Human Reproduction

Topic: Male Reproductive System; Subtopic: Male Accessory Ducts

Keyword Definitions:

• Testis: The primary male reproductive organ that produces sperms and the hormone testosterone.

• Epididymis: A long, coiled tube where sperm matures and is stored temporarily.

• Vasa efferentia: Fine ducts that transport sperms from the rete testis to the epididymis.

• Vas deferens: A muscular tube that carries mature sperms from the epididymis to the ejaculatory duct.

• Ejaculatory duct: The final duct through which sperms mix with seminal fluids before entering the urethra for ejaculation.

Lead Question - 2022 (Abroad)
Arrange the following male sex accessory ducts in the correct sequence for the transport of sperms from the testis:
(a) Epididymis
(b) Ejaculatory duct
(c) Vasa efferentia
(d) Rete testis
(e) Vas deferens
1. (d), (a), (c), (e), (b)
2. (d), (c), (e), (a), (b)
3. (d), (c), (a), (e), (b)
4. (d), (e), (a), (c), (b)

Explanation:
The correct sequence for sperm transport is rete testis → vasa efferentia → epididymis → vas deferens → ejaculatory duct. Sperms produced in seminiferous tubules enter rete testis, then pass through vasa efferentia to reach epididymis for maturation, continue through vas deferens, and finally reach the ejaculatory duct. Thus, option 3 is correct.

1. Which of the following stores the sperm temporarily before ejaculation?
1. Prostate gland
2. Epididymis
3. Urethra
4. Bulbourethral gland

Explanation:
Epididymis serves as a site for sperm maturation and temporary storage. Sperms gain motility and fertilizing ability while passing through it. During ejaculation, sperms are propelled from the epididymis through the vas deferens. Therefore, epididymis acts as the temporary sperm storage organ.

2. Which of the following connects rete testis to the epididymis?
1. Vas deferens
2. Vasa efferentia
3. Ejaculatory duct
4. Urethra

Explanation:
Vasa efferentia are fine ducts that transport immature sperms from rete testis to the epididymis. Here, sperms undergo maturation and storage before being transferred to vas deferens during ejaculation. Hence, the connecting ducts are vasa efferentia.

3. Which gland contributes fructose to the seminal fluid?
1. Prostate gland
2. Seminal vesicle
3. Bulbourethral gland
4. Cowper’s gland

Explanation:
Seminal vesicles secrete a viscous fluid rich in fructose, which provides energy to sperm cells for motility. This secretion also contains prostaglandins and proteins that support fertilization. Therefore, seminal vesicle is the gland responsible for fructose secretion in seminal fluid.

4. What is the function of the ejaculatory duct?
1. Storage of sperm
2. Conduction of sperms and seminal fluid
3. Secretion of testosterone
4. Formation of spermatids

Explanation:
The ejaculatory duct carries sperm from the vas deferens and mixes it with secretions from seminal vesicles to form semen. It acts as a short passageway that opens into the urethra during ejaculation. Hence, its main function is conduction of sperms and seminal fluid.

5. Which among the following is a paired structure in the male reproductive system?
1. Prostate gland
2. Seminal vesicle
3. Urethra
4. Penis

Explanation:
Seminal vesicles are paired glands located posterior to the urinary bladder. Each seminal vesicle contributes fluid to semen, which nourishes and protects sperm. In contrast, the prostate and urethra are single structures. Therefore, the paired structure is seminal vesicle.

6. The testis is located outside the abdominal cavity in the scrotum because:
1. High temperature is needed for spermatogenesis
2. Low temperature is required for spermatogenesis
3. It provides protection against injury
4. It helps in the secretion of testosterone

Explanation:
Spermatogenesis requires a temperature 2–2.5°C lower than the body’s core temperature. The scrotum helps maintain this lower temperature by positioning the testes outside the abdominal cavity. Therefore, the testis is located in the scrotum for optimal sperm production.

