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Hormones: general introduction: NEET MCQs with answers

50 questions on this topic of Biomolecules (NEET 2027 syllabus). Here are 12; tap one to see its answer and explanation.

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easy

1. Regarding hormones, consider the following two statements: Statement I: Hormones are chemical messengers secreted directly into the bloodstream by ductless glands. Statement II: Hormones are stored in large amounts in the human body for prolonged metabolic use. Choose the correct option:

  1. Statement I is correct, but Statement II is incorrect
  2. Both Statement I and Statement II are correct
  3. Statement I is incorrect, but Statement II is correct
  4. Both Statement I and Statement II are incorrect
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Answer: (A) Statement I is correct, but Statement II is incorrect

Hormones are produced by endocrine glands and released directly into the blood to act on target tissues. However, they are not stored in large amounts in the body (except thyroxine to some extent) and are continuously produced, utilized, and degraded.

medium

2. Given below are two statements: Statement I: Endocrine glands are ductless glands that pour their secretions directly into the bloodstream. Statement II: Hormones are non-nutrient intercellular messengers produced in trace amounts that are stored in large amounts for prolonged bodily use. In light of the above statements, choose the most appropriate answer from the options given below:

  1. Both Statement I and Statement II are correct
  2. Statement I is correct but Statement II is incorrect
  3. Statement I is incorrect but Statement II is correct
  4. Both Statement I and Statement II are incorrect
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Answer: (B) Statement I is correct but Statement II is incorrect

Statement I is correct because endocrine glands lack ducts and release hormones directly into circulation. Statement II is incorrect because hormones are not stored in large amounts in the body (except thyroxine to some extent) and are continuously metabolized and excreted after action.

hard

3. Which of the following statements is chemically INCORRECT regarding hormones?

  1. Testosterone and cortisone possess a cyclopentanoperhydrophenanthrene steroidal core.
  2. Insulin is stored in the bloodstream indefinitely because it acts merely as a catalyst.
  3. Adrenaline is an amino acid derivative containing catechol and amine functionalities.
  4. Thyroxine contains four iodine atoms covalently attached to its aromatic rings.
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Answer: (B) Insulin is stored in the bloodstream indefinitely because it acts merely as a catalyst.

Insulin is not a permanent catalyst; it is metabolized and broken down in tissues (primarily the liver and kidneys) after performing its signalling function. The other statements correctly describe the chemical nature of steroids, adrenaline, and thyroxine.

medium

4. Match the hormones in List I with their corresponding primary physiological functions in List II: List I (Hormone) A. Insulin B. Epinephrine C. Cortisone D. Thyroxine List II (Primary Function) I. Regulates the basal metabolic rate of the body II. Mediates emergency 'fight or flight' physiological responses III. Modulates carbohydrate, protein, and lipid metabolism and possesses anti-inflammatory action IV. Decreases blood glucose level by stimulating uptake and glycogen synthesis

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

Insulin lowers blood glucose level by facilitating cellular uptake and glycogenesis (A-IV). Epinephrine is released during acute stress to mediate fight-or-flight reactions (B-II). Cortisone is a glucocorticoid involved in carbohydrate metabolism and anti-inflammatory pathways (C-III). Thyroxine regulates the body's basal metabolic rate (D-I).

easy

5. Which of the following hormones is chemically an iodinated derivative of the amino acid tyrosine?

  1. Cortisone
  2. Glucagon
  3. Thyroxine
  4. Progesterone
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Answer: (C) Thyroxine

Thyroxine is an iodinated derivative of the amino acid tyrosine, produced by the thyroid gland. In contrast, cortisone and progesterone are steroid hormones, and glucagon is a polypeptide hormone.

hard

6. A biochemist isolates a pure hormone from an endocrine tissue. Elemental analysis reveals the presence of C, H, O, N, and S, but no iodine or phosphorus. Complete hydrolysis yields standard α-amino acids. The isolated hormone is most likely:

  1. Testosterone
  2. Thyroxine
  3. Aldosterone
  4. Insulin
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Answer: (D) Insulin

Insulin is a polypeptide hormone composed of 51 amino acids across two chains linked by disulfide (-S-S-) bonds formed between cysteine residues, accounting for the sulfur content. Thyroxine contains iodine, while aldosterone and testosterone are steroid hormones devoid of nitrogen and sulfur.

hard

7. A patient exhibits high blood pressure, rapid heart rate, dilated pupils, and elevated blood sugar levels following an acute fright. Which hormone was rapidly released into circulation from its corresponding gland to produce this systemic effect?

  1. Cortisol from the posterior pituitary
  2. Glucagon from the adrenal cortex
  3. Epinephrine from the adrenal medulla
  4. Thyroxine from the parathyroid gland
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Answer: (C) Epinephrine from the adrenal medulla

Epinephrine is synthesized and secreted by the adrenal medulla during stress or acute emergencies. It promotes glycogen breakdown to elevate blood glucose, increases heart rate, and elevates blood pressure.

easy

8. Which of the following hormones is directly responsible for stimulating the breakdown of glycogen into glucose in the liver, thereby raising blood sugar levels?

  1. Glucagon
  2. Insulin
  3. Testosterone
  4. Oxytocin
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Answer: (A) Glucagon

Glucagon is a hyperglycaemic peptide hormone produced by the alpha-cells of the pancreas. It promotes glycogenolysis in the liver, which increases blood glucose concentration.

easy

9. Which of the following hormones is a polypeptide hormone that contains 51 amino acids arranged in two linked peptide chains?

  1. Thyroxine
  2. Glucagon
  3. Insulin
  4. Testosterone
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Answer: (C) Insulin

Insulin is a polypeptide hormone consisting of 51 amino acids distributed across two peptide chains (chain A with 21 amino acids and chain B with 30 amino acids) connected by disulfide bridges.

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10. Given below are two statements: Assertion (A): Hormones are required in minuscule quantities to trigger physiological responses. Reason (R): They are catalytic molecules that regenerate unchanged at the end of each biological reaction like enzymes. Choose the correct option:

  1. Assertion (A) is correct, but Reason (R) is incorrect
  2. Both (A) and (R) are correct and (R) is the correct explanation of (A)
  3. Both (A) and (R) are correct, but (R) is not the correct explanation of (A)
  4. Assertion (A) is incorrect, but Reason (R) is correct
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Answer: (A) Assertion (A) is correct, but Reason (R) is incorrect

Hormones act as intercellular chemical messengers that trigger physiological events at extremely low concentrations. However, unlike enzymes, hormones are not biological catalysts; they are consumed or metabolically inactivated and excreted after exerting their action.

easy

11. Which of the following is an example of a steroid hormone secreted by the ovaries?

  1. Adrenaline
  2. Thyroxine
  3. Progesterone
  4. Glucagon
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Answer: (C) Progesterone

Progesterone is a steroid hormone produced by the ovaries that plays a crucial role in regulating pregnancy and the menstrual cycle. Thyroxine and adrenaline are amine derivatives, whereas glucagon is a polypeptide hormone.

easy

12. Hormones are best described as:

  1. Molecules that act as intercellular messengers, produced by endocrine glands
  2. Enzymes that digest food
  3. Structural proteins of muscles
  4. Energy storage molecules
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Answer: (A) Molecules that act as intercellular messengers, produced by endocrine glands

Hormones are released into the blood by endocrine glands and carried to target sites where they regulate body functions.

NCERT Class 12

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