NEET &#8211; Chemical Coordination and Regulation &#8211; 2024

1. MSH of pars intermedia of middle pituitary is responsible for
(a) darkening of skin in lower vertebrates
(b) light colouration of skin in lower vertebrates
(c) noth A and B
(d) darkening of skin in human beings

2. Which hormone possesses anti-insulin effect?
(a) Cortisol
(b) Calcitonin
(c) Oxytocin
(d) Aldosterone

3. Addition of a trace of thyroxine or iodine in water containing tadpoles will
(a) keep them in larval stage
(b) hasten their metamorphosis
(c) slow down their metamorphosis
(d) kill the tadpoles

4. Insulin is
(a) vitamin
(b) lipid
(c) hormone
(d) enzyme

5. Occurrence of Leydig‘s cells and their secretion is
(a) ovary and estrogen
(b) liver and cholesterol
(c) pancreas and glucagon
(d) testes and testosterone

6. ADH or vasopressin is
(a) enzyme that hydrolyses peptides
(b) hormone secreted by pituitary that promotes reabsorption of water from glomerular filtrate
(c) hormone that promotes glycogenolysis
(d) energy rich compound connected with muscle contraction.

7. Gastric secretion is stopped by hormone
(a) enterogastrone
(b) gastrin
(c) pancreozymin
(d) cholecystokinin

8. Testosterone is produced by
(a) sertolicells
(b) leydig‘s cells
(c) oxyntic cells
(d) pituitary gland
9. Male hormone is produced in the testis by cells of
(a) sertoli
(b) epithelial
(c) spermatocytes
(d) leydig

10. Ovulation is stimulated by
(a) LH
(b) FSH
(c) estrogen
(d) progesterone

11. Function of enterogastrone is
(a) regulation of bile flow
(b) stimulation of pancreatic flow
(c) inhibition of gastric secretion
(d) stimulation of gastric secretion

12. Ovulation occurs under the influence of
(a) LH
(b) FSH
(c) estrogen
(d) progesterone

13. The mammalian corpus luteum produces
(a) estrogen
(b) progesterone
(c) luteotropic hormone
(d) luteinizing hormone

14. Nicotine acts as a stimulant, because it mimics the effect of
(a) thyroxine
(b) acetylcholine
(c) testosterone
(d) dopamine

15. Which of the following endocrine gland stores its secretion in the extracellular space before discharging it into the blood?
(a) Pancreas
(b) Adrenal
(c) Testis
(d) Thyroid

16. According to the accepted concept of hormone action, if receptor molecules are removed from target organs, then the target organ will
(a) not respond to the hormone
(b) continue to respond to hormone without any difference
(c) continue to respond to the hormone but in the opposite way
(d) continue to respond to the hormone but will require higher concentration

17. Which of the following radioactive isotope is used in the detection of thyroid cancer?
(a) Iodine-131
(b) Carbon-14
(c) Uranium-238
(d) Phosphorus-32

18. Which one of the following hormone stimulates the ―let-down‖ (release) of milk from the mother‘s breasts when the baby is sucking?
(a) Progesterone
(b) Oxytocin
(c) Prolactin
(d) Relaxin

19. According to the ―immunity theory‖ of ageing, the process starts with the gradual atrophy and disappearance of
(a) thyroid
(b) parthyroid
(c) thymus
(d) islets of Langerhans

20. In human adult females oxytocin
(a) is secreted by anterior pituitary
(b) stimulates growth of mammary glands
(c) stimulates pituitary to secrete vasopressin
(d) causes strong uterine contractions during parturition

21. Hormones, thyroxine, adrenaline and the pigment melanin are formed from
(a) tryptophan
(b) glycine
(c) tyrosine
(d) proline

22. Calcitonin is a thyroid hormone which
(a) lowers calcium level in blood
(b) elevates calcium level in blood
(c) has no effect on calcium
(d) elevates potassium level in blood

23. The most important component of the oral contraceptive pill is
(a) growth hormone
(b) thyroxine
(c) luteinizing hormone
(d) progesterone

24. Parathormone deficiency produces muscle ramps or tetany as a result of
(a) lowered blood Ca2+
(b) enhanced blood Na+
(c) enhanced blood glucose
(d) enhanced blood Ca2+

25. Oxytocin helps in
(a) lactation
(b) child birth
(c) ovulation
(d) implantation of the embryo

26. The technique used for estimation of minute amounts of hormones and drugs is called
(a) electrophoresis
(b) electroencephalogram
(c) fractionation
(d) radioimmunoassay

27. A candidate vaccine for male contraception is based on
(a) follicle stimulating hormone
(b) progesterone
(c) testosterone
(d) luteinizing hormone

28. Insulin differs from growth hormone in that it

(a) stimulates lipoprotein lipase in vicinity of fat cells
(b) increases the transport of amino acids across the cell membranes of muscles
(c) increases mRNA/ribosome acitivity
(d) stimulates hormone sensitive lipase in fat cells

29. The gland that regresses with age is
(a) adrenal
(b) gonad
(c) thymus
(d) thyroid

30. Melatonin is produced by
(a) thymus
(b) skin
(c) pituitary
(d) pineal gland

31. Melanocyte stimulating hormone (MSH) is produced by
(a) parathyroid
(b) pars intermedia of pituitary
(c) anterior pituitary
(d) posterior pituitary

32. Progesterone, the component of the oral contraceptive pills, prevents pregnancy by

(a) preventing the cleavage of the fertilized egg
(b) preventing the formation of ova
(c) blocking ovulation

(d) creating unfavourable chemical environment for the sperms to survive in the female reproductive tract

33. Melanin protects us from
(a) U. V. rays
(b) visible rays
(c) infrared rays
(d) X-rays

34. Mainly which type of hormones control the menstrual cycle in human beings?
(a) FSH
(b) LH
(c) FSH, LH, estrogen
(d) Progesteron

