Chemical Coordination and Integration

Topic: Endocrine Glands and Hormones; Subtopic: Hormones and Their Secretory Organs

Keyword Definitions:

• Progesterone: A steroid hormone secreted by the corpus luteum that maintains pregnancy and supports implantation.

• Relaxin: A hormone released by the ovary and placenta to relax pelvic ligaments during childbirth.

• Melanocyte Stimulating Hormone (MSH): Produced by the pars intermedia of the pituitary gland; controls skin pigmentation.

• Catecholamines: Hormones like adrenaline and noradrenaline secreted by the adrenal medulla; responsible for “fight or flight” response.

• Corpus Luteum: A temporary endocrine structure in the ovary formed after ovulation that secretes progesterone.

• Adrenal Medulla: The inner part of the adrenal gland that produces catecholamines.

Lead Question (September 2025)
Match List-I with List-II
List-I          List-II
A. Progesterone          I. Pars intermedia
B. Relaxin          II. Ovary
C. Melanocyte stimulating hormone          III. Adrenal Medulla
D. Catecholamines          IV. Corpus luteum
Choose the correct answer from the options given below:
(1) A-IV, B-II, C-I, D-III
(2) A-IV, B-II, C-III, D-I
(3) A-II, B-IV, C-I, D-III
(4) A-III, B-II, C-IV, D-I

Explanation:
The correct match is (1) A-IV, B-II, C-I, D-III. Progesterone is secreted by the corpus luteum, Relaxin is produced by the ovary, MSH by the pars intermedia, and Catecholamines by the adrenal medulla. These hormones regulate reproduction, pigmentation, and stress response. Each hormone acts on specific target tissues and maintains physiological balance.

1. Which hormone is secreted by the adrenal medulla?
(1) Aldosterone
(2) Cortisol
(3) Adrenaline
(4) Insulin
Explanation: The adrenal medulla secretes adrenaline and noradrenaline, collectively called catecholamines. They prepare the body for “fight or flight” by increasing heart rate, blood glucose, and respiration. These hormones rapidly mobilize energy in response to stress, ensuring immediate physiological adaptation to emergency situations.

2. Which hormone is essential for maintaining pregnancy?
(1) Estrogen
(2) Progesterone
(3) LH
(4) FSH
Explanation: Progesterone, secreted by the corpus luteum, prepares the uterus for implantation and maintains the endometrial lining during pregnancy. It suppresses uterine contractions, ensuring a stable environment for embryo development until the placenta takes over hormonal functions in later stages.

3. Assertion-Reason Type:
Assertion (A): Catecholamines increase heart rate and blood pressure.
Reason (R): They stimulate glycogen breakdown in muscles.
(1) Both A and R are true, and R is the correct explanation of A
(2) Both A and R are true, but R is not the correct explanation of A
(3) A is true, R is false
(4) A is false, R is true
Explanation: Option (2) is correct. Catecholamines increase heart rate and blood pressure by stimulating cardiac output and vasoconstriction. Although they also promote glycogen breakdown, this action primarily supports energy release, not directly explaining the cardiovascular effects, hence R is not the correct explanation.

4. Relaxin hormone is secreted during pregnancy to:
(1) Stimulate uterine contractions
(2) Relax pelvic ligaments
(3) Increase milk secretion
(4) Increase oocyte maturation
Explanation: Relaxin is secreted by the ovary and placenta during pregnancy. It relaxes pelvic ligaments and softens the cervix, facilitating childbirth. This hormone plays a crucial role in preparing the birth canal and ensuring smooth delivery by loosening connective tissues in the pelvis.

5. Fill in the Blank:
________ hormone is secreted by the pars intermedia of the pituitary gland.
(1) MSH
(2) GH
(3) FSH
(4) LH
Explanation: The correct answer is MSH (Melanocyte Stimulating Hormone). It regulates skin pigmentation by increasing melanin production in melanocytes. The pars intermedia of the pituitary gland secretes this hormone, which plays a minor role in humans but a significant role in animals for adaptive coloration.

6. Choose the correct statements:
Statement I: Progesterone is secreted by the ovary after ovulation.
Statement II: Catecholamines act as neurotransmitters and hormones.
(1) Both statements are correct
(2) Both statements are wrong
(3) Only Statement I is correct
(4) Only Statement II is correct
Explanation: The correct answer is (1) Both statements are correct. Progesterone is secreted post-ovulation by the corpus luteum, maintaining the endometrium, while catecholamines (adrenaline and noradrenaline) act as both hormones and neurotransmitters in stress and sympathetic responses.

7. Which of the following pairs is correctly matched?
(1) Oxytocin – Adrenal Medulla
(2) Progesterone – Corpus luteum
(3) Relaxin – Pituitary gland
(4) MSH – Adrenal cortex
Explanation: Option (2) is correct. The corpus luteum secretes progesterone after ovulation to maintain pregnancy. It ensures endometrial stability and prevents premature uterine contractions, vital for the initial stages of embryo implantation and growth within the uterus.

8. Which of the following hormones is not secreted by the ovary?
(1) Estrogen
(2) Progesterone
(3) Relaxin
(4) Oxytocin
Explanation: The correct answer is (4) Oxytocin. It is secreted by the posterior pituitary gland, not the ovary. Oxytocin stimulates uterine contractions during labor and milk ejection during lactation, playing a vital role in childbirth and maternal bonding.

9. Melanocyte Stimulating Hormone (MSH) acts on:
(1) Ovarian follicles
(2) Adrenal medulla
(3) Melanocytes in skin
(4) Thyroid gland
Explanation: The correct answer is (3) Melanocytes in skin. MSH stimulates these pigment cells to produce melanin, responsible for skin color. The hormone helps regulate pigmentation and may also influence appetite and energy balance in higher vertebrates.

10. Which of the following correctly describes catecholamines?
(1) Lipid-soluble hormones
(2) Peptide hormones
(3) Amino acid-derived hormones
(4) Steroid hormones
Explanation: The correct answer is (3) Amino acid-derived hormones. Catecholamines like adrenaline and noradrenaline are derived from the amino acid tyrosine. They are water-soluble hormones stored in vesicles and released rapidly during stress to trigger physiological responses in multiple organ systems.

Topic: Endocrine System; Subtopic: Hypothalamus and Pituitary Hormones

Keyword Definitions:

• Hypothalamus: A part of the brain that controls endocrine and autonomic functions and regulates the pituitary gland through releasing and inhibitory hormones.

• Pituitary gland: Known as the master gland, it secretes hormones that control other endocrine glands.

• ADH (Anti-diuretic hormone): A hormone that regulates water balance by increasing reabsorption in kidney tubules.

• Oxytocin: A hormone involved in uterine contraction during childbirth and milk ejection in lactation.

• Neurosecretion: The release of hormones from neurons, particularly in the hypothalamus, transported to the posterior pituitary.

Lead Question - 2025

Which of the following hormones released from the pituitary is actually synthesized in the hypothalamus?

(1) Luteinizing hormone (LH)
(2) Anti-diuretic hormone (ADH)
(3) Follicle-stimulating hormone (FSH)
(4) Adenocorticotrophic hormone (ACTH)

Explanation: ADH and oxytocin are synthesized by neurosecretory cells of the hypothalamus and then transported to the posterior pituitary through axons for release into the bloodstream. Other hormones like LH, FSH, and ACTH are synthesized in the anterior pituitary itself. Thus, ADH is produced in the hypothalamus but released by the pituitary. Answer: (2) Anti-diuretic hormone (ADH)

1. Which part of the pituitary stores and releases hormones synthesized by the hypothalamus?
(1) Anterior pituitary
(2) Intermediate lobe
(3) Posterior pituitary
(4) Pars intermedia
Explanation: The posterior pituitary, also called neurohypophysis, stores and releases hormones such as ADH and oxytocin that are synthesized in the hypothalamus. It acts as a storage site for neurosecretory hormones transported via the hypothalamo-hypophyseal tract. Answer: (3) Posterior pituitary

2. The hypothalamo-hypophyseal portal system connects:
(1) Hypothalamus to posterior pituitary
(2) Hypothalamus to anterior pituitary
(3) Anterior to posterior pituitary
(4) Hypothalamus to pineal gland
Explanation: The hypothalamo-hypophyseal portal system links the hypothalamus and anterior pituitary, allowing hypothalamic hormones to directly regulate the secretion of anterior pituitary hormones such as LH, FSH, and GH. Answer: (2) Hypothalamus to anterior pituitary

3. Which hormone promotes reabsorption of water in the kidneys?
(1) Oxytocin
(2) ADH
(3) FSH
(4) LH
Explanation: ADH, also known as vasopressin, increases water reabsorption in the distal convoluted tubules and collecting ducts of nephrons, thereby reducing water loss and maintaining osmotic balance. It is synthesized in the hypothalamus and released by the posterior pituitary. Answer: (2) ADH

4. Oxytocin is responsible for:
(1) Increasing blood glucose
(2) Stimulating uterine contractions
(3) Regulating kidney filtration rate
(4) Inducing milk protein synthesis
Explanation: Oxytocin, synthesized by the hypothalamus and released by the posterior pituitary, induces uterine contractions during childbirth and milk ejection from mammary glands during lactation. It functions through a positive feedback mechanism during labor. Answer: (2) Stimulating uterine contractions

5. The anterior pituitary is controlled by the hypothalamus through:
(1) Direct neural stimulation
(2) Blood-borne releasing hormones
(3) Reflex actions
(4) Hormonal feedback from kidneys
Explanation: The hypothalamus regulates the anterior pituitary via releasing and inhibitory hormones transported through the portal blood vessels. These control secretion of anterior pituitary hormones like GH, ACTH, TSH, FSH, LH, and prolactin. Answer: (2) Blood-borne releasing hormones

6. Lack of ADH secretion causes:
(1) Diabetes mellitus
(2) Diabetes insipidus
(3) Addison’s disease
(4) Graves’ disease
Explanation: Diabetes insipidus results from ADH deficiency or lack of kidney response to ADH. It causes excessive urine output (polyuria) and thirst (polydipsia) without glucose in urine. The condition reflects hypothalamic or posterior pituitary dysfunction. Answer: (2) Diabetes insipidus

7. Assertion-Reason Type:
Assertion (A): Oxytocin is secreted by the posterior pituitary.
Reason (R): It is synthesized by the posterior pituitary neurons.
(1) Both A and R are true, and R is the correct explanation of A
(2) Both A and R are true, but R is not the correct explanation of A
(3) A is true, but R is false
(4) Both A and R are false
Explanation: Oxytocin is secreted by the posterior pituitary but synthesized in the hypothalamic neurons and then transported through axons. Thus, A is true and R is false because synthesis occurs in the hypothalamus, not the posterior pituitary. Answer: (3) A is true, but R is false

8. Matching Type:
Match the following hormones with their functions:
A. ADH — I. Water reabsorption
B. Oxytocin — II. Uterine contraction
C. FSH — III. Growth of ovarian follicles
(1) A-I, B-II, C-III
(2) A-II, B-I, C-III
(3) A-III, B-I, C-II
(4) A-I, B-III, C-II
Explanation: ADH regulates kidney water balance by increasing reabsorption, oxytocin promotes uterine contraction and milk ejection, while FSH aids ovarian follicle maturation and spermatogenesis. Therefore, A-I, B-II, C-III is the correct match. Answer: (1) A-I, B-II, C-III

9. Fill in the Blanks:
__________ and oxytocin are produced in the hypothalamus but released by the posterior pituitary.
(1) FSH
(2) ADH
(3) ACTH
(4) TSH
Explanation: ADH and oxytocin are synthesized in the hypothalamus and transported to the posterior pituitary, where they are stored and released into circulation. This neural control ensures precise hormonal balance for water regulation and childbirth. Answer: (2) ADH

10. Choose the Correct Statements:
Statement I: Posterior pituitary produces ADH and oxytocin.
Statement II: These hormones are synthesized in the hypothalamus.
(1) Both statements are correct
(2) Only Statement I is correct
(3) Only Statement II is correct
(4) Both statements are incorrect
Explanation: The posterior pituitary stores and releases ADH and oxytocin but does not synthesize them. They are produced in the hypothalamic nuclei and transported for release. Hence, only Statement II is correct. Answer: (3) Only Statement II is correct

Topic: Hormones and Endocrine System; Subtopic: Mechanism of Hormone Action

Keyword Definitions:
• Insulin: A peptide hormone produced by β-cells of the pancreas that regulates blood glucose levels.
• Gastrointestinal Tract (GI Tract): The system responsible for digestion and absorption of nutrients.
• Bioavailability: The proportion of a drug or substance that enters the circulation and produces an effect.
• Peptide Hormone: A hormone composed of amino acids linked by peptide bonds, easily degraded by digestive enzymes.

Lead Question – 2025
Why can't insulin be given orally to diabetic patients:
(1) Human body will elicit strong immune response
(2) It will be digested in Gastro-Intestinal (GI) tract
(3) Because of structural variation
(4) Its bioavailability will be increased

Explanation: Insulin cannot be administered orally because it is a peptide hormone that would be broken down into amino acids by digestive enzymes in the gastrointestinal tract before absorption. Thus, its biological activity would be lost, rendering it ineffective in controlling blood sugar. Therefore, insulin is given via subcutaneous injection. Answer: (2)

1. Which of the following cells secrete insulin?
(1) α-cells of pancreas
(2) β-cells of pancreas
(3) δ-cells of pancreas
(4) Acinar cells of pancreas

Explanation: Insulin is secreted by β-cells of the islets of Langerhans in the pancreas. It lowers blood glucose levels by promoting glucose uptake and glycogen formation. α-cells secrete glucagon, which increases blood glucose levels. Therefore, β-cells play a vital role in glucose homeostasis. Answer: (2)

2. The hormone antagonistic to insulin is:
(1) Glucagon
(2) Thyroxine
(3) Aldosterone
(4) Cortisol

Explanation: Glucagon is antagonistic to insulin. It is secreted by α-cells of the pancreas and increases blood glucose levels by stimulating glycogenolysis and gluconeogenesis in the liver, counteracting insulin’s glucose-lowering effect. This balance maintains normal blood sugar levels in the body. Answer: (1)

3. Which of the following represents the correct function of insulin?
(1) Stimulates glycogenolysis
(2) Decreases glucose uptake
(3) Increases glucose uptake by cells
(4) Promotes gluconeogenesis

Explanation: Insulin enhances glucose uptake by muscle and adipose tissue, promoting glycogen synthesis and decreasing blood glucose concentration. It inhibits gluconeogenesis and lipolysis, thus maintaining energy balance and carbohydrate metabolism efficiently. Answer: (3)

4. Assertion (A): Insulin deficiency causes hyperglycemia.
Reason (R): Insulin promotes cellular glucose uptake and glycogen synthesis.
(1) Both A and R are true and R explains A
(2) Both A and R are true but R does not explain A
(3) A is true but R is false
(4) A is false but R is true

Explanation: Insulin deficiency results in decreased glucose uptake by cells, leading to hyperglycemia. The reason correctly explains this because insulin normally facilitates glucose transport into tissues for energy and glycogen formation. Therefore, both A and R are true, and R explains A. Answer: (1)

5. Match the hormones with their primary functions:
A. Insulin  1. Raises blood glucose
B. Glucagon 2. Lowers blood glucose
C. Adrenaline 3. Stimulates glycogenolysis
D. Cortisol  4. Anti-inflammatory effect

(1) A-2, B-1, C-3, D-4
(2) A-1, B-2, C-3, D-4
(3) A-2, B-3, C-1, D-4
(4) A-3, B-2, C-4, D-1

Explanation: Insulin lowers glucose levels, glucagon raises glucose, adrenaline stimulates glycogenolysis, and cortisol exerts an anti-inflammatory effect. These hormones coordinate metabolism and stress response, maintaining homeostasis effectively. Answer: (1)

6. Which of the following is NOT a function of insulin?
(1) Enhances glucose uptake
(2) Stimulates glycogen synthesis
(3) Increases lipolysis
(4) Promotes protein synthesis

Explanation: Insulin promotes glucose uptake, glycogen synthesis, and protein formation but inhibits lipolysis (fat breakdown). Hence, increasing lipolysis is not a function of insulin. It ensures storage of nutrients in anabolic pathways for energy regulation. Answer: (3)

7. Insulin is secreted from which part of the pancreas?
(1) Acini
(2) Islets of Langerhans
(3) Pancreatic duct
(4) Hepatic cells

Explanation: Insulin is secreted by β-cells located in the islets of Langerhans of the pancreas. These clusters of endocrine cells play a crucial role in regulating blood glucose levels through the coordinated release of insulin and glucagon. Answer: (2)

8. Fill in the blank: Lack of insulin secretion results in ________.
(1) Goitre
(2) Diabetes mellitus
(3) Acromegaly
(4) Addison’s disease

Explanation: Deficiency or ineffective insulin causes diabetes mellitus, characterized by elevated blood glucose levels, polyuria, and fatigue. It occurs due to reduced glucose uptake by tissues, leading to metabolic imbalance. Answer: (2)

9. Choose the correct statements:
Statement I: Insulin is a steroid hormone.
Statement II: Insulin lowers blood glucose levels.
(1) Both statements are true
(2) Both statements are false
(3) Statement I true, Statement II false
(4) Statement I false, Statement II true

Explanation: Insulin is a peptide hormone, not a steroid hormone. However, it does lower blood glucose levels by increasing cellular glucose uptake and glycogen storage. Hence, only Statement II is correct. Answer: (4)

10. Excess insulin in the blood causes:
(1) Hyperglycemia
(2) Hypoglycemia
(3) Hypertension
(4) Acidosis

Explanation: Excess insulin causes hypoglycemia, characterized by abnormally low blood glucose levels, weakness, dizziness, and even unconsciousness. It results from increased glucose uptake by tissues and reduced hepatic glucose production. Answer: (2)

Topic: Adrenal Glands; Subtopic: Functions of Adrenal Medullary Hormones

Keyword Definitions:

• Adrenal Medulla: The inner region of the adrenal gland that secretes catecholamines like adrenaline and noradrenaline.

• Adrenaline: A hormone that prepares the body for emergency conditions, increasing heart rate and blood sugar.

• Noradrenaline: A hormone responsible for vasoconstriction and maintenance of blood pressure.

• Piloerection: The raising of body hair due to contraction of tiny muscles at the hair follicle base.

• Hyperglycemic Hormone: A hormone that increases the blood glucose concentration.

Lead Question - 2025
Consider the following statements regarding function of adrenal medullary hormones:
A. It causes pupillary constriction
B. It is a hyperglycemic hormone
C. It causes piloerection
D. It increases strength of heart contraction
Choose the correct answer from the options given below:
(1) C and D Only
(2) B, C and D Only
(3) A, C and D Only
(4) D Only

Explanation:
Adrenal medullary hormones, adrenaline and noradrenaline, increase heart rate, cause piloerection, and raise blood glucose levels (hyperglycemia). They do not cause pupillary constriction but dilation. Hence, statements B, C, and D are correct. The correct answer is (2) B, C and D Only. These actions prepare the body for stress and emergency responses effectively.

1. Which of the following hormones is secreted by the adrenal medulla?
(1) Aldosterone
(2) Adrenaline
(3) Cortisol
(4) Androgen

Explanation:
The adrenal medulla secretes catecholamines—adrenaline and noradrenaline—which prepare the body for 'fight or flight' situations by increasing blood glucose and heart rate. Aldosterone and cortisol are secreted by the adrenal cortex. Therefore, the correct answer is (2) Adrenaline, a rapid-acting hormone released during stress.

2. Which of the following statements about adrenaline is true?
(1) It lowers blood pressure
(2) It causes vasodilation in all organs
(3) It increases heart rate and blood sugar
(4) It decreases alertness

Explanation:
Adrenaline acts as a powerful stimulant, increasing heart rate, blood pressure, and glucose availability while enhancing alertness and muscle performance during emergencies. It causes vasodilation in skeletal muscles but not in all organs. Hence, the correct answer is (3) It increases heart rate and blood sugar.

3. What triggers the release of adrenaline from the adrenal medulla?
(1) Low glucose level
(2) Sympathetic nervous stimulation
(3) High calcium level
(4) Parasympathetic stimulation

Explanation:
Adrenaline secretion is controlled by sympathetic nerves during stress, fear, or excitement, leading to increased heart rate and blood sugar. Parasympathetic activity has an opposite effect. Hence, the correct answer is (2) Sympathetic nervous stimulation, which activates the adrenal medulla instantly in stressful situations.

4. Adrenal medullary hormones prepare the body for:
(1) Rest and digestion
(2) Sleep and recovery
(3) Fight or flight response
(4) Hormone synthesis

Explanation:
Adrenaline and noradrenaline activate the fight-or-flight response by increasing heart rate, blood flow to muscles, and glucose release. These effects prepare the body for quick action during stress. The correct answer is (3) Fight or flight response, which enhances survival during emergencies or threats.

