Topic: Fertilization and Early Embryonic Development; Subtopic: Timing and Site of Fertilization
Keyword Definitions:
• Fertilization: Fusion of male and female gametes to form a zygote, marking the beginning of a new organism.
• Ovulation: Release of a mature ovum from the Graafian follicle into the fallopian tube.
• Ampulla: The widest part of the fallopian tube where fertilization usually occurs.
• Zygote: The first diploid cell formed after fusion of the sperm and ovum.
Lead Question - 2014
Fertilization takes place after how much time of ovulation?
a) 1–2 days
b) 5–6 days
c) 8–12 days
d) >12 days
Explanation: Fertilization typically occurs within 1–2 days after ovulation, usually in the ampulla of the fallopian tube. The ovum remains viable for about 24 hours after ovulation, while sperm can survive up to 72 hours in the female genital tract. Hence, fertilization occurs soon after ovulation. The correct answer is (a) 1–2 days.
1. Site of fertilization in the human female reproductive tract?
a) Isthmus
b) Ampulla
c) Infundibulum
d) Cervix
Explanation: Fertilization most commonly occurs in the ampulla of the fallopian tube, which provides the optimal environment for sperm-ovum interaction. The ampulla has ciliated epithelium aiding gamete movement and nutrient support. Therefore, the correct answer is (b) Ampulla.
2. Clinical: A woman has a blockage at the ampulla of her fallopian tube. What is the likely consequence?
a) No ovulation
b) No fertilization
c) No implantation
d) Multiple ovulations
Explanation: Blockage of the ampulla prevents the meeting of sperm and ovum, thereby preventing fertilization. Ovulation may still occur, but without fertilization, pregnancy cannot result. Hence, the correct answer is (b) No fertilization.
3. Fertilization normally occurs within how many hours after ovulation?
a) 6–12 hours
b) 12–24 hours
c) 36–48 hours
d) 72 hours
Explanation: Fertilization occurs within 12–24 hours after ovulation since the ovum remains viable for only one day. Sperm deposited earlier can survive in the female reproductive tract for about three days, ready for fertilization. Thus, the correct answer is (b) 12–24 hours.
4. Clinical: Fertilization occurring in the fallopian tube can abnormally result in?
a) Ectopic pregnancy
b) Hydatidiform mole
c) Blighted ovum
d) Molar pregnancy
Explanation: If the zygote implants within the fallopian tube instead of the uterus, it results in an ectopic pregnancy, a life-threatening condition requiring emergency treatment. It usually occurs in the ampulla or isthmus. Therefore, the correct answer is (a) Ectopic pregnancy.
5. Which enzyme in sperm aids in penetrating the zona pellucida during fertilization?
a) Hyaluronidase
b) Acrosin
c) Collagenase
d) Trypsin
Explanation: The enzyme acrosin from the acrosome of sperm facilitates penetration of the zona pellucida surrounding the ovum. Hyaluronidase helps disperse the corona radiata. Both are crucial for successful fertilization. The correct answer is (b) Acrosin.
6. Clinical: A 30-year-old woman has polyspermy. What does it lead to?
a) Normal fertilization
b) Triploid zygote
c) Monosomy
d) Blastocyst formation
Explanation: Polyspermy is the entry of multiple sperms into one ovum, leading to an abnormal triploid zygote (3n) that is nonviable. The ovum normally prevents this by cortical granule release that hardens the zona pellucida. Hence, the correct answer is (b) Triploid zygote.
7. Which event follows immediately after fertilization?
a) Cleavage
b) Implantation
c) Gastrulation
d) Neurulation
Explanation: After fertilization, the zygote undergoes rapid mitotic divisions known as cleavage to form a morula and then a blastocyst before implantation. Hence, the correct answer is (a) Cleavage.
8. Clinical: Fertilization usually occurs in which part of the fallopian tube in a normal pregnancy?
a) Isthmus
b) Ampullary-isthmic junction
c) Infundibulum
d) Fimbriae
Explanation: Fertilization most commonly occurs in the ampullary-isthmic junction, where both sperm and ovum meet. It provides the right environment for capacitation and fertilization. Therefore, the correct answer is (b) Ampullary-isthmic junction.
9. Clinical: In in-vitro fertilization, when are oocytes usually retrieved post-hCG injection?
a) 6 hours
b) 12 hours
c) 34–36 hours
d) 72 hours
Explanation: Oocyte retrieval in IVF is done approximately 34–36 hours after hCG injection, just before ovulation occurs, ensuring mature oocytes are collected for fertilization. Hence, the correct answer is (c) 34–36 hours.
10. What happens to the ovum if fertilization does not occur?
a) It divides to form a zygote
b) It degenerates within 24 hours
c) It implants in the uterus
d) It undergoes mitosis
Explanation: The ovum survives only for about 24 hours after ovulation. If fertilization does not occur, it degenerates in the fallopian tube, and menstruation follows due to falling progesterone levels. Hence, the correct answer is (b) It degenerates within 24 hours.
Topic: Fertilization and Implantation; Subtopic: Timing and Process of Implantation
Keyword Definitions:
Fertilization: Fusion of sperm and ovum to form a zygote.
Zygote: The first cell formed after fertilization containing diploid chromosomes.
Blastocyst: A structure formed after multiple divisions of the zygote before implantation.
Implantation: The attachment of the blastocyst to the uterine wall.
Endometrium: The inner lining of the uterus where implantation occurs.
Luteal phase: Phase after ovulation characterized by progesterone secretion from corpus luteum.
Lead Question (2014):
Implantation occurs at ?
a) 2-3 days
b) 6-7 days
c) 15-20 days
d) 20-25 days
Explanation:
Implantation of the blastocyst normally occurs about 6-7 days after fertilization. The zygote travels through the fallopian tube for nearly 3-4 days before entering the uterus and developing into a blastocyst. It then attaches to the endometrium, facilitated by progesterone. Thus, the correct answer is (b) 6-7 days.
1) Site of fertilization in humans is:
a) Uterus
b) Vagina
c) Ampulla of fallopian tube
d) Cervix
Fertilization in humans occurs in the ampulla of the fallopian tube, which provides an ideal environment for the union of sperm and ovum. The fertilized ovum then travels to the uterus for implantation after cleavage. Therefore, the correct answer is (c) Ampulla of fallopian tube.
2) Corpus luteum mainly secretes:
a) FSH
b) LH
c) Progesterone
d) Estrogen
The corpus luteum forms from the ruptured follicle after ovulation and secretes progesterone. This hormone maintains the endometrial lining suitable for implantation. If fertilization does not occur, the corpus luteum degenerates. Hence, the correct answer is (c) Progesterone.
