MCQ on Endocrine System

🟢 Easy Level (1–20)

1. Which gland is known as the “master gland”?
   A) Thyroid
   B) Pituitary ✅
   C) Adrenal
   D) Pineal
   Explanation: The pituitary gland controls many other endocrine glands.
2. Which hormone regulates blood sugar levels?
   A) Thyroxine
   B) Insulin ✅
   C) Adrenaline
   D) Estrogen
   Explanation: Insulin lowers blood glucose levels.
3. Which gland secretes melatonin?
   A) Pituitary
   B) Thyroid
   C) Pineal ✅
   D) Adrenal
   Explanation: The pineal gland regulates circadian rhythms.
4. Which gland is located in the neck?
   A) Adrenal
   B) Thyroid ✅
   C) Pancreas
   D) Pituitary
   Explanation: The thyroid gland is located anterior to the trachea.
5. Which hormone is released during stress?
   A) Oxytocin
   B) Cortisol ✅
   C) Insulin
   D) Melatonin
   Explanation: Cortisol is a stress hormone released by the adrenal cortex.
6. Which gland produces insulin?
   A) Liver
   B) Kidney
   C) Pancreas ✅
   D) Thyroid
   Explanation: Beta cells in the pancreas produce insulin.
7. Which hormone helps regulate metabolism?
   A) Estrogen
   B) Testosterone
   C) Thyroxine ✅
   D) Oxytocin
   Explanation: Thyroxine increases metabolic activity.
8. Which gland sits on top of the kidneys?
   A) Pituitary
   B) Adrenal ✅
   C) Pancreas
   D) Thyroid
   Explanation: Adrenal glands are located above the kidneys.
9. Which hormone helps in childbirth by causing uterine contractions?
   A) Estrogen
   B) Progesterone
   C) Oxytocin ✅
   D) FSH
   Explanation: Oxytocin stimulates labor contractions.
10. Which gland controls growth and development?
    A) Pancreas
    B) Thyroid
    C) Pituitary ✅
    D) Adrenal
    Explanation: The pituitary secretes growth hormone.
11. Which hormone promotes calcium absorption in the intestines?
    A) Calcitonin
    B) PTH
    C) Vitamin D ✅
    D) Glucagon
    Explanation: Vitamin D increases calcium absorption.
12. Which hormone decreases blood calcium levels?
    A) PTH
    B) Calcitonin ✅
    C) Glucagon
    D) Insulin
    Explanation: Calcitonin inhibits osteoclast activity.
13. Which gland regulates circadian rhythm?
    A) Pineal ✅
    B) Thyroid
    C) Adrenal
    D) Pancreas
    Explanation: The pineal gland secretes melatonin, regulating sleep.
14. Which hormone stimulates milk production?
    A) Oxytocin
    B) Prolactin ✅
    C) Estrogen
    D) Testosterone
    Explanation: Prolactin triggers milk synthesis in mammary glands.
15. Which hormone is responsible for male secondary sexual characteristics?
    A) Estrogen
    B) Testosterone ✅
    C) Progesterone
    D) Insulin
    Explanation: Testosterone regulates male traits.
16. Glucagon is secreted by:
    A) Alpha cells ✅
    B) Beta cells
    C) Delta cells
    D) Acinar cells
    Explanation: Alpha cells of the pancreas release glucagon.
17. Which hormone increases blood sugar levels?
    A) Insulin
    B) Glucagon ✅
    C) ADH
    D) Calcitonin
    Explanation: Glucagon triggers glycogen breakdown in the liver.
18. Which hormone controls water balance in the body?
    A) FSH
    B) ADH ✅
    C) TSH
    D) Prolactin
    Explanation: ADH promotes water reabsorption in kidneys.
19. Parathyroid hormone (PTH) increases:
    A) Blood glucose
    B) Blood calcium ✅
    C) Water retention
    D) Metabolism
    Explanation: PTH stimulates calcium release from bones.
20. Which hormone is released by the posterior pituitary?
    A) FSH
    B) ACTH
    C) ADH ✅
    D) TSH
    Explanation: The posterior pituitary releases ADH and oxytocin.

🟡 Moderate Level (21–40)

