Zoology MCQs for NEET — Practice Questions with Answers

Pituitary hormones generally interact with cell surface receptors and require secondary messengers to express their effects. Thus, statement x is correct. However, statement y is incorrect because pituitary hormones do not interact with intracellular receptors.

Hormone receptors are specific, meaning each hormone has its own unique receptor. Therefore, statement y is correct. However, statement x is incorrect because insulin and glucagon each have their own distinct receptors.

Aldosterone is a hormone that stimulates the reabsorption of sodium (Na⁺) ions in the kidneys, which in turn promotes water reabsorption. However, deficiency of aldosterone leads to Addison's disease, not diabetes mellitus. Therefore, statement x is correct and statement y is wrong.

Parathyroid glands, which are located near the thyroid gland, regulate calcium (Ca²⁺) levels in the blood. Surgery on the thyroid gland can sometimes inadvertently damage the parathyroid glands, leading to irregularities in calcium levels. Thus, both statements x and y are correct, and y provides a correct explanation for x.

In cases of thyroid cancer, hyperthyroidism is often observed, which means an increased rate of thyroid hormone synthesis and secretion. Therefore, both statements x and y are correct, and y provides a correct explanation for x.

Over secretion of the adrenal cortex, particularly the zona reticularis, results in the increased production of androgenic steroids. This can lead to the development of male secondary sexual characteristics such as facial hair in females, a condition known as hirsutism. Therefore, both statements x and y are correct, and y provides the correct explanation for x.

Insulin facilitates the uptake of glucose by cells, particularly hepatocytes (liver cells), muscle cells, and adipose tissue. This reduces the level of glucose in the blood. Hence, both statements x and y are correct, and y correctly explains why x happens.

Hormones exert their effects by binding to specific receptors on or in their target organs. If these receptors are removed, the target organ will not be able to respond to the hormone because the signaling pathway is disrupted. Thus, the correct option is that the target organ will not respond to the hormone.

The adenohypophysis (anterior pituitary) secretes Somatotropin (growth hormone), the adrenal medulla produces epinephrine, the parathyroid gland secretes Calcitonin, and the thymus gland secretes Thymosin. Therefore, the correct matching is (p: ii), (q: i), (r: iv), (s: iii).