7. (Assertion-Reason Type)
Assertion (A): Vas deferens carries sperm from epididymis to ejaculatory duct.
Reason (R): Vas deferens is a muscular tube that conducts sperm through peristaltic contractions.
1. Both A and R are true, and R explains A
2. Both A and R are true, but R does not explain A
3. A is true but R is false
4. A is false but R is true

Explanation:
Vas deferens transports mature sperms from the epididymis to the ejaculatory duct using muscular peristalsis. This ensures efficient propulsion of sperms during ejaculation. Thus, both assertion and reason are true, and the reason correctly explains the assertion.

8. (Matching Type)
Match the following structures with their functions:
A. Epididymis – (i) Conducts sperms to ejaculatory duct
B. Vas deferens – (ii) Storage and maturation of sperms
C. Ejaculatory duct – (iii) Receives sperms and seminal vesicle secretions
1. A-(ii), B-(i), C-(iii)
2. A-(i), B-(ii), C-(iii)
3. A-(iii), B-(ii), C-(i)
4. A-(ii), B-(iii), C-(i)

Explanation:
Epididymis stores and matures sperms (A-ii), vas deferens conducts sperms to the ejaculatory duct (B-i), and the ejaculatory duct receives sperm and seminal vesicle secretions before ejaculation (C-iii). Thus, the correct matching is A-(ii), B-(i), C-(iii).

9. (Fill in the Blanks)
The site of sperm maturation and storage before ejaculation is the ________.
1. Testis
2. Epididymis
3. Vas deferens
4. Ejaculatory duct

Explanation:
Epididymis is a coiled structure on the posterior side of each testis where sperms mature and are stored. They gain motility and fertilization ability here before being transferred through vas deferens. Hence, epididymis is the correct answer.

10. (Choose the Correct Statements)
Statement I: Vas deferens and urethra are continuous ducts.
Statement II: Ejaculatory duct opens into the urethra.
1. Statement I correct, Statement II incorrect
2. Statement I incorrect, Statement II correct
3. Both statements correct
4. Both statements incorrect

Explanation:
Vas deferens joins with the duct of seminal vesicle to form the ejaculatory duct, which then opens into the urethra. Thus, vas deferens and urethra are not continuous ducts, but the ejaculatory duct indeed opens into the urethra. Hence, Statement II is correct.

Topic: Endocrinology; Subtopic: Pregnancy Hormones

Keyword Definitions:

• Relaxin: Hormone produced during pregnancy that relaxes ligaments and softens the cervix to aid childbirth.

• Oxytocin: Hormone released by posterior pituitary that stimulates uterine contractions and milk ejection, present in both sexes.

• hCG (Human Chorionic Gonadotropin): Hormone secreted by trophoblast cells during pregnancy, maintaining corpus luteum function and progesterone secretion.

• hPL (Human Placental Lactogen): Placental hormone promoting mammary gland growth and modulating maternal metabolism for fetal nutrition.

• Progesterone: Steroid hormone secreted by corpus luteum and placenta, maintains endometrial lining and inhibits uterine contractions during pregnancy.

• Corpus Luteum: Temporary endocrine structure in ovary producing progesterone after ovulation.

• Placenta: Organ connecting mother and fetus, responsible for nutrient and hormone exchange.

• Endocrinology: Study of hormones, their secretion, and physiological roles.

• Gestation: Period of fetal development in the uterus from conception to birth.

• Fetal Development: Growth and differentiation of the embryo and fetus in utero.

• Maternal Adaptation: Physiological changes in the mother to support pregnancy.

Lead Question - 2022 (Abroad)

Which of the following hormones are secreted in women only during pregnancy?