3) Which hormone prevents menstruation after implantation?
a) LH
b) hCG
c) Estrogen
d) FSH
After implantation, the trophoblast secretes human chorionic gonadotropin (hCG), which maintains the corpus luteum and continuous progesterone secretion. This prevents menstruation and supports early pregnancy. Thus, the correct answer is (b) hCG.
4) Clinical case: A woman conceives, and implantation occurs on the posterior uterine wall. This position is:
a) Normal implantation
b) Ectopic pregnancy
c) Placenta previa
d) Cervical implantation
In normal pregnancies, implantation occurs on the posterior wall of the uterus. This location provides good vascularization for placental growth. Ectopic pregnancy occurs outside the uterus, commonly in fallopian tubes. Hence, the correct answer is (a) Normal implantation.
5) Ectopic implantation most commonly occurs in:
a) Cervix
b) Ovary
c) Ampulla of fallopian tube
d) Abdominal cavity
The most common site of ectopic pregnancy is the ampulla of the fallopian tube. This occurs when the zygote fails to move into the uterus due to blockage or damage. It can cause internal bleeding and is life-threatening if untreated. Hence, the correct answer is (c) Ampulla of fallopian tube.
6) Implantation is assisted mainly by:
a) Estrogen
b) Progesterone
c) LH
d) FSH
Progesterone, secreted by the corpus luteum, makes the endometrium secretory and receptive for implantation. Estrogen only helps in proliferation of endometrial lining but not implantation. Thus, the hormone mainly assisting implantation is (b) Progesterone.
7) Clinical case: A patient with defective corpus luteum fails to sustain pregnancy. The cause is:
a) Lack of progesterone
b) Lack of estrogen
c) Lack of LH
d) Lack of FSH
Failure of implantation or early pregnancy loss due to a defective corpus luteum is because of insufficient progesterone secretion. Progesterone maintains endometrial stability and supports embryonic growth. Therefore, the correct answer is (a) Lack of progesterone.
8) Implantation usually occurs in:
a) Isthmus of uterus
b) Posterior wall of uterus
c) Cervical canal
d) Fallopian tube
The blastocyst implants normally on the posterior wall of the uterus, near the fundus. This region has a rich blood supply, ensuring proper placental development and nutrition. Thus, the correct answer is (b) Posterior wall of uterus.
9) Clinical case: A woman shows implantation in the cervix. The condition is called:
a) Placenta previa
b) Cervical pregnancy
c) Tubal pregnancy
d) Interstitial pregnancy
Implantation in the cervical canal is known as cervical pregnancy, a type of ectopic implantation. It causes severe bleeding because of poor muscular support in the cervix. Hence, the correct answer is (b) Cervical pregnancy.
10) Clinical case: A zygote implants outside the uterus in the abdominal cavity. This type of pregnancy is:
a) Normal
b) Ectopic
c) Placenta accreta
d) Uterine pregnancy
Implantation occurring outside the uterus, such as in the fallopian tube or abdominal cavity, is termed an ectopic pregnancy. It cannot proceed normally and poses a serious risk to the mother. Therefore, the correct answer is (b) Ectopic.
Topic: Fertilization and Implantation; Subtopic: Day of Implantation in Menstrual Cycle
Keyword Definitions:
Menstrual Cycle: A 28-day cycle involving hormonal changes preparing the uterus for pregnancy.
Ovulation: Release of a mature ovum from the ovary around the 14th day of the cycle.
Fertilization: Fusion of sperm and ovum forming a zygote in the fallopian tube.
Blastocyst: A multicellular structure formed after several zygotic divisions before implantation.
Implantation: Process where the blastocyst attaches to the uterine endometrium.
Endometrium: Inner uterine lining that becomes secretory under progesterone influence for implantation.
Corpus luteum: Temporary endocrine structure secreting progesterone to support pregnancy.
Lead Question (2014):
Implantation occurs on which menstrual cycle day?
a) 5-7 days
b) 20-22 days
c) 14-18 days
d) 26-28 days
Explanation:
Implantation usually occurs around the 20th to 22nd day of the menstrual cycle, approximately 6 to 7 days after ovulation and fertilization. The endometrium is in the secretory phase, rich in glycogen and blood supply, making it receptive for implantation. Progesterone secreted by the corpus luteum maintains this environment. Thus, the correct answer is (b) 20-22 days.
1) Fertilization occurs on which day of the menstrual cycle?
a) 10th day
b) 14th day
c) 20th day
d) 26th day
In a 28-day menstrual cycle, ovulation happens on the 14th day, and fertilization usually takes place within 24 hours in the fallopian tube. The sperm remains viable for about 72 hours, making this the fertile window. Hence, the correct answer is (b) 14th day.
2) The luteal phase of the menstrual cycle lasts for approximately:
a) 5 days
b) 10 days
c) 14 days
d) 20 days
The luteal phase follows ovulation and lasts about 14 days. During this phase, the corpus luteum secretes progesterone, converting the endometrium into a secretory lining ready for implantation. If fertilization doesn’t occur, the corpus luteum degenerates, leading to menstruation. Thus, the correct answer is (c) 14 days.
3) Clinical case: A woman with luteal phase defect is unable to conceive. The probable cause is:
a) Low progesterone
b) High estrogen
c) Low FSH
d) High LH
A luteal phase defect leads to inadequate progesterone secretion from the corpus luteum, resulting in an endometrium not properly prepared for implantation. This hormonal imbalance causes infertility or early miscarriage. Therefore, the correct answer is (a) Low progesterone.
4) Clinical case: Implantation occurs on day 25 of the cycle. Which statement is correct?
a) Normal implantation
b) Delayed implantation
c) Early implantation
d) Abnormal implantation
Implantation occurring beyond day 22 of the menstrual cycle is considered delayed implantation. It may happen due to late ovulation or slow zygote transport. Such delay can affect endometrial receptivity, reducing chances of pregnancy. Hence, the correct answer is (b) Delayed implantation.
5) The “implantation window” refers to:
a) Day 1-5
b) Day 14-16
c) Day 20-24
d) Day 26-28
The implantation window is the limited period when the endometrium is receptive to the blastocyst, typically from day 20 to day 24 of the menstrual cycle. Progesterone and estrogen balance is crucial during this time for successful implantation. Thus, the correct answer is (c) Day 20-24.
