Assertion (A): Oxygen is required for aerobic respiration. Reason (R): Oxygen acts as the final electron acceptor in the electron transport chain. MCQ with Answer and Explanation

Explanation:
Poultry farming involves rearing birds like chickens for the production of eggs (layers) and meat (broilers). Apiculture (beekeeping) not only produces honey but also significantly increases crop yields through enhanced pollination by bees. Dairy farming focuses on the breeding and rearing of cattle, buffaloes, etc., for milk production, not fish (which is pisciculture). Thus, statements 1 and 2 are correct.

Explanation:
Vaccination introduces antigens (weakened or killed pathogens) to stimulate the body's own immune system to produce antibodies and memory cells without causing disease. This is artificial active immunity. Natural active immunity is acquired by recovering from infection. Artificial passive immunity is direct administration of antibodies (e.g., antiserum). Natural passive immunity is transfer of maternal antibodies to fetus.

Explanation:
Plasma makes up ~55% of blood; albumin is the main protein. Mature human RBCs are anucleate. So 3 is incorrect.