Endocrine glands and hormones classification of hormones, mechanism and effects of hormonal actions.
- Hormones are classified as steroids, peptides, or amines based on:
a) Target organs
b) Chemical nature
c) Solubility in water
d) Molecular weight
Answer: b) Chemical nature
Explanation: Steroids (e.g., cortisol) are lipid-derived, peptides (e.g., insulin) are amino acid chains, and amines (e.g., epinephrine) are derived from tyrosine. - Which hormone uses intracellular receptors and gene activation?
a) Insulin
b) Thyroxine (T₄)
c) Adrenaline
d) FSH
Answer: b) Thyroxine (T₄)
Explanation: Lipid-soluble hormones (steroids, thyroid hormones) bind nuclear receptors and regulate gene transcription. - The “second messenger” for glucagon is:
a) cAMP
b) cGMP
c) IP₃
d) Calcium ions
Answer: a) cAMP
Explanation: Glucagon activates G-protein-coupled receptors, stimulating adenylyl cyclase to produce cAMP. - Which gland is both endocrine and exocrine?
a) Thyroid
b) Adrenal
c) Pancreas
d) Pituitary
Answer: c) Pancreas
Explanation: Pancreas secretes insulin/glucagon (endocrine) and digestive enzymes (exocrine). - Hypersecretion of growth hormone in adults causes:
a) Gigantism
b) Acromegaly
c) Dwarfism
d) Cushing’s syndrome
Answer: b) Acromegaly
Explanation: Post-pubertal GH excess thickens bones and enlarges organs (e.g., jaw, hands). - ADH (vasopressin) is synthesized in the:
a) Anterior pituitary
b) Posterior pituitary
c) Hypothalamus
d) Adrenal cortex
Answer: c) Hypothalamus
Explanation: ADH is produced in hypothalamic neurons, stored/released from posterior pituitary. - Cortisol secretion is regulated by:
a) TRH-TSH axis
b) CRH-ACTH axis
c) GnRH-FSH/LH axis
d) GHRH-GH axis
Answer: b) CRH-ACTH axis
Explanation: Hypothalamic CRH stimulates pituitary ACTH, which triggers cortisol release. - Insulin lowers blood glucose by:
a) Promoting glycogenolysis
b) Stimulating gluconeogenesis
c) Increasing GLUT4 translocation
d) Inhibiting glucose uptake
Answer: c) Increasing GLUT4 translocation
Explanation: Insulin recruits GLUT4 transporters to cell membranes for glucose uptake. - Iodine deficiency causes:
a) Addison’s disease
b) Graves’ disease
c) Cretinism
d) Diabetes insipidus
Answer: c) Cretinism
Explanation: Maternal iodine lack impairs fetal thyroid development, leading to stunted growth/mental retardation. - The hormone antagonistic to insulin is:
a) Cortisol
b) Thyroxine
c) Glucagon
d) Aldosterone
Answer: c) Glucagon
Explanation: Glucagon raises blood glucose via glycogenolysis and gluconeogenesis. - Oxytocin is involved in:
a) Milk ejection reflex
b) Blood pressure regulation
c) Glucose metabolism
d) Bone remodeling
Answer: a) Milk ejection reflex
Explanation: Oxytocin stimulates myoepithelial cell contraction in mammary glands. - Which is a peptide hormone?
a) Estradiol
b) Testosterone
c) Parathyroid hormone (PTH)
d) Cortisol
Answer: c) Parathyroid hormone (PTH)
Explanation: PTH is an 84-amino-acid peptide; others are steroids. - Calcium homeostasis is regulated by:
a) Insulin and glucagon
b) PTH and calcitonin
c) Aldosterone and ADH
d) TSH and thyroxine
Answer: b) PTH and calcitonin
Explanation: PTH raises blood Ca²⁺; calcitonin lowers it. - The “fight-or-flight” response involves:
a) Mineralocorticoids
b) Glucocorticoids
c) Catecholamines
d) Gonadocorticoids
Answer: c) Catecholamines
Explanation: Epinephrine/norepinephrine from adrenal medulla increase heart rate, BP, and glucose. - Hypothyroidism in adults causes:
a) Myxedema
b) Exophthalmos
c) Hirsutism
d) Virilism
Answer: a) Myxedema
Explanation: Symptoms include edema, weight gain, and cold intolerance. - Which hormone uses the PIP₂ pathway?