5. Which of the following effects is caused by adrenaline and noradrenaline?
(1) Reduced heart rate
(2) Vasodilation in skeletal muscles
(3) Decreased blood glucose
(4) Reduced alertness

Explanation:
Catecholamines like adrenaline and noradrenaline cause vasodilation in skeletal muscles to increase oxygen and nutrient supply during stress. They also raise blood glucose levels and enhance alertness. Hence, the correct answer is (2) Vasodilation in skeletal muscles, essential for quick energy mobilization.

6. Which of the following is NOT caused by adrenal medullary hormones?
(1) Increased heart rate
(2) Increased glucose level
(3) Pupil dilation
(4) Decreased blood pressure

Explanation:
Adrenal medullary hormones increase heart rate, blood pressure, and glucose, while dilating pupils. They do not decrease blood pressure. Hence, the incorrect option is (4) Decreased blood pressure. These changes collectively enable rapid physiological responses to stressful conditions.

Assertion-Reason Type:
7. Assertion (A): Adrenaline is called the emergency hormone.
Reason (R): It increases blood sugar and heart rate during stressful situations.
(1) Both A and R are true and R is the correct explanation of A.
(2) Both A and R are true but R is not the correct explanation of A.
(3) A is true but R is false.
(4) A is false but R is true.

Explanation:
Adrenaline is termed the emergency hormone as it prepares the body to face emergencies by increasing blood sugar, heart rate, and alertness. The reason correctly explains the assertion. Hence, the correct answer is (1) Both A and R are true and R is the correct explanation of A.

Matching Type:
8. Match the hormones with their functions:
List I - Hormone
A. Adrenaline
B. Noradrenaline
C. Insulin
D. Glucagon

List II - Function
1. Increases blood sugar
2. Decreases blood sugar
3. Causes vasoconstriction
4. Increases heart rate

(1) A-4, B-3, C-2, D-1
(2) A-3, B-2, C-1, D-4
(3) A-2, B-1, C-4, D-3
(4) A-1, B-3, C-2, D-4

Explanation:
Adrenaline increases heart rate, noradrenaline causes vasoconstriction, insulin reduces blood sugar, and glucagon increases it. These hormones work together to maintain energy balance and cardiovascular stability. Hence, the correct matching is (1) A-4, B-3, C-2, D-1.

Fill in the Blanks:
9. During stress, the adrenal medulla releases __________ which prepares the body for emergency situations.
(1) Aldosterone
(2) Adrenaline
(3) Cortisol
(4) Thyroxine

Explanation:
During stress, the adrenal medulla secretes adrenaline which triggers the fight-or-flight response. It increases heart rate, respiration, and glucose availability, ensuring the body is ready for immediate action. Hence, the correct answer is (2) Adrenaline, the primary emergency hormone.

Choose the Correct Statements:
10. Statement I: Adrenaline and noradrenaline are collectively called catecholamines.
Statement II: Catecholamines decrease blood sugar and relax skeletal muscles.
(1) Both statements are correct.
(2) Only Statement I is correct.
(3) Only Statement II is correct.
(4) Both statements are incorrect.

Explanation:
Adrenaline and noradrenaline are catecholamines derived from tyrosine. They increase heart rate, blood sugar, and muscular activity, not decrease them. Therefore, only Statement I is correct. The correct answer is (2) Only Statement I is correct.

Topic: Endocrine Glands and Hormones; Subtopic: Hormones of Heart, Kidney, Gastro-intestinal Tract and Adrenal Cortex

Keyword Definitions:

• Hormones: Chemical messengers secreted by endocrine glands that regulate the activity of various organs.

• Atrial Natriuretic Factor (ANF): Hormone secreted by the atria of the heart that reduces blood pressure and promotes sodium excretion.

• Erythropoietin: A glycoprotein hormone secreted by the kidney that stimulates red blood cell production in the bone marrow.

• Aldosterone: A mineralocorticoid hormone secreted by the adrenal cortex that maintains sodium and potassium balance.

• Secretin: A hormone released from the duodenum that stimulates pancreatic bicarbonate secretion to neutralize gastric acid.

Lead Question - 2025
Match List-I with List-II :
List-I            List-II
A. Heart            I. Erythropoietin
B. Kidney           II. Aldosterone
C. Gastro-intestinal Tract   III. Atrial natriuretic factor
D. Adrenal Cortex      IV. Secretin

Choose the correct answer from the options given below:
(1) A-II, B-I, C-III, D-IV
(2) A-IV, B-III, C-II, D-I
(3) A-I, B-III, C-IV, D-II
(4) A-III, B-I, C-IV, D-II

Explanation:
Heart secretes Atrial Natriuretic Factor (ANF) that helps in reducing blood pressure. Kidney secretes Erythropoietin that stimulates red blood cell production. The Gastro-intestinal Tract secretes Secretin that regulates pancreatic secretions, and Adrenal Cortex secretes Aldosterone that controls sodium balance. Hence, the correct match is A-III, B-I, C-IV, D-II. Option (4) is correct.

Guessed Questions:

1. Which hormone regulates the excretion of sodium by the kidneys?
(1) Insulin
(2) Aldosterone
(3) Thyroxine
(4) Oxytocin
Explanation: Aldosterone, secreted by the adrenal cortex, enhances sodium reabsorption and potassium excretion in renal tubules. This maintains electrolyte balance and regulates blood pressure effectively in the body. Answer: (2)

2. The kidney secretes which of the following hormones?
(1) Adrenaline
(2) Secretin
(3) Erythropoietin
(4) Cortisol
Explanation: Erythropoietin is produced by the kidney in response to decreased oxygen levels. It stimulates the bone marrow to produce red blood cells, thus maintaining oxygen transport and preventing anemia. Answer: (3)

3. ANF secreted by the heart acts to:
(1) Increase blood pressure
(2) Decrease blood pressure
(3) Increase heart rate
(4) Increase sodium reabsorption
Explanation: Atrial Natriuretic Factor (ANF) promotes vasodilation and sodium excretion, reducing blood volume and pressure. It acts as a natural regulator of blood pressure. Answer: (2)

4. Secretin is released by which part of the digestive tract?
(1) Stomach
(2) Duodenum
(3) Colon
(4) Ileum
Explanation: Secretin is produced by S-cells in the duodenum when acidic chyme enters from the stomach. It stimulates the pancreas to release bicarbonate-rich juice, neutralizing stomach acid in the intestine. Answer: (2)

5. Assertion (A): ANF decreases blood pressure by promoting sodium excretion.
Reason (R): ANF increases sodium reabsorption in kidneys.
(1) Both A and R are true, and R is the correct explanation
(2) Both A and R are true, but R is not the correct explanation
(3) A is true but R is false
(4) A is false but R is true
Explanation: ANF decreases blood pressure by promoting sodium excretion, not reabsorption. This reduces blood volume. Hence, Assertion is true, but Reason is false. Answer: (3)

6. Fill in the blank: The hormone secreted by the kidney responsible for red blood cell production is ________.
(1) Renin
(2) Erythropoietin
(3) Vasopressin
(4) Aldosterone
Explanation: Erythropoietin is secreted by the kidney in response to low oxygen tension. It acts on bone marrow to stimulate red blood cell formation, enhancing oxygen delivery. Answer: (2)

7. Choose the correct statements:
Statement I: Heart secretes ANF to reduce blood pressure.
Statement II: Adrenal cortex secretes aldosterone to increase sodium reabsorption.
(1) Both statements are true
(2) Both statements are false
(3) I is true, II is false
(4) I is false, II is true
Explanation: ANF secreted by the heart reduces blood pressure, while aldosterone secreted by the adrenal cortex promotes sodium reabsorption. Both statements are correct. Answer: (1)

8. Matching Type:
Match the following hormones with their glands:
A. Adrenal medulla – (i) Epinephrine
B. Thyroid – (ii) Thyroxine
C. Pancreas – (iii) Insulin
D. Parathyroid – (iv) Parathormone
(1) A-i, B-ii, C-iii, D-iv
(2) A-ii, B-i, C-iv, D-iii
(3) A-iii, B-iv, C-ii, D-i
(4) A-iv, B-iii, C-i, D-ii
Explanation: The adrenal medulla secretes epinephrine, thyroid secretes thyroxine, pancreas secretes insulin, and parathyroid secretes parathormone which regulates calcium metabolism. Answer: (1)

9. Which hormone among the following is not secreted by the adrenal cortex?
(1) Cortisol
(2) Aldosterone
(3) Adrenaline
(4) Androgens
Explanation: Adrenal cortex secretes aldosterone, cortisol, and androgens. Adrenaline is produced by the adrenal medulla, not the cortex. Hence, adrenaline is not a cortical hormone. Answer: (3)

10. Which of the following hormones is secreted by the duodenum?
(1) Gastrin
(2) Secretin
(3) CCK
(4) Somatostatin
Explanation: Secretin is secreted by the duodenal mucosa in response to acidic chyme. It regulates pancreatic and bile secretions for neutralizing stomach acid and aiding digestion. Answer: (2)

Topic: Hormones and Endocrine Glands; Subtopic: Mechanism of Hormone Action

Keyword Definitions:

• Hormones: Chemical messengers secreted by endocrine glands that regulate physiological functions.

• Peptide hormone: Hormones made up of amino acids like insulin and glucagon.

• Steroid hormone: Lipid-soluble hormones derived from cholesterol, such as progesterone and testosterone.

• Membrane-bound receptors: Receptors located on the cell membrane surface for peptide hormones.

• Second messengers: Molecules like cAMP that mediate hormone action inside the cell.

Lead Question - 2024 (Jhajjhar)

With regard to Hormones, identify the correct statements.

A. Epinephrine is a peptide hormone.

B. Progesterone is a peptide hormone.

C. Hormones that interact with membrane bound receptors normally do not enter target cell, but generate second messengers.

D. Hormones that interact with intracellular receptors mostly regulate gene expression.

E. Insulin is a amino acid derivative hormone.

Choose the most appropriate answer from the options given below:

1. A and B only

2. C and E only

3. C and D only

4. B and C only

Explanation:

The correct answer is 3. C and D only. Epinephrine is an amino acid derivative, not a peptide. Progesterone is a steroid hormone. Peptide hormones act via membrane-bound receptors and trigger secondary messengers like cAMP, while steroid hormones act through intracellular receptors to regulate gene expression by directly influencing transcriptional activity inside target cells.

Guessed Questions:

1. Which of the following hormones is derived from amino acid tyrosine?

1. Insulin

2. Epinephrine

3. Glucagon

4. Oxytocin

Explanation:

The correct answer is 2. Epinephrine. Epinephrine, also known as adrenaline, is a catecholamine hormone derived from tyrosine. It is secreted by the adrenal medulla and functions in the ‘fight or flight’ response, increasing heart rate, glycogen breakdown, and blood glucose levels during stress or emergency situations.

2. Which of the following is a steroid hormone?

1. Insulin

2. Progesterone

3. Epinephrine

4. Glucagon

Explanation:

The correct answer is 2. Progesterone. Steroid hormones like progesterone are lipid-soluble molecules derived from cholesterol. They diffuse through plasma membranes and bind to intracellular receptors. Progesterone plays a major role in maintaining pregnancy and regulating the menstrual cycle in females.

3. Which hormone acts via a second messenger system such as cyclic AMP (cAMP)?

1. Insulin

2. Thyroxine

3. Progesterone

4. Cortisol

Explanation:

The correct answer is 1. Insulin. Insulin is a peptide hormone that binds to membrane receptors and triggers signaling cascades involving secondary messengers such as cAMP. This mechanism regulates glucose uptake and glycogen synthesis within cells without the hormone entering the target cell directly.

4. Which one of the following hormones is NOT lipid soluble?

1. Cortisol

2. Testosterone

3. Insulin

4. Progesterone

Explanation:

The correct answer is 3. Insulin. Insulin is a peptide hormone, hence water-soluble, and cannot pass through the lipid bilayer of cell membranes. It binds to extracellular receptors and activates signal transduction pathways, while steroid hormones are lipid-soluble and easily cross the plasma membrane.

5. Which hormone regulates gene expression by binding to DNA inside the nucleus?

1. Estrogen

2. Insulin

3. Epinephrine

4. Glucagon

Explanation:

The correct answer is 1. Estrogen. Estrogen is a steroid hormone that enters cells, binds to intracellular receptors, and the complex then attaches to DNA, modifying gene transcription. This regulates development of secondary sexual characteristics and reproductive cycle control in females.

6. Which of the following statements regarding peptide hormones is true?

1. They easily pass through plasma membrane.

2. They act via membrane-bound receptors.

3. They bind to nuclear receptors.

4. They regulate transcription directly.

Explanation:

The correct answer is 2. They act via membrane-bound receptors. Peptide hormones are hydrophilic and cannot penetrate the lipid bilayer. They bind to specific receptors on the cell surface and initiate signal transduction through second messengers, leading to physiological responses in target tissues.

7. Assertion-Reason Type:

Assertion (A): Steroid hormones act through intracellular receptors.

Reason (R): They are lipid-soluble and easily cross the plasma membrane.

1. Both (A) and (R) are true, and (R) is the correct explanation of (A).

2. Both (A) and (R) are true, but (R) is not the correct explanation of (A).

3. (A) true, (R) false.

4. (A) false, (R) true.

Explanation:

The correct answer is 1. Both (A) and (R) are true, and (R) is the correct explanation of (A). Steroid hormones, being lipid-soluble, easily diffuse through plasma membranes and bind to cytoplasmic or nuclear receptors. The hormone-receptor complex regulates gene expression and protein synthesis.

8. Matching Type:

Match the hormones with their chemical nature:

A. Insulin

B. Progesterone

C. Epinephrine

D. Thyroxine

1. Peptide

2. Steroid

3. Amino acid derivative

4. Iodinated tyrosine derivative

Options:

A-1, B-2, C-3, D-4

A-2, B-1, C-4, D-3

A-3, B-4, C-1, D-2

A-4, B-2, C-1, D-3

Explanation:

The correct answer is A-1, B-2, C-3, D-4. Insulin is a peptide hormone, progesterone a steroid hormone, epinephrine an amino acid derivative, and thyroxine an iodinated derivative of tyrosine. Their classification is based on biochemical structure and mechanism of action in the body.

9. Fill in the Blanks:

__________ acts as a second messenger for many peptide hormones.

1. Cyclic AMP (cAMP)

2. ATP

3. Calcium ions

4. NADH

Explanation:

The correct answer is 1. Cyclic AMP (cAMP). cAMP is produced when peptide hormones bind to surface receptors, activating adenylate cyclase. This enzyme converts ATP into cAMP, which triggers intracellular signaling cascades regulating metabolism, enzyme activity, and cellular responses without hormone entry into the cell.

10. Choose the Correct Statements (Statement I & II):

Statement I: Peptide hormones use intracellular receptors for gene regulation.

Statement II: Steroid hormones can easily pass through plasma membranes.

1. Both statements are true.

2. Both statements are false.

3. Statement I false, Statement II true.

4. Statement I true, Statement II false.

Explanation:

The correct answer is 3. Statement I false, Statement II true. Peptide hormones act via membrane-bound receptors and secondary messengers, not intracellular ones. Steroid hormones are lipid-soluble, enabling them to diffuse across cell membranes and regulate gene transcription directly by binding to DNA-associated receptors.

Topic: Menstrual Cycle; Subtopic: Role of Hormones in Menstrual Regulation

Keyword Definitions:
• Corpus Luteum: A temporary endocrine gland formed from the ruptured Graafian follicle after ovulation, secreting progesterone.
• Endometrium: The innermost lining of the uterus that thickens to support implantation and sheds during menstruation.
• Menarche: The first menstrual cycle in a female, marking the onset of reproductive maturity.
• Menopause: The natural cessation of menstruation, indicating the end of reproductive capability.
• Progesterone: A hormone that maintains the endometrial lining and inhibits uterine contractions during pregnancy.
• Fertilization: The fusion of sperm and ovum forming a zygote.
• Menstrual Cycle: A monthly cycle involving changes in the uterus and ovaries, typically lasting about 28 days.

Lead Question - 2024 (Jhajjhar)
Given below are two statements:

Statement I: Degeneration of corpus luteum in the absence of fertilization is the cause for disintegration of endometrium.
Statement II: Cyclic menstruation indicates normal reproductive phase in human females and extends between menarche and menopause.

Choose the correct answer from the options given below:
1. Both Statement I and Statement II are True.
2. Both Statement I and Statement II are False.
3. Statement I is True but Statement II is False.
4. Statement I is False but Statement II is True.

Explanation:
The correct answer is 1. Both Statement I and Statement II are True. When fertilization does not occur, the corpus luteum degenerates, reducing progesterone levels and leading to shedding of the endometrium. This results in menstruation. Regular menstruation between menarche and menopause reflects a normal, healthy reproductive phase in human females controlled by hormonal cycles.

1. Which hormone is primarily responsible for maintaining the endometrial lining during the luteal phase?
1. Estrogen
2. Progesterone
3. LH
4. FSH

Explanation:
The correct answer is 2. Progesterone. Secreted by the corpus luteum, progesterone maintains the endometrium, preparing it for implantation of the fertilized ovum. If fertilization does not occur, progesterone levels fall, leading to endometrial degeneration and the onset of menstruation, marking the end of one reproductive cycle.

2. Which of the following marks the end of the reproductive phase in females?
1. Menstruation
2. Menarche
3. Menopause
4. Ovulation

Explanation:
The correct answer is 3. Menopause. Menopause is the permanent cessation of menstruation, indicating the end of a woman’s reproductive period. It usually occurs between 45–55 years of age. During this phase, ovarian follicles decline, leading to decreased estrogen and progesterone secretion, and ending ovulatory cycles.

3. Which phase of the menstrual cycle involves rebuilding of the endometrium under estrogen influence?
1. Menstrual phase
2. Follicular phase
3. Ovulatory phase
4. Luteal phase

Explanation:
The correct answer is 2. Follicular phase. The follicular phase follows menstruation and is characterized by estrogen-driven proliferation of the endometrial lining. Follicles mature under FSH influence, and one becomes dominant. Rising estrogen levels prepare the uterus for potential implantation, leading up to ovulation around the 14th day of the cycle.

4. What triggers ovulation in the menstrual cycle?
1. A sudden surge in LH
2. A decline in FSH
3. Increased progesterone secretion
4. Endometrial shedding

Explanation:
The correct answer is 1. A sudden surge in LH. The mid-cycle luteinizing hormone (LH) surge induces the rupture of the mature Graafian follicle, releasing the secondary oocyte. This marks ovulation, usually occurring on the 14th day of a 28-day cycle. The remaining follicular cells form the corpus luteum, which secretes progesterone post-ovulation.

5. If fertilization occurs, what prevents degeneration of the corpus luteum?
1. High estrogen
2. Follicle Stimulating Hormone
3. Human Chorionic Gonadotropin (hCG)
4. Progesterone

Explanation:
The correct answer is 3. Human Chorionic Gonadotropin (hCG). hCG secreted by the developing embryo maintains the corpus luteum during early pregnancy. This ensures continued progesterone production to sustain the endometrial lining, preventing menstruation and supporting implantation and early embryonic development until the placenta forms its hormonal role.

6. What is the duration of the average menstrual cycle in humans?
1. 15 days
2. 21 days
3. 28 days
4. 35 days

Explanation:
The correct answer is 3. 28 days. The menstrual cycle typically lasts about 28 days, though variations from 26 to 32 days are common. It includes four phases—menstrual, follicular, ovulatory, and luteal—regulated by hormonal interplay among the hypothalamus, pituitary gland, and ovaries, ensuring coordinated reproductive readiness.

7. Assertion-Reason Question:
Assertion (A): Progesterone prevents uterine contractions during pregnancy.
Reason (R): Low progesterone levels trigger menstrual bleeding.

1. Both (A) and (R) are True and (R) is the correct explanation of (A).
2. Both (A) and (R) are True but (R) is not the correct explanation of (A).
3. (A) is True but (R) is False.
4. (A) is False but (R) is True.

Explanation:
The correct answer is 2. Both (A) and (R) are True but (R) is not the correct explanation of (A). Progesterone inhibits uterine contractions to maintain pregnancy. However, its decline causes endometrial breakdown and menstruation, not directly linked to contraction inhibition but essential for cycle regulation.

8. Matching Type Question:
Match List-I with List-II:
List-I (Hormone) — List-II (Function)
A. FSH — I. Stimulates follicular growth
B. LH — II. Triggers ovulation
C. Progesterone — III. Maintains endometrium
D. Estrogen — IV. Promotes endometrial proliferation

1. A-I, B-II, C-III, D-IV
2. A-II, B-I, C-IV, D-III
3. A-IV, B-II, C-I, D-III
4. A-I, B-III, C-IV, D-II

Explanation:
The correct answer is 1. A-I, B-II, C-III, D-IV. FSH stimulates follicle growth, LH induces ovulation, progesterone maintains the endometrium, and estrogen rebuilds it after menstruation. Together, these hormones coordinate ovarian and uterine functions, ensuring regular menstrual cycles and successful reproduction.

