Assertion (A): Fishes are ammonotelic. Reason (R): Ammonia is highly toxic and requires a large amount of water for excretion, which is available in aquatic environments. MCQ with Answer and Explanation

Explanation:
Vitamin C is a cofactor for enzymes that hydroxylate proline and lysine in procollagen, essential for proper collagen triple helix formation. Deficiency results in weak collagen and scurvy. Vitamin A is for vision, D for calcium, K for clotting.

Explanation:
Prophase I of meiosis is divided into five sub-stages: leptotene, zygotene, pachytene, diplotene, and diakinesis. Crossing over, the exchange of genetic material between non-sister chromatids of homologous chromosomes, occurs specifically during the pachytene stage at structures called recombination nodules.

Explanation:
Vitamin E is a group of tocopherols and tocotrienols, acting as fat-soluble antioxidants. They protect cell membranes from oxidative damage. Deficiency is rare but can cause hemolytic anemia and neurological problems.