Which branch of biology deals with the study of heredity and variation? MCQ with Answer and Explanation

Explanation:
Cytokinins are plant hormones that promote cytokinesis (cell division) and shoot initiation. They are used in tissue culture along with auxins to induce organogenesis. Auxins promote cell elongation and root initiation, gibberellins stem elongation, abscisic acid stress responses and dormancy.

Explanation:
The small intestine is highly specialized for absorption, with circular folds, villi, and microvilli massively increasing its surface area. The duodenum is the first, shortest part, receiving the hepatopancreatic duct carrying bile and pancreatic juice. The ileum is the third and final part, connecting to the large intestine. Thus, statements 1 and 2 are correct.

Explanation:
Vitamin D (cholecalciferol) is synthesized in the skin from 7-dehydrocholesterol under UV-B radiation. It then undergoes activation in the liver and kidneys. It regulates calcium and phosphate metabolism.