35. When both ovaries are removed from rat then which hormone is decreased in blood?
(a) Oxytocin
(b) Prolactin
(c) Estrogen
(d) Gonadotropin releasing factor

36. Adrenaline directly affects on
(a) S. A. node
(b) b-cells of Langerhans
(c) dorsal root of spinal cord
(d) epithelial cells of stomach

37. Acromegaly is caused by
(a) excess of G.H.
(b) excess of thyroxin
(c) deficiency of thyroxin
(d) excess of adrenalin

38. Which steroid is used for microbial
transformation?

(a) Cortisol
(b) Cholesterol
(c) Testosterone
(d) Progesterone

39. Which one of the following pairs correctly matches a hormone with a disease resulting from its deficiency?
(a) Insulin – Diabetes insipidus
(b) Relaxin – Gigantism
(c) Prolactin – Cretinism
(d) Parathyroid hormone – Tetany

40. Chemically hormones are
(a) biogenic amines only
(b) proteins, steroids and biogenic amines
(c) proteins only
(d) steroids only

41. Which one of the following pairs correctly matches a hormone with a disease resulting from its deficiency?

(a) Luteinizing – Failure of ovulation
(b) Insulin – Diabetes insipidus
(c) Thyroxine – Tetany
(d) Parathyroid – Diabetes mellitus

42. Which of the following hormones is not a secretion product of human placenta?
(a) Human chorionic gonadotropin
(b) Prolactin
(c) Estrogen
(d) Progesterone

43. Which one of the following hormones is a modified amino acid?
(a) Epinephrine
(b) Progesterone
(c) Prostaglandin
(d) Estrogen

44. Parkinson‘s disease (characterized by tremors and progressive rigidity of limbs) is caused by degeneration of brain neurons that are involved in movement control and make use of neurotransmitter
(a) acetylcholine
(b) norepinephrine
(c) dopamine
(d) GABA

45. Sertoli cells are regulated by the pituitary hormone known as
(a) GH
(b) Prolactin
(c) LH
(d) FSH

46. A steroid hormone which regulates glucose metabolism is
(a) corticosterone
(b) 11- deoxycorticosterone
(c) cortisone
(d) cortisol

47. Which one of the following is not a second messenger in hormone action?
(a) Calcium
(b) Sodium
(c) cAMP
(d) cGMP

48. Which one of the following does not act as a neurotransmitter?
(a) Epinephrine
(b) Norepinephrine
(c) Cortisone
(d) Acetylcholine

49. Which of the following is an accumulation and release centre of neurohormones?
(a) Intermediate lobe of the pituitary
(b) Hypothalamus
(c) Anterior pituitary lobe
(d) Posterior pituitary lobe

50. Which hormone causes dilation of blood vessels, increased oxygen consumption and glucogenesis?
(a) Insulin
(b) Adrenaline
(c) Glucagon
(d) ACTH

51. Which one of the following statement is correct ?

(a) Endocrine glands regulate neural activity and system regulates endocrine glands

(b) Neither hormones control neural activity nor the neurons control endocrine activity.

(d) Neurons regulate endocrine activity , but not vice versa

52. Which part of ovary in mammals acts as an endocrine gland after ovulation?
(a) Stroma
(b) Germinal epithelium
(c) Vetelline membrane
(d) Graafian follicle.

53. A person is having problems with calcium and phosphorus metabolism in his body. Which one of following glands may not be functioning properly?
(a) Parotid
(b) Pancreas
(c) Thyroid
(d) Parathyroid

54. Feeling the tremors of an earthquake a scared resident of seventh floor of a multistored building starts climbing down the stairs rapidly. Which hormone initiated this action?
(a) adrenaline
(b) glucagon
(b) gastrin
(d) thyroxine

55. The blood calcium level is lowered by the deficiency of
(a) parathormone
(b) thyroxine
(c) both calcitonin and parathormone
(d) calcitonin

56. Which one of the following pairs of organs includes only the endocrine glands?
(a) Parathyroid and Adrenal
(b) Pancreas and Parathyroid
(c) Thymus and Testes
(d) Adrenal and Ovary

57. A health disorder that results from the deficiency of thyroxine in adults and characterised by (i) a low metabolic rate, (ii) increase in body weight and (iii) tendency to retain water in tissues is:
(a) simple goitre
(b) myxoedema
(c) cretinism
(d) hypothyroidism

58. Injury to adrenal cortex is not likely to affect the secretion of which one of the following?
(a) Aldosterone
(b) Both Androstenedione and
Dehydroepiandrosterone
(c) Adrenaline
(d) Cortisol

59. Low Ca++ in the body fluid may be the cause of:
(a) tetany
(b) anaemia
(c) angina pectoris
(d) gout

60. Which one of the following pairs is incorrectly matched?
(a) Glucagon – Beta cells (source)
(b) Somatostatin – Delta cells (source)
(c) Corpus luteum – Relaxin (secretion)
(d) Insulin – Diabetes mellitus (disease)

61. Toxic agents present in food which interfere with thyroxine synthesis lead to the development of:
(a) toxic goitre
(b) cretinism
(c) simple goitre
(d) thyrotoxicosis

62. Match the source gland with the respective hormone as well as function correctly Source gland – Hormone – Function

(a) Anterior pituatory – Oxytocin – Contraction of uterus muscles during child birth

(b) Posterior pituitary –vasopressin—Stimulates reabsorption of water in the distal tubules in the nephron.
(c) Corpus luteum — Estrogen — Supports pregnancy
(d) Thyroid — Thyroxine –Regulates blood calcium level