1. Relaxin

2. Oxytocin

3. hCG

4. hPL

5. Progesterone

Choose the most appropriate answer from the options given below:

1. (c), (d) and (e) only

2. (b) and (e) only

3. (b), (c) and (d) only

4. (a), (c) and (d) only

Explanation: The hormones secreted only during pregnancy include hCG, hPL, and Progesterone. hCG maintains corpus luteum function in early gestation, progesterone sustains endometrial lining and prevents contractions, and hPL modulates maternal metabolism and mammary development. Relaxin is also secreted in pregnancy, but primarily near parturition. Oxytocin is present in both sexes and is not exclusive to pregnancy. These pregnancy-specific hormones coordinate maternal adaptation, fetal development, and preparation for parturition. Correct answer is option 1 (c), (d) and (e) only.

1. SINGLE CORRECT ANSWER MCQ

Which hormone is primarily responsible for maintaining the endometrium during pregnancy?

1. Relaxin

2. Progesterone

3. Oxytocin

4. hPL

Explanation: Progesterone is the key hormone maintaining the endometrial lining during pregnancy. It is secreted initially by the corpus luteum and later by the placenta. Progesterone prevents uterine contractions, supports embryo implantation, and prepares the maternal system for fetal development. Relaxin softens ligaments, hPL aids metabolism, and oxytocin stimulates contractions. Therefore, progesterone is the primary hormone for endometrial maintenance. Correct answer: 2

2. SINGLE CORRECT ANSWER MCQ

Which hormone is secreted by trophoblast cells during early pregnancy?

1. Oxytocin

2. hCG

3. Relaxin

4. Progesterone

Explanation: Human Chorionic Gonadotropin (hCG) is secreted by trophoblast cells of the embryo during early pregnancy. It maintains the corpus luteum and ensures continued progesterone secretion. This hormone is essential for establishing pregnancy and is detected in pregnancy tests. Oxytocin, relaxin, and progesterone play different roles. Understanding hCG secretion is critical for early pregnancy physiology and monitoring gestational health. Correct answer: 2

3. SINGLE CORRECT ANSWER MCQ

Which hormone aids mammary gland growth and modulates maternal metabolism during pregnancy?

1. hPL

2. Oxytocin

3. Progesterone

4. Relaxin

Explanation: Human Placental Lactogen (hPL) is secreted by the placenta and promotes mammary gland development and maternal metabolic adaptation for fetal nutrition. It ensures glucose and lipid availability for fetal growth. Oxytocin controls contractions, progesterone maintains endometrium, and relaxin softens ligaments. hPL’s role is crucial for preparing the maternal body for lactation and supporting fetal energy needs. Correct answer: 1

4. SINGLE CORRECT ANSWER MCQ

Relaxin primarily functions in pregnancy to:

1. Stimulate uterine contractions

2. Soften ligaments and cervix

3. Maintain endometrium

4. Promote fetal growth

Explanation: Relaxin is secreted mainly by the corpus luteum and placenta during late pregnancy. Its main function is to relax pelvic ligaments and soften the cervix, facilitating childbirth. It does not maintain the endometrium, stimulate contractions, or directly promote fetal growth. Relaxin, combined with other pregnancy hormones, ensures proper maternal adaptation for labor. Understanding relaxin’s specific role helps differentiate pregnancy-specific hormonal functions. Correct answer: 2

5. SINGLE CORRECT ANSWER MCQ

Which hormone is not exclusive to pregnancy and is present in both sexes?

1. hCG

2. Oxytocin

3. hPL

4. Relaxin

Explanation: Oxytocin is produced by the posterior pituitary in both sexes and regulates uterine contractions in women and social bonding in both genders. It is not exclusive to pregnancy. In contrast, hCG, hPL, and relaxin are secreted specifically during pregnancy. Understanding this distinction is important in endocrinology, as it separates general pituitary hormones from pregnancy-specific placental hormones. Correct answer: 2

6. SINGLE CORRECT ANSWER MCQ

Which hormone ensures corpus luteum maintenance in early pregnancy?

1. Progesterone

2. hCG

3. Oxytocin

4. Relaxin

Explanation: hCG secreted by trophoblast cells maintains the corpus luteum during early pregnancy, ensuring continuous progesterone production to support the endometrium and prevent miscarriage. Progesterone alone cannot maintain the corpus luteum without hCG signaling. Oxytocin and relaxin perform different roles unrelated to corpus luteum maintenance. Recognizing hCG’s critical role is essential for understanding early pregnancy physiology. Correct answer: 2

7. ASSERTION-REASON MCQ

Assertion (A): hPL is secreted only during pregnancy.

