The oxygen-carrying protein in muscles is: MCQ with Answer and Explanation

Explanation:
NAD⁺ (nicotinamide adenine dinucleotide) is a coenzyme derived from vitamin B₃, serving as an electron carrier in redox reactions. Pepsin is an enzyme, collagen a structural protein, hemoglobin a transport protein. Coenzymes are organic non-protein molecules that assist enzymes.

Explanation:
Lichens represent mutualism where the fungal partner provides shelter, water, and minerals, and the algal or cyanobacterial partner provides food through photosynthesis. Both benefit. Parasitism is harmful to host; commensalism benefits one without affecting the other; predation involves one killing and eating the other. Lichens are bioindicators of air pollution, sensitive to SO₂. This association is obligate.

Explanation:
BCG (Bacille Calmette-Guérin) is a live attenuated vaccine derived from Mycobacterium bovis, used against tuberculosis, primarily in children. Polio vaccine (OPV/IPV) prevents poliomyelitis, DPT prevents diphtheria, pertussis, tetanus, and MMR prevents measles, mumps, rubella. BCG is often administered at birth in TB-endemic countries.