a) ACTH
b) Oxytocin
c) TRH
d) FSH
Answer: c) TRH
Explanation: TRH activates phospholipase C, cleaving PIP₂ into IP₃ (Ca²⁺ release) and DAG. - Melatonin regulates:
a) Blood glucose
b) Sleep-wake cycles
c) Sodium balance
d) Body temperature
Answer: b) Sleep-wake cycles
Explanation: Pineal gland secretes melatonin in response to darkness, promoting sleep. - Addison’s disease results from:
a) Hyposecretion of cortisol
b) Hypersecretion of aldosterone
c) Hyposecretion of insulin
d) Hypersecretion of GH
Answer: a) Hyposecretion of cortisol
Explanation: Adrenal insufficiency causes weakness, hyperpigmentation, and hypotension. - The hormone that stimulates uterine contractions is:
a) Prolactin
b) Progesterone
c) Oxytocin
d) Relaxin
Answer: c) Oxytocin
Explanation: Oxytocin induces labor contractions and milk ejection. - Type 1 diabetes is due to:
a) Insulin resistance
b) Autoimmune destruction of β-cells
c) Hyposecretion of glucagon
d) Excess cortisol
Answer: b) Autoimmune destruction of β-cells
Explanation: T-cell-mediated attack on pancreatic β-cells eliminates insulin production. - Which hormone is NOT secreted by the anterior pituitary?
a) TSH
b) ACTH
c) ADH
d) Prolactin
Answer: c) ADH
Explanation: ADH (vasopressin) is released by the posterior pituitary. - Aldosterone functions to:
a) Increase blood glucose
b) Promote Na⁺ reabsorption
c) Stimulate bone growth
d) Lower blood Ca²⁺
Answer: b) Promote Na⁺ reabsorption
Explanation: Aldosterone acts on renal distal tubules for Na⁺/K⁺ exchange. - The receptor for steroid hormones is located:
a) On the cell membrane
b) In the cytoplasm/nucleus
c) In mitochondria
d) On the ER
Answer: b) In the cytoplasm/nucleus
Explanation: Lipid-soluble steroids diffuse through membranes to bind intracellular receptors. - Graves’ disease is caused by:
a) Hypothyroidism
b) Hyperthyroidism due to autoantibodies
c) Pituitary tumor
d) Iodine deficiency
Answer: b) Hyperthyroidism due to autoantibodies
Explanation: Autoantibodies mimic TSH, causing excess T₃/T₄ secretion. - Which hormone uses cGMP as a second messenger?
a) Epinephrine
b) ANP
c) Insulin
d) Cortisol
Answer: b) ANP
Explanation: Atrial natriuretic peptide (ANP) activates guanylyl cyclase to produce cGMP. - Prolactin is secreted by the:
a) Hypothalamus
b) Anterior pituitary
c) Posterior pituitary
d) Adrenal cortex
Answer: b) Anterior pituitary
Explanation: Lactotrophs in the anterior pituitary secrete prolactin. - The “master gland” is the:
a) Hypothalamus
b) Pituitary
c) Thyroid
d) Adrenal
Answer: b) Pituitary
Explanation: Pituitary controls other endocrine glands via tropic hormones. - Testosterone is produced by:
a) Sertoli cells
b) Leydig cells
c) Seminiferous tubules
d) Prostate gland
Answer: b) Leydig cells
Explanation: Leydig cells in testes synthesize testosterone. - Which hormone decreases blood calcium?
a) PTH
b) Calcitriol
c) Calcitonin
d) Aldosterone
Answer: c) Calcitonin
Explanation: Calcitonin from thyroid parafollicular cells inhibits osteoclasts. - Hormonal “up-regulation” refers to:
a) Decreased receptor sensitivity
b) Increased receptor number
c) Hormone degradation
d) Negative feedback
Answer: b) Increased receptor number
Explanation: Low hormone levels increase target cell receptors to enhance sensitivity. - The hormone responsible for ovulation is:
a) FSH
b) LH
c) Progesterone
d) Estrogen
Answer: b) LH
Explanation: LH surge triggers ovulation and corpus luteum formation. - Cushing’s syndrome involves excess:
a) Growth hormone
b) Thyroxine
c) Cortisol
d) Insulin
Answer: c) Cortisol
Explanation: Symptoms include moon face, buffalo hump, and hyperglycemia. - Which hormone is water-soluble?
a) Cortisol
b) Estrogen
c) Thyroxine
d) Epinephrine
Answer: d) Epinephrine
Explanation: Catecholamines (epinephrine) bind surface receptors and use second messengers. - Corticosteroids are synthesized from:
a) Tyrosine
b) Tryptophan
c) Cholesterol
d) Glucose
Answer: c) Cholesterol
Explanation: All steroid hormones derive from cholesterol. - The primary effect of FSH in males is:
a) Spermatogenesis initiation
b) Testosterone production
c) Sperm maturation
d) Libido regulation
Answer: a) Spermatogenesis initiation
Explanation: FSH acts on Sertoli cells to support spermatogenesis. - Hypoparathyroidism causes:
a) Hypercalcemia
b) Hypocalcemia
c) Hypernatremia
d) Hyponatremia
Answer: b) Hypocalcemia
Explanation: Low PTH reduces blood Ca²⁺, leading to tetany and seizures. - Which hormone is NOT tropic?