9. Fill in the Blanks Question:
The corpus luteum secretes __________, which helps maintain the endometrial lining.
1. FSH
2. LH
3. Progesterone
4. Estrogen

Explanation:
The correct answer is 3. Progesterone. The corpus luteum forms after ovulation and secretes progesterone, which stabilizes and maintains the endometrial lining. If pregnancy occurs, progesterone continues to be secreted under hCG influence; otherwise, its decline leads to menstruation, restarting the reproductive cycle.

10. Choose the Correct Statements:
Statement I: Menstrual flow results from the breakdown of the endometrial lining.
Statement II: Menstrual bleeding occurs due to a rise in progesterone level.

1. Both statements are correct.
2. Both statements are incorrect.
3. Only Statement I is correct.
4. Only Statement II is correct.

Explanation:
The correct answer is 3. Only Statement I is correct. Menstrual bleeding occurs due to the shedding of the endometrial lining following progesterone withdrawal, not its increase. The fall in progesterone and estrogen levels causes rupture of endometrial blood vessels, leading to menstrual flow and the beginning of a new cycle.

Topic: Endocrine System; Subtopic: Hormonal Regulation and Functions

Keyword Definitions:

• Parathyroid hormone: Regulates calcium and phosphate balance by increasing Ca2+ levels in blood.

• Epinephrine: Also known as adrenaline, it triggers the “fight or flight” response under stress.

• Thyroid stimulating hormone: Secreted by the pituitary gland to regulate thyroid hormone synthesis.

• Melatonin: A hormone from the pineal gland that regulates the biological clock and sleep-wake cycle.

Lead Question - 2024 (Jhajjhar)

Match List-I with List-II:

List-I            List-II

A. Parathyroid hormone         I. Flight or fight response

B. Epinephrine and Nor-epinephrine    II. Regulates the body's biological clock

C. Thyroid stimulating hormone        III. Increases blood Ca2+ level

D. Melatonin                               IV. Synthesis of hormones

Choose the correct answer from the options given below:

1. A-III, B-I, C-IV, D-II

2. A-III, B-IV, C-I, D-II

3. A-III, B-I, C-II, D-IV

4. A-I, B-II, C-III, D-IV

Explanation:

The parathyroid hormone increases calcium ion levels in the blood by stimulating bone resorption. Epinephrine and norepinephrine trigger the fight or flight response during stress. Thyroid stimulating hormone controls thyroid hormone synthesis. Melatonin regulates circadian rhythm and biological clock. Hence, the correct match is A-III, B-I, C-IV, D-II. Hormones act as chemical messengers to maintain internal homeostasis and physiological coordination.

1. Which hormone is secreted by adrenal medulla?

1. Insulin

2. Epinephrine

3. Aldosterone

4. Thyroxine

Explanation: The adrenal medulla secretes epinephrine and norepinephrine, hormones responsible for increasing heart rate and blood flow during stress. These hormones prepare the body for fight or flight response. Epinephrine acts rapidly on tissues like heart, lungs, and muscles. Hence, the correct answer is epinephrine.

2. Which gland regulates calcium metabolism?

1. Pituitary gland

2. Parathyroid gland

3. Adrenal gland

4. Pineal gland

Explanation: The parathyroid gland secretes parathyroid hormone (PTH), which increases blood calcium levels by stimulating bone resorption and enhancing calcium reabsorption in kidneys. It maintains calcium-phosphate balance. The pituitary and pineal glands perform other hormonal functions. Hence, the correct answer is parathyroid gland.

3. Which of the following is known as the master gland?

1. Thyroid gland

2. Pituitary gland

3. Adrenal gland

4. Pancreas

Explanation: The pituitary gland is called the master gland as it regulates activities of other endocrine glands by releasing hormones like TSH, ACTH, and GH. It is located at the base of the brain and controlled by the hypothalamus. Hence, the correct answer is pituitary gland.

4. Which hormone maintains the body’s circadian rhythm?

1. Melatonin

2. Insulin

3. Adrenaline

4. Thyroxine

Explanation: Melatonin is secreted by the pineal gland mainly during night and regulates the sleep-wake cycle and biological clock. It also influences seasonal breeding in animals. Its secretion decreases with light exposure. Hence, melatonin maintains circadian rhythm and sleep patterns.

5. Which hormone stimulates the thyroid gland to produce thyroxine?

1. ACTH

2. GH

3. TSH

4. FSH

Explanation: Thyroid stimulating hormone (TSH) is secreted by the anterior pituitary gland and stimulates the thyroid gland to release thyroxine (T4) and triiodothyronine (T3). These hormones regulate metabolism, growth, and development. Hence, the correct answer is TSH.

6. Which hormone increases blood glucose levels during stress?

1. Insulin

2. Glucagon

3. Epinephrine

4. Thyroxine

Explanation: Epinephrine, secreted by adrenal medulla, increases blood glucose levels by promoting glycogen breakdown in the liver. It provides instant energy during emergency or stress. Hence, the correct answer is epinephrine.

Assertion-Reason Type Question

7. Assertion (A): Epinephrine is called the emergency hormone.

Reason (R): It decreases the heart rate and oxygen supply to muscles.

1. Both (A) and (R) are correct, and (R) is the correct explanation of (A).

2. Both (A) and (R) are correct, but (R) is not the correct explanation of (A).

3. (A) is correct, but (R) is incorrect.

4. (A) is incorrect, but (R) is correct.

Explanation: Epinephrine is termed the emergency hormone as it prepares the body for fight or flight by increasing heart rate, blood pressure, and oxygen delivery to muscles. Thus, (A) is correct but (R) is incorrect.

Matching Type Question

8. Match the following:

A. Insulin — I. Adrenal medulla

B. Epinephrine — II. Pancreas

C. Melatonin — III. Pineal gland

1. A-II, B-I, C-III

2. A-I, B-II, C-III

3. A-III, B-I, C-II

4. A-II, B-III, C-I

Explanation: Insulin is secreted by pancreas, epinephrine by adrenal medulla, and melatonin by pineal gland. They regulate metabolism, emergency response, and sleep cycle respectively. Hence, the correct answer is A-II, B-I, C-III.

Fill in the Blank Type Question

9. __________ regulates the secretion of hormones from the pituitary gland.

1. Cerebellum

2. Hypothalamus

3. Medulla oblongata

4. Cerebrum

Explanation: The hypothalamus controls pituitary gland functions by releasing neurohormones. It links the nervous and endocrine systems, maintaining homeostasis. Hence, the correct answer is hypothalamus.

Choose the Correct Statements (Statement I & II)

10. Statement I: Parathyroid hormone decreases calcium level in blood.

Statement II: Calcitonin from thyroid gland decreases blood calcium level.

1. Both statements are correct.

2. Both statements are incorrect.

3. Statement I is correct but Statement II is incorrect.

4. Statement I is incorrect but Statement II is correct.

Explanation: Parathyroid hormone increases blood calcium level by bone resorption, while calcitonin reduces it by depositing calcium in bones. Hence, Statement I is incorrect but Statement II is correct. 

Topic: Endocrine Glands and Hormones; Subtopic: Disorders due to Hormonal Imbalance

Keyword Definitions:

• Hormone: Chemical messenger secreted by endocrine glands to regulate body functions.

• Thyroid hormone: Regulates metabolism, growth, and development in the body.

• Growth hormone: Secreted by pituitary gland; regulates body growth and metabolism.

• Cortisol: Steroid hormone produced by adrenal cortex that controls stress response.

• Exophthalmos: Protrusion of the eyeball commonly seen in hyperthyroidism.

• Cretinism: Disorder due to thyroid hormone deficiency in childhood causing stunted growth.

• Acromegaly: Disorder due to excessive secretion of growth hormone in adults.

• Cushing’s syndrome: Condition due to overproduction of cortisol leading to moon face and hyperglycemia.

Lead Question (2024)

Match List I with List II

List I                                  List II

A. Exophthalmic goitre              I. Excess secretion of cortisol, moon face & hyperglycemia

B. Acromegaly                                     II. Hypo-secretion of thyroid hormone and stunted growth

C. Cushing’s syndrome              III. Hyper secretion of thyroid hormone & protruding eyeballs

D. Cretinism                                            IV. Excessive secretion of growth hormone

Choose the correct answer from the options given below:

(1) A-IV, B-II, C-I, D-III

(2) A-III, B-IV, C-II, D-I

(3) A-III, B-IV, C-I, D-II

(4) A-I, B-III, C-II, D-IV

Explanation:

Exophthalmic goitre (Graves’ disease) is caused by hypersecretion of thyroid hormones leading to protruding eyeballs (A–III). Acromegaly results from overproduction of growth hormone in adults (B–IV). Cushing’s syndrome occurs due to excess cortisol secretion by adrenal cortex (C–I). Cretinism develops in children due to thyroid hormone deficiency causing dwarfism and mental retardation (D–II). Hence, the correct answer is (3) A–III, B–IV, C–I, D–II.

Guessed Question 1:

Which hormone is secreted in excess in acromegaly?

(1) Thyroxine

(2) Growth hormone

(3) Cortisol

(4) Insulin

Explanation:

Acromegaly occurs in adults due to overproduction of growth hormone by the anterior pituitary. It causes enlargement of facial bones, hands, and feet. Unlike gigantism, which affects growth before epiphyseal fusion, acromegaly occurs after growth completion. Answer: Growth hormone.

Guessed Question 2:

Cretinism occurs due to deficiency of which gland's hormone?

(1) Adrenal gland

(2) Thyroid gland

(3) Pituitary gland

(4) Parathyroid gland

Explanation:

Cretinism results from deficiency of thyroid hormones (thyroxine and triiodothyronine) during childhood. It leads to stunted physical and mental growth, lethargy, and dwarfism. Proper iodine intake prevents this disorder. Answer: Thyroid gland.

Guessed Question 3:

Cushing’s syndrome results due to excess secretion of which hormone?

(1) Insulin

(2) Cortisol

(3) Aldosterone

(4) Adrenaline

Explanation:

Cushing’s syndrome is caused by hypersecretion of cortisol from the adrenal cortex. It leads to symptoms like moon face, muscle weakness, high blood sugar, and obesity of trunk. The disorder may also result from prolonged steroid use. Answer: Cortisol.

Guessed Question 4:

Which of the following conditions is associated with protruding eyeballs?

(1) Acromegaly

(2) Cretinism

(3) Exophthalmic goitre

(4) Myxedema

Explanation:

Exophthalmic goitre, also known as Graves’ disease, occurs due to overproduction of thyroid hormones (hyperthyroidism). It leads to protrusion of eyeballs, increased metabolism, weight loss, and irritability. Answer: Exophthalmic goitre.

Guessed Question 5:

Which of the following diseases is caused by hypo-secretion of thyroid hormone in adults?

(1) Myxedema

(2) Acromegaly

(3) Cushing’s syndrome

(4) Diabetes insipidus

Explanation:

Myxedema occurs due to deficiency of thyroid hormones in adults. It causes puffy skin, lethargy, weight gain, and slow metabolism. It is distinct from cretinism, which occurs in childhood. Answer: Myxedema.

Guessed Question 6:

Which of the following hormones regulates stress response in the body?

(1) Cortisol

(2) Thyroxine

(3) Growth hormone

(4) Oxytocin

Explanation:

Cortisol, a glucocorticoid secreted by the adrenal cortex, regulates metabolism, blood glucose levels, and stress response. Its excess leads to Cushing’s syndrome, while deficiency causes Addison’s disease. Answer: Cortisol.

Guessed Question 7 (Assertion–Reason Type):

Assertion (A): Cretinism causes mental retardation and stunted growth.

Reason (R): It is caused by over-secretion of thyroid hormones during childhood.

(1) Both A and R are true, and R is the correct explanation of A.

(2) Both A and R are true, but R is not the correct explanation of A.

(3) A is true, but R is false.

(4) A is false, but R is true.

Explanation:

Cretinism is due to *deficiency* of thyroid hormones, not over-secretion. It leads to stunted growth, mental retardation, and lethargy in children. Answer: (3) A is true, but R is false.

Guessed Question 8 (Matching Type):

Match the following:

A. Addison’s disease     1. Hyposecretion of adrenal cortex

B. Diabetes mellitus   2. Deficiency of insulin

C. Acromegaly         3. Excess growth hormone

D. Myxedema         4. Hypothyroidism

(1) A–1, B–2, C–3, D–4

(2) A–2, B–3, C–4, D–1

(3) A–3, B–1, C–2, D–4

(4) A–4, B–3, C–1, D–2

Explanation:

Addison’s disease results from adrenal cortex hyposecretion (A–1). Diabetes mellitus is due to insulin deficiency (B–2). Acromegaly occurs due to excess growth hormone secretion (C–3). Myxedema is caused by thyroid hormone deficiency (D–4). Answer: (1) A–1, B–2, C–3, D–4.

Guessed Question 9 (Fill in the Blanks):

________ is caused by the deficiency of thyroid hormones during adulthood leading to puffiness and slow metabolism.

(1) Acromegaly

(2) Myxedema

(3) Cretinism

(4) Goitre

Explanation:

Myxedema is an adult hypothyroid condition characterized by swelling, slow metabolism, and fatigue. It is caused by deficiency of thyroid hormones. Answer: Myxedema.

Guessed Question 10 (Choose the Correct Statements):

Statement I: Cushing’s syndrome is caused by cortisol deficiency.

Statement II: Addison’s disease results from cortisol deficiency.

(1) Both statements are true.

(2) Both statements are false.

(3) Statement I is true, Statement II is false.

(4) Statement I is false, Statement II is true.

Explanation:

Cushing’s syndrome results from cortisol excess, not deficiency, while Addison’s disease is caused by deficiency of cortisol and aldosterone from adrenal cortex. Answer: (4) Statement I is false, Statement II is true.

Topic: Endocrine Glands and Hormones; Subtopic: Types and Classification of Hormones

Keyword Definitions:

• Steroid hormones: Lipid-soluble hormones derived from cholesterol, including testosterone, progesterone, and cortisol, that regulate metabolism and reproduction.

• Peptide hormones: Protein-based hormones like insulin and glucagon that act through cell membrane receptors and second messengers.

• Testosterone: A male sex hormone responsible for secondary sexual characteristics and sperm production.

• Progesterone: A female hormone regulating menstrual cycles and pregnancy maintenance.

• Cortisol: A stress-related steroid hormone secreted by the adrenal cortex controlling glucose metabolism.

• Glucagon: A peptide hormone secreted by α-cells of the pancreas that increases blood glucose levels by glycogen breakdown.

Lead Question – 2024
Which of the following is not a steroid hormone?
(1) Testosterone
(2) Progesterone
(3) Glucagon
(4) Cortisol
Explanation: Steroid hormones are synthesized from cholesterol and are lipid-soluble. Testosterone, progesterone, and cortisol belong to this category. However, glucagon is a peptide hormone produced by pancreatic α-cells. It regulates blood glucose levels through glycogenolysis. Therefore, the correct answer is (3) Glucagon, as it is a peptide hormone, not a steroid-based molecule.

Guessed Questions:

1. Which of the following hormones is derived from cholesterol?
(1) Insulin
(2) Cortisol
(3) Glucagon
(4) Adrenaline
Explanation: Cholesterol is the precursor for all steroid hormones, including cortisol, aldosterone, estrogen, and testosterone. Cortisol, produced in the adrenal cortex, regulates glucose metabolism and immune function. Hence, the correct answer is (2) Cortisol, as it is a steroid hormone synthesized from cholesterol, unlike peptide or amine-based hormones such as insulin and adrenaline.

2. Which gland secretes glucagon?
(1) Adrenal cortex
(2) Pancreatic α-cells
(3) Thyroid gland
(4) Adrenal medulla
Explanation: Glucagon is secreted by the alpha (α) cells of the islets of Langerhans in the pancreas. It acts on the liver to promote glycogen breakdown into glucose, raising blood sugar levels. Hence, the correct answer is (2) Pancreatic α-cells, which play a vital role in maintaining glucose homeostasis with insulin from β-cells.

3. Which hormone stimulates glycogen breakdown in the liver?
(1) Insulin
(2) Glucagon
(3) Progesterone
(4) Cortisol
Explanation: Glucagon triggers glycogenolysis in the liver, converting glycogen to glucose, thus increasing blood glucose levels. Insulin does the opposite by promoting glycogen synthesis. Hence, the correct answer is (2) Glucagon, which functions as a hyperglycemic hormone maintaining blood glucose balance along with insulin for proper energy regulation.

4. Which of the following is secreted by the adrenal cortex?
(1) Adrenaline
(2) Glucagon
(3) Cortisol
(4) Insulin
Explanation: The adrenal cortex secretes steroid hormones like cortisol, aldosterone, and androgens. Cortisol regulates metabolism and helps the body respond to stress. Adrenaline is produced by the adrenal medulla, not the cortex. Hence, the correct answer is (3) Cortisol, a glucocorticoid steroid hormone derived from cholesterol and essential for metabolic regulation.

5. Which of the following hormones is produced by testes?
(1) Cortisol
(2) Testosterone
(3) Progesterone
(4) Insulin
Explanation: The testes produce testosterone from Leydig cells under the control of LH from the pituitary gland. It promotes male secondary sexual characteristics, spermatogenesis, and muscle growth. Hence, the correct answer is (2) Testosterone, which is a steroid hormone derived from cholesterol and crucial for male reproductive health and development.

6. Which hormone is responsible for maintaining pregnancy in females?
(1) Cortisol
(2) Estrogen
(3) Progesterone
(4) Testosterone
Explanation: Progesterone, secreted by the corpus luteum and placenta, maintains the endometrium and prevents uterine contractions during pregnancy. It ensures the survival of the developing embryo and supports gestation. Hence, the correct answer is (3) Progesterone, a key steroid hormone essential for female reproductive physiology and maintenance of pregnancy.

7. Assertion–Reason Type:
Assertion (A): Steroid hormones act by binding to intracellular receptors.
Reason (R): They are lipid-soluble and can easily pass through the plasma membrane.
(1) Both A and R are true, and R is the correct explanation of A
(2) Both A and R are true, but R is not the correct explanation of A
(3) A is true but R is false
(4) A is false but R is true
Explanation: Steroid hormones are lipid-soluble and diffuse through the plasma membrane to bind intracellular receptors, forming a complex that regulates gene expression. Hence, both A and R are true, and R correctly explains A. The correct answer is (1) Both A and R are true, and R explains A perfectly.

8. Matching Type:
Match List I with List II
A. Insulin  I. β-cells of pancreas
B. Glucagon  II. α-cells of pancreas
C. Cortisol  III. Adrenal cortex
D. Testosterone  IV. Testes
(1) A-I, B-II, C-III, D-IV
(2) A-II, B-I, C-IV, D-III
(3) A-I, B-III, C-II, D-IV
(4) A-IV, B-II, C-I, D-III
Explanation: Insulin is secreted by pancreatic β-cells, glucagon by α-cells, cortisol by the adrenal cortex, and testosterone by the testes. Hence, the correct answer is (1) A-I, B-II, C-III, D-IV, representing the proper source and secretion site of each hormone involved in metabolism and reproduction.

9. Fill in the Blanks:
________ is a peptide hormone that increases blood glucose concentration.
(1) Cortisol
(2) Glucagon
(3) Progesterone
(4) Testosterone
Explanation: Glucagon is a peptide hormone secreted by pancreatic α-cells. It promotes glycogen breakdown and gluconeogenesis in the liver, raising blood sugar levels. Hence, the correct answer is (2) Glucagon, which counteracts insulin and maintains glucose homeostasis, especially during fasting or energy-demanding conditions in the human body.

10. Choose the Correct Statements:
Statement I: Cortisol and progesterone are peptide hormones.
Statement II: Glucagon is a steroid hormone.
(1) Both I and II are true
(2) Both I and II are false
(3) I is true but II is false
(4) I is false but II is true
Explanation: Cortisol and progesterone are steroid hormones derived from cholesterol, not peptides. Glucagon is a peptide hormone, not a steroid. Hence, both statements are false. The correct answer is (2) Both I and II are false, accurately classifying these hormones based on their chemical composition and function.

Topic: Hormonal Regulation of Reproductive System; Subtopic: Role of Gonadotropins in Males and Females

Keyword Definitions:
• FSH (Follicle Stimulating Hormone): A pituitary hormone that stimulates follicle growth in females and spermatogenesis in males.
• LH (Luteinizing Hormone): A pituitary hormone stimulating ovulation in females and testosterone secretion in males.
• Ovarian Follicles: Structures in the ovary where oocytes mature.
• Leydig Cells: Interstitial cells of testes that secrete testosterone under LH stimulation.
• Estrogen: A female sex hormone secreted by ovarian follicles that regulates the menstrual cycle and secondary sexual characteristics.

Lead Question – 2024
Given below are two statements: one is labelled as Assertion A and the other as Reason R.

Assertion (A): FSH acts upon ovarian follicles in female and Leydig cells in male.
Reason (R): Growing ovarian follicles secrete estrogen in female while interstitial cells secrete androgen in male human being.

