AP BIOLOGY

Detailed explanation-1: -Osmoreceptors are sensory receptors in the thirst center in the hypothalamus that monitor the concentration of solutes (osmolality) of the blood. If blood osmolality increases above its ideal value, the hypothalamus transmits signals that result in a conscious awareness of thirst.

Detailed explanation-2: -The primary osmoreceptors that control AVP secretion and thirst are located in the anterior hypothalamus.

Detailed explanation-3: -Water homeostasis cannot be maintained by antidiuresis alone but also requires thirst and the drinking behavior induced by it. A drinking center is thought to be located near the feeding center in the lateral hypothalamus.

Detailed explanation-4: -The correct answer is option a because angiotensin II, produced by the kidneys stimulates the thirst center in the brain which causes a person to feel the need to drink water.