a) TSH
b) ACTH
c) Prolactin
d) FSH
Answer: c) Prolactin
Explanation: Tropic hormones (TSH, ACTH, FSH, LH) target other glands; prolactin acts directly. - The zona glomerulosa secretes:
a) Cortisol
b) Aldosterone
c) Androgens
d) Epinephrine
Answer: b) Aldosterone
Explanation: Adrenal cortex layers: glomerulosa (mineralocorticoids), fasciculata (glucocorticoids), reticularis (androgens). - Leptin is secreted by:
a) Pancreas
b) Adipose tissue
c) Stomach
d) Liver
Answer: b) Adipose tissue
Explanation: Leptin regulates appetite and energy expenditure. - Diabetes insipidus results from deficiency of:
a) Insulin
b) Glucagon
c) ADH
d) Aldosterone
Answer: c) ADH
Explanation: ADH deficiency causes large volumes of dilute urine (polyuria). - Hormone synergy is demonstrated by:
a) Glucagon and insulin
b) Epinephrine and cortisol
c) FSH and testosterone
d) PTH and calcitonin
Answer: b) Epinephrine and cortisol
Explanation: Cortisol enhances epinephrine’s vasoconstrictive effects. - The primary female sex hormone is:
a) Progesterone
b) Estrogen
c) Prolactin
d) Oxytocin
Answer: b) Estrogen
Explanation: Estrogen (estradiol) regulates female reproductive development. - Which gland atrophies after puberty?
a) Thyroid
b) Thymus
c) Adrenal
d) Pituitary
Answer: b) Thymus
Explanation: Thymus (site of T-cell maturation) involutes post-puberty. - The hormone that stimulates erythropoiesis is:
a) Thyroxine
b) Cortisol
c) Erythropoietin
d) Growth hormone
Answer: c) Erythropoietin
Explanation: EPO from kidneys promotes RBC production. - Negative feedback regulates secretion of:
a) Oxytocin during labor
b) TRH-TSH-T₃/T₄ axis
c) ADH in dehydration
d) Epinephrine in stress
Answer: b) TRH-TSH-T₃/T₄ axis
Explanation: High T₃/T₄ inhibits TRH and TSH release. - Cholecalciferol (Vitamin D₃) is activated by:
a) Liver and kidneys
b) Skin and intestines
c) Pancreas and spleen
d) Lungs and heart
Answer: a) Liver and kidneys
Explanation: Liver converts D₃ to 25-OH-D₃; kidneys to active 1,25-(OH)₂-D₃ (calcitriol). - The hormone that inhibits gastric secretion is:
a) Gastrin
b) Secretin
c) CCK
d) GIP
Answer: b) Secretin
Explanation: Secretin from duodenum reduces gastric acid and motility. - Acromegaly is diagnosed by elevated:
a) ACTH
b) IGF-1
c) TSH
d) Prolactin
Answer: b) IGF-1
Explanation: GH stimulates liver IGF-1 production, causing tissue growth. - Which is a local hormone?
a) Insulin
b) Prostaglandin
c) Thyroxine
d) Cortisol
Answer: b) Prostaglandin
Explanation: Prostaglandins act locally as autocrine/paracrine agents. - The hormone that promotes milk production is:
a) Prolactin
b) Oxytocin
c) Estrogen
d) Progesterone
Answer: a) Prolactin
Explanation: Prolactin from anterior pituitary stimulates mammary gland development and lactation.
Hormonal regulation of gametogenesis in males and females of mammals, reproductive cycle in mammals.
- Which hormone directly stimulates spermatogenesis in males?
A) FSH
B) LH
C) Testosterone
D) GnRH
Answer: A
Explanation: FSH acts on Sertoli cells to promote spermatogenesis. LH stimulates Leydig cells to produce testosterone, which indirectly supports spermatogenesis. - In females, the surge of which hormone triggers ovulation?
A) Estrogen
B) Progesterone
C) LH
D) FSH
Answer: C
Explanation: The mid-cycle LH surge induces rupture of the Graafian follicle, leading to ovulation. - What is the role of inhibin in the male reproductive system?
A) Stimulates FSH release
B) Inhibits FSH release
C) Stimulates testosterone production
D) Inhibits GnRH secretion
Answer: B
Explanation: Inhibin, produced by Sertoli cells, negatively regulates FSH secretion from the pituitary. - During the menstrual cycle, the corpus luteum secretes:
A) Estrogen and FSH
B) Progesterone and LH
C) Progesterone and estrogen
D) FSH and LH
Answer: C
Explanation: The corpus luteum secretes progesterone and estrogen to maintain the endometrium. - Which phase of the menstrual cycle coincides with follicular development?