Reason (R): hPL promotes maternal metabolic adaptations and mammary development for fetal support.

1. Both A and R are true and R explains A

2. Both A and R are true but R does not explain A

3. A is true but R is false

4. A is false but R is true

Explanation: Human Placental Lactogen (hPL) is secreted by the placenta exclusively during pregnancy. It modulates maternal metabolism, ensures nutrient supply to the fetus, and promotes mammary gland growth. Both Assertion and Reason are true, and the Reason correctly explains why hPL is pregnancy-specific. This hormone is a critical component of maternal adaptation, ensuring adequate fetal growth and preparation for lactation. Correct answer: 1

8. MATCHING TYPE MCQ

Match the hormones with their primary pregnancy function:

Column A:

1. hCG

2. Progesterone

3. hPL

4. Relaxin

Column B:

1. Maintains corpus luteum

2. Maintains endometrium

3. Maternal metabolic adaptation and mammary growth

4. Softens ligaments and cervix

Explanation: Correct matching: hCG → Maintains corpus luteum, Progesterone → Maintains endometrium, hPL → Maternal metabolism and mammary growth, Relaxin → Softens ligaments and cervix. Each hormone plays a distinct role in pregnancy, ensuring maternal adaptation, fetal development, and preparation for parturition. Understanding their functions is critical for clinical and physiological studies. Answer: hCG-1, Progesterone-2, hPL-3, Relaxin-4

9. FILL IN THE BLANKS / COMPLETION MCQ

The hormone secreted by the placenta that prepares maternal metabolism for fetal nutrition is _______.

1. Progesterone

2. hPL

3. Relaxin

4. Oxytocin

Explanation: Human Placental Lactogen (hPL) is secreted by the placenta during pregnancy. It ensures maternal metabolic adaptations, such as increased glucose and lipid availability, to support fetal growth. Additionally, hPL promotes mammary gland development for lactation. Progesterone maintains endometrium, relaxin softens ligaments, and oxytocin stimulates contractions. Understanding hPL’s role is vital for studying endocrine regulation and maternal-fetal physiology. Correct answer: 2

10. CHOOSE THE CORRECT STATEMENTS MCQ

Statement I: hCG, hPL, and Progesterone are secreted only during pregnancy.
Statement II: Oxytocin is exclusive to pregnant women.

1. Only Statement I is correct

2. Only Statement II is correct

3. Both Statements I and II are correct

4. Both Statements I and II are incorrect

Explanation: hCG, hPL, and progesterone are pregnancy-specific hormones, secreted only during gestation, coordinating maternal adaptation and fetal development. Oxytocin is present in both sexes and is not exclusive to pregnancy, performing roles in social bonding and labor. Therefore, only Statement I is correct. Recognizing pregnancy-specific versus general hormones is essential in endocrinology, clinical assessments, and understanding maternal-fetal physiology. Correct answer: 1

Topic: Gametogenesis; Subtopic: Polar Bodies in Oogenesis

Keyword Definitions:

• Polar body: Small haploid cell formed during oogenesis that generally does not develop into an ovum.

• Oogenesis: Process of formation of female gametes (ova) through meiosis.

• Meiosis: Cell division resulting in four haploid daughter cells from one diploid parent cell.

• Haploid (n): Cells containing a single set of chromosomes, like gametes.

• Diploid (2n): Cells containing two sets of chromosomes, one from each parent.

• Secondary oocyte: The haploid cell formed after the first meiotic division in oogenesis.

• Y-chromosome: Male sex chromosome that determines maleness in humans.

• Fertilization: Fusion of male and female gametes to form a zygote.

