Question

Student to attempt either option (A) or (B): (A) Ravi lives in a village where he suggested to the local farmers to introduce a fungus as biofertilizer into their crop fields. State the benefits provided by the fungus to the crop.
OR
(B)

• [(i)] How do secondary lymphoid organs provide immunity?
• [(ii)] Highlight the role of spleen as an organ that provides immunity.

Hint:

Mycorrhiza improves nutrient uptake and resistance in crops. Secondary lymphoid organs are essential for initiating adaptive immune responses.

Answer 1

(A) Step 1: The fungus suggested as a biofertilizer is mycorrhiza.
Step 2: Mycorrhizal fungi form a symbiotic association with plant roots. 
Step 3: They enhance water and nutrient (especially phosphorus) absorption. 
Step 4: They also offer protection from pathogens and improve plant growth and resistance. 
OR 
(B) (i) Secondary lymphoid organs like lymph nodes and spleen are sites where lymphocytes interact with antigens. These organs provide an environment for the activation and proliferation of immune cells. 
(ii) The spleen filters blood, traps blood-borne antigens, and provides a site for immune responses. It also destroys old RBCs and stores immune cells like lymphocytes.