A) Luteal phase
B) Secretory phase
C) Proliferative phase
D) Menstrual phase
Answer: C
Explanation: The proliferative phase (uterine) aligns with the follicular phase (ovarian), driven by estrogen. - In males, testosterone is produced by:
A) Sertoli cells
B) Leydig cells
C) Hypothalamus
D) Seminiferous tubules
Answer: B
Explanation: Leydig cells in the testes synthesize testosterone under LH stimulation. - What characterizes the estrous cycle but NOT the menstrual cycle?
A) Ovulation
B) Endometrial shedding
C) Sexual receptivity limited to “heat”
D) Corpus luteum formation
Answer: C
Explanation: In estrous cycles, females are sexually receptive only during estrus (“heat”). Menstrual cycles lack this restriction. - Which hormone maintains the endometrium during pregnancy?
A) hCG
B) FSH
C) Estrogen
D) Relaxin
Answer: A
Explanation: hCG (human chorionic gonadotropin) rescues the corpus luteum, ensuring progesterone/estrogen secretion to sustain the endometrium. - Spermiogenesis involves:
A) Meiotic division of spermatogonia
B) Transformation of spermatids to spermatozoa
C) Spermiation into the lumen
D) Mitosis of primary spermatocytes
Answer: B
Explanation: Spermiogenesis is the maturation of spermatids into functional spermatozoa without cell division. - The absence of which hormone causes menopause?
A) GnRH
B) Estrogen
C) Progesterone
D) Inhibin
Answer: B
Explanation: Menopause results from declining estrogen due to ovarian follicle depletion. - Which structure degenerates if fertilization does not occur?
A) Graafian follicle
B) Corpus albicans
C) Corpus luteum
D) Tertiary follicle
Answer: C
Explanation: The corpus luteum degenerates into corpus albicans without hCG signaling from an embryo. - In males, FSH primarily targets:
A) Leydig cells
B) Sertoli cells
C) Epididymis
D) Hypothalamus
Answer: B
Explanation: FSH binds to receptors on Sertoli cells to support spermatogenesis and inhibin secretion. - Which hormone peaks during the ovulatory phase?
A) Progesterone
B) Estrogen
C) FSH
D) LH
Answer: D
Explanation: The LH surge peaks just before ovulation. - What inhibits GnRH release via negative feedback?
A) Low estrogen in females
B) High testosterone in males
C) Low progesterone in females
D) High FSH in males
Answer: B
Explanation: High testosterone inhibits GnRH secretion in males. In females, high estrogen/progesterone exert negative feedback. - Which phase follows ovulation in the menstrual cycle?
A) Follicular phase
B) Luteal phase
C) Menstrual phase
D) Proliferative phase
Answer: B
Explanation: The luteal phase begins after ovulation and involves corpus luteum activity. - In oogenesis, the first meiotic division completes:
A) Before birth
B) At puberty
C) After fertilization
D) During ovulation
Answer: D
Explanation: The first meiotic division completes just before ovulation, producing a secondary oocyte. - Which hormone is responsible for the development of female secondary sexual characteristics?
A) Progesterone
B) Estrogen
C) LH
D) Prolactin
Answer: B
Explanation: Estrogen promotes breast development, hip widening, and other female secondary traits. - What triggers the onset of puberty in mammals?
A) Surge in FSH
B) Activation of the hypothalamic-pituitary axis
C) Decline in inhibin
D) Increase in adrenal androgens
Answer: B
Explanation: Puberty begins when GnRH secretion from the hypothalamus increases, activating the HPG axis. - During the menstrual cycle, the highest estrogen level occurs in:
A) Menstrual phase
B) Proliferative phase
C) Ovulatory phase
D) Secretory phase
Answer: C
Explanation: Estrogen peaks just before ovulation, triggering the LH surge. - Which cell type is diploid in spermatogenesis?
A) Spermatid
B) Secondary spermatocyte
C) Primary spermatocyte
D) Spermatozoon
Answer: C
Explanation: Primary spermatocytes are diploid (2n) and undergo meiosis I to form haploid secondary spermatocytes. - Which cell type is diploid in spermatogenesis?
A) Spermatid
B) Secondary spermatocyte
C) Primary spermatocyte
D) Spermatozoon
Answer: C
Explanation: Primary spermatocytes are diploid and undergo meiosis I to form haploid secondary spermatocytes. - In the absence of fertilization, menstruation occurs due to:
A) Decline in FSH
B) Degeneration of the corpus luteum
C) Surge in progesterone
D) Rise in estrogen
Answer: B
Explanation: Degeneration of the corpus luteum causes a drop in estrogen and progesterone, leading to menstruation. - Which hormone is secreted by the placenta during pregnancy?