Lead Question - 2022 (Abroad)
How many Y-chromosomes are present in the 2nd polar body in human beings?
1. 01
2. 00
3. 23
4. 02
Explanation: The correct answer is 00. During human oogenesis, the primary oocyte undergoes meiosis I to form a secondary oocyte and the first polar body. The secondary oocyte contains one X chromosome from the female. Upon fertilization, if a sperm contributes a Y-chromosome, the resulting zygote can be male. The second meiotic division produces the ovum and the 2nd polar body, which is a byproduct and does not retain any Y-chromosome, as females only have X chromosomes. Polar bodies are haploid but contain only maternal chromosomes, meaning no Y-chromosome is present. This explains the absence of Y-chromosome in the 2nd polar body.

1. Single Correct Answer Type:
The first polar body in a human female may contain:
1. One X chromosome
2. One Y chromosome
3. Both X and Y chromosomes
4. No chromosomes
Explanation: The correct answer is One X chromosome. During meiosis I in oogenesis, the homologous X chromosomes separate. One goes to the secondary oocyte, the other to the first polar body. Since females have only X chromosomes, the polar body cannot contain a Y chromosome. Polar bodies are haploid and do not participate in fertilization. They help discard extra genetic material to ensure the ovum has the correct haploid number. This division maintains genomic balance and allows for normal fertilization and zygote formation, demonstrating the proper segregation of sex chromosomes during oogenesis.

2. Single Correct Answer Type:
Which of the following is true about polar bodies?
1. They develop into ova
2. They are usually nonfunctional
3. They fertilize sperm
4. They carry Y-chromosome in females
Explanation: The correct answer is They are usually nonfunctional. Polar bodies are byproducts of oogenesis that discard extra haploid chromosomes. They are generally small, lack sufficient cytoplasm, and do not develop into ova. Their function is to maintain proper chromosomal content in the ovum, ensuring haploid status. Polar bodies do not fertilize sperm and, in females, contain only maternal X chromosomes, never Y-chromosomes. Occasionally, they may undergo apoptosis. This mechanism allows the ovum to retain most cytoplasmic resources, essential for early embryonic development after fertilization.

3. Single Correct Answer Type:
The 2nd polar body is formed after:
1. Meiosis I
2. Meiosis II
3. Fertilization
4. Cleavage
Explanation: The correct answer is Meiosis II. During oogenesis, the secondary oocyte arrests at metaphase II until fertilization occurs. After fertilization, meiosis II completes, producing the ovum and the 2nd polar body. The polar body is a small haploid cell that contains maternal chromosomes but does not participate in zygote formation. It helps maintain the haploid chromosome number in the ovum while discarding extra genetic material. Since females only contribute X chromosomes, the 2nd polar body contains no Y-chromosome. This step is crucial for genomic stability and ensures proper chromosomal distribution in human reproduction.

4. Single Correct Answer Type:
How many chromosomes are present in the second polar body of a human female?
1. 46
2. 23
3. 0
4. 92
Explanation: The correct answer is 23. The second polar body is a haploid cell containing one set of chromosomes derived from the secondary oocyte. It ensures the ovum retains a single haploid set of maternal chromosomes, preparing it for fertilization. Polar bodies do not develop into gametes. They contain maternal chromosomes only, with no Y-chromosome present, and are discarded as cellular byproducts. This process maintains the correct ploidy in the ovum, essential for normal zygote formation and early embryonic development. Chromosome counting in polar bodies helps understand meiosis and sex chromosome inheritance.

5. Single Correct Answer Type:
Which chromosome does the ovum contribute during fertilization?
1. Y chromosome
2. X chromosome
3. Both X and Y
4. None
Explanation: The correct answer is X chromosome. Female gametes always carry an X chromosome because females are XX. The ovum provides this X chromosome to the zygote during fertilization. The male sperm determines the sex of the offspring by contributing either an X or Y chromosome. Polar bodies generated during oogenesis discard extra X chromosomes but do not affect the ovum's genetic content. This ensures haploid status in the ovum and proper chromosome number in the zygote. Understanding the chromosomal contribution of ovum is fundamental in human reproduction, sex determination, and genetic counseling.