63. Which of the following represents the action of insulin?

(a) Increase blood glucose levels by hydrolys is of glycongen

(b) Increase blood glucose levels by stimulating glucagon production

(d) Thyroid – Thyroxine – Regulates blood calcium Test

64. The 24 hour (diurnal) rhythm of our body such as the sleep-wake cycle is regulated by the hormone:
(a) calcitonin
(b) prolactin
(c) adrenaline
(d) melatonin

65. Which one of the following pairs of hormones are the examples of those that can easily pass through the cell
membrane of the target cell and bind to a receptor inside it (Mostly in the nucleus)
(a) Insulin, glucagon
(b) Thyroxin, insulin
(c) Somatostain, oxytocin
(d) Cortisol, testosterone

66. What is correct to say about the hormone action in humans
(a) Glucagon is secreted by β-cells of islets of Langerhans and stimulates glycogenolysis
(b) Secretion of thymosins is stimulated with ageing
(c) In females FSH first binds with specific receptors on ovarian cell membrane
(d) FSH stimulates the secretion of estrogen and progesterone

67. F2 generation in a Mendelian cross showed that both genotypic and phenotypic ratios are same as 1: 2: 1. It represents a case of:
(a) Co-dominance
(b) Dihybrid cross

(d) Monohybrid cross with incompletes dominance

68. Which of the following statements is correct in relation to the endocrine system?
(a) Organs in the body like gastrointestinal tract, heart, kidney and liver do not produce any hormones.
(b) Non-nutrient chemicals produced by the body in trace amount that act as
(d) Adenohypophysis is under direct neural regulation of the hypothalamus.

69. A pregnant female deliver a baby who suffers from stunted growth, mental retardation/low intelligence quotient and abnormal skin. This is the result of:
(a) Low secretion of growth hormone
(b) Cancer of the thyroid gland
(c) Over secretion of pars distalis
(d) Deficiency of iodine in diet

70. The blood calcium level is lowered by the deficiency of
(a) parathormone
(b) thyroxine
(c) both calcitonin and parathormone
(d) calcitonin

71. Which of the following represents the action of insulin?

(a) Increase blood glucose levels by hydrolysis of glycogen

(b) Increase blood glucose levels by stimulating glucagon production

(d) Increase blood glucose level by promoting cellular uptake of glucose

72. Norepinephrine: (1) Is released by sympathetic fibres (2) Is released by parasympathetic fibres (3) Increases the heart rate (4) Decreases blood pressure Which of the above said statements are correct?
(a) (1) and (4)
(b) (1) and (3)
(c) (2) and (3)

(d) (2) and (4)

73.Hormones thyroxine, adrenaline and the pigment melanin are formed from

(a) tryptophan

(b) tyrosine

(d) prolline

74.GnRH, a hypothalamic hormone, needed in reproduction, acts on

(a) anterior pituitary gland and stimulates secretion of LH and FSH

(b) posterior pituitary gland and stimulates secretion of oxytocin and FSH

(d) anterior pituitary gland and stimulates secretion of LH and oxytocin

75.The pituitary gland by virtue of its tropic hormones controls the secretory activity of other endocrine glands. Which one of the following endocrine gland can function independently of the pituitary gland?

(a) Gonads

(b) Thyroid

(d) Parathyroid

76. Graves’ disease is caused due to

(a) hyposecretion of adrenal gland

(b) hypersecretion of adrenal gland

(d) hypersecretion of thyroid gland

77. Which of the following pairs of hormones are not antagonistic (having opposite effects) to each other?

(a) Aldosterone Atrial Natriuretic Factor

(b) Relaxin Inhibin

(d) Insulin Glucagon

78. Which of the following statements regarding glucagon is false?

(a) It is secreted by a -cells of Langerhans.

(b) It acts antagonistically to insulin.

(d) The gland responsible for its secretion is heterocrine gland.

79. Which A person entering an empty room suddenly finds a snake right in front on opening the door. Which one of the following is likely to happen in his Neurohormonal control system?

(a) Sympathetic nervous system is activated releasing epinephrine and norepinephrine from adrenal medulla.

(b) Neurotransmitters diffuse rapidly across the cleft and transmit a nerve impulse.

(d) Sympathetic nervous system is activated releasing epinephrine and norepinephrine from adrenal cortex.

80. The amino acid tryptophan is the precursor for the synthesis of

(a) melatonin and serotonin

(b) estrogen and progesterone

(d) thyroxine and triiodothyronine

81. Which one of the following hormones though synthesised elsewhere, is stored and released by the master gland?

(a) Melanocyte stimulating hormone

(b) Antidiuretic hormone

(d) Luteinising hormone

82. Fightor flight reactions cause activation of

(a) the parathyroid glands, leading to increased metabolic rate

(b) the kidney, leading to suppression of renin angiotensinaldosterone pathway

(d) the pancreas leading to a reduction in the blood sugar levels

83. Addison’s disease result from

(a) hyposecretion of adrenal gland

(b) hypertrophy of kidney

(d) hyposecretion of gonads

84. A pregnant female delivers a baby who suffers from stunted growth, mental retardation, low intelligence quotient and abnormal skin. This is the result of

(a) deficiency of iodine in diet

(b) low secretion of growth hormone

(d) oversecretion of pars distalis

85. Secretion of progesterone by corpus luteum is initiated by

(a) thyroxine

(b) MSH

(d) testosterone

86. Which of the following statements is correct in relation to the endocrine system?

(a) Adenohypophysis is under direct neural regulation of the hypothalamus.

(b) Nonnutrient chemicals produced by the body in trace amounts that act as intercellular messenger are known as hormones.

(d) Organs in the body like gastrointestinal tract, heart, kidney and liver do not produce any hormones

87. Norepinephrine

(i) is released by sympathetic fibers

(ii) is released by parasympathetic fibers

(iii) increases the heart rate

(iv) decreases blood pressure.

Which of the above statements are correct?