A) FSH
B) LH
C) hPL
D) GnRH
Answer: C
Explanation: Human placental lactogen (hPL) is secreted by the placenta and supports fetal growth and maternal metabolism. - The acrosome of sperm is derived from:
A) Mitochondria
B) Nucleus
C) Golgi apparatus
D) Centriole
Answer: C
Explanation: The acrosome forms from the Golgi apparatus and contains enzymes to penetrate the ovum. - Which phase of the estrous cycle is analogous to the luteal phase?
A) Proestrus
B) Estrus
C) Metestrus
D) Diestrus
Answer: D
Explanation: Diestrus is the phase when the corpus luteum is active, similar to the luteal phase in humans. - What causes the LH surge in females?
A) Low progesterone
B) High estrogen
C) High FSH
D) Low inhibin
Answer: B
Explanation: A sustained high level of estrogen exerts positive feedback, triggering the LH surge. - Sperm gain motility in the:
A) Seminiferous tubules
B) Epididymis
C) Vas deferens
D) Ejaculatory duct
Answer: B
Explanation: The epididymis is where sperm mature and gain motility. - Which hormone induces the development of the corpus luteum?
A) FSH
B) Estrogen
C) LH
D) Progesterone
Answer: C
Explanation: The LH surge after ovulation promotes the formation of the corpus luteum. - In females, androgen-binding protein is secreted by:
A) Theca cells
B) Granulosa cells
C) Sertoli cells
D) Leydig cells
Answer: B
Explanation: In the ovary, granulosa cells can produce ABP under FSH stimulation to concentrate androgens for conversion to estrogen. - What is the function of relaxin?
A) Induces labor contractions
B) Softens the cervix
C) Inhibits uterine contractions
D) Promotes follicle growth
Answer: B
Explanation: Relaxin softens the cervix and loosens the pelvic ligaments during childbirth. - Which is NOT a function of testosterone?
A) Spermatogenesis
B) Libido enhancement
C) Negative feedback on GnRH
D) Milk production
Answer: D
Explanation: Testosterone is not involved in milk production; that is regulated by prolactin. - The menstrual cycle typically lasts:
A) 14 days
B) 21 days
C) 28 days
D) 35 days
Answer: C
Explanation: The average cycle lasts 28 days, though it may vary between individuals. - In oogenesis, polar bodies are formed during:
A) Oogonial mitosis
B) Meiosis I and II
C) Follicular maturation
D) Fertilization
Answer: B
Explanation: Polar bodies are formed as a result of unequal cytoplasmic division during both meiotic divisions. - Which hormone is tested in pregnancy kits?
A) FSH
B) LH
C) hCG
D) Progesterone
Answer: C
Explanation: hCG is secreted by trophoblasts after implantation and is detected by pregnancy kits. - Theca interna cells produce:
A) Estrogen
B) Progesterone
C) Androgens
D) Inhibin
Answer: C
Explanation: Theca interna cells produce androgens that are converted to estrogen by granulosa cells. - What initiates the follicular phase?
A) Decline in progesterone
B) Rise in FSH
C) LH surge
D) Estrogen peak
Answer: B
Explanation: Rising FSH at the beginning of the cycle stimulates the growth of ovarian follicles. - Which is true for both spermatogenesis and oogenesis?
A) Equal cytoplasmic division
B) Formation of polar bodies
C) Completion before fertilization
D) Production of haploid gametes
Answer: D
Explanation: Both processes result in haploid gametes through meiosis. - Which cell type is directly responsible for forming the blood-testis barrier?
A) Leydig cells
B) Spermatogonia
C) Sertoli cells
D) Spermatids
Answer: C
Explanation: Tight junctions between Sertoli cells form the blood-testis barrier. - Which hormone stimulates milk ejection (let-down reflex)?
A) Prolactin
B) Estrogen
C) Progesterone
D) Oxytocin
Answer: D
Explanation: Oxytocin causes contraction of myoepithelial cells, resulting in milk ejection. - At what point is meiosis II completed in oogenesis?
A) At birth
B) During ovulation
C) At fertilization
D) At puberty
Answer: C
Explanation: Meiosis II in oogenesis completes only after the ovum is fertilized. - Which structure ensures unidirectional movement of sperm in the male reproductive tract?
A) Vas deferens
B) Epididymis
C) Seminiferous tubule
D) Peristaltic muscles
Answer: D
Explanation: Peristaltic movements of smooth muscles propel sperm through the ducts. - The dominant follicle is also known as:
A) Primary follicle
B) Secondary follicle
C) Graafian follicle
D) Corpus luteum
Answer: C
Explanation: The mature, dominant follicle ready for ovulation is called a Graafian follicle. - Which hormone suppresses FSH secretion during the luteal phase?
A) Progesterone
B) Inhibin
C) Estrogen
D) LH
Answer: B
Explanation: Inhibin from granulosa and luteal cells inhibits FSH secretion. - Leydig cells are located in the:
A) Epididymis
B) Interstitial space of the testes
C) Seminiferous tubules
D) Vas deferens
Answer: B
Explanation: Leydig cells lie in the interstitial tissue between seminiferous tubules and produce testosterone. - Which hormone stimulates the synthesis of estrogen in ovarian follicles?