6) Clinical case: A woman undergoes IVF, and embryo transfer is done on day 5 post-ovulation. Implantation is expected around:
a) Day 10
b) Day 14
c) Day 19-21
d) Day 26
In IVF, embryo transfer usually occurs on day 5 post-ovulation (blastocyst stage). Implantation follows about 5 to 6 days later, coinciding with day 19 to 21 of a natural cycle. Synchronization of endometrial receptivity is crucial for success. Thus, the correct answer is (c) Day 19-21.
7) Which hormone prepares the endometrium for implantation?
a) LH
b) Estrogen
c) Progesterone
d) FSH
The hormone responsible for preparing the endometrium for implantation is progesterone. It transforms the proliferative endometrium into a secretory one, rich in nutrients for the developing blastocyst. It also suppresses uterine contractions, allowing attachment of the embryo. Hence, the correct answer is (c) Progesterone.
8) Clinical case: In ectopic pregnancy, implantation occurs most commonly at:
a) Cervix
b) Ovary
c) Fallopian tube
d) Uterus
In ectopic pregnancy, implantation occurs outside the uterine cavity. The most common site is the ampulla of the fallopian tube. It results from impaired transport of the zygote and may cause rupture and internal bleeding. Hence, the correct answer is (c) Fallopian tube.
9) Implantation in the uterus is facilitated by which layer of the endometrium?
a) Basalis
b) Functionalis
c) Compact layer
d) Spongy layer
Implantation occurs in the compact layer of the functionalis part of the endometrium, where trophoblast cells invade maternal tissues. The spongy layer contributes to early placental development. The basal layer regenerates after menstruation. Therefore, the correct answer is (c) Compact layer.
10) Clinical case: If implantation fails repeatedly, which diagnostic test is useful to evaluate endometrial receptivity?
a) AMH test
b) Endometrial biopsy
c) FSH level
d) Karyotyping
An endometrial biopsy helps evaluate whether the endometrium has undergone proper secretory transformation, indicating its receptivity for implantation. It detects progesterone deficiency or luteal phase defects. Therefore, for recurrent implantation failure, the correct test is (b) Endometrial biopsy.
Topic: Fertilization and Early Development; Subtopic: Blastocyst Formation and Hatching
Keyword Definitions:
Blastocyst: A hollow ball of cells formed about 5–6 days after fertilization, consisting of the inner cell mass and trophoblast.
Zona pellucida: A glycoprotein shell around the zygote that protects it until implantation.
Hatching: The process by which the blastocyst breaks free from the zona pellucida before implantation.
Fertilization: Union of sperm and ovum in the fallopian tube forming a zygote.
Implantation: Attachment of the blastocyst to the uterine endometrium.
Cleavage: Rapid mitotic divisions of the zygote without cell growth.
Trophoblast: Outer layer of cells in the blastocyst that forms part of the placenta.
Lead Question (2014):
Blastocyst comes out on which day after fertilization?
a) 4-7 days
b) 10-12 days
c) 12-15 days
d) 15-20 days
Explanation:
The blastocyst emerges from the zona pellucida around the 5th to 6th day after fertilization, a process known as hatching. This allows it to implant into the endometrial lining. Hatching is crucial for implantation as the zona pellucida prevents premature adhesion. The correct answer is (a) 4–7 days.
1) The blastocyst stage in humans occurs around which day after fertilization?
a) Day 2
b) Day 3
c) Day 5
d) Day 8
After fertilization, the zygote undergoes cleavage to form a morula by day 3 and then a blastocyst by day 5. The blastocyst then moves toward the uterus and prepares for implantation. This transformation marks the start of embryonic development. Hence, the correct answer is (c) Day 5.
2) Clinical case: A 30-year-old woman undergoing IVF has embryos transferred on day 5. What stage are they at?
a) Zygote
b) Morula
c) Blastocyst
d) Gastrula
In in vitro fertilization (IVF), embryos are commonly transferred on day 5 when they reach the blastocyst stage. This stage offers higher implantation potential due to cellular differentiation. Blastocyst transfer synchronizes better with endometrial receptivity. Hence, the correct answer is (c) Blastocyst.
3) Zona hatching of the blastocyst is essential for:
a) Cleavage
b) Implantation
c) Gastrulation
d) Placenta formation
The blastocyst must break free from the zona pellucida to implant into the uterus. This process, known as zona hatching, occurs around the 5th–6th day post-fertilization and allows trophoblast cells to attach to the endometrium. Hence, the correct answer is (b) Implantation.
4) Clinical case: A patient with thin endometrium after IVF shows failure of implantation. What could be the likely reason?
a) Early hatching
b) Late hatching
c) Early cleavage
d) Multiple zygotes
If implantation fails due to delayed blastocyst hatching or endometrial asynchrony, the embryo cannot adhere to the uterine wall. Late hatching delays implantation timing and reduces pregnancy chances. Therefore, the correct answer is (b) Late hatching.
5) Which layer of the blastocyst forms the placenta?
a) Inner cell mass
b) Trophoblast
c) Zona pellucida
d) Blastocoel
The trophoblast forms the outer layer of the blastocyst and gives rise to the placenta and extraembryonic membranes. It provides nutrients and supports the embryo. The inner cell mass develops into the embryo proper. Hence, the correct answer is (b) Trophoblast.
6) The fluid-filled cavity within the blastocyst is called:
a) Morula
b) Amnion
c) Blastocoel
d) Yolk sac
The blastocoel is a fluid-filled cavity within the blastocyst that forms as the morula differentiates. It separates the inner cell mass from the trophoblast and helps expand the blastocyst before implantation. Thus, the correct answer is (c) Blastocoel.
7) Clinical case: A woman with blocked fallopian tubes is unable to conceive naturally. Which process is most affected?
a) Fertilization and zygote transport
b) Ovulation
c) Blastocyst hatching
d) Endometrial development
Blocked fallopian tubes prevent the sperm from reaching the ovum and hinder zygote transport to the uterus. Therefore, both fertilization and zygote transport are affected. Implantation cannot occur as the blastocyst never reaches the uterus. Hence, the correct answer is (a) Fertilization and zygote transport.
8) The morula contains approximately how many cells?
a) 4
b) 8
c) 16
d) 32
The morula is a 16-cell stage embryo formed by cleavage of the zygote around day 3 after fertilization. It resembles a mulberry in appearance and precedes the blastocyst stage. The correct answer is (c) 16 cells.
