Assertion (A): Double circulation is seen in birds and mammals. Reason (R): It ensures complete separation of oxygenated and deoxygenated blood. MCQ with Answer and Explanation

Explanation:
The epidermis is the avascular, outermost layer of skin, composed mainly of keratinized stratified squamous epithelium. It provides a waterproof barrier and creates skin tone via melanocytes. The dermis is below, containing vessels and nerves, hypodermis is subcutaneous fat, endodermis is a root layer in plants.

Explanation:
Pinocytosis ('cell drinking') is a form of endocytosis where the cell membrane invaginates to take in a small droplet of extracellular fluid and dissolved solutes. Phagocytosis is 'cell eating' of large particles, exocytosis is secretion, osmosis is water movement across a semipermeable membrane.

Explanation:
UV radiation can induce mutations; germline mutations are passed on. Not all mutations change protein sequence (silent mutations). So 2 is incorrect.