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Chemical coordination and regulation: NEET MCQs with answers

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

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easy

1. Adrenaline and noradrenaline, the "emergency hormones" or hormones of fight or flight, are secreted by the:

  1. Adrenal medulla
  2. Thyroid
  3. Pancreas
  4. Adrenal cortex
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Answer: (A) Adrenal medulla

The adrenal medulla secretes the catecholamines adrenaline (epinephrine) and noradrenaline in response to stress or emergency. They increase alertness, heart rate, breathing and blood glucose.

NCERT Class 11

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2. In a classic experiment, a hormone 'X' was shown to cross the plasma membrane freely, bind to an intracellular receptor, and regulate gene expression via the hormone-receptor complex binding to the chromosome. Which of the following could hormone 'X' be?

  1. Insulin
  2. Estrogen
  3. Adrenaline
  4. Thyroid-stimulating hormone (TSH)
Show answer and explanation

Answer: (B) Estrogen

Hormones that interact with intracellular receptors are lipid-soluble, such as steroid hormones (e.g., estrogen, progesterone, testosterone, cortisol) and iodothyronines. Insulin, adrenaline, and TSH act via membrane-bound receptors and second messengers.

hard

3. How many of the following hormones are secreted by the anterior pituitary (pars distalis)? GH, Prolactin, TSH, ACTH, LH, FSH, Oxytocin, Vasopressin, MSH

  1. Eight
  2. Seven
  3. Six
  4. Five
Show answer and explanation

Answer: (C) Six

Pars distalis secretes GH, PRL, TSH, ACTH, LH and FSH (six). MSH is from pars intermedia; oxytocin and vasopressin are released by the posterior pituitary.

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4. Parathyroid hormone (PTH) is considered a hypercalcemic hormone because it increases blood Ca²⁺ levels by:

  1. Inhibiting the dissolution of bone salts by osteoclasts
  2. Promoting Ca²⁺ excretion by renal tubules and intestinal mucosa
  3. Stimulating bone resorption and increasing Ca²⁺ reabsorption in renal tubules
  4. Decreasing the absorption of digested calcium from the gastrointestinal tract
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Answer: (C) Stimulating bone resorption and increasing Ca²⁺ reabsorption in renal tubules

PTH increases Ca²⁺ levels in the blood by stimulating bone resorption (demineralisation/dissolution), promoting reabsorption of Ca²⁺ by renal tubules, and enhancing Ca²⁺ absorption from digested food in the alimentary canal.

easy

5. The hypophyseal portal system is of great physiological significance in humans because it transports:

  1. Feedback signals directly from the thyroid gland to the posterior pituitary
  2. Oxytocin and vasopressin from the hypothalamus to the neurohypophysis
  3. Trophic hormones from the anterior pituitary directly to peripheral target endocrine glands
  4. Releasing and inhibiting hormones from the hypothalamus directly to the adenohypophysis
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Answer: (D) Releasing and inhibiting hormones from the hypothalamus directly to the adenohypophysis

The hypothalamic hormones reach the anterior pituitary (adenohypophysis) gland through a hypophyseal portal circulatory system, whereas the posterior pituitary is under direct neural regulation. Oxytocin and vasopressin are transported axonally to the neurohypophysis, not via portal blood vessels.

hard

6. Which of the following sequences accurately depicts the signal transduction pathway triggered by follicle stimulating hormone (FSH) in an ovarian cell?

  1. FSH → Diffusion through plasma membrane → Binding to intracellular receptor → Gene activation → Biochemical response
  2. FSH → Binding to ovarian membrane receptor → Generation of cAMP/Ca²⁺ → Biochemical responses → Physiological response
  3. FSH → Generation of IP₃ → Intracellular receptor binding → Protein synthesis → Nuclear membrane lysis
  4. FSH → Binding to nuclear receptor → Hormone-receptor complex → Direct activation of transcription → Physiological response
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Answer: (B) FSH → Binding to ovarian membrane receptor → Generation of cAMP/Ca²⁺ → Biochemical responses → Physiological response

FSH is a peptide/proteinaceous hormone that binds to its specific membrane-bound receptor on the ovarian follicular cell membrane. This binding leads to the generation of second messengers such as cyclic AMP (cAMP) or Ca²⁺, which cascade into biochemical responses leading to ovarian growth.

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7. Exophthalmic goitre (Graves' disease) is a form of:

  1. Hypopituitarism
  2. Hypothyroidism
  3. Hyperthyroidism
  4. Hypoparathyroidism
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Answer: (C) Hyperthyroidism

Exophthalmic goitre is hyperthyroidism with enlargement of the thyroid, protrusion of the eyeballs, increased basal metabolic rate and weight loss.

NCERT Class 11

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8. The pituitary hormone MSH acts on:

  1. Kidney tubules
  2. Thyroid follicles
  3. Uterine muscles
  4. Melanocytes and regulates pigmentation of the skin
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Answer: (D) Melanocytes and regulates pigmentation of the skin

The pars intermedia secretes MSH, which acts on melanocytes and regulates skin pigmentation.

NCERT Class 11

hard

9. Given below are two statements. Statement I: Oxytocin is synthesised by the posterior pituitary. Statement II: Vasopressin is also called antidiuretic hormone. Choose the correct answer.

  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: (C) Statement I is incorrect but Statement II is correct

Oxytocin and vasopressin are synthesised by the hypothalamus and only stored and released by the posterior pituitary. Vasopressin is indeed ADH.

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10. Androgens regulate the development, maturation and functions of the male accessory sex organs, which include:

  1. Epididymis, vas deferens, seminal vesicles, prostate gland and urethra
  2. Ovaries and fallopian tubes
  3. Mammary glands only
  4. Thyroid and parathyroid
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Answer: (A) Epididymis, vas deferens, seminal vesicles, prostate gland and urethra

Androgens regulate development and functions of the epididymis, vas deferens, seminal vesicles, prostate and urethra, and stimulate secondary sex characters.

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11. Adrenaline and noradrenaline are referred to as emergency hormones because they are rapidly secreted in response to stress and cause:

  1. Increased alertness, pupillary dilation, piloerection, sweating and increased heartbeat
  2. Decreased heart rate and pupil constriction
  3. Increased water reabsorption only
  4. Increased milk formation
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Answer: (A) Increased alertness, pupillary dilation, piloerection, sweating and increased heartbeat

These 'fight or flight' hormones increase alertness, dilate pupils, cause piloerection and sweating, and raise heartbeat, strength of contraction and rate of respiration.

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12. Gonadotrophin-releasing hormone (GnRH) from the hypothalamus stimulates the pituitary to secrete:

  1. Oxytocin
  2. Growth hormone
  3. Gonadotrophins
  4. Thyroxine
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Answer: (C) Gonadotrophins

GnRH stimulates pituitary synthesis and release of gonadotrophins (LH and FSH).

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