A) LH
B) FSH
C) Progesterone
D) GnRH
Answer: B
Explanation: FSH stimulates granulosa cells to convert androgens to estrogens via aromatase. - The first menstrual bleeding in a girl’s life is called:
A) Menopause
B) Menarche
C) Ovulation
D) Amenorrhea
Answer: B
Explanation: Menarche is the onset of menstruation, typically occurring during puberty. - What hormone is essential for implantation of the embryo?
A) Estrogen
B) FSH
C) LH
D) Progesterone
Answer: D
Explanation: Progesterone prepares the endometrium for implantation and maintains it. - Which hormone shows a positive feedback effect during mid-cycle in females?
A) Estrogen
B) Progesterone
C) LH
D) Inhibin
Answer: A
Explanation: High estrogen levels mid-cycle stimulate LH surge via positive feedback. - Which hormone increases uterine contractions during labor?
A) Relaxin
B) Oxytocin
C) Progesterone
D) Estrogen
Answer: B
Explanation: Oxytocin stimulates strong uterine contractions during childbirth. - Sertoli cells are analogous to which cells in the ovary?
A) Theca externa
B) Granulosa cells
C) Theca interna
D) Oogonia
Answer: B
Explanation: Granulosa cells, like Sertoli cells, support developing gametes and respond to FSH. - What marks the end of the luteal phase in the menstrual cycle?
A) Ovulation
B) Onset of menstruation
C) LH surge
D) Follicle rupture
Answer: B
Explanation: Menstruation begins with the degeneration of the corpus luteum, ending the luteal phase.
Brief notes on Endocrine disorders, RIA, ELISA, cry preservation of gametes.
- Addison’s disease results from:
A) Hypersecretion of cortisol
B) Hyposecretion of aldosterone and cortisol
C) Autoimmune destruction of beta cells
D) Overproduction of ACTH
Answer: B
Explanation: Addison’s involves adrenal insufficiency, leading to deficient aldosterone and cortisol. - Acromegaly in adults is caused by excess secretion of:
A) Thyroxine
B) Growth hormone (GH)
C) Prolactin
D) Insulin
Answer: B
Explanation: Excess GH in adults causes acromegaly (enlarged hands, feet, jaw). - Graves’ disease is characterized by:
A) Hypothyroidism
B) Hyperthyroidism with exophthalmos
C) Adrenal hyperplasia
D) Hypoparathyroidism
Answer: B
Explanation: Graves’ is autoimmune hyperthyroidism with symptoms like bulging eyes (exophthalmos). - Diabetes insipidus arises due to deficiency of:
A) Insulin
B) Glucagon
C) ADH (vasopressin)
D) Aldosterone
Answer: C
Explanation: ADH deficiency causes excessive urine output (polyuria) and thirst. - Cushing’s syndrome is associated with:
A) Moon face and buffalo hump
B) Bronze skin and weight loss
C) Myxedema and cold intolerance
D) Tetany and muscle cramps
Answer: A
Explanation: High cortisol causes fat redistribution (moon face, buffalo hump). - Hashimoto’s thyroiditis is an example of:
A) Autoimmune hypothyroidism
B) Iodine-deficiency disorder
C) Thyroid cancer
D) Hyperthyroidism
Answer: A
Explanation: Autoimmune destruction of the thyroid leads to hypothyroidism. - Which hormone deficiency causes cretinism?
A) Thyroxine
B) Growth hormone
C) Parathormone
D) Cortisol
Answer: A
Explanation: Congenital thyroxine deficiency causes stunted growth and intellectual disability. - Insulin resistance in Type 2 diabetes is primarily observed in:
A) Liver
B) Pancreas
C) Adipose tissue and skeletal muscle
D) Kidneys
Answer: C
Explanation: Target tissues (muscle, fat) fail to respond to insulin. - Tetany is a symptom of:
A) Hypoparathyroidism
B) Hyperparathyroidism
C) Addison’s disease
D) Acromegaly
Answer: A
Explanation: Low PTH reduces blood Ca²⁺, causing muscle spasms and tetany. - Gigantism results from GH hypersecretion:
A) Before puberty
B) After puberty
C) In adulthood
D) During pregnancy
Answer: A
Explanation: Excess GH before epiphyseal plate closure causes abnormal height. - RIA (Radioimmunoassay) uses:
A) Enzymes for detection
B) Radioactive labels
C) Fluorescent dyes
D) Magnetic beads
Answer: B
Explanation: RIA quantifies antigens/antibodies using radioactive isotopes (e.g., I¹²⁵). - Which component is essential in ELISA?
