The blood group that lacks both antigens A and B is: MCQ with Answer and Explanation

Explanation:
Vitamin D (cholecalciferol) is unique as it can be synthesized in the skin from 7-dehydrocholesterol in the presence of UV-B radiation. It acts as a hormone to regulate calcium and phosphate homeostasis. It must be activated in the liver and kidneys. It is also obtained from dietary sources like fatty fish, egg yolk. Deficiency causes rickets/osteomalacia.

Explanation:
Fungal cell walls contain chitin, a strong, flexible polysaccharide also found in arthropod exoskeletons. Cellulose is in plant walls, peptidoglycan in bacterial walls, lignin in secondary plant walls. Chitin provides structural support and protection against environmental stress.

Explanation:
Archaeopteryx is a famous fossil that exhibits characteristics of both reptiles and birds, making it a classic connecting link. It had reptilian features like teeth, a long bony tail, and clawed fingers, but also avian features like feathers, wings, and a bird-like beak. It provides strong evidence for the evolutionary theory that birds evolved from theropod dinosaurs.