21. What stimulates the release of ACTH?
    A) TRH
    B) CRH ✅
    C) GHRH
    D) GnRH
    Explanation: CRH from the hypothalamus stimulates ACTH secretion.
22. Which hormone stimulates ovulation?
    A) FSH
    B) LH ✅
    C) Estrogen
    D) Progesterone
    Explanation: LH surge triggers ovulation.
23. Which gland controls other endocrine glands?
    A) Pancreas
    B) Pituitary ✅
    C) Thyroid
    D) Adrenal
    Explanation: The pituitary is often referred to as the “master gland.”
24. Hyposecretion of insulin leads to:
    A) Diabetes mellitus ✅
    B) Diabetes insipidus
    C) Goitre
    D) Cushing’s syndrome
    Explanation: Lack of insulin results in high blood glucose levels.
25. Excess GH in adults causes:
    A) Gigantism
    B) Acromegaly ✅
    C) Dwarfism
    D) Rickets
    Explanation: Acromegaly is characterized by bone thickening in adults.
26. Graves’ disease is associated with:
    A) Hypothyroidism
    B) Hyperthyroidism ✅
    C) Adrenal insufficiency
    D) Hypopituitarism
    Explanation: It is an autoimmune condition causing excess thyroid hormone.
27. Which hormone regulates the menstrual cycle along with estrogen?
    A) Testosterone
    B) Progesterone ✅
    C) FSH
    D) LH
    Explanation: Progesterone maintains the uterine lining.
28. Adrenal medulla secretes:
    A) Cortisol
    B) Aldosterone
    C) Epinephrine and norepinephrine ✅
    D) Insulin
    Explanation: These hormones help in “fight or flight” response.
29. Which hormone increases sodium reabsorption in the kidneys?
    A) ADH
    B) Aldosterone ✅
    C) Cortisol
    D) Glucagon
    Explanation: Aldosterone conserves sodium and water.
30. Which hormone is a steroid hormone?
    A) Insulin
    B) Cortisol ✅
    C) Oxytocin
    D) ADH
    Explanation: Cortisol is derived from cholesterol.
31. Which part of the brain links the nervous and endocrine systems?
    A) Cerebrum
    B) Hypothalamus ✅
    C) Thalamus
    D) Cerebellum
    Explanation: The hypothalamus regulates pituitary function.
32. Which hormone regulates basal metabolic rate?
    A) Insulin
    B) Thyroxine (T4) ✅
    C) Cortisol
    D) Glucagon
    Explanation: T4 increases oxygen consumption and heat production.
33. Hormones are transported by:
    A) Neurons
    B) Bloodstream ✅
    C) Lymph
    D) Digestive tract
    Explanation: Endocrine hormones travel via blood to target organs.
34. Addison’s disease is caused by:
    A) Excess cortisol
    B) Deficiency of adrenal hormones ✅
    C) Thyroid overactivity
    D) High insulin
    Explanation: It leads to fatigue, hypotension, and low cortisol.
35. Goitre is caused by deficiency of:
    A) Calcium
    B) Iodine ✅
    C) Iron
    D) Potassium
    Explanation: Iodine is essential for thyroid hormone synthesis.
36. Negative feedback mechanism in endocrine system maintains:
    A) Instability
    B) Imbalance
    C) Homeostasis ✅
    D) Growth
    Explanation: It helps maintain hormone levels within normal range.
37. Which hormone increases heart rate and blood pressure?
    A) Glucagon
    B) Epinephrine ✅
    C) Insulin
    D) FSH
    Explanation: Epinephrine acts as a stress hormone.
38. TSH stimulates:
    A) Pituitary
    B) Thyroid ✅
    C) Pancreas
    D) Liver
    Explanation: TSH triggers thyroid hormone production.
39. Hyperparathyroidism leads to:
    A) Hypocalcemia
    B) Hypercalcemia ✅
    C) Hypoglycemia
    D) Low cortisol
    Explanation: Excess PTH raises blood calcium levels.
40. Which hormone suppresses appetite?
    A) Ghrelin
    B) Leptin ✅
    C) Insulin
    D) Glucagon
    Explanation: Leptin signals fullness to the brain.

🔴 Hard Level (41–50)

41. Which hormone regulates the sleep-wake cycle?
    A) Melatonin ✅
    B) Thyroxine
    C) Serotonin
    D) Oxytocin
    Explanation: Melatonin regulates circadian rhythm.
42. Which hormone increases during dehydration?
    A) Aldosterone
    B) ADH ✅
    C) Insulin
    D) TSH
    Explanation: ADH promotes water retention.
43. Hyposecretion of ADH causes:
    A) Diabetes mellitus
    B) Diabetes insipidus ✅
    C) Hyperthyroidism
    D) Gigantism
    Explanation: Leads to excessive urination and thirst.
44. Cushing’s syndrome is caused by excess:
    A) Aldosterone
    B) Cortisol ✅
    C) Insulin
    D) Thyroxine
    Explanation: It causes fat redistribution, hypertension, and hyperglycemia.
45. Which hormone binds to intracellular receptors?
    A) Insulin
    B) Cortisol ✅
    C) Oxytocin
    D) FSH
    Explanation: Steroid hormones act inside the cell.
46. Gonadotropins include:
    A) FSH and LH ✅
    B) TSH and ACTH
    C) ADH and Oxytocin
    D) Insulin and Glucagon
    Explanation: They regulate function of gonads.
47. Which disorder is due to lack of thyroid hormones at birth?
    A) Cretinism ✅
    B) Acromegaly
    C) Myxedema
    D) Addison’s disease
    Explanation: Leads to stunted physical and mental development.
48. Which hormone inhibits growth hormone secretion?
    A) GHRH
    B) Somatostatin ✅
    C) CRH
    D) TRH
    Explanation: Somatostatin suppresses GH and TSH.
49. Which hormone is not produced by the anterior pituitary?
    A) Prolactin
    B) ADH ✅
    C) GH
    D) ACTH
    Explanation: ADH is secreted by the posterior pituitary.
50. Hormone that triggers release of T3 and T4 is:
    A) ACTH
    B) TSH ✅
    C) FSH
    D) CRH
    Explanation: TSH stimulates thyroid to produce its hormones.