Question

Assertion: Phosphorus cycle involve microorganisms.

Reason: Microorganisms are mainly associated with nitrogen cycle.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
• B. Both Assertion and Reason are correct and Reason is the not correct explanation for Assertion.
• C. Assertion is correct and Reason is not the correct.
  
• D. Assertion is not correct and Reason correct.

Answer 1

The correct option is (B):

Assertion statement:

1. ​Animals either release phosphorus through urination or defecation or when they die and broken down by bacteria.
   
2. The organic phosphorus is released and converted back into inorganic phosphorus, through decomposition.
3. The microorganisms are involved in the decomposition that moves the phosphorus back to the soil.
4. The phosphorus cycle differs from other nutrient cycles, because it never passes through a gaseous phase, like the nitrogen or carbon cycles.
   
5. Hence, the assertion is true.
   

Reason statement:

1. Several micro-organisms are associated with nitrogen cycle, like Rhizobium, Azotobacter, etc.
2. This is because in the presence of microorganism nitrogen fixation occurs in the soil and some of the nitrogen again moves back to the soil.
   
3. Therefore, the reason is true, but it is not the correct explanation for the assertion.
   

Final Answer: Both Assertion and Reason are correct and Reason is the not correct explanation for Assertion.