(a) (ii) and (iv)

(b) (i) and (iii)

(d) (i) and (iv)

88. Which hormone possesses anti-insulin effect?

(a) Cortisol

(b) Aldosterone

(d) Oxytocin

89. According to the accepted concept of hormone action, if receptor molecules are removed from target organs, then the target organ will

(a) continue to respond to the hormone without any difference

(b) not respond to the hormone

(d) continue to respond to the hormone but in the opposite way.

90. Which one of the following pairs correctly matches a hormone with a disease resulting from its deficiency ?

(a) Luteinising hormone – Failure of

ovulation

(b) Insulin – Diabetes insipidus

(d)Parathyroid hormone – Diabetes mellitus

91. How does steroid hormone influence the cellular activities?

(a) Changing the permeability of the cell membrane

(b) Binding to DNA and forming a genehormone complex

(d) Using aquaporin channels as second messengers

92. Toxic agents present in food which interfere with thyroxine synthesis lead to the development of

(a) simple goitre

(b) thyrotoxicosis

(d) cretinism

93. A decrease in blood pressure / volume will not cause the release of :

(a) Atrial natriuretic factor

(b) Aldosterone

(d) Renin

94. GnRH, a hypothalamic hormone, needed in reproduction, acts on:

(a) anterior pituitary gland and stimulates secretion of LH and FSH.

(b) posterior pituitary gland and stimulates secretion of oxytocin and FSH.

(d) anterior pituitary gland and stimulates secretion of LH and oxytocin.

95. Hypersecretion of Growth Hormone in adults does not cause further increase in height, because:

(a) Epiphyseal plates close after adolescence.

(b) Bones loose their sensitivity to Growth Hormone in adults.

(d) Growth Hormone becomes inactive in adults.

96. Which of the following is an amino acid derived hormone?

(a) Epinephrine

(b) Ecdysone

(d) Estradiol

97. Which of the following hormones can play a significant role in osteoporosis?

(a) Aldosterone and Prolactin

(b) Progesterone and Aldosterone

(d) Estrogen and Parathyroid hormone

98. How does steroid hormone influence the cellular activities?

(a) Changing the permeability of the cell membrane

(b) Binding to DNA and forming a genehormone complex

(d) Using aquaporin channels as second messenger

99. Match the following columns and select the correct option.

Column-I Column-II

(a) Pituitary gland (i) Grave’s disease

(b) Thyroid gland (ii) Diabetes mellitus

(d) Pancreas (iv) Addison’s disease

(a) (b) (c) (d)

(1) (iii) (i) (iv) (ii)

(2) (ii) (i) (iv) (iii)

(3) (iv) (iii) (i) (ii)

(4) (iii) (ii) (i) (iv)

100. Select the correct statement.

(a) Insulin acts on pancreatic cells and adipocytes.

(b) Insulin is associated with hyperglycemia.

(d) Glucagon is associated with hypoglycemia.

101. Erythropoietin hormone which stimulates R.B.C. formation is produced by:

(a) Juxtaglomerular cells of the kidney

(b) Alpha cells of pancreas

(d) The cells of bone marrow

1.Solution: (a)Melanocyte-stimulating hormone (MSH) or Melanotropin is secreted by the intermediate lobe of adenohypophysis (pars
intermedia) of pituitary gland in mammals (other than man) so named ‗intermedin‘. In lower vertebrates, it targets chromatophores& does wider distribution of the melanin grannules in chromatophores, so that the skin colour darkens. In birds & human beings and other mammals its role is uncertain but in man it is probably responsible for bronzing of skin, moles etc.
2.Solution: (a)Cortisol is secreted by the middle region of adrenal cortex. It increases the blood glucose level (which is anti-insulin effect) by converting proteins & fats into glucose.
3.Solution: (b) In 1912, Gudernatsch discovered that metamorphosis in frog‘s tadpole is controlled by the thyroxine hormone which
has the iodine as the main constituent. If thyroxin or iodine is added in water having tadpoles in it, then it increases the rate of metamorphosis in tadpole.
4.Solution: (c)Insulin is a hormone secreted by the bcells of pancreas and it controls the sugar level in blood.
5.Solution: (d)Leydig‘s cells are present in testes and they secrete male hormone testesterone. Small groups of polygonal, large cells present in the connective tissue in between the seminiferous tubules are known as Leydig‘s cells are interstitial cells. They secret male sex hormone testosterone.
6.Solution: (b)ADH: Antidiuretic hormone – vasopressin in secreted by neurohypophysis (posterior lobe) of pituitary gland. This hormone
increases the reabsorption of water from the urine and hence urine gets concentrated and ECF gets diluted. Diabetes insipidus caused by the
hyposecretion of ADH.
7.Solution: (a)Enterogastrone secreted by the mucosa of duodenum slows gastric contractions and stops the secretion of gastric juice.
8.Solution: (b)Leydig‘s cells.
9.Solution: (d)Male hormones are secreted by the Interstitial or Leydig‘s cells present in the stroma of connective tissue in between the
seminiferous tubules in testis. They produce androgens (mainly testosterone) Sertoli cells are elongated epithelial cells present inside the seminal vesicle to nourish the growing spermatozoa.
10.Solution: (a)Luteinizing Hormone (LH) induces the Leideyg‘s cells in males to produce testesterone and in female it causes ovulation and secretion of female sex hormone estrogen from mature ovarian follicle & progesterone by corpus luteum.
11.Solution: (c)Enterogastrone is a hormone released by the upper intestinal mucosa that inhibits gastric orotility and secretion.motility and
secretion.
12.Solution: (a)Ovulation occurs under the influence of luteinizing hormone-LH secreted by the anterior lobe of pituitary.
13.Solution: (b)

Solutions :14.Mammalian corpus luteum produces progesterone. It is essential for the continuation of pregnancy and it also stimulates acini glands.