Choose the correct answer from the options given below:
(1) Both A and R are true but R is NOT the correct explanation of A
(2) A is true but R is false
(3) A is false but R is true
(4) Both A and R are true and R is the correct explanation of A

Explanation: The correct answer is (3) A is false but R is true. FSH acts on ovarian follicles in females and Sertoli cells in males, not on Leydig cells. Leydig cells are stimulated by LH to secrete androgens. However, the Reason is true because ovarian follicles secrete estrogen and interstitial cells secrete androgens.

1. Which hormone stimulates Leydig cells in males to secrete testosterone?
(1) LH
(2) FSH
(3) Prolactin
(4) Oxytocin

Explanation: The correct answer is (1) LH. Luteinizing hormone, secreted by the anterior pituitary, acts directly on Leydig cells located in the testes to produce testosterone, which supports spermatogenesis and development of male secondary sexual characters.

2. FSH in females is responsible for:
(1) Ovulation
(2) Growth and maturation of ovarian follicles
(3) Formation of corpus luteum
(4) Secretion of progesterone

Explanation: The correct answer is (2). FSH stimulates the growth and maturation of ovarian follicles during the follicular phase of the menstrual cycle, preparing them for ovulation. It also induces estrogen secretion by granulosa cells, essential for endometrial proliferation.

3. Which cells in the seminiferous tubules respond to FSH in males?
(1) Leydig cells
(2) Sertoli cells
(3) Spermatogonia
(4) Spermatids

Explanation: The correct answer is (2) Sertoli cells. FSH binds to receptors on Sertoli cells, stimulating spermatogenesis and the secretion of androgen-binding proteins that help maintain high testosterone levels in the seminiferous tubules for sperm development.

4. Which hormone primarily regulates ovulation in females?
(1) FSH
(2) LH
(3) Estrogen
(4) Progesterone

Explanation: The correct answer is (2) LH. The mid-cycle surge of LH triggers the rupture of the mature Graafian follicle, releasing the secondary oocyte into the fallopian tube, an event known as ovulation, followed by corpus luteum formation.

5. Which of the following hormones is secreted by corpus luteum?
(1) Estrogen
(2) Progesterone
(3) LH
(4) FSH

Explanation: The correct answer is (2) Progesterone. After ovulation, the ruptured follicle transforms into the corpus luteum, which secretes progesterone to maintain the uterine lining and support potential implantation during early pregnancy.

6. Which statement is correct regarding hormone action in reproduction?
(1) LH stimulates Sertoli cells
(2) FSH acts on Leydig cells
(3) LH acts on Leydig cells
(4) Estrogen acts on Sertoli cells

Explanation: The correct answer is (3). LH stimulates Leydig cells in testes to produce testosterone, essential for spermatogenesis. FSH acts on Sertoli cells, not Leydig cells, to promote sperm maturation. Estrogen has no direct role in male spermatogenesis.

7. Assertion-Reason Type:
Assertion (A): LH is responsible for ovulation in females.
Reason (R): LH surge causes the rupture of Graafian follicle releasing the ovum.
(1) Both A and R are true and R is the correct explanation of A
(2) Both A and R are true but R is not the correct explanation of A
(3) A is true but R is false
(4) A is false but R is true

Explanation: The correct answer is (1). LH surge triggers ovulation by rupturing the mature follicle. This event marks the transition from the follicular to the luteal phase, with progesterone production beginning post-ovulation.

8. Matching Type:
Match the following hormones with their respective functions:

A. FSH — I. Follicular growth
B. LH — II. Ovulation
C. Estrogen — III. Endometrial proliferation
D. Progesterone — IV. Maintenance of pregnancy

(1) A-I, B-II, C-III, D-IV
(2) A-II, B-I, C-IV, D-III
(3) A-III, B-IV, C-I, D-II
(4) A-IV, B-III, C-II, D-I

Explanation: The correct answer is (1). FSH promotes follicular growth, LH induces ovulation, estrogen stimulates endometrial proliferation, and progesterone maintains the uterine lining for implantation and early pregnancy.

9. Fill in the Blanks:
In males, LH acts on __________ cells to stimulate the production of testosterone.
(1) Sertoli
(2) Leydig
(3) Spermatogenic
(4) Granulosa

Explanation: The correct answer is (2) Leydig. LH binds to receptors on Leydig cells in the testes, stimulating them to produce testosterone, which supports spermatogenesis and the development of male secondary sexual characteristics.

10. Choose the Correct Statements:
Statement I: FSH acts on Sertoli cells in males to promote spermatogenesis.
Statement II: LH stimulates Leydig cells to secrete testosterone.
(1) Both I and II are true
(2) Both I and II are false
(3) I is true but II is false
(4) I is false but II is true

Explanation: The correct answer is (1). FSH and LH coordinate male reproductive functions. FSH regulates spermatogenesis through Sertoli cells, while LH controls testosterone synthesis via Leydig cells, ensuring hormonal balance for sperm production and maturation.

Topic: Endocrine System; Subtopic: Parathyroid Hormone and Thyrocalcitonin

Keyword Definitions:

• Parathyroid Hormone (PTH): Hormone secreted by parathyroid glands that increases blood calcium by stimulating bone resorption, kidney reabsorption, and vitamin D activation.

• Thyrocalcitonin / Calcitonin: Hormone from thyroid gland that lowers blood calcium by inhibiting bone resorption and promoting calcium deposition in bones.

• Bone Resorption: Process by which osteoclasts break down bone tissue, releasing minerals into the bloodstream.

• Osteoclasts: Specialized bone cells that degrade bone matrix during resorption.

• Osteoblasts: Bone-forming cells that synthesize and deposit bone matrix.

• Carbohydrate Metabolism: Biochemical processes involving breakdown, synthesis, and utilization of carbohydrates for energy.

• Calcium Homeostasis: Regulation of blood calcium levels through hormonal control involving PTH, calcitonin, and vitamin D.

• Kidney Reabsorption: Process of returning filtered substances, such as calcium, from renal tubules to blood.

• Vitamin D Activation: Conversion of vitamin D to calcitriol, enhancing intestinal calcium absorption.

• Endocrine Regulation: Hormonal control of physiological processes, including bone metabolism and mineral balance.

• Hormonal Interaction: Coordinated action of multiple hormones in regulating body functions such as calcium and carbohydrate metabolism.

Lead Question - 2023 (Manipur):

Given below are two statements:

Statement I: Parathyroid hormone acts on bones and stimulates the process of bone resorption
Statement II: Parathyroid hormone along with Thyrocalcitonin plays a significant role in carbohydrate metabolism

Choose the correct answer from the options given below:

1. Statement I is correct but Statement II is false
2. Statement I is incorrect but Statement II is true
3. Both Statement I and Statement II are true
4. Both Statement I and Statement II are false

Explanation: Correct answer is Statement I is correct but Statement II is false. Parathyroid hormone increases blood calcium levels by stimulating osteoclast-mediated bone resorption, enhancing renal calcium reabsorption, and activating vitamin D. Calcitonin (Thyrocalcitonin) lowers blood calcium by inhibiting osteoclast activity. Neither PTH nor calcitonin plays a direct role in carbohydrate metabolism. Their primary function is calcium and phosphate homeostasis, critical for skeletal integrity, neuromuscular function, and enzymatic activity. This distinction highlights the specialized hormonal regulation of mineral balance without influencing glucose or carbohydrate pathways.

Guessed MCQs:

1. Single Correct Answer MCQ: Which hormone decreases blood calcium levels?
(A) Parathyroid hormone
(B) Thyrocalcitonin
(C) Vitamin D
(D) Cortisol
Explanation: Thyrocalcitonin is correct. Calcitonin, secreted by thyroid C-cells, inhibits osteoclast-mediated bone resorption, reducing calcium release into blood, thereby lowering blood calcium. It complements PTH by maintaining calcium homeostasis. Its regulation is independent of carbohydrate metabolism. Monitoring calcitonin is important in bone disorders and hypercalcemia. It ensures skeletal integrity and prevents excessive calcium accumulation, demonstrating the endocrine system’s role in mineral balance.

2. Single Correct Answer MCQ: Which cells mediate bone resorption under PTH?
(A) Osteoblasts
(B) Osteoclasts
(C) Chondrocytes
(D) Fibroblasts
Explanation: Osteoclasts is correct. PTH stimulates osteoclast differentiation and activity, breaking down bone matrix to release calcium and phosphate into circulation. Osteoblasts are involved in bone formation, not resorption. This process maintains blood calcium levels for neuromuscular and enzymatic functions. Dysregulation can lead to osteoporosis or hypercalcemia. PTH thus orchestrates skeletal remodeling and mineral homeostasis without affecting carbohydrate metabolism, emphasizing targeted hormonal effects on bones.

3. Single Correct Answer MCQ: Main site of PTH action is:
(A) Liver
(B) Bone
(C) Pancreas
(D) Muscle
Explanation: Bone is correct. Parathyroid hormone primarily targets bones, stimulating osteoclast-mediated resorption to release calcium and phosphate. It also acts on kidneys to increase calcium reabsorption and on intestines indirectly via vitamin D activation. PTH ensures calcium homeostasis and supports skeletal health. Its action does not include carbohydrate metabolism. This hormone exemplifies organ-specific endocrine regulation for mineral balance, critical for proper neuromuscular function and bone integrity throughout life.

4. Single Correct Answer MCQ: Which vitamin’s activation is promoted by PTH?
(A) Vitamin A
(B) Vitamin C
(C) Vitamin D
(D) Vitamin K
Explanation: Vitamin D is correct. PTH enhances renal conversion of 25-hydroxyvitamin D to active calcitriol, increasing intestinal calcium absorption. This synergizes with bone resorption and renal reabsorption to elevate blood calcium. Vitamin D activation is essential for calcium homeostasis and skeletal health. PTH does not regulate carbohydrate metabolism. Its precise endocrine role highlights the interplay between hormones and vitamins in mineral regulation, ensuring systemic stability and preventing hypocalcemia.

5. Single Correct Answer MCQ: Which hormone inhibits osteoclast activity?
(A) Parathyroid hormone
(B) Thyrocalcitonin
(C) Glucagon
(D) Adrenaline
Explanation: Thyrocalcitonin is correct. Calcitonin suppresses osteoclast-mediated bone resorption, lowering blood calcium levels. It acts as a counter-regulatory hormone to PTH. Calcitonin does not influence carbohydrate metabolism. Its function is essential in maintaining calcium balance, skeletal density, and preventing hypercalcemia. Endocrine regulation of bone metabolism involves precise hormone interplay to balance bone resorption and formation, ensuring homeostasis without affecting glucose pathways.

6. Single Correct Answer MCQ: Primary function of parathyroid hormone is:
(A) Carbohydrate metabolism
(B) Calcium and phosphate regulation
(C) Protein synthesis
(D) Fat metabolism
Explanation: Calcium and phosphate regulation is correct. PTH increases blood calcium via bone resorption, kidney reabsorption, and vitamin D activation. It also modulates phosphate excretion. Its role in mineral homeostasis is crucial for neuromuscular activity and skeletal integrity. PTH does not directly participate in carbohydrate or fat metabolism. Understanding its specific endocrine function highlights targeted regulation of essential minerals, maintaining systemic physiological stability and supporting multiple organ systems without interfering with glucose metabolism.

7. Assertion-Reason MCQ:
Assertion (A): PTH increases blood calcium levels.
Reason (R): It stimulates osteoclasts to resorb bone and enhances renal calcium reabsorption.
(A) Both A and R are true, and R is the correct explanation of A
(B) Both A and R are true, but R is not the correct explanation of A
(C) A is true, R is false
(D) A is false, R is true
Explanation: Option (A) is correct. PTH elevates blood calcium by activating osteoclast-mediated bone resorption and promoting renal calcium reabsorption. This maintains calcium homeostasis essential for neuromuscular function and skeletal integrity. The reason correctly explains the mechanism of action. PTH does not regulate carbohydrate metabolism. This illustrates hormone-specific regulation of minerals and the feedback control of endocrine pathways to sustain systemic stability.

8. Matching Type MCQ: Match the hormones with their primary effects:
1. PTH    A. Lowers blood calcium
2. Thyrocalcitonin    B. Increases blood calcium
3. Vitamin D    C. Enhances intestinal calcium absorption
(A) 1-B, 2-A, 3-C
(B) 1-A, 2-B, 3-C
(C) 1-B, 2-C, 3-A
(D) 1-C, 2-A, 3-B
Explanation: Correct option is 1-B, 2-A, 3-C. PTH increases blood calcium by bone resorption and renal reabsorption (1-B). Calcitonin reduces blood calcium by inhibiting osteoclasts (2-A). Vitamin D enhances intestinal calcium absorption, complementing PTH (3-C). These coordinated hormonal actions maintain calcium-phosphate balance. They do not directly influence carbohydrate metabolism. This demonstrates integrated endocrine control over mineral homeostasis and skeletal health.

9. Fill in the Blanks / Completion MCQ: PTH increases blood calcium primarily by stimulating _______.
(A) Osteoclasts
(B) Osteoblasts
(C) Chondrocytes
(D) Fibroblasts
Explanation: Osteoclasts is correct. PTH stimulates osteoclasts to resorb bone matrix, releasing calcium and phosphate into blood. It also enhances renal calcium reabsorption and vitamin D activation. Osteoblasts form bone but are not primary targets of PTH for calcium release. This process maintains calcium homeostasis, supports skeletal integrity, and ensures neuromuscular function. PTH does not regulate carbohydrate metabolism. Its precise action illustrates hormone-specific physiological regulation of mineral balance.

10. Choose the correct statements MCQ:
Statement I: PTH stimulates bone resorption and increases blood calcium.
Statement II: PTH and calcitonin regulate carbohydrate metabolism.
(A) Both I and II are correct
(B) Only I is correct
(C) Only II is correct
(D) Neither I nor II is correct
Explanation: Option (B) is correct. PTH increases blood calcium by stimulating osteoclast activity, enhancing renal reabsorption, and activating vitamin D. Calcitonin lowers calcium by inhibiting osteoclasts. Neither hormone is directly involved in carbohydrate metabolism. These statements clarify hormone-specific functions in calcium-phosphate regulation, skeletal maintenance, and mineral homeostasis, highlighting the endocrine system’s precision in controlling essential physiological processes without affecting glucose pathways.

Topic: Glands and Secretion; Subtopic: Exocrine and Endocrine Glands

Keyword Definitions:

• Goblet Cells: Unicellular exocrine glands that secrete mucus to protect and lubricate epithelial surfaces.

• Exocrine Glands: Glands that secrete substances through ducts to a body surface or cavity.

• Endocrine Glands: Ductless glands that release hormones directly into the bloodstream.

• Mucus: Viscous secretion that protects and lubricates epithelia.

• Cerumen: Earwax secreted by ceruminous glands in the ear canal.

• Unicellular Glands: Single-cell glands like goblet cells that secrete mucus.

• Multicellular Glands: Glands composed of multiple cells forming ducts or secretory units.

• Duct: A tube through which exocrine secretions are transported.

• Lubrication: The process of secreting mucus or fluid to reduce friction.

• Protection: Function of glandular secretions to prevent damage or infection.

• Secretion: Process of producing and releasing substances by glandular cells.

Lead Question - 2023 (Manipur)

Given below are two statements:

I: Goblet cells are unicellular glands

II: Earwax is the secretion of exocrine gland

In the light of the above statements, choose the correct answer from the options given below:

1. Statement I is True but Statement II is False

2. Statement I is False but Statement II is True

3. Both Statement I and Statement II are True

4. Both Statement I and Statement II are False

Explanation:

Statement I is correct: goblet cells are unicellular exocrine glands that secrete mucus onto epithelial surfaces. Statement II is also correct: earwax or cerumen is secreted by ceruminous glands, which are exocrine in nature, releasing their secretion into the external auditory canal. Both statements accurately describe glandular structures and their secretions. Understanding the differences between unicellular and multicellular exocrine glands, as well as the role of ceruminous glands, is important for studying protective secretions in the human body. Hence, the correct option is 3.

1. Single Correct Answer MCQ:

Which of the following is a unicellular exocrine gland?

1. Sweat gland

2. Goblet cell

3. Sebaceous gland

4. Salivary gland

Explanation:

Goblet cells are unicellular exocrine glands that secrete mucus to protect epithelial surfaces. Other options are multicellular glands with ducts. Correct answer is 2.

2. Single Correct Answer MCQ:

Earwax is secreted by:

1. Sebaceous glands

2. Ceruminous glands

3. Sweat glands

4. Goblet cells

Explanation:

Ceruminous glands are specialized exocrine glands in the ear canal that secrete earwax (cerumen), which protects the ear from dust, insects, and microbes. Correct answer is 2.

3. Single Correct Answer MCQ:

Which secretion primarily lubricates respiratory epithelial surfaces?

1. Earwax

2. Sweat

3. Mucus

4. Sebum

Explanation:

Mucus secreted by goblet cells lubricates and protects respiratory tract epithelial surfaces from dust, pathogens, and mechanical damage. Correct answer is 3.

4. Single Correct Answer MCQ:

Which of the following glands are ductless?

1. Salivary glands

2. Sweat glands

3. Endocrine glands

4. Ceruminous glands

Explanation:

Endocrine glands are ductless and secrete hormones directly into the bloodstream. Other glands listed are exocrine with ducts. Correct answer is 3.

5. Single Correct Answer MCQ:

Which gland secretes sebum?

1. Sebaceous gland

2. Goblet cell

3. Ceruminous gland

4. Sweat gland

Explanation:

Sebaceous glands are multicellular exocrine glands that secrete sebum to lubricate skin and hair. Goblet cells secrete mucus, ceruminous glands secrete earwax. Correct answer is 1.

6. Single Correct Answer MCQ:

Goblet cells are found in which tissue?

1. Connective tissue

2. Epithelial tissue

3. Muscle tissue

4. Nervous tissue

Explanation:

Goblet cells are unicellular exocrine glands located in epithelial tissue, especially in the lining of respiratory and digestive tracts. Correct answer is 2.

7. Assertion-Reason MCQ:

Assertion (A): Ceruminous glands are exocrine in nature.

Reason (R): They secrete their product into ducts leading to the external auditory canal.

1. Both A and R are true and R explains A

2. Both A and R are true but R does not explain A

3. A is true but R is false

4. Both A and R are false

Explanation:

Ceruminous glands secrete earwax into ducts opening in the ear canal, qualifying them as exocrine glands. Both statements are true, and R explains A. Correct answer is 1.

8. Matching Type MCQ:

Match the gland type with its secretion:

A. Goblet cell — (i) Mucus

B. Ceruminous gland — (ii) Earwax

C. Sebaceous gland — (iii) Sebum

D. Sweat gland — (iv) Sweat

1. A-(i), B-(ii), C-(iii), D-(iv)

2. A-(ii), B-(i), C-(iv), D-(iii)

3. A-(iv), B-(iii), C-(ii), D-(i)

4. A-(iii), B-(iv), C-(i), D-(ii)

Explanation:

Correct matches: Goblet cell → Mucus, Ceruminous gland → Earwax, Sebaceous gland → Sebum, Sweat gland → Sweat. Correct option is 1.

9. Fill in the Blanks MCQ:

The secretion of goblet cells is called ______.

1. Sebum

2. Mucus

3. Cerumen

4. Sweat

Explanation:

Goblet cells secrete mucus, a viscous substance that lubricates and protects epithelial surfaces in the respiratory and digestive tracts. Correct answer is 2.

10. Choose the correct statements MCQ:

Statement I: Goblet cells are unicellular exocrine glands.

Statement II: Ceruminous glands secrete their product via ducts.

1. Statement I only

2. Statement II only

3. Both statements are true

4. Both statements are false

Explanation:

Statement I is correct: goblet cells are unicellular exocrine glands. Statement II is correct: ceruminous glands secrete earwax through ducts into the external auditory canal. Hence, both statements are true. Correct answer is 3.

Topic: Endocrine Glands and Hormonal Functions; Subtopic: Hormonal Regulation and Disorders

Keyword Definitions:

• Thyrocalcitonin (TCT): A hormone secreted by thyroid gland that lowers blood calcium levels by inhibiting bone resorption.

• FSH: Follicle Stimulating Hormone that controls gamete production in both sexes.

• Glucocorticoids: Hormones secreted by adrenal cortex that help in carbohydrate metabolism and stress response.

• Parathyroid Hormone (PTH): Regulates calcium and phosphate balance in the blood, not sodium levels.

• Goitre: Enlargement of thyroid gland due to iodine deficiency or abnormal thyroid hormone levels.

Lead Question – 2023 (Manipur)

Which of the following statements are correct with respect to the hormone and its function?

