Chapter 19: Chemical Coordination and Integration Assertion-Reason Questions | biology Class 11 CBSE

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 1

Logic Check

Assertion (A): Endocrine glands are called ductless glands. Reason (R): Their secretions (hormones) are released directly into the bloodstream and transported to target organs.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 2

Logic Check

Assertion (A): The hypothalamus is considered the master regulator of the endocrine system. Reason (R): The hypothalamus produces releasing and inhibiting hormones that regulate the secretion of pituitary hormones through the portal circulatory system.

Reasoning Options

ByteNotes

Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 3

Logic Check

Assertion (A): Oxytocin and vasopressin are synthesised by the neurohypophysis (posterior pituitary). Reason (R): The neurohypophysis stores and releases these two hormones into the bloodstream.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 4

Logic Check

Assertion (A): Excess secretion of growth hormone in adults causes acromegaly. Reason (R): In adults, long bones have already fused, so excess GH causes disfigurement of the face and extremities rather than increase in height.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 5

Logic Check

Assertion (A): Iodine deficiency leads to enlargement of the thyroid gland (goitre). Reason (R): Iodine is essential for the synthesis of thyroid hormones; its deficiency reduces hormone production, causing the gland to enlarge compensatorily.

Reasoning Options

ByteNotes

Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 6

Logic Check

Assertion (A): Thyrocalcitonin (TCT) is a hypercalcaemic hormone. Reason (R): TCT is secreted by the thyroid gland and increases blood calcium levels by stimulating bone resorption.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 7

Logic Check

Assertion (A): PTH is classified as a hypercalcaemic hormone. Reason (R): PTH stimulates bone resorption, increases renal Ca2+ reabsorption, and enhances Ca2+ absorption from digested food, all of which raise blood calcium levels.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 8

Logic Check

Assertion (A): The thymus gland degenerates in old age, leading to weakened immune responses. Reason (R): Thymosins are required for differentiation of T-lymphocytes and promotion of antibody production; reduced thymosin levels impair both cell-mediated and humoral immunity.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 9

Logic Check

Assertion (A): Adrenaline and noradrenaline are called emergency hormones. Reason (R): They are secreted slowly over days in response to chronic stress and reduce heart rate to conserve energy.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 10

Logic Check

Assertion (A): Aldosterone helps maintain blood pressure. Reason (R): Aldosterone stimulates reabsorption of Na+ and water in the renal tubules, increasing blood volume and thereby blood pressure.

Reasoning Options

ByteNotes

Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 11

Logic Check

Assertion (A): Glucagon is a hypoglycaemic hormone. Reason (R): Glucagon stimulates glycogenolysis and gluconeogenesis in hepatocytes, which raise blood glucose levels.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 12

Logic Check

Assertion (A): Insulin deficiency leads to prolonged hyperglycaemia and diabetes mellitus. Reason (R): Insulin normally stimulates cellular glucose uptake, utilisation, and glycogenesis; its absence results in glucose accumulation in the blood and its loss through urine.

Reasoning Options

ByteNotes

Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 13

Logic Check

Assertion (A): The corpus luteum secretes estrogen as its main hormone. Reason (R): After ovulation, the ruptured graafian follicle is converted to the corpus luteum, which primarily secretes progesterone to support pregnancy.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 14

Logic Check

Assertion (A): Atrial natriuretic factor (ANF) decreases blood pressure. Reason (R): ANF causes dilation of blood vessels, which reduces peripheral resistance and thereby lowers blood pressure.

Reasoning Options

ByteNotes

Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 15

Logic Check

Assertion (A): Protein hormones do not enter the target cell to exert their effects. Reason (R): Protein hormones are lipid-soluble and can freely diffuse through the cell membrane to bind intracellular receptors.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 16

Logic Check

Assertion (A): Steroid hormones regulate gene expression in target cells. Reason (R): Steroid hormones bind to intracellular receptors to form hormone-receptor complexes that interact with the genome, regulating gene expression or chromosome function.

Reasoning Options

ByteNotes

Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 17

Logic Check

Assertion (A): MSH acts on melanocytes to regulate pigmentation of the skin. Reason (R): MSH is secreted by the pars distalis (anterior pituitary) in humans.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 18

Logic Check

Assertion (A): Erythropoietin is produced by the kidney and stimulates RBC formation. Reason (R): Patients with chronic kidney disease often develop anaemia because damaged kidneys produce less erythropoietin.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 19

Logic Check

Assertion (A): The pancreas functions only as an endocrine gland. Reason (R): The Islets of Langerhans in the pancreas secrete insulin and glucagon, which regulate blood glucose.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 20

Logic Check

Assertion (A): GnRH from the hypothalamus stimulates the pituitary to release gonadotrophins. Reason (R): GnRH reaches the anterior pituitary through the portal circulatory system to stimulate synthesis and release of LH and FSH.