Solution: (b)Nicotine and acetylcholine have the same receptors-Nicotinic cholinergic receptors and hence have the same action.
15.Solution: (d)The thyroid gland stores its hormone secretion thyroglobulin in its follicles called extracellular space before discharing it into
the blood.
16.Solution: (a)The hormones in blood act on specific sites or receptors of target organ. So if we remove the receptor molecule from the
target organs, there will be no response.
17.Solution: (a)Iodine is an element used by thyroid gland for the synthesis of thyroid hormones. Thus radioactive isotope Iodine -131 is used as
radioactive material for detection of thyroid cancer.
18.Solution: (b)Prolactin is a proteinaceous hormone released by anterior lobe of pituitary. Prolactin supplements the action of gonadal hormones in stimulating the growth and activity of female mammary gland during pregnancy and lactation. Oxytocin released by the posterior lobe of
pituitary gland, is important for the mechanism of ejection of milk from the mammary glands due to sucking of breasts by infant. Progesterone, released by corpus luteum brings about pregnancy changes such as uterine growth, implantation of embryo etc. Relaxin is a proteinaceous
hormone secreted by corpus luteum towards the end of gestation period for loosening and softening of pelvic ligaments,relaxing of uterus for easing parturition.
19.Solution: (c)According to the immunity theory ageing occurs due to the loss of power of defence against the invasion of germs and
pathogens. The process starts with the gradual atrophy and disappearance of the thymus gland during middle age.
20.Solution: (d)Oxytocin also known as pitocin. It is an important hormone which is released in neurohypophysis of pituitary. It stimulate
the contraction of smooth muscles. It stimulate labour pain and also increase labour pain. It is a hormone for quick birth.1Its more secretion results in parturition.
21.Solution: (c)The amino acid glycine forms porphyrin ring in chlorophyll and haeme proteins like haemoglobin. Tryptophan gives rise to
plant hormone indole- 3 – acetic acid.
22.Solution: (a)Calcitonin is a polypeptide hormone which lowers calcium and phosphate level of plasma by inhibiting bone degradation and
stimulating their uptake by bone parathyroid harmone elevates calcium level in blood.
23.Solution: (d)Use of contraceptive pills is a wide spread form of birth control. contraceptive pills contain estrogen and progesterone. The
production of the pituitary hormones FSH & LH in the normal sexual cycle of a female is shut down by these hormones. In theabsence of FSH, the ovarian follicles do not ripe and ovulation does not occur in the absence of LH.
24.Solution: (a) Parathormone released by the parathyroid gland elevates the level of Ca2+ in blood. The deficiency of this hormone lowers blood
Ca2+. As a result, the excitability of muscles and nerves increases producing tetany – sustained contraction.
25.Solution: (b) Oxytocin is also called the ‗child birth hormone‘. Prolactin helps in lactation. Luteinizing hormone levels trigger ovulation.
26.Solution: (d)Electroencephalogram is the recording of electric potentials originating from different parts of the brain in the form of waves.
Fractionation is the technique of rupturing cells and separating their components especially cell organelles for studying their chemistry and functions. Electrophoresis is the technique of separation of charged solutes on the basis of their differential migration in an applied electric field.
27.Solution: (c)Progesterone is a steroid hormone secreted by corpus luteum and causes routine temporary changes in the endometrial
lining of uterus. Follicle stimulating hormone secreted by anterior pituitary lobe males. Luteinizing hormone activates Leydig‘s cells of testes to secrete testosterones.
28.Solution: (d)Insulin is released from the pancreas it helps in conversion of glucose to fatty acids. It increases fat synthesis in adipose
tissues.
29.Solution: (c)Thymus gland is present in children with maximum development at puberty and thereafter it begins to shrink and atrophies
with the development of sex glands.
30.Solution: (d)Melatonin is secreted by pineal gland present between the cerebral hemispheres. Melatonin concentration in blood follows a
diurnal cycle, it rises in the evening and drops at noon. Melatonin lightens skin colour in certain animals and regulates working of gonads.
31.Solution: (b)Parathyroid gland secretes parathormone which regulates Ca2+ level in blood. Anterior lobe of pituitary secretes the following
hormones growth hormone, ACTH, TSH, FSH, LH. Posterior pituitary secretes vasopressin and oxytocin. The intermediate lobe (pars intermedium) of the pitutary gland secretes MSH which causes dispersal of pigment granules in the pigment cells which give colour to the skin
32. Progesterone, the compoment of the oral contraceptive pills, prevents preganancy by

(a) Preventing the cleavage of the fertilizers egg

(b) preventing the formation of ova

(d) cremating unfavourable chemical environment for the sperms to survive in the female reproductive tract
33.Solution: (a)Melanin is secreted from the intermediate lobe of pituitary. Melanin mainly protects the skin from harmful effects of UV-rays.
People living in tropics tend to disperse more melanin in their skin – an adaptive feature.
34.Solution: (c)Estrogens are steroid hormones secreted by growing ovarian follicles. During menstrual cycle a negative feedback
prevents the over secretion of estrogen. FSH stimulates maturation of Graafian follicles. LH stimulates ovulation and development of corpus luteum.
35.Solution: (c)Estrogen is released from the ovarian follicles. Oxytocin is secreted by posterior pituitary and prolactin is released by
anterior pituitary. Gonadotropin releasing factor is produced by hypothalamus.