9) Which event marks the transition from morula to blastocyst?
a) Formation of blastocoel
b) Zona hardening
c) Cleavage
d) Fertilization
The formation of the blastocoel cavity marks the transition from morula to blastocyst. Fluid accumulates between cells, creating a cavity that differentiates the trophoblast and inner cell mass. Hence, the correct answer is (a) Formation of blastocoel.
10) Clinical case: A 35-year-old woman conceives after IVF. Ultrasound on day 7 post-transfer shows no implantation. What is the likely reason?
a) Early hatching
b) Failed hatching
c) Normal delay
d) Progesterone excess
In IVF, if no implantation is seen after day 7, the most probable cause is failed hatching of the blastocyst. Without shedding the zona pellucida, it cannot attach to the uterine wall. Assisted hatching techniques are used to improve success rates. Hence, the correct answer is (b) Failed hatching.
Topic: Pituitary Hormones; Subtopic: Regulation of Growth Hormone Secretion
Keyword Definitions:
Growth Hormone (GH): A peptide hormone produced by the anterior pituitary that stimulates growth, cell reproduction, and regeneration.
Somatostatin: A hypothalamic hormone that inhibits the secretion of GH and TSH.
GHRH (Growth Hormone-Releasing Hormone): A hypothalamic hormone that stimulates GH release.
Hypoglycemia: A condition where blood glucose levels fall below normal, stimulating GH secretion.
Sleep and Exercise: Natural physiological stimuli that enhance GH secretion through hypothalamic activation.
Lead Question - 2014
Growth hormone secretion is stimulated by?
a) Increased blood glucose
b) Decreased blood glucose
c) Cortisol
d) Somatostatin
Explanation: Growth hormone (GH) secretion is stimulated by decreased blood glucose, stress, exercise, and sleep. Hypoglycemia increases GHRH release and suppresses somatostatin, enhancing GH secretion. Elevated GH then promotes gluconeogenesis and lipolysis to restore glucose levels. Hence, the correct answer is decreased blood glucose.
1. Growth hormone secretion is inhibited by?
a) GHRH
b) Dopamine
c) Somatostatin
d) Hypoglycemia
Explanation: GH secretion is mainly inhibited by somatostatin, a peptide hormone released by the hypothalamus. It suppresses both GH and TSH secretion. Elevated blood glucose, aging, and obesity also reduce GH levels. Thus, the correct answer is somatostatin.
2. Which hormone increases during deep sleep and fasting?
a) Insulin
b) Growth hormone
c) Cortisol
d) Aldosterone
Explanation: Growth hormone secretion peaks during deep sleep (slow-wave sleep) and fasting. This pattern supports tissue repair and mobilization of fat for energy. GH opposes insulin action to conserve glucose for essential organs. The correct answer is growth hormone.
3. A 20-year-old athlete experiences increased muscle mass after intensive workouts due to elevated?
a) Cortisol
b) Growth hormone
c) Prolactin
d) TSH
Explanation: Physical exercise stimulates GH release, promoting protein synthesis, muscle growth, and tissue repair. GH enhances amino acid uptake and decreases protein breakdown. Hence, increased muscle mass is due to elevated growth hormone.
4. Which of the following inhibits growth hormone secretion?
a) Sleep
b) Stress
c) Somatostatin
d) Hypoglycemia
Explanation: Somatostatin inhibits GH secretion by acting on the anterior pituitary. It counterbalances the stimulatory action of GHRH and prevents excessive GH levels. Therefore, somatostatin inhibits GH secretion effectively.
5. Growth hormone acts through which secondary messenger system?
a) cAMP
b) cGMP
c) JAK-STAT pathway
d) Calcium-calmodulin
Explanation: GH acts via the JAK-STAT (Janus kinase-signal transducer and activator of transcription) pathway. This mechanism promotes gene transcription related to growth and metabolism. Hence, the correct answer is JAK-STAT pathway.
6. A 10-year-old boy with short stature shows low GH levels but normal GHRH. Likely defect is in?
a) Hypothalamus
b) Anterior pituitary
c) Thyroid gland
d) Liver
Explanation: Normal GHRH with low GH indicates a defect in the anterior pituitary somatotroph cells that secrete GH. The hypothalamus is intact. Hence, the defect lies in the anterior pituitary.
7. GH promotes growth mainly by stimulating the release of?
a) Thyroxine
b) Insulin-like growth factor 1 (IGF-1)
c) Cortisol
d) Adrenaline
Explanation: GH promotes growth through IGF-1, synthesized in the liver under GH stimulation. IGF-1 mediates anabolic effects like cell proliferation and bone elongation. The correct answer is Insulin-like Growth Factor 1 (IGF-1).
8. A patient with acromegaly shows excess GH. The most likely cause is?
a) Pituitary adenoma
b) Hypothalamic failure
c) Adrenal tumor
d) Thyroid dysfunction
Explanation: Acromegaly results from a GH-secreting pituitary adenoma. It causes enlargement of hands, feet, and facial bones due to excessive GH and IGF-1. Therefore, the cause is pituitary adenoma.
9. Which of the following decreases growth hormone secretion?
a) Fasting
b) Obesity
c) Exercise
d) Hypoglycemia
Explanation: Obesity suppresses GH secretion due to altered feedback mechanisms and insulin resistance. GH response to stimuli like sleep and exercise diminishes in obesity. Hence, obesity decreases GH secretion.
10. A newborn with hypoglycemia and micrognathia may have deficiency of?
a) Growth hormone
b) Prolactin
c) Cortisol
d) Insulin
Explanation: Neonatal GH deficiency leads to hypoglycemia (due to impaired gluconeogenesis) and growth retardation with micrognathia and delayed bone age. Thus, the correct answer is growth hormone.
Topic: Puberty and Reproductive Hormones; Subtopic: Hormonal Regulation of Puberty
Keyword Definitions:
Puberty: The transitional phase during which sexual maturity is achieved, marked by the development of secondary sexual characteristics and reproductive capability.
Leptin: A hormone from adipose tissue that signals the hypothalamus to initiate puberty once sufficient body fat is accumulated.
LH (Luteinizing Hormone): A pituitary hormone that stimulates testosterone production in males and ovulation in females.
Testosterone: The primary male sex hormone responsible for male secondary sexual traits and spermatogenesis.
GnRH (Gonadotropin-Releasing Hormone): A hypothalamic hormone that triggers LH and FSH secretion to start puberty.
