation is done by the above microorganisms. Nitrogen is also fixed by photochemical and electrochemical reactions of the atmosphere. Dead bodies of plants and animals also possess nitrogenous compounds. These dead bodies are acted upon by decomposers, which release ammonia and utilise the remaining organic acids for their body building