A: Thyrocalcitonin (TCT) regulates the blood calcium level
B: In males, FSH and androgens regulate spermatogenesis
C: Hyperthyroidism can lead to goitre
D: Glucocorticoids are secreted in Adrenal Medulla
E: Parathyroid hormone is regulated by circulated levels of sodium ions

Choose the most appropriate answer from the options given below:
1. (C) and (E) only
2. (A) and (B) only
3. (B) and (C) only
4. (A) and (D) only

Explanation: The correct answer is (2) (A) and (B) only. Thyrocalcitonin controls calcium levels, and FSH with androgens regulate spermatogenesis. Hyperthyroidism causes excessive thyroid hormone but not always goitre. Glucocorticoids are secreted by adrenal cortex, not medulla, and PTH is regulated by calcium levels, not sodium. Hence, only A and B are correct.

Guessed Question 1: Which hormone regulates calcium and phosphate metabolism in the human body?
1. Insulin
2. Parathyroid Hormone
3. Glucagon
4. Cortisol
Explanation: The correct answer is Parathyroid Hormone. It maintains calcium and phosphate homeostasis by increasing calcium reabsorption in kidneys, stimulating bone resorption, and enhancing intestinal absorption. Secreted by parathyroid glands, its secretion is regulated by blood calcium levels through negative feedback mechanisms for maintaining bone and neuromuscular functions.

Guessed Question 2: Hypersecretion of growth hormone in adults leads to:
1. Gigantism
2. Cretinism
3. Acromegaly
4. Myxedema
Explanation: The correct answer is Acromegaly. Excess growth hormone after epiphyseal closure causes abnormal growth of bones in hands, feet, and face. Gigantism occurs before puberty, while cretinism and myxedema are due to thyroid hormone deficiency. Acromegaly is associated with pituitary adenoma affecting somatotroph cells.

Guessed Question 3: Adrenal medulla secretes:
1. Cortisol and Aldosterone
2. Epinephrine and Norepinephrine
3. Glucagon and Insulin
4. Thyroxine and Calcitonin
Explanation: The correct answer is Epinephrine and Norepinephrine. These are catecholamines that prepare the body for fight or flight response. They increase heart rate, blood pressure, and glucose levels. Cortisol and Aldosterone are secreted by the adrenal cortex, not medulla. Thus, option 2 correctly identifies the medullary hormones.

Guessed Question 4: Which hormone is directly regulated by blood calcium concentration?
1. Thyroxine
2. Parathyroid Hormone
3. Insulin
4. Glucocorticoids
Explanation: The correct answer is Parathyroid Hormone. It is secreted when calcium levels fall below normal. It acts on bones, kidneys, and intestines to increase calcium concentration. This negative feedback system ensures calcium balance essential for nerve transmission and muscle contraction.

Guessed Question 5: Identify the hormone secreted by the anterior pituitary:
1. Oxytocin
2. ADH
3. Prolactin
4. Melatonin
Explanation: The correct answer is Prolactin. Secreted by lactotroph cells of anterior pituitary, prolactin stimulates milk production post childbirth. Oxytocin and ADH are posterior pituitary hormones, while melatonin is secreted by pineal gland. Prolactin also influences immune regulation and reproductive functions.

Guessed Question 6: Which disorder is caused by hyposecretion of insulin?
1. Diabetes insipidus
2. Diabetes mellitus
3. Acromegaly
4. Addison’s disease
Explanation: The correct answer is Diabetes mellitus. It occurs due to reduced insulin production or sensitivity, leading to hyperglycemia, polyuria, and polydipsia. Insulin regulates glucose uptake and glycogen formation. Diabetes insipidus is related to ADH deficiency, while Addison’s disease affects adrenal cortex.

Guessed Question 7 (Assertion-Reason Type):
Assertion (A): Aldosterone helps in maintaining sodium balance.
Reason (R): Aldosterone increases sodium reabsorption and potassium excretion in distal tubules.
1. (A) and (R) are true, and (R) is the correct explanation of (A)
2. (A) and (R) are true, but (R) is not the correct explanation of (A)
3. (A) is true, (R) is false
4. (A) is false, (R) is true
Explanation: The correct answer is Option 1. Aldosterone secreted by adrenal cortex enhances sodium reabsorption and potassium excretion in renal tubules. This regulates extracellular fluid volume and blood pressure. Both statements are true and reason correctly explains the assertion.

Guessed Question 8 (Matching Type):
Match the hormones with their glands:
A. Insulin — (i) Adrenal cortex
B. Thyroxine — (ii) Thyroid
C. Cortisol — (iii) Pancreas
D. Melatonin — (iv) Pineal

1. A–iii, B–ii, C–i, D–iv
2. A–ii, B–i, C–iii, D–iv
3. A–iv, B–iii, C–ii, D–i
4. A–i, B–iv, C–ii, D–iii
Explanation: The correct answer is 1. A–iii, B–ii, C–i, D–iv. Insulin is secreted by pancreas, thyroxine by thyroid, cortisol by adrenal cortex, and melatonin by pineal gland. Each hormone maintains homeostasis and regulates distinct physiological activities like metabolism, stress, and sleep cycle.

Guessed Question 9 (Fill in the Blanks):
______ hormone promotes reabsorption of water in kidney tubules to maintain body fluid balance.
1. Oxytocin
2. ADH
3. Cortisol
4. FSH
Explanation: The correct answer is ADH (Antidiuretic Hormone). Secreted by posterior pituitary, ADH increases water permeability of distal convoluted tubules and collecting ducts, thus reducing urine volume and preventing dehydration. Its secretion increases during dehydration or high plasma osmolarity conditions.

Guessed Question 10 (Choose the Correct Statements):
Statement I: Glucagon increases blood glucose levels.
Statement II: Insulin promotes glucose uptake by cells.
1. Both statements are true.
2. Both statements are false.
3. Only Statement I is true.
4. Only Statement II is true.
Explanation: The correct answer is 1. Both statements are true. Glucagon from α-cells increases glucose by glycogenolysis and gluconeogenesis, while insulin from β-cells lowers glucose by promoting its uptake. Both act antagonistically to maintain glucose homeostasis essential for metabolic stability.

Topic: Gametogenesis and Hormonal Regulation; Subtopic: Hormonal Control of Spermatogenesis

Keyword Definitions:

• Gonadotropin: Hormones secreted by the anterior pituitary that regulate the function of gonads (FSH and LH).

• FSH (Follicle-Stimulating Hormone): Stimulates Sertoli cells and promotes spermiogenesis in males.

• LH (Luteinizing Hormone): Stimulates Leydig cells in testes to produce androgens like testosterone.

• GnRH (Gonadotropin-Releasing Hormone): Secreted from hypothalamus to regulate release of FSH and LH.

• Androgens: Male sex hormones responsible for spermatogenesis and development of secondary sexual characters.

• Spermatogenesis: Process of formation of sperm cells from spermatogonia.

• Spermiogenesis: Final maturation process of spermatids into spermatozoa.

Lead Question - 2023 (Manipur)

Arrange the sequence of different hormones for their role during gametogenesis:
A. Gonadotropin LH stimulates synthesis and secretion of Androgen
B. Gonadotropin releasing hormone from hypothalamus
C. Androgen stimulates spermatogenesis
D. Gonadotropin FSH helps in the process of spermiogenesis
E. Gonadotropins from anterior pituitary gland

Choose the correct answer from the options given below:

1. (E), (A), (D), (B), (C)
2. (C), (A), (D), (E), (B)
3. (B), (E), (A), (C), (D)
4. (D), (B), (A), (C), (E)

Explanation: The hormonal regulation of spermatogenesis begins with GnRH from the hypothalamus (B) which stimulates anterior pituitary (E) to secrete gonadotropins FSH and LH. LH (A) stimulates Leydig cells to secrete androgens that trigger spermatogenesis (C). FSH (D) helps in spermiogenesis. Hence, the correct sequence is (B), (E), (A), (C), (D).

Guessed Question 1: Which hormone stimulates Leydig cells to secrete testosterone?

1. FSH 2. LH 3. GnRH 4. Prolactin

Explanation: Luteinizing Hormone (LH) acts on Leydig cells in the testes to promote the synthesis and secretion of testosterone. Testosterone further stimulates spermatogenesis in seminiferous tubules. FSH acts on Sertoli cells, whereas GnRH from the hypothalamus regulates both FSH and LH release from the anterior pituitary gland.

Guessed Question 2: Which of the following is secreted by Sertoli cells?

1. Testosterone 2. Inhibin 3. LH 4. GnRH

Explanation: Sertoli cells secrete inhibin, a hormone that provides negative feedback to the anterior pituitary to regulate FSH secretion. They also help in nurturing developing spermatogenic cells and facilitate spermiogenesis. Testosterone is secreted by Leydig cells under LH stimulation from the anterior pituitary gland.

Guessed Question 3: FSH in males is primarily responsible for:

1. Development of secondary sexual characters
2. Spermatogenesis
3. Spermiogenesis
4. Testosterone secretion

Explanation: Follicle Stimulating Hormone (FSH) acts on Sertoli cells of the seminiferous tubules and promotes spermiogenesis — the final maturation of spermatids into spermatozoa. LH, on the other hand, acts on Leydig cells to produce testosterone. Thus, FSH’s role is crucial in sperm maturation and reproductive function.

Guessed Question 4: Which of the following acts as a feedback regulator of FSH secretion?

1. Inhibin 2. Testosterone 3. Progesterone 4. Estrogen

Explanation: Inhibin, produced by Sertoli cells in males, specifically inhibits FSH secretion from the anterior pituitary gland through a negative feedback mechanism. Testosterone regulates LH secretion, whereas inhibin selectively controls FSH levels, ensuring balanced spermatogenesis and hormonal control of male reproduction.

Guessed Question 5: Identify the correct sequence of spermatogenic stages:

1. Spermatid → Spermatogonia → Spermatozoa
2. Spermatogonia → Spermatocyte → Spermatid → Spermatozoa
3. Spermatocyte → Spermatogonia → Spermatid → Spermatozoa
4. Spermatogonia → Spermatid → Spermatocyte → Spermatozoa

Explanation: Spermatogenesis begins with spermatogonia which divide mitotically to form primary spermatocytes. These undergo meiosis to produce spermatids, which further differentiate into spermatozoa during spermiogenesis. Thus, the correct order of stages is Spermatogonia → Spermatocyte → Spermatid → Spermatozoa.

Guessed Question 6: Which of the following hormones is secreted by the hypothalamus?

1. GnRH 2. LH 3. FSH 4. Testosterone

Explanation: Gonadotropin-Releasing Hormone (GnRH) is secreted by the hypothalamus. It stimulates the anterior pituitary to release FSH and LH, which regulate testicular function. LH acts on Leydig cells, and FSH acts on Sertoli cells, together ensuring proper hormonal control of spermatogenesis in males.

Assertion-Reason Type Question:

Assertion (A): LH stimulates Leydig cells to produce testosterone.
Reason (R): Testosterone inhibits FSH secretion from the anterior pituitary.

1. Both A and R are true, and R is the correct explanation of A.
2. Both A and R are true, but R is not the correct explanation of A.
3. A is true, but R is false.
4. A is false, but R is true.

Explanation: LH indeed stimulates Leydig cells to produce testosterone, which provides negative feedback on LH secretion, not FSH. FSH is mainly regulated by inhibin from Sertoli cells. Hence, Assertion is true, but the Reason is false. The correct answer is option 3.

Matching Type Question:

Match the hormones with their function:
A. LH
B. FSH
C. Testosterone
D. Inhibin

1. Stimulates Sertoli cells
2. Regulates secondary sexual traits
3. Inhibits FSH
4. Stimulates Leydig cells

Codes: A-4, B-1, C-2, D-3

Explanation: LH acts on Leydig cells to promote testosterone secretion. FSH stimulates Sertoli cells to support spermatogenesis. Testosterone regulates male secondary sexual traits, and inhibin inhibits FSH. Correct matching is A-4, B-1, C-2, D-3.

Fill in the Blanks Type Question:

________ secreted from Sertoli cells provides negative feedback to control FSH secretion.

1. Testosterone 2. Inhibin 3. Estrogen 4. LH

Explanation: Inhibin is secreted by Sertoli cells and inhibits FSH secretion by acting on the anterior pituitary gland. This feedback mechanism maintains hormonal balance during spermatogenesis. Testosterone mainly regulates LH secretion, while estrogen has a minor role in males.

Choose the Correct Statements Type Question:

Statement I: FSH acts on Leydig cells to produce testosterone.
Statement II: LH acts on Leydig cells to produce testosterone.

1. Both statements are true.
2. Both statements are false.
3. Statement I is true, Statement II is false.
4. Statement I is false, Statement II is true.

Explanation: LH, not FSH, acts on Leydig cells to produce testosterone, which promotes spermatogenesis. FSH instead acts on Sertoli cells to assist in spermiogenesis and secretes inhibin. Therefore, Statement I is false and Statement II is true. The correct answer is option 4.

Subtopic: Hormonal Regulation of Gametogenesis

Keyword Definitions:

• Gametogenesis: The process by which male and female gametes (sperm and ova) are produced through meiosis and differentiation.

• LH (Luteinizing Hormone): Gonadotropin hormone from anterior pituitary stimulating testosterone production in males and ovulation in females.

• FSH (Follicle Stimulating Hormone): Gonadotropin that stimulates spermatogenesis in males and follicular development in females.

• GnRH (Gonadotropin Releasing Hormone): Hormone secreted by hypothalamus controlling the release of FSH and LH from anterior pituitary.

• Androgen: Male sex hormones like testosterone that stimulate spermatogenesis.

• Spermiogenesis: The final stage of spermatogenesis where spermatids differentiate into mature spermatozoa.

• Spermatogenesis: Process of formation of sperm cells from spermatogonia under hormonal control.

• Anterior Pituitary: Endocrine gland secreting FSH and LH essential for reproductive function.

Lead Question – 2023 (Manipur)

Arrange the sequence of different hormones for their role during gametogenesis:
A. Gonadotropin LH stimulates synthesis and secretion of Androgen
B. Gonadotropin releasing hormone from hypothalamus
C. Androgen stimulates spermatogenesis
D. Gonadotropin FSH helps in the process of spermiogenesis
E. Gonadotropins from anterior pituitary gland

Explanation: The sequence of hormonal events during gametogenesis starts with GnRH from hypothalamus (B), which stimulates gonadotropins release from anterior pituitary (E). LH specifically stimulates androgen synthesis (A), which promotes spermatogenesis (C). FSH helps in spermiogenesis (D). Correct sequential order of hormonal action is: B → E → A → C → D. This pathway ensures proper maturation of gametes through coordinated endocrine control. Correct answer: B, E, A, C, D.

1. Single Correct Answer MCQ:
Which hormone directly stimulates testosterone production in males?
1. FSH
2. LH
3. GnRH
4. Prolactin
Explanation: Luteinizing Hormone (LH) secreted by anterior pituitary stimulates Leydig cells in testes to produce testosterone, which is essential for spermatogenesis and secondary sexual characteristics. Correct answer: 2. LH.

2. Single Correct Answer MCQ:
FSH primarily supports which stage in male reproduction?
1. Spermatogenesis
2. Spermiogenesis
3. Androgen synthesis
4. Ovulation
Explanation: Follicle Stimulating Hormone (FSH) promotes the final maturation of spermatids into spermatozoa during spermiogenesis by acting on Sertoli cells. Correct answer: 2. Spermiogenesis.

3. Single Correct Answer MCQ:
Which hormone is secreted by hypothalamus to regulate pituitary gonadotropins?
1. Testosterone
2. FSH
3. LH
4. GnRH
Explanation: Gonadotropin Releasing Hormone (GnRH) from hypothalamus stimulates the anterior pituitary to release FSH and LH, regulating gametogenesis. Correct answer: 4. GnRH.

4. Single Correct Answer MCQ:
Androgens primarily act on:
1. Hypothalamus
2. Pituitary
3. Testes
4. Sertoli cells
Explanation: Androgens, mainly testosterone, act on the testes to promote spermatogenesis and on Sertoli cells indirectly, supporting sperm maturation and male secondary sexual characteristics. Correct answer: 3. Testes.

5. Single Correct Answer MCQ:
Which hormone triggers both FSH and LH secretion?
1. Testosterone
2. GnRH
3. Inhibin
4. Estrogen
Explanation: GnRH from hypothalamus stimulates anterior pituitary to secrete both FSH and LH, initiating gametogenesis and regulating male reproductive functions. Correct answer: 2. GnRH.

6. Single Correct Answer MCQ:
LH acts mainly on:
1. Sertoli cells
2. Leydig cells
3. Hypothalamus
4. Seminiferous tubules
Explanation: LH binds Leydig cells in the testes, stimulating androgen (testosterone) production crucial for spermatogenesis and male secondary sexual characteristics. Correct answer: 2. Leydig cells.

7. Assertion-Reason MCQ:
Assertion (A): GnRH stimulates anterior pituitary to release gonadotropins.
Reason (R): Gonadotropins directly act on hypothalamus.
1. Both A and R true, R explains A
2. Both A and R true, R does not explain A
3. A true, R false
4. A false, R true
Explanation: GnRH stimulates anterior pituitary to release FSH and LH. Gonadotropins act on gonads, not hypothalamus. Correct answer: 3. A true, R false.

8. Matching Type MCQ:
Match hormone with function:
A. GnRH – (i) Stimulates pituitary
B. LH – (ii) Androgen synthesis
C. FSH – (iii) Spermiogenesis
D. Androgen – (iv) Spermatogenesis
1. A–i, B–ii, C–iii, D–iv
2. A–i, B–iii, C–ii, D–iv
3. A–ii, B–i, C–iv, D–iii
4. A–iii, B–iv, C–i, D–ii
Explanation: GnRH stimulates pituitary, LH triggers androgen synthesis, FSH promotes spermiogenesis, Androgens stimulate spermatogenesis. Correct answer: 1.

9. Fill in the Blanks MCQ:
__________ from hypothalamus controls __________ and LH secretion, which in turn stimulates __________ production.
1. GnRH, FSH, androgen
2. FSH, GnRH, estrogen
3. LH, GnRH, testosterone
4. Androgen, LH, GnRH
Explanation: GnRH from hypothalamus stimulates FSH and LH release from pituitary; LH then triggers androgen production in Leydig cells. Correct answer: 1.

10. Choose the Correct Statements MCQ:
Statement I: FSH helps in spermiogenesis.
Statement II: Androgen stimulates spermatogenesis.
1. Both true
2. Both false
3. I true, II false
4. I false, II true
Explanation: FSH acts on Sertoli cells to promote spermiogenesis; Androgens stimulate spermatogenesis in testes. Both statements are correct. Correct answer: 1.

Topic: Endocrine System; Subtopic: Thyroid Hormone Functions

Keyword Definitions:
Thyroid hormone: Hormones produced by the thyroid gland, mainly thyroxine (T4) and triiodothyronine (T3), regulating metabolism.
Basal metabolic rate (BMR): The rate of energy expenditure of the body at rest.
Sleep-wake cycle: Circadian rhythm regulating periods of sleep and wakefulness.
Water and electrolyte balance: Regulation of fluid and ion concentrations in body.
RBC formation: Production of red blood cells, also called erythropoiesis.
Metabolism: Chemical processes maintaining life and energy production.
Endocrine control: Hormonal regulation of physiological processes.
Triiodothyronine (T3): Active thyroid hormone regulating growth and metabolism.
Thyroxine (T4): Precursor of T3, regulates metabolic activity.
Homeostasis: Maintenance of stable internal environment.
Hormone deficiency: Inadequate secretion of a hormone affecting body function.

Lead Question (2023):
Which of the following are NOT under the control of thyroid hormone?
A. Maintenance of water and electrolyte balance
B. Regulation of basal metabolic rate
C. Normal rhythm of sleep-wake cycle
D. Support the process of RBC formation
Choose the correct answer from the options given below:
(1) C and D only
(2) D and E only
(3) A and D only
(4) B and C only

Answer & Explanation: Option 3 is correct. Thyroid hormones regulate basal metabolic rate, energy expenditure, and growth, but they do not directly control water-electrolyte balance (regulated by ADH, aldosterone) or RBC formation (regulated primarily by erythropoietin). Sleep-wake cycles are influenced by melatonin and circadian rhythms. Understanding the specific physiological roles of thyroid hormones is critical in endocrinology, for diagnosing hypo- or hyperthyroidism, and differentiating hormonal effects from those of other endocrine glands in maintaining overall homeostasis in the body.

1. Single Correct Answer MCQ: Which hormone primarily regulates basal metabolic rate?
A) Thyroid hormone
B) Insulin
C) Cortisol
D) Growth hormone

Answer & Explanation: Option A is correct. Thyroid hormones (T3 and T4) increase basal metabolic rate by enhancing oxygen consumption, protein synthesis, and energy production. Insulin regulates glucose metabolism, cortisol affects stress response, and growth hormone influences growth and tissue repair. Proper thyroid function is crucial for energy homeostasis, thermogenesis, and maintaining normal metabolism in all tissues.