A) Radioisotope
B) Enzyme-conjugated antibody
C) Scintillation counter
D) Electrophoresis gel
Answer: B
Explanation: ELISA uses enzyme-linked antibodies (e.g., horseradish peroxidase) for colorimetric detection. - The “sandwich ELISA” detects:
A) Only antibodies
B) Only antigens
C) Antigens between two antibodies
D) DNA fragments
Answer: C
Explanation: Capture antibody binds antigen, detected by enzyme-linked secondary antibody. - RIA was first developed to measure:
A) Glucose
B) Insulin
C) Thyroxine
D) Growth hormone
Answer: B
Explanation: Rosalyn Yalow developed RIA for insulin (Nobel Prize, 1977). - In direct ELISA, the primary antibody is:
A) Unlabeled
B) Enzyme-linked
C) Radioactive
D) Fluorescent
Answer: B
Explanation: Direct ELISA uses enzyme-conjugated primary antibodies. - Which technique is safer for routine diagnostics?
A) RIA
B) ELISA
C) Both pose equal risk
D) Western blot
Answer: B
Explanation: ELISA avoids radiation hazards, using safer enzyme-substrate reactions. - The sensitivity of RIA is attributed to:
A) Enzymatic amplification
B) Radioisotope detection precision
C) Fluorescence intensity
D) Magnetic separation
Answer: B
Explanation: Radioisotopes allow highly sensitive measurement of low-abundance molecules. - HIV diagnosis commonly uses:
A) RIA
B) Indirect ELISA
C) Radioimmunodiffusion
D) Immunoelectrophoresis
Answer: B
Explanation: Indirect ELISA detects anti-HIV antibodies in serum. - Competitive RIA involves:
A) Unlabeled antigen competing with labeled antigen
B) Antigen-antibody complex precipitation
C) Direct binding to solid phase
D) Fluorescence quenching
Answer: A
Explanation: Unlabeled (sample) and labeled antigens compete for antibody binding sites. - Which is a disadvantage of RIA?
A) Long procedure time
B) Radiation disposal issues
C) Low specificity
D) High cost of enzymes
Answer: B
Explanation: Radioactive waste management is a significant challenge. - Cryopreservation of sperm typically uses:
A) Liquid nitrogen (−196°C)
B) Dry ice (−78°C)
C) Ultrafreezers (−80°C)
D) Refrigeration (4°C)
Answer: A
Explanation: Liquid nitrogen ensures long-term storage at ultra-low temperatures. - The most common cryoprotectant for ova is:
A) DMSO (Dimethyl sulfoxide)
B) Ethylene glycol
C) Glycerol
D) Sucrose
Answer: A
Explanation: DMSO prevents ice crystal formation in oocytes. - Cryopreservation is crucial for:
A) In vitro fertilization (IVF) programs
B) Blood transfusion
C) Organ transplantation
D) Enzyme storage
Answer: A
Explanation: Preserves sperm/ova for assisted reproductive technologies (ART). - Slow freezing vs. vitrification differs in:
A) Cooling rate and cryoprotectant concentration
B) Storage temperature
C) Use of antibiotics
D) Centrifugation steps
Answer: A
Explanation: Vitrification uses rapid cooling and high cryoprotectant concentration to avoid ice formation. - The main challenge in oocyte cryopreservation is:
A) High lipid content increasing chilling injury
B) Small cell size
C) Low water content
D) Rapid motility
Answer: A
Explanation: Oocytes are sensitive due to lipid-rich membranes. - Sperm cryopreservation benefits include:
A) Preserving fertility in cancer patients
B) Preventing genetic disorders
C) Enhancing sperm motility
D) Reducing DNA fragmentation
Answer: A
Explanation: Used pre-chemotherapy/radiation to safeguard fertility. - Cryobanking of endangered species is part of:
A) Bioremediation
B) Germplasm conservation
C) Eutrophication control
D) Bioaccumulation studies
Answer: B
Explanation: Preserves genetic material for biodiversity conservation. - Ice crystal formation during cryopreservation causes damage by:
A) Mechanical stress and membrane rupture
B) Denaturing proteins
C) Inducing mutations
D) Increasing pH
Answer: A
Explanation: Ice crystals physically disrupt cell structures. - Which gamete is more resilient to cryopreservation?