Lead Question - 2014
Hormones required during puberty?
a) LH
b) Testosterone
c) Leptin
d) All of the above
Explanation: Puberty is regulated by a coordinated rise in GnRH, LH, FSH, sex steroids, and leptin. LH and FSH stimulate gonadal maturation, while testosterone and estrogen induce secondary sexual traits. Leptin, secreted by fat cells, signals adequate energy stores to initiate reproductive maturation. Thus, the correct answer is All of the above.
1. The first hormonal change during puberty is the increased secretion of?
a) LH
b) FSH
c) GnRH
d) Estrogen
Explanation: Puberty begins with increased pulsatile secretion of GnRH from the hypothalamus. This stimulates LH and FSH release, activating gonadal steroidogenesis. GnRH pulses are more frequent during sleep initially, marking the onset of puberty. Hence, the correct answer is GnRH.
2. Which of the following is the earliest sign of puberty in girls?
a) Menarche
b) Thelarche
c) Pubarche
d) Growth spurt
Explanation: The earliest sign of puberty in girls is thelarche (breast development) due to estrogen secretion stimulated by FSH. Menarche occurs later as ovulatory cycles establish. Pubarche and growth spurts follow in sequence during normal pubertal progression.
3. In boys, puberty is marked by increased secretion of?
a) Progesterone
b) Testosterone
c) Estrogen
d) LH only
Explanation: Puberty in boys begins with a rise in LH stimulating Leydig cells to produce testosterone. This hormone induces spermatogenesis, deepens the voice, and promotes muscle growth. Hence, testosterone is the primary hormone responsible for male pubertal changes.
4. Leptin acts primarily on which structure to initiate puberty?
a) Pituitary gland
b) Adrenal cortex
c) Hypothalamus
d) Thyroid gland
Explanation: Leptin acts on the hypothalamus to enhance GnRH secretion. It signals adequate energy reserves to begin reproductive function. Low leptin levels in undernutrition delay puberty, highlighting its role as a metabolic gatekeeper of sexual maturation.
5. A 14-year-old boy shows delayed puberty and low testosterone with high LH. Likely cause?
a) Pituitary defect
b) Testicular failure
c) Hypothalamic defect
d) Adrenal hyperplasia
Explanation: High LH with low testosterone indicates primary testicular failure (hypergonadotropic hypogonadism). The pituitary tries to compensate by secreting more LH, but the testes fail to respond, delaying puberty. The correct answer is testicular failure.
6. Which of the following hormones rises first during female puberty?
a) LH
b) FSH
c) Estrogen
d) Progesterone
Explanation: In girls, FSH secretion rises first, stimulating follicle growth and estrogen production. LH surges later to trigger ovulation. Estrogen then leads to breast development and uterine growth. Hence, FSH is the earliest to rise during puberty.
7. A 12-year-old girl with normal height but absent breast development and low estrogen likely has deficiency of?
a) GnRH
b) FSH
c) LH
d) All of the above
Explanation: The absence of breast development and low estrogen with normal growth suggests hypogonadotropic hypogonadism, often due to GnRH deficiency. Without GnRH, LH and FSH are not released, preventing estrogen production and secondary sexual traits.
8. Puberty may be delayed in anorexic individuals due to low levels of?
a) Cortisol
b) Leptin
c) Insulin
d) Growth hormone
Explanation: Anorexia leads to decreased adipose tissue and reduced leptin levels. Leptin deficiency inhibits GnRH release, delaying puberty. Hence, delayed puberty in anorexia is primarily due to low leptin levels affecting hypothalamic-pituitary-gonadal axis activation.
9. The main cause of precocious puberty in girls is?
a) Pituitary tumor
b) Hypothalamic activation
c) Ovarian failure
d) Adrenal insufficiency
Explanation: True precocious puberty is usually due to premature activation of the hypothalamic-pituitary-gonadal axis (central type). This leads to early GnRH, LH, and FSH secretion. Hence, the cause is hypothalamic activation.
10. In males, the hormone responsible for spermatogenesis initiation during puberty is?
a) LH
b) FSH
c) Prolactin
d) Testosterone
Explanation: FSH acts on Sertoli cells to initiate spermatogenesis during puberty. LH supports Leydig cells to produce testosterone, which also facilitates sperm maturation. Thus, FSH plays a crucial role in initiating spermatogenesis during male puberty.
Topic: Puberty and Secondary Sexual Characteristics; Subtopic: Hormonal Control of Pubarche
Keyword Definitions:
Pubarche: The onset of pubic and axillary hair growth during puberty, resulting from increased secretion of adrenal androgens.
Adrenarche: The phase before puberty when adrenal glands begin producing more androgens like DHEA and androstenedione.
Androgens: Steroid hormones, such as testosterone and DHEA, responsible for male characteristics and hair growth in both sexes.
Estrogen: The main female sex hormone that regulates breast development and menstrual cycles.
Growth Hormone (GH): A pituitary hormone that promotes body growth and metabolism but does not cause pubic hair development.
Lead Question - 2014
Pubarche is due to?
a) GH
b) Progesterone
c) Testosterone
d) Estrogen
Explanation: Pubarche, the appearance of pubic and axillary hair, occurs due to increased secretion of adrenal androgens such as dehydroepiandrosterone (DHEA) and androstenedione during adrenarche. These androgens are converted peripherally to testosterone, which stimulates hair follicle growth. Therefore, the correct answer is Testosterone.
1. The onset of adrenarche occurs at approximately what age?
a) 2–4 years
b) 5–7 years
c) 8–10 years
d) 12–14 years
Explanation: Adrenarche begins around 5–7 years of age, preceding puberty. During this period, the adrenal cortex (zona reticularis) matures and begins secreting higher levels of DHEA and androstenedione, leading to pubarche and other androgenic effects before gonadal activation.
2. Which adrenal zone is responsible for androgen production leading to pubarche?
a) Zona glomerulosa
b) Zona fasciculata
c) Zona reticularis
d) Zona pellucida
Explanation: The zona reticularis of the adrenal cortex secretes weak androgens like DHEA and androstenedione. These androgens are responsible for the development of pubic and axillary hair, marking the event known as pubarche. Hence, the correct answer is zona reticularis.
3. In girls, which event occurs first during puberty?
a) Pubarche
b) Thelarche
c) Menarche
d) Growth spurt
Explanation: Thelarche (breast development) usually occurs first, followed by pubarche, growth spurt, and finally menarche. Thelarche is due to estrogen effects, whereas pubarche is androgen-mediated. Hence, the earliest event is thelarche.