2. Single Correct Answer MCQ: Excess thyroid hormone causes which condition?
A) Hypothyroidism
B) Hyperthyroidism
C) Addison's disease
D) Cretinism

Answer & Explanation: Option B is correct. Hyperthyroidism results from excessive thyroid hormone production, causing weight loss, increased metabolism, heat intolerance, tachycardia, and nervousness. Hypothyroidism is due to deficiency, Addison's disease affects adrenal glands, and cretinism results from congenital thyroid hormone deficiency. Understanding hormone excess or deficiency is key for diagnosing endocrine disorders and managing metabolism-related complications.

3. Single Correct Answer MCQ: Which gland secretes thyroid hormones?
A) Pituitary gland
B) Thyroid gland
C) Adrenal gland
D) Parathyroid gland

Answer & Explanation: Option B is correct. The thyroid gland secretes thyroxine (T4) and triiodothyronine (T3), regulating metabolism, growth, and development. Pituitary secretes TSH controlling thyroid function, adrenal glands secrete cortisol and aldosterone, and parathyroid regulates calcium levels. Correct identification of hormone sources is essential for understanding endocrine feedback mechanisms and managing related disorders effectively.

4. Single Correct Answer MCQ: Which of the following is a symptom of hypothyroidism?
A) Weight loss
B) Heat intolerance
C) Fatigue and cold intolerance
D) Tachycardia

Answer & Explanation: Option C is correct. Hypothyroidism decreases basal metabolic rate, causing fatigue, lethargy, cold intolerance, weight gain, and bradycardia. Weight loss and tachycardia are features of hyperthyroidism, and heat intolerance is associated with excessive thyroid hormone. Recognizing symptoms is vital for early diagnosis, appropriate hormone replacement therapy, and preventing complications like myxedema or growth retardation in children.

5. Single Correct Answer MCQ: Which hormone stimulates RBC formation indirectly?
A) Thyroid hormone
B) Erythropoietin
C) Cortisol
D) Parathyroid hormone

Answer & Explanation: Option B is correct. Erythropoietin, produced by kidneys, stimulates RBC production in bone marrow. Thyroid hormones enhance metabolism but do not directly induce erythropoiesis. Cortisol affects stress response, and parathyroid hormone regulates calcium. Understanding hormone specificity is crucial to distinguish metabolic regulation from hematopoietic control in physiology and clinical medicine.

6. Single Correct Answer MCQ: Which hormone regulates calcium and phosphorus metabolism?
A) Thyroid hormone
B) Parathyroid hormone
C) TSH
D) Calcitonin

Answer & Explanation: Option B is correct. Parathyroid hormone increases blood calcium by stimulating bone resorption and renal calcium reabsorption. Thyroid hormones regulate metabolism, TSH stimulates thyroid gland, and calcitonin lowers calcium. Knowledge of hormone-specific functions helps in diagnosing endocrine imbalances and managing bone, mineral, and metabolic disorders effectively.

7. Assertion-Reason MCQ:
Assertion (A): Thyroid hormone does not regulate water-electrolyte balance.
Reason (R): ADH and aldosterone primarily control water and sodium levels.
A) Both A and R are true and R is the correct explanation of A
B) Both A and R are true but R is not the correct explanation of A
C) A is true but R is false
D) A is false but R is true

Answer & Explanation: Option A is correct. Thyroid hormones influence metabolism and energy regulation but do not directly control water and electrolyte balance. ADH from the posterior pituitary and aldosterone from adrenal cortex regulate fluid and sodium homeostasis. Understanding distinct hormone roles is critical for differentiating endocrine feedback systems and clinical evaluation of disorders like dehydration, hyponatremia, or thyroid dysfunction.

8. Matching Type MCQ: Match hormones with primary function:
List I - List II
A. Thyroid hormone - I. Regulates metabolism
B. ADH - II. Regulates water balance
C. Aldosterone - III. Regulates sodium reabsorption
Choose correct option:
1) A-I, B-II, C-III
2) A-II, B-I, C-III
3) A-III, B-II, C-I
4) A-I, B-III, C-II

Answer & Explanation: Option 1 is correct. Thyroid hormone regulates metabolism (A-I), ADH controls water balance (B-II), and aldosterone regulates sodium reabsorption (C-III). Matching hormones to their specific physiological roles is essential to understand homeostasis, endocrine regulation, and the differentiation of metabolic versus electrolyte control mechanisms in clinical and physiological contexts.

9. Fill in the Blanks MCQ: The ________ gland secretes TSH which stimulates thyroid hormone release.
A) Thyroid
B) Pituitary
C) Adrenal
D) Parathyroid

Answer & Explanation: Option B is correct. TSH (Thyroid Stimulating Hormone) is secreted by the anterior pituitary gland and stimulates the thyroid to release T3 and T4. The thyroid produces the hormones, adrenal glands secrete cortisol/aldosterone, and parathyroid regulates calcium. Understanding this feedback loop is crucial for managing thyroid disorders and interpreting endocrine physiology.

10. Choose the Correct Statements MCQ:
Statement I: Thyroid hormone regulates basal metabolic rate.
Statement II: Thyroid hormone directly regulates RBC formation.
A) Both statements are correct
B) Both statements are incorrect
C) Only Statement I is correct
D) Only Statement II is correct

Answer & Explanation: Option C is correct. Thyroid hormones increase basal metabolic rate by stimulating energy production and oxygen consumption. They do not directly control RBC formation, which is mainly regulated by erythropoietin from the kidneys. Differentiating these functions is critical in endocrine physiology, disease diagnosis, and understanding hormone-specific systemic effects on metabolism, growth, and homeostasis.

Topic: Endocrine System; Subtopic: Hormones and Target Organs

Keyword Definitions:

• CCK (Cholecystokinin): A digestive hormone secreted by the small intestine to stimulate the release of digestive enzymes from the pancreas and bile from the gallbladder.

• GIP (Gastric Inhibitory Peptide): Hormone released by the small intestine that inhibits gastric motility and stimulates insulin secretion.

• ANF (Atrial Natriuretic Factor): Hormone produced by the atria of the heart to regulate blood pressure by promoting sodium excretion in kidneys.

• ADH (Antidiuretic Hormone): Hormone secreted by the posterior pituitary that regulates water balance by acting on the kidneys.

• Pancreas: Endocrine and exocrine gland producing insulin, glucagon, and digestive enzymes.

• Kidney: Organ responsible for filtering blood, producing urine, and maintaining water and electrolyte balance.

• Heart: Muscular organ that pumps blood and produces hormones like ANF for regulating blood pressure.

• Gastric Gland: Gastric secretory glands in the stomach producing enzymes and acids for digestion.

• Hormone: Chemical messenger secreted by endocrine glands regulating physiological processes.

• Target Organ: Specific organ or tissue on which a hormone exerts its effect.

• Endocrine System: System of glands secreting hormones directly into the bloodstream to regulate body functions.

Lead Question - 2023

Match List I with List II.
List I | List II
A. CCK | I. Kidney
B. GIP | II. Heart
C. ANF | III. Gastric gland
D. ADH | IV. Pancreas

Choose the correct answer from the options given below:
(1) A-II, B-IV, C-I, D-III
(2) A-IV, B-II, C-III, D-I
(3) A-IV, B-III, C-II, D-I
(4) A-III, B-II, C-IV, D-I

Answer & Explanation: (4) A-III, B-II, C-IV, D-I.
CCK (Cholecystokinin) is secreted by the small intestine and acts on the gastric glands to stimulate enzyme secretion. GIP (Gastric Inhibitory Peptide) acts on the heart to modulate cardiac functions indirectly. ANF (Atrial Natriuretic Factor) targets the kidney to increase sodium excretion and lower blood pressure. ADH (Antidiuretic Hormone) also targets the kidney to retain water. Understanding these hormone-target relationships is critical for comprehending physiological regulation of digestion, blood pressure, and water balance. The structural specificity of each hormone ensures precise action on its corresponding target organ.

1. Which hormone primarily regulates water balance in the body?

(1) ANF
(2) ADH
(3) GIP
(4) CCK

ADH (Antidiuretic Hormone) regulates water balance by acting on the kidneys to retain water, reducing urine output. ANF promotes sodium excretion, CCK stimulates digestive enzyme release, and GIP influences insulin secretion. ADH’s role is critical in maintaining osmotic pressure and preventing dehydration, demonstrating hormonal control of homeostasis.

2. Which hormone stimulates pancreatic enzyme secretion?

(1) GIP
(2) ADH
(3) CCK
(4) ANF

CCK (Cholecystokinin) stimulates the pancreas to release digestive enzymes and the gallbladder to secrete bile. This process is essential for protein and fat digestion in the small intestine. GIP regulates insulin, ADH affects water retention, and ANF modulates blood pressure, highlighting specific organ-targeted hormonal action.

3. ANF is secreted by which organ?

(1) Kidney
(2) Heart
(3) Pancreas
(4) Stomach

ANF (Atrial Natriuretic Factor) is secreted by the atria of the heart. It lowers blood pressure by promoting sodium excretion in the kidneys and reducing blood volume. This hormone is part of the cardiovascular-endocrine interaction to maintain homeostasis, in contrast to digestive or water balance hormones like CCK or ADH.

4. Assertion-Reason Type:

Assertion (A): GIP regulates insulin secretion.
Reason (R): GIP is released from the small intestine in response to glucose and fatty acids in the duodenum.
(1) Both A and R are true and R explains A
(2) Both A and R are true but R does not explain A
(3) A is true but R is false
(4) A is false but R is true

Both A and R are true and R explains A. GIP is secreted by the duodenal mucosa when nutrients enter, particularly glucose and lipids. It stimulates insulin release from pancreatic beta cells, linking nutrient detection to metabolic response. This incretin effect is vital for controlling postprandial blood glucose.

5. Fill in the blanks:

______ stimulates bile and pancreatic enzyme secretion, whereas ______ increases water reabsorption in kidneys.
(1) CCK, ADH
(2) GIP, ANF
(3) ANF, ADH
(4) ADH, CCK

CCK stimulates bile release from the gallbladder and pancreatic enzyme secretion for digestion. ADH acts on the kidney to increase water reabsorption, reducing urine output. This demonstrates hormone-specific targeting and functional specialization within the endocrine system.

6. Which hormone targets the gastric gland to regulate digestion?

(1) ADH
(2) ANF
(3) CCK
(4) GIP

CCK indirectly affects gastric glands by stimulating enzyme release for digestion. While GIP inhibits gastric motility, ADH regulates water, and ANF regulates sodium excretion. CCK coordinates digestive secretions in response to food in the duodenum, facilitating nutrient breakdown efficiently.

7. Which hormone is directly involved in lowering blood pressure?

(1) ADH
(2) ANF
(3) CCK
(4) GIP

ANF lowers blood pressure by promoting sodium and water excretion via the kidneys, reducing blood volume. ADH increases water retention, potentially raising blood pressure. CCK and GIP mainly influence digestion and insulin regulation, highlighting the cardiovascular-specific role of ANF.

8. Matching Type:

Match the hormone with its primary target:
List I | List II
A. ADH | I. Pancreas
B. ANF | II. Kidney
C. CCK | III. Gastric gland
D. GIP | IV. Heart

(1) A-II, B-IV, C-III, D-I
(2) A-II, B-IV, C-I, D-III
(3) A-I, B-II, C-III, D-IV
(4) A-IV, B-II, C-III, D-I

Answer: (1) A-II, B-IV, C-III, D-I. ADH acts on the kidney to regulate water reabsorption. ANF targets the heart to modulate blood pressure. CCK stimulates gastric glands and pancreas for digestion. GIP affects insulin secretion via the pancreas. This matching illustrates precise hormone-target specificity in human physiology.

9. Choose the correct statements:

Statement I: ADH increases water retention in kidneys.
Statement II: ANF promotes sodium excretion and lowers blood pressure.
(1) Only Statement I is correct
(2) Only Statement II is correct
(3) Both Statements I and II are correct
(4) Both Statements I and II are false

Both statements are correct. ADH increases water reabsorption in renal collecting ducts, conserving body water. ANF promotes natriuresis (sodium excretion) and decreases blood volume, thereby reducing blood pressure. These complementary hormonal mechanisms maintain fluid balance and cardiovascular homeostasis.

10. Single Correct Answer:

Which hormone inhibits gastric motility while stimulating insulin secretion?
(1) CCK
(2) GIP
(3) ANF
(4) ADH

GIP (Gastric Inhibitory Peptide) inhibits gastric motility and stimulates insulin secretion after food intake. This incretin effect coordinates digestion with glucose metabolism. CCK stimulates enzyme secretion, ANF affects sodium excretion, and ADH regulates water retention. GIP thus integrates nutrient sensing with endocrine response.

11. Single Correct Answer:

Which hormone stimulates enzyme secretion from pancreas and bile release from gallbladder?
(1) ADH
(2) ANF
(3) CCK
(4) GIP

CCK stimulates pancreatic enzyme secretion and gallbladder contraction to release bile, facilitating fat and protein digestion. ADH and ANF regulate water and sodium balance, respectively, while GIP primarily influences insulin secretion. CCK ensures efficient chemical digestion through coordinated secretory responses.

Topic: Endocrine System; Subtopic: Thyroid Hormone Functions

Keyword Definitions:
Thyroid hormone: Hormones produced by the thyroid gland, mainly thyroxine (T4) and triiodothyronine (T3), regulating metabolism.
Basal metabolic rate (BMR): The rate of energy expenditure of the body at rest.
Sleep-wake cycle: Circadian rhythm regulating periods of sleep and wakefulness.
Water and electrolyte balance: Regulation of fluid and ion concentrations in body.
RBC formation: Production of red blood cells, also called erythropoiesis.
Metabolism: Chemical processes maintaining life and energy production.
Endocrine control: Hormonal regulation of physiological processes.
Triiodothyronine (T3): Active thyroid hormone regulating growth and metabolism.
Thyroxine (T4): Precursor of T3, regulates metabolic activity.
Homeostasis: Maintenance of stable internal environment.
Hormone deficiency: Inadequate secretion of a hormone affecting body function.

Lead Question (2023):
Which of the following are NOT under the control of thyroid hormone?
A. Maintenance of water and electrolyte balance
B. Regulation of basal metabolic rate
C. Normal rhythm of sleep-wake cycle
D. Support the process of RBC formation
Choose the correct answer from the options given below:
(1) C and D only
(2) D and E only
(3) A and D only
(4) B and C only

Answer & Explanation: Option 3 is correct. Thyroid hormones regulate basal metabolic rate, energy expenditure, and growth, but they do not directly control water-electrolyte balance (regulated by ADH, aldosterone) or RBC formation (regulated primarily by erythropoietin). Sleep-wake cycles are influenced by melatonin and circadian rhythms. Understanding the specific physiological roles of thyroid hormones is critical in endocrinology, for diagnosing hypo- or hyperthyroidism, and differentiating hormonal effects from those of other endocrine glands in maintaining overall homeostasis in the body.

1. Single Correct Answer MCQ: Which hormone primarily regulates basal metabolic rate?
A) Thyroid hormone
B) Insulin
C) Cortisol
D) Growth hormone

Answer & Explanation: Option A is correct. Thyroid hormones (T3 and T4) increase basal metabolic rate by enhancing oxygen consumption, protein synthesis, and energy production. Insulin regulates glucose metabolism, cortisol affects stress response, and growth hormone influences growth and tissue repair. Proper thyroid function is crucial for energy homeostasis, thermogenesis, and maintaining normal metabolism in all tissues.

2. Single Correct Answer MCQ: Excess thyroid hormone causes which condition?
A) Hypothyroidism
B) Hyperthyroidism
C) Addison's disease
D) Cretinism

Answer & Explanation: Option B is correct. Hyperthyroidism results from excessive thyroid hormone production, causing weight loss, increased metabolism, heat intolerance, tachycardia, and nervousness. Hypothyroidism is due to deficiency, Addison's disease affects adrenal glands, and cretinism results from congenital thyroid hormone deficiency. Understanding hormone excess or deficiency is key for diagnosing endocrine disorders and managing metabolism-related complications.

3. Single Correct Answer MCQ: Which gland secretes thyroid hormones?
A) Pituitary gland
B) Thyroid gland
C) Adrenal gland
D) Parathyroid gland

Answer & Explanation: Option B is correct. The thyroid gland secretes thyroxine (T4) and triiodothyronine (T3), regulating metabolism, growth, and development. Pituitary secretes TSH controlling thyroid function, adrenal glands secrete cortisol and aldosterone, and parathyroid regulates calcium levels. Correct identification of hormone sources is essential for understanding endocrine feedback mechanisms and managing related disorders effectively.

4. Single Correct Answer MCQ: Which of the following is a symptom of hypothyroidism?
A) Weight loss
B) Heat intolerance
C) Fatigue and cold intolerance
D) Tachycardia

Answer & Explanation: Option C is correct. Hypothyroidism decreases basal metabolic rate, causing fatigue, lethargy, cold intolerance, weight gain, and bradycardia. Weight loss and tachycardia are features of hyperthyroidism, and heat intolerance is associated with excessive thyroid hormone. Recognizing symptoms is vital for early diagnosis, appropriate hormone replacement therapy, and preventing complications like myxedema or growth retardation in children.

5. Single Correct Answer MCQ: Which hormone stimulates RBC formation indirectly?
A) Thyroid hormone
B) Erythropoietin
C) Cortisol
D) Parathyroid hormone

Answer & Explanation: Option B is correct. Erythropoietin, produced by kidneys, stimulates RBC production in bone marrow. Thyroid hormones enhance metabolism but do not directly induce erythropoiesis. Cortisol affects stress response, and parathyroid hormone regulates calcium. Understanding hormone specificity is crucial to distinguish metabolic regulation from hematopoietic control in physiology and clinical medicine.

6. Single Correct Answer MCQ: Which hormone regulates calcium and phosphorus metabolism?
A) Thyroid hormone
B) Parathyroid hormone
C) TSH
D) Calcitonin

Answer & Explanation: Option B is correct. Parathyroid hormone increases blood calcium by stimulating bone resorption and renal calcium reabsorption. Thyroid hormones regulate metabolism, TSH stimulates thyroid gland, and calcitonin lowers calcium. Knowledge of hormone-specific functions helps in diagnosing endocrine imbalances and managing bone, mineral, and metabolic disorders effectively.

7. Assertion-Reason MCQ:
Assertion (A): Thyroid hormone does not regulate water-electrolyte balance.
Reason (R): ADH and aldosterone primarily control water and sodium levels.
A) Both A and R are true and R is the correct explanation of A
B) Both A and R are true but R is not the correct explanation of A
C) A is true but R is false
D) A is false but R is true

Answer & Explanation: Option A is correct. Thyroid hormones influence metabolism and energy regulation but do not directly control water and electrolyte balance. ADH from the posterior pituitary and aldosterone from adrenal cortex regulate fluid and sodium homeostasis. Understanding distinct hormone roles is critical for differentiating endocrine feedback systems and clinical evaluation of disorders like dehydration, hyponatremia, or thyroid dysfunction.

8. Matching Type MCQ: Match hormones with primary function:
List I - List II
A. Thyroid hormone - I. Regulates metabolism
B. ADH - II. Regulates water balance
C. Aldosterone - III. Regulates sodium reabsorption
Choose correct option:
1) A-I, B-II, C-III
2) A-II, B-I, C-III
3) A-III, B-II, C-I
4) A-I, B-III, C-II

Answer & Explanation: Option 1 is correct. Thyroid hormone regulates metabolism (A-I), ADH controls water balance (B-II), and aldosterone regulates sodium reabsorption (C-III). Matching hormones to their specific physiological roles is essential to understand homeostasis, endocrine regulation, and the differentiation of metabolic versus electrolyte control mechanisms in clinical and physiological contexts.

9. Fill in the Blanks MCQ: The ________ gland secretes TSH which stimulates thyroid hormone release.
A) Thyroid
B) Pituitary
C) Adrenal
D) Parathyroid

Answer & Explanation: Option B is correct. TSH (Thyroid Stimulating Hormone) is secreted by the anterior pituitary gland and stimulates the thyroid to release T3 and T4. The thyroid produces the hormones, adrenal glands secrete cortisol/aldosterone, and parathyroid regulates calcium. Understanding this feedback loop is crucial for managing thyroid disorders and interpreting endocrine physiology.

10. Choose the Correct Statements MCQ:
Statement I: Thyroid hormone regulates basal metabolic rate.
Statement II: Thyroid hormone directly regulates RBC formation.
A) Both statements are correct
B) Both statements are incorrect
C) Only Statement I is correct
D) Only Statement II is correct

Answer & Explanation: Option C is correct. Thyroid hormones increase basal metabolic rate by stimulating energy production and oxygen consumption. They do not directly control RBC formation, which is mainly regulated by erythropoietin from the kidneys. Differentiating these functions is critical in endocrine physiology, disease diagnosis, and understanding hormone-specific systemic effects on metabolism, growth, and homeostasis.

Topic: Endocrine System; Subtopic: Hormones and Target Organs

Keyword Definitions:

• CCK (Cholecystokinin): A digestive hormone secreted by the small intestine to stimulate the release of digestive enzymes from the pancreas and bile from the gallbladder.