36. Solution: (a)Adrenaline is a neurotransmitter that directly acts on the S A node. The hormone adrenaline (epinephrine) is secreted by
adrenal medulla. This was first hormone to be isolated in crystalline form. This hormone is primarily responsible for the alarming reactions. It increases the heart rate, breathing blood glucose level.
37.Solution: (a)Deficiency of thyroxin causes cretinism ininfants and myxoedema in adults. Excess of adrenalin does not cause any disorder.
Acromegaly is caused by over secretion of STH or somatotrophic hormone (Growth hormone).
38.Solution: (b)Microbial transformation is a biological process in which organic compounds are modified into reversible products. These
biotransformation reactions are catalysed by purified enzymes present in microbial cells or pure cullures of microorganisms.Cholesterol forms a major component of animal cell membranes liposomes (artificially created spheres surrounded by a phospholipid bilayer like a membrane).
Cholesterol is used for microbial transformation (transgenics).
39.Solution: (d)Deficiency of parathyroid hormone causes tetany. The disease causes sustained contraction of muscles of larynx, face,
hands and feet.
40.Solution: (b)Hormones are chemical messengers formed by endocrine cells. Chemically hormones are of the following types:Amines–composed of amino group e.g.,Melatonin. Amino acids – eg. thyroxine Peptides – eg. insulin Steroids – eg.aldosterone
41.Solution: (a)Luteinizing hormone (LH) stimulates ovulation. Deficiency of insulin causes diabetes mellitus. Deficiency of ADH or
vasopressin causes diabetes insipidus.Deficiency of parathormone causes tetany.Deficiency of thyroxine causes cretinism in infants and myxoedema in adults.
42.Solution: (b)Human chorionic gonadotropin is released by Anophoblast cells of the placenta.Estrogen and progesterone are also
released by placental cells to maintain pregnancy. Prolactin is secreted from anterior lobe of pituitary. Placenta secretes Human Placental Lactogenic Factor which prepare mammary glands to secrete milk.
43.Solution: (a)Epinephrine is synthesized from amino acid tyrosine. While estrogen and progesterone are modified steroids and prostaglandins are basically fat.
44.Solution: (c)Parkinson‘s disease (Paralysis agitans) (i) It develops due to deficiency of neuro transmitter, dopamine. The dopamine is
not produced due to gradual destruction of neurons in the substantia nigra. (ii) It produces muscle tremors so called shaking palsy. (iii) There is lack of control and coordination of movements resulting in expression less face and stooping posture which gradually produces physical
disability.
45.Solution: (d)During spermatogenetic developments spermatids get nourished by nurse or sertoli cells. The function of sertoli cells
and hence the spermatogenesis is under the direct influence of folliclestimulating hormone (FSH) secreted by adenohypophyses of pituitary gland.
46. Solution: (d)Cortisole is the steroid hormone secreted by adrenal cortex and plays an important role in carbohydrate metabolism. It retards
the glucose consumption & hence level of glucose in blood increases & blood pressure increases.
47.Solution: (b)In heart cells AMP acts as secondary messenger which is made in the response of adrenaline and it stimulates Ca2+ ions to
come out from the sarcoplasmic reticulum of muscle fibres which causes muscle contraction. cGMP (Cyclic Guanosine Monophosphate) which acts as secondary messenger works on the action of acetylcholine, increase in flow of Ca2+ into muscle fibres & hence causes muscle
relaxation. There is no role of sodium in hormonal action.
48.Solution: (c)Epinephrine or adrenaline, norepinephrine or noradrenaline and acetylchloline are the neurotransmitters. These are released by
the nerve fibres to transmit the impulse to the next neurone. Cortisone is not the neurotransmitter.
49.Solution: (d) Neurohormones are actually secreted by the neurosecretory cells of the hypothalamus. They are circulated to the posterior part of the pituitary gland through the blood & stored there and released when required.
50.Solution: (b) Adrenaline (called Frieght-Flight-Fight hormone) in responsible for the dilation of blood vessels, increased oxygen consumption by tissues &glucogenesis to prepare the body for emergency reactions under the threatening conditions.

51.Solution: (a)Endocrine glands regulate neural activity as endocrine glands secrete epinephrine & norepinephrine which have their effects on
neuron activity. On the other hand neuron also controls the activity of endocrine glands by secreting neurohormones which regulate the activity of many endocrine glands.
52.Solution: (d)Graafian follicle – the ovarian medulla contains many rounded or oval bodies, called ovarian, or grafian follicles, at various stages of development. Each follicle contains a large ovum surrounded by many layers of follicle cells.
53.Solution: (d)Parathyroid disorders : it causes the lowering of blood calcium level. This increases the excitability of nerves and
muscles causing cramps and convulsions.
54.Solution: (a)It is commonly called as ‗emergency hormone‘ or 3F – hormone (For fear, fight & flight). Its secretion is regulated by SNS,
and not by pituitary as in case of adrenal cortex. It stimulates sweating, heart beat and breathing rate. It causes the dilation of coronary artery (supplying blood to the heart muscles), bronchioles (for increasing inspiratory volume) and pupil (for better vision).
55.Solution: (a) A peptide hormone secreted by the parathyroid gland in response to low levels of calcium in the blood. It acts to maintain
normal blood levels of calcium by increasing the number of osteoclasts, which break down the bone matrix and release calcium into the blood. It also increases the reabsorption of calcium and magnesium ions in the kideny tubules, so that their concentration is maintained in the blood.
56.Solution: (a)Parathyroid and adrenal are the endocrine glands. Adrenal glands are the pairs of endocrine glands situated immediately
above the kidneys. Hence they are also known as suprarenal glands. Parathyroid glands are the two pairs of endocrine glands -situated behind or embedded within, the thyroid gland in higher vertebrates. They produce parathyroid hormone, which controls the amount of calcium in the blood.
57.Solution: (b)Myxoedema is caused by deficiency of thyroid hormone or thyroxine in adults. It is characterised by increase in body weight,
puffy appearance, low metabolic rate, and tendency to retain water in tissues.
58.Solution: (c)Adrenal gland has two parts-cortex and medulla. The medulla is stimulated by sympathetic nervous tissue to produce
adrenaline and non-adrenaline while the cortex is stimulated by pituitary hormone to release cortisol, aldosterone and estrogens. Thus injury to adrenal cortex is not likely to affect the secretion of adrenaline.
59.Solution: (a) Tetany is caused by reduction in the calcium level due to underactive parathyroid hormone.
60.Solution: (a) Glucagon is secreted by a-cells of the islets of Langerhans in the pancreas. It increases the concentration of glucose in the blood by stimulating the breakdown of glycogen.
61.Solution: (c) Goitre is caused by deficiency of iodine in diet. Iodine is needed for the synthesis of thyroxine. Toxic agents present in food
interfere with thyroxine synthesis and lead to goitre.