4. Pubarche occurs due to increased secretion of?
a) FSH
b) LH
c) DHEA
d) Prolactin
Explanation: The adrenal androgen DHEA (dehydroepiandrosterone) is primarily responsible for the appearance of pubic and axillary hair. Its secretion increases during adrenarche, preceding gonadal activation, and stimulates hair follicle maturation and sebaceous gland activity.
5. A 10-year-old girl presents with early pubic hair but no breast development. Likely diagnosis?
a) True precocious puberty
b) Premature adrenarche
c) Gonadal tumor
d) Central hypothyroidism
Explanation: Early appearance of pubic hair without other secondary sexual features indicates premature adrenarche. It results from early adrenal androgen secretion without activation of the hypothalamic-pituitary-gonadal axis. It is usually benign and self-limiting.
6. Which hormone does not contribute directly to pubarche?
a) Testosterone
b) DHEA
c) Estrogen
d) Androstenedione
Explanation: Estrogen primarily regulates female reproductive tissues and breast development but does not cause hair growth. Pubarche depends on adrenal androgens like testosterone, DHEA, and androstenedione. Hence, estrogen is not directly involved in pubic hair development.
7. In males, pubarche coincides with which event?
a) Voice deepening
b) Spermarche
c) Penile enlargement
d) Facial hair development
Explanation: In males, pubarche coincides with penile enlargement due to rising androgen levels. Facial hair and voice deepening occur later. Hence, penile enlargement typically occurs concurrently with pubic hair development during puberty.
8. Which of the following is true about adrenarche and gonadarche?
a) Adrenarche follows gonadarche
b) Both start simultaneously
c) Adrenarche precedes gonadarche
d) They are unrelated processes
Explanation: Adrenarche precedes gonadarche. Adrenarche involves adrenal androgen secretion, while gonadarche marks gonadal hormone activation (testosterone, estrogen). Although independent, both processes overlap during puberty and contribute to secondary sexual characteristics.
9. A 13-year-old boy with delayed puberty has low DHEA and low LH. The defect is most likely in?
a) Testes
b) Adrenal cortex
c) Hypothalamus
d) Pituitary gland
Explanation: Low levels of both DHEA (adrenal androgen) and LH (pituitary hormone) suggest a hypothalamic defect leading to decreased GnRH secretion. This causes underactivity of both adrenal and gonadal axes, resulting in delayed puberty.
10. Which enzyme is essential for androgen synthesis during adrenarche?
a) 21-hydroxylase
b) 11β-hydroxylase
c) 17,20-lyase
d) Aromatase
Explanation: The enzyme 17,20-lyase catalyzes the conversion of pregnenolone and progesterone into DHEA and androstenedione, which are key androgens responsible for pubarche. Deficiency of this enzyme leads to reduced androgen synthesis and delayed onset of secondary hair growth.
Topic: Female Reproductive Physiology; Subtopic: Graafian Follicle and Ovum Maturation
Keyword Definitions:
• Graafian follicle: The mature ovarian follicle containing the secondary oocyte ready for ovulation.
• Oocyte: The female gamete that undergoes meiotic division to form the ovum.
• Cumulus oophorus: A cluster of granulosa cells surrounding the oocyte that nourishes and supports it.
• Luteal cells: Cells formed from granulosa and theca after ovulation that secrete progesterone.
Lead Question - 2014
Cells which surround the oocyst in graafian follicle are called?
a) Discus proligerus
b) Cumulus oophoricus
c) Luteal cells
d) Villus cells
Explanation: The correct answer is (b) Cumulus oophoricus. These granulosa cells form a protective mass around the oocyte, connecting it to the follicular wall via the discus proligerus. They supply nutrients and signaling molecules essential for oocyte maturation and release during ovulation. The luteal cells form later after ovulation.
1) The hormone responsible for follicular growth is?
a) LH
b) FSH
c) Estrogen
d) Progesterone
Explanation: The correct answer is (b) FSH. Follicle-stimulating hormone stimulates the growth of ovarian follicles and the proliferation of granulosa cells. FSH also promotes estrogen secretion by granulosa cells. Its surge, along with LH, leads to follicle maturation before ovulation. FSH is secreted by the anterior pituitary gland.
2) Ovulation is triggered by a surge in which hormone?
a) LH
b) FSH
c) Progesterone
d) Oxytocin
Explanation: The correct answer is (a) LH. The mid-cycle surge of luteinizing hormone causes rupture of the mature Graafian follicle, releasing the secondary oocyte. LH acts on the follicular wall, increasing proteolytic enzyme activity. It also transforms granulosa cells into luteal cells after ovulation for progesterone secretion.
3) The corpus luteum primarily secretes?
a) Estrogen
b) LH
c) Progesterone
d) FSH
Explanation: The correct answer is (c) Progesterone. Corpus luteum forms from the remnants of the ruptured Graafian follicle and secretes progesterone, which prepares the endometrium for implantation. If fertilization doesn’t occur, it degenerates into corpus albicans, leading to decreased hormone levels and menstruation.
4) Theca interna cells of Graafian follicle produce?
a) Estrogen
b) Progesterone
c) LH
d) FSH
Explanation: The correct answer is (a) Estrogen. Theca interna cells synthesize androgens under LH stimulation. These androgens are converted to estrogen by granulosa cells through the enzyme aromatase. Estrogen promotes proliferation of the endometrium and feedback regulation of gonadotropin release.
5) Which of the following cells are derived from granulosa cells after ovulation?
a) Luteal cells
b) Theca externa
c) Germ cells
d) Stromal cells
Explanation: The correct answer is (a) Luteal cells. After ovulation, granulosa and theca cells luteinize to form luteal cells in the corpus luteum. These cells secrete progesterone and small amounts of estrogen, maintaining the endometrium for potential implantation and early pregnancy support.
6) (Clinical) A woman with anovulatory cycles likely lacks a surge of which hormone?
a) FSH
b) LH
c) Estrogen
d) Progesterone
Explanation: The correct answer is (b) LH. The absence of LH surge prevents follicular rupture, causing anovulation. Such cycles are common in polycystic ovarian syndrome (PCOS), stress, or hormonal imbalance. Lack of progesterone due to no corpus luteum formation may lead to irregular menstrual bleeding.
7) (Clinical) In polycystic ovarian syndrome, which hormone is typically elevated?
a) LH
b) FSH
c) Estrogen
d) Prolactin
Explanation: The correct answer is (a) LH. PCOS is characterized by an increased LH:FSH ratio, anovulation, and hyperandrogenism. Excess LH stimulates theca cells to produce androgens, while insufficient FSH prevents normal follicular maturation. This leads to multiple immature cysts in ovaries and infertility.