A) Sperm
B) Ova
C) Both equally
D) Zygotes
Answer: A
Explanation: Sperm are smaller and less prone to cryodamage than ova. - Vitrification is preferred for ova as it:
A) Prevents ice crystallization
B) Uses lower cryoprotectant concentrations
C) Is slower and cheaper
D) Avoids liquid nitrogen
Answer: A
Explanation: Rapid cooling solidifies cells into a glass-like state without ice. - ELISA is superior to RIA for:
A) Avoiding radiation hazards
B) Detecting low-abundance hormones
C) Lower cost of isotopes
D) Faster results
Answer: A
Explanation: ELISA replaces radioactive labels with safer enzymes. - A patient with polyuria, polydipsia, and hyperglycemia likely has:
A) Diabetes mellitus
B) Diabetes insipidus
C) Addison’s disease
D) Cushing’s syndrome
Answer: A
Explanation: Classic symptoms of diabetes mellitus (Type 1/2). - Cryopreservation of testicular tissue is used for:
A) Pre-pubertal cancer patients
B) Treating hypothyroidism
C) Insulin production
D) Stem cell therapy
Answer: A
Explanation: Preserves spermatogonial stem cells before puberty. - In indirect ELISA, the secondary antibody binds to:
A) Antigen
B) Primary antibody
C) Enzyme substrate
D) Solid phase
Answer: B
Explanation: Secondary antibody (enzyme-linked) detects the primary antibody. - Myxedema is a symptom of:
A) Hypothyroidism
B) Hyperthyroidism
C) Hyperparathyroidism
D) Hypoadrenalism
Answer: A
Explanation: Swelling of skin and tissues in severe hypothyroidism. - Which technique quantifies thyroid hormones?
A) RIA
B) PCR
C) Gel electrophoresis
D) Flow cytometry
Answer: A
Explanation: RIA is historically used for hormone assays like T3/T4. - A key advantage of cryopreservation in IVF is:
A) Synchronizing donor-recipient cycles
B) Reducing multiple pregnancies
C) Eliminating genetic screening
D) Preventing ectopic pregnancies
Answer: A
Explanation: Frozen embryos allow flexible timing in recipient cycles. - Which disorder involves insulin resistance?
A) Type 1 diabetes
B) Type 2 diabetes
C) Gestational diabetes
D) Both B and C
Answer: D
Explanation: Type 2 and gestational diabetes feature insulin resistance. - The “window period” in HIV testing is best detected by:
A) RIA
B) Direct ELISA
C) PCR
D) Western blot
Answer: C
Explanation: PCR detects viral DNA before antibodies develop (window period). - Lyophilization is used in cryopreservation for:
A) Sperm
B) Embryos
C) Enzymes and proteins
D) Ova
Answer: C
Explanation: Freeze-drying preserves proteins, not viable gametes. - Nelson’s syndrome occurs after:
A) Adrenalectomy in Cushing’s disease
B) Thyroidectomy in Graves’ disease
C) Parathyroid removal
D) Pituitary tumor resection
Answer: A
Explanation: Post-adrenalectomy, pituitary tumors may enlarge due to loss of feedback. - Which ELISA variant is used for antibody detection?
A) Direct
B) Indirect
C) Sandwich
D) Competitive
Answer: B
Explanation: Indirect ELISA detects antibodies (e.g., in infection screening). - Ovarian hyperstimulation syndrome (OHSS) is a risk in:
A) Natural conception
B) Cryopreserved embryo transfer
C) Ovarian tissue freezing
D) IVF with hormone stimulation
Answer: D
Explanation: Hormones used in IVF can cause OHSS (ovarian enlargement). - Radioimmunoassay was pioneered by:
A) Kary Mullis
B) Rosalyn Yalow and Solomon Berson
C) Robert Koch
D) Louis Pasteur
Answer: B
Explanation: Yalow and Berson developed RIA in the 1950s. - A fasting blood glucose level >126 mg/dl indicates:
A) Diabetes mellitus
B) Hypoglycemia
C) Normal range
D) Gestational diabetes
Answer: A
Explanation: WHO criteria: fasting glucose ≥126 mg/dl confirms diabetes. - Cryopreservation media often include:
A) Cryoprotectants and antibiotics
B) Growth hormones
C) Radioisotopes
D) Enzymes
Answer: A
Explanation: Prevents ice damage and microbial contamination. - In RIA, the “bound” fraction refers to:
A) Antigen-antibody complex
B) Free antigen
C) Unbound antibody
D) Enzyme-substrate complex
Answer: A
Explanation: Bound fraction is the radiolabeled antigen bound to antibodies. - Turner syndrome is associated with:
A) Short stature and ovarian dysgenesis
B) Tall stature and infertility
C) Thyroid dysfunction
D) Adrenal insufficiency
Answer: A
Explanation: Caused by 45,X karyotype; features include short stature and streak ovaries. - The principle of ELISA is based on:
A) Antigen-antibody specificity
B) DNA hybridization
C) Radioactive decay
D) Centrifugation
Answer: A
Explanation: Immunoassays rely on highly specific antigen-antibody binding. - Slow freezing in cryopreservation:
A) Minimizes osmotic shock
B) Uses high cryoprotectant concentrations
C) Is faster than vitrification
D) Avoids cryoprotectants
Answer: A
Explanation: Controlled cooling reduces osmotic stress and ice formation.