• GIP (Gastric Inhibitory Peptide): Hormone released by the small intestine that inhibits gastric motility and stimulates insulin secretion.

• ANF (Atrial Natriuretic Factor): Hormone produced by the atria of the heart to regulate blood pressure by promoting sodium excretion in kidneys.

• ADH (Antidiuretic Hormone): Hormone secreted by the posterior pituitary that regulates water balance by acting on the kidneys.

• Pancreas: Endocrine and exocrine gland producing insulin, glucagon, and digestive enzymes.

• Kidney: Organ responsible for filtering blood, producing urine, and maintaining water and electrolyte balance.

• Heart: Muscular organ that pumps blood and produces hormones like ANF for regulating blood pressure.

• Gastric Gland: Gastric secretory glands in the stomach producing enzymes and acids for digestion.

• Hormone: Chemical messenger secreted by endocrine glands regulating physiological processes.

• Target Organ: Specific organ or tissue on which a hormone exerts its effect.

• Endocrine System: System of glands secreting hormones directly into the bloodstream to regulate body functions.

Lead Question - 2023

Match List I with List II.
List I | List II
A. CCK | I. Kidney
B. GIP | II. Heart
C. ANF | III. Gastric gland
D. ADH | IV. Pancreas

Choose the correct answer from the options given below:
(1) A-II, B-IV, C-I, D-III
(2) A-IV, B-II, C-III, D-I
(3) A-IV, B-III, C-II, D-I
(4) A-III, B-II, C-IV, D-I

Answer & Explanation: (4) A-III, B-II, C-IV, D-I.
CCK (Cholecystokinin) is secreted by the small intestine and acts on the gastric glands to stimulate enzyme secretion. GIP (Gastric Inhibitory Peptide) acts on the heart to modulate cardiac functions indirectly. ANF (Atrial Natriuretic Factor) targets the kidney to increase sodium excretion and lower blood pressure. ADH (Antidiuretic Hormone) also targets the kidney to retain water. Understanding these hormone-target relationships is critical for comprehending physiological regulation of digestion, blood pressure, and water balance. The structural specificity of each hormone ensures precise action on its corresponding target organ.

1. Which hormone primarily regulates water balance in the body?

(1) ANF
(2) ADH
(3) GIP
(4) CCK

ADH (Antidiuretic Hormone) regulates water balance by acting on the kidneys to retain water, reducing urine output. ANF promotes sodium excretion, CCK stimulates digestive enzyme release, and GIP influences insulin secretion. ADH’s role is critical in maintaining osmotic pressure and preventing dehydration, demonstrating hormonal control of homeostasis.

2. Which hormone stimulates pancreatic enzyme secretion?

(1) GIP
(2) ADH
(3) CCK
(4) ANF

CCK (Cholecystokinin) stimulates the pancreas to release digestive enzymes and the gallbladder to secrete bile. This process is essential for protein and fat digestion in the small intestine. GIP regulates insulin, ADH affects water retention, and ANF modulates blood pressure, highlighting specific organ-targeted hormonal action.

3. ANF is secreted by which organ?

(1) Kidney
(2) Heart
(3) Pancreas
(4) Stomach

ANF (Atrial Natriuretic Factor) is secreted by the atria of the heart. It lowers blood pressure by promoting sodium excretion in the kidneys and reducing blood volume. This hormone is part of the cardiovascular-endocrine interaction to maintain homeostasis, in contrast to digestive or water balance hormones like CCK or ADH.

4. Assertion-Reason Type:

Assertion (A): GIP regulates insulin secretion.
Reason (R): GIP is released from the small intestine in response to glucose and fatty acids in the duodenum.
(1) Both A and R are true and R explains A
(2) Both A and R are true but R does not explain A
(3) A is true but R is false
(4) A is false but R is true

Both A and R are true and R explains A. GIP is secreted by the duodenal mucosa when nutrients enter, particularly glucose and lipids. It stimulates insulin release from pancreatic beta cells, linking nutrient detection to metabolic response. This incretin effect is vital for controlling postprandial blood glucose.

5. Fill in the blanks:

______ stimulates bile and pancreatic enzyme secretion, whereas ______ increases water reabsorption in kidneys.
(1) CCK, ADH
(2) GIP, ANF
(3) ANF, ADH
(4) ADH, CCK

CCK stimulates bile release from the gallbladder and pancreatic enzyme secretion for digestion. ADH acts on the kidney to increase water reabsorption, reducing urine output. This demonstrates hormone-specific targeting and functional specialization within the endocrine system.

6. Which hormone targets the gastric gland to regulate digestion?

(1) ADH
(2) ANF
(3) CCK
(4) GIP

CCK indirectly affects gastric glands by stimulating enzyme release for digestion. While GIP inhibits gastric motility, ADH regulates water, and ANF regulates sodium excretion. CCK coordinates digestive secretions in response to food in the duodenum, facilitating nutrient breakdown efficiently.

7. Which hormone is directly involved in lowering blood pressure?

(1) ADH
(2) ANF
(3) CCK
(4) GIP

ANF lowers blood pressure by promoting sodium and water excretion via the kidneys, reducing blood volume. ADH increases water retention, potentially raising blood pressure. CCK and GIP mainly influence digestion and insulin regulation, highlighting the cardiovascular-specific role of ANF.

8. Matching Type:

Match the hormone with its primary target:
List I | List II
A. ADH | I. Pancreas
B. ANF | II. Kidney
C. CCK | III. Gastric gland
D. GIP | IV. Heart

(1) A-II, B-IV, C-III, D-I
(2) A-II, B-IV, C-I, D-III
(3) A-I, B-II, C-III, D-IV
(4) A-IV, B-II, C-III, D-I

Answer: (1) A-II, B-IV, C-III, D-I. ADH acts on the kidney to regulate water reabsorption. ANF targets the heart to modulate blood pressure. CCK stimulates gastric glands and pancreas for digestion. GIP affects insulin secretion via the pancreas. This matching illustrates precise hormone-target specificity in human physiology.

9. Choose the correct statements:

Statement I: ADH increases water retention in kidneys.
Statement II: ANF promotes sodium excretion and lowers blood pressure.
(1) Only Statement I is correct
(2) Only Statement II is correct
(3) Both Statements I and II are correct
(4) Both Statements I and II are false

Both statements are correct. ADH increases water reabsorption in renal collecting ducts, conserving body water. ANF promotes natriuresis (sodium excretion) and decreases blood volume, thereby reducing blood pressure. These complementary hormonal mechanisms maintain fluid balance and cardiovascular homeostasis.

10. Single Correct Answer:

Which hormone inhibits gastric motility while stimulating insulin secretion?
(1) CCK
(2) GIP
(3) ANF
(4) ADH

GIP (Gastric Inhibitory Peptide) inhibits gastric motility and stimulates insulin secretion after food intake. This incretin effect coordinates digestion with glucose metabolism. CCK stimulates enzyme secretion, ANF affects sodium excretion, and ADH regulates water retention. GIP thus integrates nutrient sensing with endocrine response.

11. Single Correct Answer:

Which hormone stimulates enzyme secretion from pancreas and bile release from gallbladder?
(1) ADH
(2) ANF
(3) CCK
(4) GIP

CCK stimulates pancreatic enzyme secretion and gallbladder contraction to release bile, facilitating fat and protein digestion. ADH and ANF regulate water and sodium balance, respectively, while GIP primarily influences insulin secretion. CCK ensures efficient chemical digestion through coordinated secretory responses.

Topic : Excretory and Endocrine Systems; Subtopic : Renin-Angiotensin-Aldosterone System (RAAS) and Hormonal Regulation of Blood Pressure

Keyword Definitions :

• Angiotensin II : Hormone that stimulates adrenal cortex to release aldosterone and causes vasoconstriction.

• Aldosterone : Mineralocorticoid hormone from adrenal cortex that increases sodium reabsorption, leading to higher blood pressure.

• ANF (Atrial Natriuretic Factor) : Hormone from atria that decreases blood volume and pressure, antagonizing RAAS.

• ADH (Vasopressin) : Hormone from posterior pituitary that promotes water reabsorption in kidneys and vasoconstriction.

• Adenohypophysis : Anterior lobe of pituitary gland that secretes hormones like ACTH, GH, TSH, but not vasopressin.

• Vasodilation : Widening of blood vessels, which decreases blood pressure.

• Renin : Enzyme secreted by kidneys that converts angiotensinogen to angiotensin I, leading to RAAS activation.

• RAAS : Renin-Angiotensin-Aldosterone System, regulates blood pressure and fluid balance.

Lead Question - 2022 (Ganganagar)
Select the correct statements.
(a) Angiotensin II activates the cortex of adrenal gland to release aldosterone.
(b) Aldosterone leads to increase in blood pressure.
(c) ANF acts as a check on renin-angiotensin mechanism.
(d) ADH causes vasodilation.
(e) Vasopressin is released from adenohypophysis.
Choose the most appropriate answer from the options given below:
1. (a), (b) and (e) only
2. (c), (d) and (e) only
3. (b), (c) and (d) only
4. (a), (b) and (c) only

Explanation : Angiotensin II stimulates the adrenal cortex to release aldosterone, which increases sodium reabsorption and raises blood pressure. ANF acts as a negative regulator of the renin-angiotensin system. ADH (vasopressin) causes vasoconstriction, not vasodilation, and is released from the posterior pituitary, not adenohypophysis. Therefore, statements (a), (b), and (c) are correct. Hence, Option 4 is correct.

1. Single Correct Answer:
Which hormone directly promotes sodium reabsorption in distal tubules?
1. ADH
2. Aldosterone
3. ANF
4. Cortisol

Explanation : Aldosterone, secreted by the adrenal cortex in response to angiotensin II, increases sodium reabsorption in distal tubules and collecting ducts, leading to increased water retention and elevated blood pressure. ADH regulates water but not sodium, ANF decreases sodium, and cortisol has minor sodium effects. Hence, Option 2 is correct.

2. Single Correct Answer:
ANF lowers blood pressure by:
1. Increasing renin secretion
2. Promoting sodium excretion
3. Stimulating aldosterone release
4. Increasing ADH secretion

Explanation : ANF (Atrial Natriuretic Factor) is released from atrial myocytes in response to high blood volume. It promotes natriuresis (sodium excretion), reduces water reabsorption, and inhibits RAAS. This decreases blood volume and blood pressure. It does not increase renin, aldosterone, or ADH. Hence, Option 2 is correct.

3. Single Correct Answer:
Which organ secretes renin?
1. Liver
2. Kidney
3. Adrenal cortex
4. Posterior pituitary

Explanation : Renin is secreted by the juxtaglomerular cells of the kidney in response to low blood pressure, low sodium, or sympathetic stimulation. It converts angiotensinogen to angiotensin I, initiating RAAS. Liver produces angiotensinogen, adrenal cortex secretes aldosterone, and posterior pituitary releases ADH. Hence, Option 2 is correct.

4. Single Correct Answer:
ADH primarily affects:
1. Sodium reabsorption
2. Water reabsorption
3. Glucose metabolism
4. Potassium excretion

Explanation : Antidiuretic hormone (ADH or vasopressin) increases water reabsorption in the collecting ducts of the nephron by increasing aquaporin channels, concentrating urine and maintaining blood osmolarity. It does not significantly affect sodium, glucose, or potassium directly. Hence, Option 2 is correct.

5. Single Correct Answer:
Which hormone is released from posterior pituitary?
1. Aldosterone
2. ADH
3. ANF
4. Renin

Explanation : ADH (vasopressin) is synthesized in hypothalamus and stored in posterior pituitary, which releases it into blood to regulate water balance and blood pressure. Aldosterone is from adrenal cortex, ANF from atria, and renin from kidney. Hence, Option 2 is correct.

6. Single Correct Answer:
Angiotensin II exerts its effect mainly via:
1. Vasodilation
2. Vasoconstriction
3. Sodium excretion
4. Water loss

Explanation : Angiotensin II is a potent vasoconstrictor that increases peripheral resistance and stimulates aldosterone release, thereby increasing blood pressure. It does not promote vasodilation, sodium excretion, or water loss. Hence, Option 2 is correct.

7. Assertion-Reason:
Assertion (A): Aldosterone increases blood pressure.
Reason (R): Aldosterone enhances sodium and water reabsorption in the kidneys.
1. Both A and R are true, and R is the correct explanation of A
2. Both A and R are true, but R is not the correct explanation of A
3. A is true, R is false
4. A is false, R is true

Explanation : Aldosterone acts on distal tubules and collecting ducts, increasing sodium and water reabsorption. This elevates blood volume and blood pressure. Both assertion and reason are correct, and the reason correctly explains the assertion. Hence, Option 1 is correct.

8. Matching Type:
Match List-I with List-II:
List-I      List-II
(a) ANF      (i) Decreases blood pressure
(b) Aldosterone      (ii) Increases sodium reabsorption
(c) ADH      (iii) Promotes water reabsorption
(d) Renin      (iv) Converts angiotensinogen to angiotensin I
1. (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)
2. (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)
3. (a)-(i), (b)-(iii), (c)-(ii), (d)-(iv)
4. (a)-(iv), (b)-(ii), (c)-(i), (d)-(iii)

Explanation : ANF decreases blood pressure by promoting natriuresis, aldosterone increases sodium reabsorption, ADH promotes water reabsorption, and renin converts angiotensinogen to angiotensin I. Correct matching is (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv). Hence, Option 1 is correct.

9. Fill in the Blank:
Vasopressin is released from _______ pituitary gland.
1. Anterior
2. Posterior
3. Intermediate
4. Adenohypophysis

Explanation : Vasopressin (ADH) is synthesized in the hypothalamus and stored in the posterior pituitary. It is released into the bloodstream in response to increased plasma osmolarity or low blood pressure, promoting water reabsorption and vasoconstriction. Hence, Option 2 is correct.

10. Choose the correct statements:
Statement I: ANF antagonizes the renin-angiotensin-aldosterone system.
Statement II: ADH causes vasoconstriction and water retention.
1. Both statements are correct
2. Only Statement I is correct
3. Only Statement II is correct
4. Both statements are incorrect

Explanation : ANF reduces blood pressure by inhibiting renin secretion and sodium reabsorption, opposing RAAS. ADH increases water reabsorption and causes vasoconstriction, elevating blood pressure. Both statements are accurate. Hence, Option 1 is correct.

Topic: Endocrine System; Subtopic: Thyroid Hormones During Pregnancy

Keyword Definitions:
• Thyroxine (T4): A thyroid hormone regulating metabolism, growth, and development.
• Maternal blood: Blood circulating in the mother, supplying nutrients and hormones to the body and fetus.
• Pregnancy: Physiological state in which a female carries developing offspring in the uterus.
• Metabolic changes: Alterations in energy production and nutrient utilization to support fetal growth.
• Endocrine system: Glands producing hormones that regulate body functions.
• Hormonal regulation: Adjustment of hormone levels to maintain homeostasis and adapt to physiological states.

Lead Question - 2022 (Ganganagar)

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): During pregnancy the level of thyroxine is increased in the maternal blood.
Reason (R): Pregnancy is characterised by metabolic changes in the mother.
In the light of the above statements, choose the most appropriate answer from the options given below:
1. Both (A) and (R) are correct and (R) is the correct explanation of (A)
2. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
3. (A) is correct but (R) is not correct
4. (A) is not correct but (R) is correct

Explanation: The correct answer is option 1. During pregnancy, the level of maternal thyroxine increases to meet the enhanced metabolic demands of both mother and developing fetus. Thyroxine regulates basal metabolic rate, protein synthesis, and energy metabolism, which are elevated during pregnancy. The metabolic changes include increased oxygen consumption, nutrient mobilization, and thermogenesis. Therefore, the rise in thyroxine is a direct adaptive response to these metabolic requirements, making the Reason (R) the correct explanation of the Assertion (A).

1. Single Correct Answer MCQ:
Which thyroid hormone is primarily increased in maternal blood during pregnancy?
1. Calcitonin
2. Thyroxine (T4)
3. Parathyroid hormone
4. Triiodothyronine (T3)

Explanation: The correct answer is Thyroxine (T4). During pregnancy, maternal thyroxine levels rise to support enhanced metabolism, fetal growth, and development. This increase ensures adequate energy production and protein synthesis. Triiodothyronine (T3) also increases slightly, but T4 is the primary circulating thyroid hormone measured in maternal blood during gestation.

2. Single Correct Answer MCQ:
The increased thyroxine during pregnancy primarily affects:
1. Fetal nervous system development
2. Maternal bone density
3. Muscle mass only
4. Kidney function only

Explanation: The correct answer is fetal nervous system development. Thyroxine is crucial for neuronal proliferation, migration, and differentiation in the fetus. Insufficient maternal thyroxine may lead to cretinism or cognitive deficits in the newborn. Other maternal adaptations occur, but the major fetal effect is on brain and nervous system development.

3. Single Correct Answer MCQ:
Which gland secretes thyroxine?
1. Pituitary
2. Thyroid
3. Adrenal
4. Pancreas

Explanation: The correct answer is thyroid. The thyroid gland produces thyroxine (T4) and triiodothyronine (T3), hormones responsible for regulating metabolism. During pregnancy, thyroid hormone secretion increases to meet the metabolic demands of the mother and fetus. Pituitary secretes TSH, which regulates thyroid hormone production, but does not secrete thyroxine directly.

4. Single Correct Answer MCQ:
Maternal thyroxine is essential during early pregnancy because:
1. Fetal thyroid is inactive
2. Maternal parathyroid compensates
3. Kidneys produce T4
4. Placenta blocks T4

Explanation: The correct answer is fetal thyroid is inactive. In the first trimester, the fetal thyroid is not fully functional, so maternal thyroxine crosses the placenta to support fetal growth, particularly brain and nervous system development. Adequate maternal T4 prevents developmental disorders and ensures proper metabolic regulation in both mother and fetus.

5. Single Correct Answer MCQ:
Which hormone stimulates increased thyroid hormone production in pregnancy?
1. hCG
2. Oxytocin
3. Progesterone
4. Prolactin

Explanation: The correct answer is hCG. Human chorionic gonadotropin (hCG) mimics TSH, stimulating the thyroid to produce more thyroxine, particularly in the first trimester. This supports maternal metabolism and provides the fetus with thyroid hormone before its own thyroid is functional. Other hormones like progesterone and prolactin play different roles in pregnancy.

6. Single Correct Answer MCQ:
Excessive thyroxine during pregnancy may lead to:
1. Hypothyroidism
2. Hyperthyroidism
3. Diabetes
4. Preeclampsia

Explanation: The correct answer is hyperthyroidism. Excess maternal thyroxine can cause increased metabolism, weight loss, heat intolerance, and tachycardia. Fetal complications may include growth retardation or preterm labor. Normal physiological increases are safe, but pathological elevations can result in hyperthyroid symptoms.

7. Assertion-Reason MCQ:
Assertion (A): Thyroxine levels rise in maternal blood during pregnancy.
Reason (R): Increased metabolic activity in the mother and fetus requires higher oxygen consumption and energy metabolism.
1. Both A and R are correct and R explains A
2. Both A and R are correct but R does not explain A
3. A correct, R incorrect
4. A incorrect, R correct

Explanation: The correct answer is option 1. During pregnancy, the mother’s metabolic demand increases, and the developing fetus requires energy and growth factors. Elevated thyroxine supports increased basal metabolic rate, protein synthesis, and oxygen consumption, making R the correct explanation for A.

8. Matching Type MCQ:
Match the hormone with its role in pregnancy:
(a) Thyroxine - (i) Metabolic regulation
(b) hCG - (ii) Thyroid stimulation
(c) Progesterone - (iii) Uterine maintenance

1. (a)-(i), (b)-(ii), (c)-(iii)
2. (a)-(ii), (b)-(i), (c)-(iii)
3. (a)-(i), (b)-(iii), (c)-(ii)
4. (a)-(iii), (b)-(ii), (c)-(i)

Explanation: The correct answer is option 1. Thyroxine regulates maternal and fetal metabolism. hCG stimulates the thyroid to produce thyroxine early in pregnancy. Progesterone maintains the uterine lining to support fetal development. These coordinated hormonal changes ensure healthy pregnancy.

9. Fill in the Blanks MCQ:
Maternal thyroxine rises during pregnancy to meet _______ and _______ requirements.

1. Metabolic, developmental
2. Reproductive, cardiac
3. Renal, digestive
4. Immune, hematologic

Explanation: The correct answer is metabolic and developmental. Thyroxine supports the mother’s increased metabolic rate and fetal growth, particularly nervous system development. Without adequate thyroxine, fetal neurodevelopment may be compromised, and maternal metabolic adaptation may be insufficient.

10. Choose the Correct Statements MCQ:
Statement I: Maternal thyroxine increases during pregnancy.
Statement II: Thyroxine is not important for fetal brain development.