8) (Clinical) Luteal phase defect results in?
a) Early ovulation
b) Infertility
c) Multiple ovulations
d) Increased FSH
Explanation: The correct answer is (b) Infertility. In luteal phase defect, corpus luteum fails to produce adequate progesterone, causing poor endometrial development. This results in failed implantation or early miscarriage. Hormonal imbalance, stress, or inadequate LH support may contribute to this defect.
9) (Clinical) A patient with excessive estrogen but no ovulation likely has?
a) Follicular cyst
b) Corpus luteum cyst
c) Endometrial polyp
d) Luteal cyst
Explanation: The correct answer is (a) Follicular cyst. Follicular cysts form when Graafian follicles fail to rupture and continue growing, producing estrogen. This condition can cause menstrual irregularities, mild pain, and endometrial hyperplasia due to prolonged estrogen exposure.
10) (Clinical) Absence of corpus luteum indicates failure of?
a) Ovulation
b) Fertilization
c) Implantation
d) Menstruation
Explanation: The correct answer is (a) Ovulation. Corpus luteum develops only after ovulation. Its absence suggests no follicular rupture, typical in anovulatory cycles. This leads to absence of progesterone and failure of endometrial secretory changes, contributing to infertility and abnormal uterine bleeding.
Topic: Male Reproductive Physiology; Subtopic: Sperm Capacitation and Fertilization
Keyword Definitions:
• Capacitation: The physiological process that sperm undergo in the female reproductive tract to gain the ability to fertilize an ovum.
• Acrosome: A cap-like vesicle on the sperm head containing enzymes that help penetrate the ovum.
• Calcium permeability: Calcium influx is essential for sperm motility and acrosomal reaction.
• Cholesterol removal: Cholesterol efflux from the sperm membrane enhances its fluidity during capacitation.
Lead Question - 2014
Following changes are seen during capacitation of sperms except?
a) Increased permeability to calcium
b) Decreased permeability to calcium
c) Removal of cholesterol from acrosome
d) Increased motility
Explanation: The correct answer is (b) Decreased permeability to calcium. During capacitation, spermatozoa undergo biochemical modifications including increased permeability to calcium ions, removal of cholesterol from the plasma membrane, and enhanced motility. These changes prepare sperm for the acrosomal reaction necessary for fertilization. Decreased calcium permeability would inhibit capacitation and prevent fertilization.
1) Which enzyme helps sperm to penetrate the zona pellucida?
a) Hyaluronidase
b) Acrosin
c) Lipase
d) Trypsin
Explanation: The correct answer is (b) Acrosin. Acrosin is a proteolytic enzyme released from the acrosome of the sperm during the acrosomal reaction. It helps digest the glycoprotein matrix of the zona pellucida, facilitating sperm entry into the oocyte. This reaction occurs after capacitation, enabling successful fertilization in the ampulla of the fallopian tube.
2) Where does sperm capacitation occur in the female reproductive tract?
a) Uterus
b) Cervix
c) Vagina
d) Fallopian tube
Explanation: The correct answer is (d) Fallopian tube. Capacitation mainly occurs in the ampullary region of the fallopian tube, where sperm are exposed to female tract secretions. These secretions remove surface glycoproteins and cholesterol, enhancing membrane fluidity. This environment activates sperm motility and prepares them for the acrosome reaction necessary for fertilization.
3) Capacitation leads to which of the following outcomes?
a) Reduced sperm motility
b) Acrosome stabilization
c) Hyperactivated motility
d) DNA fragmentation
Explanation: The correct answer is (c) Hyperactivated motility. Capacitation increases sperm motility due to calcium influx and cAMP signaling. This hyperactivation enables sperm to move vigorously and penetrate the cumulus oophorus and zona pellucida. The acrosomal reaction then allows sperm to fuse with the oocyte membrane, leading to fertilization.
4) (Clinical) A male patient with defective sperm capacitation may have infertility due to failure of?
a) Sperm motility
b) Acrosome reaction
c) Testosterone production
d) Spermatogenesis
Explanation: The correct answer is (b) Acrosome reaction. Defective capacitation prevents sperm from undergoing acrosomal reaction, thereby inhibiting penetration of the zona pellucida. This leads to fertilization failure. Capacitation failure may result from abnormalities in seminal plasma proteins or impaired membrane cholesterol efflux affecting calcium ion channels.
5) What is the time duration required for human sperm capacitation?
a) 15 minutes
b) 1 hour
c) 6–8 hours
d) 24 hours
Explanation: The correct answer is (c) 6–8 hours. Human sperm typically require 6–8 hours within the female genital tract to undergo capacitation. During this period, the sperm membranes undergo enzymatic and ionic modifications. These changes are essential for preparing sperm for the acrosome reaction and subsequent fertilization.
6) (Clinical) A couple with normal sperm count but failure of fertilization in IVF may have a defect in?
a) Sperm capacitation
b) Sperm motility
c) Zona pellucida
d) Endometrium
Explanation: The correct answer is (a) Sperm capacitation. Even with normal count and motility, defective capacitation prevents acrosome reaction and sperm-egg binding. In IVF labs, capacitation can be induced artificially using media containing albumin and calcium ions. Proper capacitation ensures successful zona penetration and fertilization.
7) Which ion is most essential for the process of sperm capacitation?
a) Sodium
b) Potassium
c) Calcium
d) Magnesium
Explanation: The correct answer is (c) Calcium. Calcium influx triggers biochemical signaling pathways that regulate motility and acrosome exocytosis. Calcium channels in the sperm plasma membrane become more active during capacitation, contributing to increased motility and preparation for zona pellucida penetration.
8) During capacitation, sperm membrane loses?
a) Cholesterol
b) Calcium
c) Sodium
d) Protein
Explanation: The correct answer is (a) Cholesterol. The removal of cholesterol and glycoproteins from the sperm membrane enhances membrane fluidity, making it responsive to signals from the oocyte’s zona pellucida. This step is critical for successful fertilization and membrane fusion between gametes.
9) (Clinical) A patient undergoing IVF is given heparin in the capacitation medium because it?
a) Activates calcium channels
b) Removes cholesterol from sperm membrane
c) Inhibits sperm motility
d) Prevents acrosomal damage
Explanation: The correct answer is (b) Removes cholesterol from sperm membrane. Heparin is used in vitro to induce sperm capacitation by promoting cholesterol efflux. This increases membrane fluidity, enabling calcium influx and hyperactivation. Such preparation mimics the natural capacitation environment of the female reproductive tract.