Reasoning Options

ByteNotes

Chapter sections

Chapter 19: Chemical Coordination and Integration | Assertion-Reason

Assertion (A): Endocrine glands are called ductless glands. Reason (R): Their secretions (hormones) are released directly into the bloodstream and transported to target organs.

Assertion (A): The hypothalamus is considered the master regulator of the endocrine system. Reason (R): The hypothalamus produces releasing and inhibiting hormones that regulate the secretion of pituitary hormones through the portal circulatory system.

Assertion (A): Oxytocin and vasopressin are synthesised by the neurohypophysis (posterior pituitary). Reason (R): The neurohypophysis stores and releases these two hormones into the bloodstream.

Assertion (A): Excess secretion of growth hormone in adults causes acromegaly. Reason (R): In adults, long bones have already fused, so excess GH causes disfigurement of the face and extremities rather than increase in height.

Assertion (A): Iodine deficiency leads to enlargement of the thyroid gland (goitre). Reason (R): Iodine is essential for the synthesis of thyroid hormones; its deficiency reduces hormone production, causing the gland to enlarge compensatorily.

Assertion (A): Thyrocalcitonin (TCT) is a hypercalcaemic hormone. Reason (R): TCT is secreted by the thyroid gland and increases blood calcium levels by stimulating bone resorption.

Assertion (A): PTH is classified as a hypercalcaemic hormone. Reason (R): PTH stimulates bone resorption, increases renal Ca2+ reabsorption, and enhances Ca2+ absorption from digested food, all of which raise blood calcium levels.

Assertion (A): The thymus gland degenerates in old age, leading to weakened immune responses. Reason (R): Thymosins are required for differentiation of T-lymphocytes and promotion of antibody production; reduced thymosin levels impair both cell-mediated and humoral immunity.

Assertion (A): Adrenaline and noradrenaline are called emergency hormones. Reason (R): They are secreted slowly over days in response to chronic stress and reduce heart rate to conserve energy.

Assertion (A): Aldosterone helps maintain blood pressure. Reason (R): Aldosterone stimulates reabsorption of Na+ and water in the renal tubules, increasing blood volume and thereby blood pressure.

Assertion (A): Glucagon is a hypoglycaemic hormone. Reason (R): Glucagon stimulates glycogenolysis and gluconeogenesis in hepatocytes, which raise blood glucose levels.

Assertion (A): Insulin deficiency leads to prolonged hyperglycaemia and diabetes mellitus. Reason (R): Insulin normally stimulates cellular glucose uptake, utilisation, and glycogenesis; its absence results in glucose accumulation in the blood and its loss through urine.

Assertion (A): The corpus luteum secretes estrogen as its main hormone. Reason (R): After ovulation, the ruptured graafian follicle is converted to the corpus luteum, which primarily secretes progesterone to support pregnancy.

Assertion (A): Atrial natriuretic factor (ANF) decreases blood pressure. Reason (R): ANF causes dilation of blood vessels, which reduces peripheral resistance and thereby lowers blood pressure.

Assertion (A): Protein hormones do not enter the target cell to exert their effects. Reason (R): Protein hormones are lipid-soluble and can freely diffuse through the cell membrane to bind intracellular receptors.

Assertion (A): Steroid hormones regulate gene expression in target cells. Reason (R): Steroid hormones bind to intracellular receptors to form hormone-receptor complexes that interact with the genome, regulating gene expression or chromosome function.

Assertion (A): MSH acts on melanocytes to regulate pigmentation of the skin. Reason (R): MSH is secreted by the pars distalis (anterior pituitary) in humans.

Assertion (A): Erythropoietin is produced by the kidney and stimulates RBC formation. Reason (R): Patients with chronic kidney disease often develop anaemia because damaged kidneys produce less erythropoietin.

Assertion (A): The pancreas functions only as an endocrine gland. Reason (R): The Islets of Langerhans in the pancreas secrete insulin and glucagon, which regulate blood glucose.

Assertion (A): GnRH from the hypothalamus stimulates the pituitary to release gonadotrophins. Reason (R): GnRH reaches the anterior pituitary through the portal circulatory system to stimulate synthesis and release of LH and FSH.

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