62.Solution: (b)Posterior pituitary releases vasopressin which stimulates reabsorption of water in the distal tubules in nephron.
63.Solution: (c)Insulin is a peptide hormone, which plays a major role in the regulation of glucose homeostasis. Insulin acts mainly on
hepatocytes and adipocytes (cells of adipose tissue), and enhances cellular glucose uptake and utilization. Insulin also stimulates conversion of glucose to glycogen (glycogenesis) in the target cells.
64.Solution: (d)Melatonin is a hormone that regulates the 24 hour rhythm of our body such as the sleep-wake cycle etc. Melatonin is produced
by pineal gland in the brain, which is responsible for operation and regulation of the biological clock in mammals.
65.Solution: (d)Cortisol and testosterone are steroid hormones which are lipid soluble and easily pass through the cell membrane of a
target cell and bind to specific intracellular receptor.
66.Solution: (c)Glucagon is secreted by α cells of islets of langerhans and stimulate glycogenolysis i.e. breakdown of glycogen into glucose
Thymosin hormone secreted from thymus gland stimulates the development of certain kinds of white blood cells involved in producing immunity. It also hostens attainment of sexual maturity.
67.Solution: (d)Incomplete (partial or mosaic) dominance is the phenomenon where none of the two contrasting alleles or factors is dominant.
The expression of the character in a hybrid or F1 individual is intermediate or a fine mixture of the expression of the two factors (as found in homozygous state). Incomplete or mosaic inheritance is not an example of pre-mendelian concept of blending inheritance because the parental types reappear in the F2 generation. It is however, considered by some workers to be an example of quantitative inheritance where only a single gene pair is involved. F2 phenotypic ratio is 1: 2: 1, similar to genotypic ratio. (i) Crl incomplete dominance is reported in flowers of Four
O‘Clock or Mirabilis jalapa and Antirrhinum majus (Snapdragon or Dog flower).
68.Solution: (b)Hormones are non-nutrient chemicals which act as intercellular messengers and are produced in trace amounts. Gastrointestinal tracts secretes four major peptide hormones – gastrin, secretin,cholecystokinin (CCK) and gastric inhibitory peptide (GIP) while juxtaglomerular cells of kidney secretes erythropoietin, a peptide hormone. Releasing and inhibitory hormones are produced by hypothalamus. Neurohypophysis or posterior pituitary is under direct neural regulation of the hypothalamus.
69. Solution: (d)Iodine is essential for the normal rate of hormone synthesis in the thyroid. Deficiency of iodine in our diet results in hypothyroidism and enlargement of the thyroid gland, commonly called goitre. Hypothyroidism during pregnancy causes defective development and maturation of the growing baby leading to stunted growth (cretinism), mental retardation, low intelligence quotient, abnormal skin, deafmutism, etc.
70.Solution: (a)A peptide hormone secreted by the parathyroid gland in response to low levels of calcium in the blood. It acts to maintain
normal blood levels of calcium by increasing the number of osteoclasts, which break down the bone matrix and release calcium into the blood. It also increases the reabsorption of calcium and magnesium ions in the kideny tubules, so that their concentration is maintained in the blood.
71.Solution: (c)Insulin is a peptide hormone, which plays a major role in the regulation of glucose homeostasis. Insulin acts mainly on
hepatocytes and adipocytes (cells of adipose tissue), and enhances cellular glucose uptake and utilization. Insulin also stimulates conversion of glucose to glycogen (glycogenesis) in the target cells.
72.Solution: (b)Norepinephrine is released by sympathetic fibres i.e, rapidly secreted in response to stress of any kind and during emergency
situations. It increases the heart beat, the strength of heart contraction and the rate of respiration. :

73.(b) Hormones thyroxine, adrenaline and the pigment melanin are formed from tyrosine. Tyrosine is a non-essential amino acid. In animals it is synthesized from [phenylalanine]. It is also the precursor of [epinephrine], thyroid hormones, and melanin.

74.(a) Hypothalamus secretes GnRH which stimulates anterior pituitary gland for the secretion of gonadotropins (FSH and LH).

75.(d) Parathyroid gland is not controlled by pituitary. The parathormone which secrets from this gland regulates calcium and phosphorus ion in body.Parathyroid glands are four small glands of the endocrine system which regulate the calcium in our bodies. Parathyroid glands are located in the neck behind the thyroid where they continuously monitor and regulate blood calcium levels

76.(b) Grave’s disease is caused by hypersection of thyeoxine.

77.(b) Relaxin – inhibin

78.(c) When glucose builds up in your bloodstream, your blood glucose (blood sugar) levels rise

79.(a) Sympathetic nervous system is activated releasing epinephrine and norepinephrine from adrenal medulla.

80.(a) Tryptaphan is the precursor of synthesis of melatonin and serotonin.

81.(b) Two hormones viz oxytocin (OT) and antidiuretic hormone (ADH) are synthesised in the hypothalamus, but stored and released by the posterior lobe of pituitary gland.