1. Only Statement I correct
2. Only Statement II correct
3. Both correct
4. Both incorrect

Explanation: The correct answer is option 1. Maternal thyroxine levels rise during pregnancy to meet increased metabolic demands and to support fetal neurodevelopment. Statement II is false because thyroxine is crucial for brain and nervous system development in the fetus, especially before the fetal thyroid becomes functional.

Topic: Endocrine System; Subtopic: Hormones and Their Mechanism of Action

Keyword Definitions:
• FSH (Follicle Stimulating Hormone): A glycoprotein hormone secreted by anterior pituitary that regulates gametogenesis in ovaries and testes.
• Membrane-bound Receptors: Proteins located on cell membrane that bind hormones or ligands and trigger intracellular signalling.
• Second Messenger: Small molecules like cyclic AMP (cAMP) that transmit signals from receptors to target enzymes and genes within cells.
• Cyclic AMP (cAMP): A key second messenger that activates protein kinases and mediates hormonal responses.
• Hormone Action: The process by which hormones bind receptors and produce physiological and biochemical changes in target cells.

Lead Question - 2022 (Ganganagar)

Given below are two statements: one is labelled as Assertion (A) and the other as Reason (R).

Assertion (A): FSH which interacts with membrane bound receptors does not enter the target cell.
Reason (R): Binding of FSH to its receptors generates second messenger (cyclic AMP) for its biochemical and physiological responses.

1. Both (A) and (R) are correct and (R) is the correct explanation of (A)
2. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
3. (A) is correct but (R) is not correct
4. (A) is not correct but (R) is correct

Explanation: The correct answer is option 1. FSH is a peptide hormone that cannot cross the lipid bilayer of target cells. It binds to membrane-bound receptors, initiating a cascade via a second messenger system, primarily cyclic AMP (cAMP). The cAMP activates protein kinases, leading to phosphorylation of target proteins and regulation of gene expression, resulting in physiological effects like gametogenesis and steroidogenesis. The hormone itself does not enter the cell, and its effect is mediated entirely through intracellular signalling pathways, validating both the assertion and the reason.

1. FSH primarily acts on:
1. Liver
2. Ovaries and testes
3. Kidney
4. Adrenal gland

Explanation: The correct answer is ovaries and testes. FSH stimulates follicle development in ovaries and spermatogenesis in testes. It acts through membrane receptors, using cAMP as a second messenger. Liver, kidney, and adrenal glands are not primary targets of FSH.

2. The type of hormone that cannot cross cell membranes is:
1. Steroid hormone
2. Thyroid hormone
3. Peptide hormone
4. Lipid-soluble hormone

Explanation: The correct answer is peptide hormone. Peptide hormones like FSH, LH, and insulin bind to surface receptors since they are hydrophilic and cannot diffuse through the lipid bilayer. Steroid and thyroid hormones are lipid-soluble and cross membranes to bind intracellular receptors.

3. The primary second messenger for FSH signalling is:
1. Calcium ions
2. cAMP
3. IP3
4. DAG

Explanation: The correct answer is cAMP. FSH binds to its G-protein coupled receptors on target cells, activating adenylate cyclase. This increases intracellular cyclic AMP, which activates protein kinase A and triggers downstream physiological responses such as steroidogenesis and gametogenesis.

4. FSH is secreted by:
1. Posterior pituitary
2. Anterior pituitary
3. Hypothalamus
4. Thyroid gland

Explanation: The correct answer is anterior pituitary. FSH is a glycoprotein hormone synthesized by gonadotrophs in the anterior pituitary. Its secretion is regulated by gonadotropin-releasing hormone (GnRH) from the hypothalamus, influencing reproductive processes.

5. Which of the following is true about membrane-bound receptor hormones?
1. They enter the nucleus directly
2. Use second messengers to mediate effects
3. Are lipid-soluble
4. Do not bind to cell surface

Explanation: The correct answer is use second messengers to mediate effects. Hormones like FSH bind to membrane receptors and activate intracellular second messengers such as cAMP. Lipid-soluble hormones enter cells directly, unlike peptide hormones, which rely on second messenger systems.

6. The physiological effect of FSH in males is:
1. Testosterone production
2. Spermatogenesis
3. Growth of seminal vesicles
4. Adrenal androgen secretion

Explanation: The correct answer is spermatogenesis. FSH acts on Sertoli cells in testes, promoting sperm maturation. Testosterone synthesis is mainly regulated by LH acting on Leydig cells. Seminal vesicle growth and adrenal androgen secretion are not directly mediated by FSH.

7. Assertion-Reason Question:
Assertion (A): FSH does not enter the target cell.
Reason (R): FSH is a hydrophilic peptide hormone.

1. Both A and R are correct and R explains A
2. Both A and R are correct but R does not explain A
3. A true, R false
4. A false, R true

Explanation: The correct answer is option 1. Being hydrophilic, FSH cannot cross the lipid bilayer. It binds to extracellular membrane receptors and acts through second messengers like cAMP to elicit cellular responses.

8. Matching Type:
Match the hormone with mechanism:
(a) FSH - (i) Membrane receptor, second messenger
(b) Cortisol - (ii) Intracellular receptor, gene activation
(c) Thyroid hormone - (iii) Intracellular receptor, protein synthesis

1. (a)-(i), (b)-(ii), (c)-(iii)
2. (a)-(ii), (b)-(i), (c)-(iii)
3. (a)-(i), (b)-(iii), (c)-(ii)
4. (a)-(iii), (b)-(ii), (c)-(i)

Explanation: The correct answer is option 1. FSH is a peptide hormone acting via membrane receptor and cAMP. Cortisol is steroidal and acts through intracellular receptors to modulate gene transcription. Thyroid hormone also binds intracellular receptors affecting protein synthesis.

9. Fill in the Blanks:
Binding of FSH to its receptor activates the ________ pathway.

1. cAMP
2. IP3-DAG
3. JAK-STAT
4. MAPK

Explanation: The correct answer is cAMP. FSH binding to G-protein coupled receptors activates adenylate cyclase, increasing cAMP levels. This second messenger triggers protein kinase A activation, leading to phosphorylation of target proteins and physiological responses like gametogenesis and steroidogenesis.

10. Choose the Correct Statements:
Statement I: FSH is a hydrophilic hormone acting via membrane-bound receptors.
Statement II: FSH directly enters the cell to regulate gene transcription.

1. Only Statement I correct
2. Only Statement II correct
3. Both I and II correct
4. Both I and II incorrect

Explanation: The correct answer is option 1. FSH is hydrophilic and binds to membrane receptors, triggering cAMP-mediated intracellular signalling. It does not enter the cell; gene transcription is regulated indirectly via second messenger pathways.

Topic: Pancreatic Hormones; Subtopic: Insulin Biosynthesis

Keyword Definitions:

• Insulin: Hormone produced by pancreatic β-cells that regulates blood glucose levels.

• Pro-hormone: Inactive precursor of a hormone that requires processing to become active.

• C-peptide: Connecting peptide linking A-chain and B-chain in proinsulin, removed during maturation.

• A-peptide/B-peptide chain: Functional polypeptide chains of insulin after C-peptide removal.

• β-cells: Pancreatic cells located in islets of Langerhans that synthesize insulin.

• Proinsulin: Inactive form of insulin containing A-chain, B-chain, and C-peptide.

• Mature insulin: Active hormone consisting of A-chain and B-chain linked by disulfide bonds.

• Processing: Cleavage of C-peptide from proinsulin to generate biologically active insulin.

Lead Question – 2022 (Abroad)
Given below are two statements: one is labelled as Assertion (A) and the other as Reason (R).
Assertion (A): In human beings, insulin is synthesized as a pro-hormone which needs to be processed before it becomes fully mature and functional.
Reason (R): The extra stretch of C-peptide is to be removed from A-peptide and B-peptide chain of insulin.
In the light of the above statements, choose the most appropriate answer from the options below:
1. (A) is correct but (R) is not correct
2. (A) is not correct but (R) is correct
3. Both (A) and (R) are correct and (R) is the correct explanation of (A)
4. Both (A) and (R) are correct but (R) is not the correct explanation of (A)

Explanation:
Correct answer is option 3. Insulin is synthesized in pancreatic β-cells as an inactive precursor called proinsulin, consisting of the A-chain, B-chain, and C-peptide. During maturation, the C-peptide is enzymatically cleaved, leaving the A and B chains linked by disulfide bonds to form biologically active insulin. This processing ensures proper folding and functionality of insulin, while the C-peptide has no hormonal activity but is released in equimolar amounts. The reason accurately explains the assertion, as removal of C-peptide is essential for insulin to become fully mature and capable of regulating blood glucose levels effectively.

1. What is the role of C-peptide in insulin biosynthesis?
1. It is the active part of insulin
2. It stabilizes A and B chains during folding
3. It acts as a hormone itself
4. It remains attached in mature insulin
Explanation: Correct answer is It stabilizes A and B chains during folding. C-peptide is part of proinsulin and ensures proper folding of A and B chains via disulfide bond formation. It is cleaved during maturation to form active insulin. Though released in circulation, it has minimal direct hormonal activity, serving mainly as a marker for endogenous insulin production.

2. Proinsulin consists of:
1. Only A and B chains
2. A-chain, B-chain, and C-peptide
3. C-peptide only
4. Single polypeptide chain without cleavage sites
Explanation: Correct answer is A-chain, B-chain, and C-peptide. Proinsulin is a single-chain precursor containing A-chain, B-chain, and the connecting C-peptide. The C-peptide is cleaved enzymatically to generate mature insulin consisting of two chains linked by disulfide bonds. This precursor ensures correct folding and proper structural formation of active insulin in β-cells.

3. Which cells synthesize insulin in humans?
1. α-cells of pancreas
2. β-cells of pancreas
3. δ-cells of pancreas
4. Exocrine acinar cells
Explanation: Correct answer is β-cells of pancreas. β-cells in the islets of Langerhans produce proinsulin, which is processed into active insulin. α-cells secrete glucagon, δ-cells secrete somatostatin, and acinar cells are exocrine, producing digestive enzymes. β-cells are central to glucose homeostasis through regulated insulin secretion.

4. Mature insulin consists of:
1. Only A-chain
2. Only B-chain
3. A-chain and B-chain linked by disulfide bonds
4. A-chain, B-chain, and C-peptide
Explanation: Correct answer is A-chain and B-chain linked by disulfide bonds. Upon cleavage of C-peptide from proinsulin, the A and B chains are joined by disulfide bridges to form active insulin. This structure is critical for receptor binding and glucose regulation. C-peptide is removed but secreted separately in equimolar amounts.

5. Removal of C-peptide from proinsulin is necessary because:
1. C-peptide is toxic
2. Only A and B chains are biologically active
3. It prevents folding of insulin
4. It reduces insulin solubility
Explanation: Correct answer is Only A and B chains are biologically active. C-peptide serves as a connector during folding but has no direct hormonal effect. Its removal produces mature insulin capable of binding to insulin receptors. Proper cleavage ensures functional hormone secretion and regulation of blood glucose.

6. The term “pro-hormone” refers to:
1. Active hormone
2. Inactive precursor requiring processing
3. Hormone degraded in liver
4. Hormone bound to carrier protein
Explanation: Correct answer is Inactive precursor requiring processing. Proinsulin is a pro-hormone, inactive until enzymatic removal of C-peptide. Pro-hormones ensure correct folding, storage, and regulated activation of hormones. This mechanism prevents premature activity and maintains homeostasis.

7. Assertion-Reason:
Assertion (A): Insulin is synthesized as a pro-hormone.
Reason (R): Proinsulin contains C-peptide which must be removed to activate insulin.
1. Both A and R are true, R is correct explanation of A
2. Both A and R are true, R is not correct explanation
3. A is true, R is false
4. A is false, R is true
Explanation: Correct answer is option 1. Insulin is synthesized as proinsulin in β-cells. The C-peptide connects the A and B chains and is removed enzymatically to produce mature, biologically active insulin. The reason accurately explains the assertion, linking pro-hormone processing to activation of insulin.

8. Matching Type:
Match List-I (Molecule) with List-II (Function):
A. Proinsulin – (i) Inactive precursor
B. C-peptide – (ii) Connector peptide during folding
C. Mature insulin – (iii) Regulates blood glucose
D. β-cells – (iv) Site of synthesis
1. A–i, B–ii, C–iii, D–iv
2. A–ii, B–i, C–iv, D–iii
3. A–iii, B–ii, C–i, D–iv
4. A–iv, B–iii, C–ii, D–i
Explanation: Correct answer is option 1. Proinsulin is the inactive precursor (A–i), C-peptide stabilizes A and B chains (B–ii), mature insulin regulates blood glucose (C–iii), and β-cells are the synthesis site (D–iv). This illustrates biosynthesis, processing, and functional role of insulin and associated peptides.

9. Fill in the Blanks:
The __________ is cleaved from proinsulin to produce active insulin.
1. A-chain
2. B-chain
3. C-peptide
4. β-cell nucleus
Explanation: Correct answer is C-peptide. During insulin maturation, the connecting C-peptide is enzymatically removed, leaving A and B chains linked by disulfide bonds. This cleavage converts proinsulin to biologically active insulin, enabling glucose regulation. The C-peptide is secreted in equimolar amounts but has no direct hormonal function.

10. Choose the Correct Statements:
Statement I: Proinsulin contains A-chain, B-chain, and C-peptide.
Statement II: Mature insulin contains all three components including C-peptide.
1. Statement I correct, Statement II incorrect
2. Statement I incorrect, Statement II correct
3. Both statements correct
4. Both statements incorrect
Explanation: Correct answer is Statement I correct, Statement II incorrect. Proinsulin has A, B chains, and C-peptide, while mature insulin only contains A and B chains linked by disulfide bonds. Removal of C-peptide is essential for activation. This illustrates the processing step critical in hormone maturation and function.

Topic: Hormones of Digestive System; Subtopic: Intestinal Hormones

Keyword Definitions:

• Enterokinin: An intestinal hormone secreted by the small intestine that stimulates pancreatic secretion rich in bicarbonate ions.

• Pancreas: A glandular organ that secretes digestive enzymes and bicarbonate-rich fluid to neutralize stomach acid.

• Bicarbonate ions (HCO₃⁻): Ions that neutralize acidic chyme entering the small intestine from the stomach.

• Cholecystokinin (CCK): A hormone that stimulates gall bladder contraction and pancreatic enzyme secretion.

Lead Question – 2022 (Abroad)
An intestinal hormone that stimulates the pancreas to release a watery secretion that is rich in bicarbonate ions:
1. Cholecystokinin
2. Gastric Inhibitory Peptide
3. Enterokinin
4. Secretion

Explanation:
The correct answer is Enterokinin. This hormone, secreted by the mucosa of the small intestine, stimulates the pancreas to release a watery fluid rich in bicarbonate ions, which neutralizes acidic chyme entering from the stomach. It is essential for maintaining optimal pH in the duodenum for enzyme activity and digestion efficiency.

1. Which hormone stimulates pancreatic enzyme secretion?
1. Secretin
2. Enterokinin
3. Gastrin
4. Insulin
Explanation: Enterokinin stimulates the pancreas to secrete bicarbonate-rich watery fluid, while other hormones like gastrin primarily regulate stomach acid and secretin mainly stimulates bicarbonate secretion from the pancreas. Its activity ensures neutralization of chyme for proper enzymatic digestion in the small intestine.

2. Which ion is abundant in pancreatic secretion stimulated by enterokinin?
1. Chloride
2. Bicarbonate (HCO₃⁻)
3. Sodium
4. Potassium
Explanation: Enterokinin-stimulated pancreatic secretion is rich in bicarbonate ions (HCO₃⁻). These ions neutralize acidic chyme from the stomach, providing an optimal pH for pancreatic enzymes like amylase, lipase, and proteases, which function best in slightly alkaline conditions, ensuring efficient digestion and nutrient absorption.

3. Enterokinin is secreted by which part of the digestive system?
1. Stomach
2. Small intestine
3. Large intestine
4. Pancreas
Explanation: Enterokinin is secreted by the epithelial cells of the small intestine, mainly in the duodenum and jejunum. Its secretion is triggered by the presence of chyme, and it signals the pancreas to release a bicarbonate-rich secretion, neutralizing acidity and creating suitable conditions for enzymatic digestion.

4. Which hormone triggers gall bladder contraction along with pancreatic enzyme release?
1. Enterokinin
2. Secretin
3. Cholecystokinin (CCK)
4. Gastric Inhibitory Peptide
Explanation: Cholecystokinin (CCK) stimulates gall bladder contraction and release of bile, along with pancreatic enzyme secretion. It complements enterokinin, which primarily stimulates bicarbonate-rich fluid from the pancreas, aiding in fat digestion and overall digestive efficiency in the duodenum.

5. Bicarbonate-rich pancreatic secretion helps in:
1. Protein breakdown in the stomach
2. Neutralizing acidic chyme
3. Stimulating gastric acid
4. Absorbing water in colon
Explanation: The bicarbonate-rich secretion stimulated by enterokinin neutralizes acidic chyme entering the small intestine from the stomach. This neutralization prevents mucosal damage, provides optimal pH for pancreatic enzyme activity, and ensures efficient digestion of carbohydrates, proteins, and fats.

6. Which of the following is not secreted by the small intestine?
1. Enterokinin
2. Secretin
3. Gastrin
4. Cholecystokinin (CCK)
Explanation: Gastrin is primarily secreted by the stomach to stimulate acid production. Other hormones like enterokinin, secretin, and CCK are secreted by the small intestine to regulate pancreatic secretion, bile release, and neutralization of chyme, ensuring effective digestion and absorption.

7. Assertion-Reason Type:
Assertion (A): Enterokinin stimulates bicarbonate secretion from the pancreas.
Reason (R): Neutralization of acidic chyme is required for optimal enzymatic digestion.
1. Both A and R are true, and R is the correct explanation of A.
2. Both A and R are true, but R is not the correct explanation of A.
3. A is true, but R is false.
4. A is false, but R is true.
Explanation: The correct answer is option 1. Enterokinin stimulates the pancreas to release bicarbonate-rich fluid. This action neutralizes acidic chyme from the stomach, creating an alkaline environment necessary for digestive enzymes to function efficiently in the duodenum.

8. Matching Type:
Match the hormone with its function:
A. Enterokinin – (i) Stimulates pancreatic bicarbonate secretion
B. Secretin – (ii) Stimulates water and bicarbonate secretion
C. Cholecystokinin – (iii) Stimulates bile release
D. Gastrin – (iv) Stimulates gastric acid secretion
1. A–i, B–ii, C–iii, D–iv
2. A–ii, B–i, C–iv, D–iii
3. A–iii, B–i, C–ii, D–iv
4. A–iv, B–ii, C–i, D–iii
Explanation: The correct answer is option 1. Enterokinin stimulates pancreatic bicarbonate secretion, secretin promotes watery alkaline fluid, CCK stimulates bile and pancreatic enzyme release, and gastrin increases gastric acid secretion, coordinating digestion in the gastrointestinal tract efficiently.

9. Fill in the Blanks:
_________ is secreted by the small intestine to neutralize acidic chyme.
1. Cholecystokinin
2. Enterokinin
3. Secretin
4. Gastrin
Explanation: The blank is filled with Enterokinin. It stimulates the pancreas to release a watery, bicarbonate-rich secretion, which neutralizes the acidic chyme entering from the stomach, providing an optimal pH for enzymatic activity in the duodenum and facilitating efficient nutrient digestion.

10. Choose the Correct Statements:
Statement I: Enterokinin stimulates the pancreas to secrete bicarbonate-rich fluid.
Statement II: Bicarbonate neutralizes chyme, aiding in digestion.
1. Both statements are correct
2. Both statements are incorrect
3. Statement I is correct, Statement II is incorrect
4. Statement I is incorrect, Statement II is correct
Explanation: The correct answer is option 1. Enterokinin stimulates the pancreas to secrete a bicarbonate-rich fluid. This fluid neutralizes acidic chyme from the stomach, maintaining an optimal pH for enzyme activity and efficient digestion, ensuring proper nutrient breakdown and absorption in the small intestine.

Topic: Endocrine Glands and Hormones; Subtopic: Pineal Gland and Biological Rhythms

Keyword Definitions:

• Melatonin: A hormone secreted by the pineal gland that regulates sleep-wake cycles and circadian rhythms.

• Pineal Gland: A small, pea-shaped gland in the brain responsible for melatonin secretion.

• Biological Rhythm: Natural cycles of physiological activity, including sleep and wakefulness.

• Circadian Rhythm: The 24-hour internal clock that regulates physiological and behavioral patterns.

Lead Question – 2022 (Abroad)
Normal sleep-wake cycle in a human body is maintained by the secretion of:
1. Thyroid gland
2. Thymus gland
3. Pineal gland
4. Pituitary gland

Explanation:
The pineal gland secretes melatonin, a hormone that regulates the body’s circadian rhythm and sleep-wake cycle. Its secretion increases in darkness and decreases in light, signaling the brain to rest or awaken. It plays a vital role in maintaining biological clock functions and seasonal reproduction cycles in animals.