10) (Clinical) Failure of zona pellucida penetration by sperm indicates a defect in?
a) Acrosin release
b) Flagellar motion
c) Sertoli cells
d) Leydig cells
Explanation: The correct answer is (a) Acrosin release. Acrosin is vital for enzymatic digestion of the zona pellucida. Its absence or defective release prevents sperm penetration and fertilization. This can occur due to abnormal capacitation or defective acrosomal enzymes, commonly leading to infertility.
Topic: Female Reproductive Hormones; Subtopic: Estrogen Receptors and their Distribution
Keyword Definitions:
• Estrogen: A steroid hormone produced mainly by the ovaries responsible for secondary sexual characteristics and reproductive cycle regulation.
• Estrogen Receptors (ER): Proteins that mediate estrogen’s effects; two main types are ER-α and ER-β.
• ER-β (Estrogen Beta Receptors): Receptor subtype found predominantly in ovary, vascular endothelium, and certain brain regions.
• Ovary: The female gonad producing ova and hormones such as estrogen and progesterone.
Lead Question - 2014
Estrogen Beta receptors are found on:
a) Uterus
b) Blood vessels
c) Ovary
d) Vagina
Explanation: The correct answer is (c) Ovary. Estrogen β receptors (ER-β) are expressed in high concentrations in the ovary, prostate, lungs, and cardiovascular tissues. They modulate gene transcription distinct from ER-α, influencing follicular growth, vascular tone, and cellular differentiation. ER-α is abundant in the uterus and breast, while ER-β plays a key role in ovarian physiology and vascular health.
1) Which type of estrogen receptor is predominantly found in the uterus?
a) ER-α
b) ER-β
c) Both equally
d) None
Explanation: The correct answer is (a) ER-α. Estrogen receptor alpha (ER-α) is mainly expressed in the uterus, mammary glands, and liver. It regulates gene transcription that promotes uterine growth and endometrial proliferation. In contrast, ER-β dominates in ovaries, brain, and vascular tissues, mediating different cellular functions including anti-proliferative effects.
2) ER-β receptors in ovaries primarily regulate which of the following?
a) Ovum maturation
b) LH secretion
c) Endometrial thickening
d) Progesterone synthesis
Explanation: The correct answer is (a) Ovum maturation. ER-β is crucial for follicular development, ovum maturation, and prevention of granulosa cell apoptosis. It modulates follicle-stimulating hormone (FSH) signaling pathways to ensure proper oocyte growth and release during ovulation. Thus, ER-β is central to reproductive function in the ovary.
3) (Clinical) Deficiency of ER-β receptors can cause?
a) Anovulation
b) Amenorrhea
c) Premature menopause
d) Increased fertility
Explanation: The correct answer is (a) Anovulation. ER-β deficiency disrupts follicular development and ovum maturation, leading to anovulatory cycles. Clinically, this presents as infertility or irregular menses. Animal models lacking ER-β show impaired folliculogenesis despite normal ER-α expression, emphasizing its specific role in ovarian physiology.
4) Which organ expresses both ER-α and ER-β equally?
a) Brain
b) Uterus
c) Kidney
d) Thyroid
Explanation: The correct answer is (a) Brain. Both estrogen receptor subtypes coexist in the hypothalamus and hippocampus. ER-α modulates reproductive hormone regulation, while ER-β contributes to neuroprotection, synaptic plasticity, and cognitive functions. Together, they influence mood regulation and sexual behavior in both sexes.
5) (Clinical) In postmenopausal women, ER-β activation in blood vessels helps by?
a) Increasing blood pressure
b) Reducing endothelial damage
c) Causing thrombosis
d) Reducing nitric oxide release
Explanation: The correct answer is (b) Reducing endothelial damage. Estrogen acting on ER-β receptors enhances nitric oxide release, improving vasodilation and vascular health. Postmenopausal estrogen loss increases cardiovascular risk due to reduced ER-β-mediated protection. Thus, selective ER-β modulators are being explored for cardiovascular benefits without stimulating uterine proliferation.
6) Estrogen receptor alpha (ER-α) gene is located on which chromosome?
a) Chromosome 4
b) Chromosome 6
c) Chromosome 14
d) Chromosome 1
Explanation: The correct answer is (d) Chromosome 1. The gene for ER-α (ESR1) resides on chromosome 1, while ER-β (ESR2) is located on chromosome 14. These distinct genetic origins explain their different tissue distributions and functional roles in estrogen signaling and target gene activation.
7) (Clinical) A woman on selective estrogen receptor modulators (SERMs) has uterine proliferation but reduced breast risk. Which receptor subtype is likely targeted?
a) ER-α agonist, ER-β antagonist
b) ER-α antagonist, ER-β agonist
c) ER-β antagonist
d) ER-α agonist only
Explanation: The correct answer is (b) ER-α antagonist, ER-β agonist. SERMs like raloxifene act as ER-β agonists (beneficial for bones and vessels) and ER-α antagonists (reducing uterine and breast proliferation), achieving tissue-selective estrogenic effects useful in osteoporosis and breast cancer prevention.
8) Estrogen receptors belong to which receptor class?
a) G-protein coupled receptor
b) Ligand-gated ion channel
c) Nuclear receptor
d) Enzyme-linked receptor
Explanation: The correct answer is (c) Nuclear receptor. Estrogen receptors are nuclear hormone receptors that act as transcription factors. Upon binding estrogen, they form dimers, bind estrogen response elements (ERE) on DNA, and regulate gene expression involved in reproduction, metabolism, and growth regulation.
9) Which estrogen type has the highest affinity for both ER-α and ER-β?
a) Estrone
b) Estriol
c) Estradiol
d) Ethinyl estradiol
Explanation: The correct answer is (c) Estradiol. Estradiol (E2) is the most potent natural estrogen with high affinity for both receptor subtypes. It plays a vital role in maintaining reproductive function, bone density, and cardiovascular health in premenopausal women through receptor-mediated genomic and non-genomic effects.
10) (Clinical) ER-β agonists are being developed for the treatment of?
a) Endometrial carcinoma
b) Osteoporosis
c) Hypertension
d) Hypothyroidism
Explanation: The correct answer is (b) Osteoporosis. ER-β agonists enhance bone formation and reduce bone resorption without stimulating uterine or breast tissue. By promoting osteoblastic activity and inhibiting osteoclasts, they mimic estrogen’s beneficial skeletal effects while minimizing risks associated with traditional hormone replacement therapy.