82.(c) Fight or flight reaction is a physiological reaction that occurs is response to emergency. Emergency hormone is secreted by adrenal medulla of adrenal gland. Adrenal medulla secretes epinephrine and non-epinephrine commonly called catecholamines hormones which stimulates sweating, heartbeat and breathing rate. These hormones also causes dilation of coronary artery (supplying blood to heart muscles) a bronchioles ( for increasing inspiratory volume) and pupil ( for better vision).

83.(a) Hyposecretion of the glucocorticoid hormone cortisol leads to a disorder called Addison’s disease. There may also be hyposecretion of mineralocorticoids with this disorder.

84. (a) deficiency of iodine in diet

85.(b) LH (Luteinising Hormone), secreted by anterior pituitary, stimulates the corpus luteum to secrete the hormone progesterone.

86.(b) Hormones are non-nutrient chemicals, which act as intracellular messengers and are produced in trace amounts. Endocrine cells are present in different parts of the gastrointestinal tract, e.g., gastric, secret in, GIP. Atrial wall of our heart secretes a peptide hormone called ANF (Atrial Natriuretic Factor), RH/IH are produced by hypothalamus. Adenohypophysis is not directly under neural control, it is under the control of hypothalamic hormones, brought by portal system.

87.(b) Norepinephrine is a naturally occurring chemical in the body that acts as both a stress hormone and neurotransmitter (a substance that sends signals between nerve cells). It’s released into the blood as a stress hormone when the brain perceives that a stressful event has occurred. Together with adrenaline, norepinephrine increases heart rate and blood pumping from the heart. It also increases blood pressure and helps break down fat and increase blood sugar levels to provide more energy to the body.

88.(a) Cortisol is a glucocorticoid, secreted by adrenal cortex. It is primarily meant for carbohydrate metabolism, which increases the rate of gluconeogenesis (conversion of proteins in liver into sugars) and decreases peripheral utilisation of glucose, thus it possess anti-insulin effect.

89.(b) The molecules of hormones that are amino acid derivatives, peptides or proteins are large and insoluble in lipids, and cannot enter the target cell. Therefore, they act at the cell surface. They bind to specific receptor molecules located on the surface of the cell membrane. Therefore, if receptor molecules are removed from target organs, then the target organ will not respond to the hormone.

90. (a)

Disease	Deficiency
Diabetes mellitus	Insulin
Tetany	Parathormone
Diabetes insipid	ADH

91(d) Steroid hormones directly enter into the cell and bind with intracellular receptors in nucleus to form hormone receptor complex.
Hormone receptor complex interacts with the genome.

92(a) Simple goitre is caused by deficiency of iodine in diet because iodine is needed for the synthesis of thyroid hormone. Toxic agents present in the food may also interfere with thyroxine (thyroid hormones) synthesis. It causes thyroid enlargement. It may lead to cretinism or myxoedema. This disease is common in hilly areas.

93 (a)A decrease in blood pressure / volume stimulates the release of renin, aldosterone, and ADH while increase in blood pressure / volume stimulates the release of Atrial Natriuretic FactorAtrial natriuretic factor is a 28 amino acid polypeptide hormone secreted mainly by the heart atria in response to atrial stretch. ANF acts on the kidney to increase sodium excretion and GFR, to antagonize renal vasoconstriction, and to inhibit renin secretion.

94.(a)Gonadotropin hormone-releasing hormone (GnRH) is the key regulator of the reproductive axis. Its pulsatile secretion determines the pattern of secretion of the gonadotropins follicle stimulating hormone and luteinising hormone, which then regulate both the endocrine function and gamete maturation in the gonads.

95.(a)GH hypersecretion results in gigantism or acromegaly, a condition associated with significant morbidity and mortality, while GH deficiency results in growth retardation in children and the GH deficiency syndrome in adults.Epiphyseal plates are composed of the hyaline cartilage. It is present at the end of the long bones. The bones stops growing at early adulthood, due to the closure of epiphyseal plates.

96 (a)amino acid-derived hormones include epinephrine and norepinephrine, which are synthesized in the medulla of the adrenal glands, and thyroxine, which is produced by the thyroid gland. The pineal gland in the brain makes and secretes melatonin which regulates sleep cycles.Epinephrine, also known as adrenaline, is a medication and hormone. As a medication, it is used to treat a number of conditions, including anaphylaxis, cardiac arrest, asthma, and superficial bleeding. Inhaled epinephrine may be used to improve the symptoms of croup

97 (d)Osteoporosis is a bone disease that occurs when the body loses too much bone, makes too little bone, or both. As a result, bones become weak and may break from a fall or, in serious cases, from sneezing or minor bumps. Osteoporosis means “porous bone.” Viewed under a microscope, healthy bone looks like a honeycomb.Estrogen is a sex hormone that is essential to female bone health because it promotes the activity of osteoblasts, which are cells that produce bone. When estrogen levels drop during menopause, the osteoblasts aren’t able to effectively produce bone.Parathyroid hormone (PTH) increases bone formation and thereby improves bone density and bone strength in postmenopausal women with osteoporosis

98 (b)A steroid hormone is a steroid that acts as a hormone. Steroid hormones directly enter into the cell and bind with intracellular receptors in nucleus to form hormone receptor complex.

99(1)• Pituitary gland—Diabetes insipidus
• Thyroid gland—Grave’s disease
• Adrenal gland—Addison’s disease
• Pancreas—Diabetes mellitus

100 (c)• Glucagon is associated with hyperglycemia.
• Insulin acts on adipocytes and hepatocytes.
• Insulin is associated with hypoglycemia.

101 (a)The juxtaglomerular cells of kidney produce a peptide hormone called erythropoietin which stimulates erythropoiesis (formation of RBC)

NEET – Chemical Coordination and Regulation – 2024

NEET – Ecosystem – 2024

NEET – Excretory Products and Their Elimination – 2024

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NEET - Excretory Products and Their Elimination - 2024

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