6. Single Correct Answer Type:
Which of the following is true about Y-chromosome in human oogenesis?
1. Found in 1st polar body
2. Found in 2nd polar body
3. Present only in sperm
4. Present in all female gametes
Explanation: The correct answer is Present only in sperm. Females have two X chromosomes; thus, their gametes, including ovum and polar bodies, carry only X chromosomes. Y-chromosome is contributed solely by sperm. Polar bodies discard extra X chromosomes but never carry Y. The Y chromosome determines male sex in the zygote. Understanding this distinction clarifies sex chromosome inheritance, explains the absence of Y in polar bodies, and highlights the male contribution to sex determination in humans.

7. Single Correct Answer Type:
Which statement is correct about polar bodies in human females?
1. They participate in fertilization
2. They are haploid and nonfunctional
3. They carry male chromosomes
4. They develop into ovum
Explanation: The correct answer is They are haploid and nonfunctional. Polar bodies are byproducts of meiosis in oogenesis. They carry maternal chromosomes but do not develop into gametes or participate in fertilization. The 1st polar body forms after meiosis I, and the 2nd after meiosis II. They help discard extra genetic material while ensuring the ovum has the correct haploid chromosome number. Females only contribute X chromosomes, so polar bodies never contain Y. Understanding polar body formation explains chromosomal segregation, haploidy of gametes, and the mechanisms maintaining genome integrity in human reproduction.

8. Assertion-Reason Type:
Assertion (A): Polar bodies do not contain Y-chromosome.
Reason (R): Females have only X chromosomes, and polar bodies derive from maternal chromosomes.
1. Both A and R are correct, and R explains A
2. Both A and R are correct, but R does not explain A
3. A is correct, R is incorrect
4. A is incorrect, R is correct
Explanation: The correct answer is Both A and R are correct, and R explains A. Polar bodies are byproducts

Topic: Gametogenesis
Subtopic: Oogenesis

Keyword Definitions:
• Oogenesis: The process of formation and development of female gametes or ova in the ovaries.
• Embryonic development stage: The stage of life from fertilization to birth where organogenesis occurs.
• Puberty: The developmental stage when reproductive organs become functional.
• Adult stage: Post-pubertal period when reproductive capacity is fully achieved.
• Gametogenesis: The process of formation of gametes, including spermatogenesis and oogenesis.
• Primary oocytes: Cells formed during oogenesis that enter meiosis I.
• Follicular development: Growth and maturation of ovarian follicles containing oocytes.
• Meiosis: A type of cell division producing haploid gametes.
• Ovum: Mature female gamete ready for fertilization.
• Menstrual cycle: Hormone-regulated cyclic process in females preparing ovum release.

Lead Question (2022):
At which stage of life the oogenesis process is initiated:
(1) Embryonic development stage
(2) Birth
(3) Adult
(4) Puberty

Explanation: The correct answer is (1). Oogenesis is initiated during the embryonic development stage when oogonia proliferate and differentiate into primary oocytes, which enter meiosis I but get arrested in prophase I. This process ensures that all primary oocytes are formed before birth and remain dormant until puberty.

Guessed MCQs:

1. Single Correct Answer:
During which stage does meiosis I of oocytes resume?
(a) Embryonic development
(b) Puberty
(c) Birth
(d) Adult
Explanation: The correct answer is (b). Meiosis I of primary oocytes resumes at puberty under hormonal influence, allowing the formation of secondary oocytes during each menstrual cycle.

2. Single Correct Answer:
Which cells in the ovary are arrested at prophase I until puberty?
(a) Secondary oocytes
(b) Primary oocytes
(c) Polar bodies
(d) Spermatogonia
Explanation: The correct answer is (b). Primary oocytes, formed during embryonic development, are arrested at prophase I of meiosis and remain dormant until hormonal signals during puberty resume meiosis.

3. Single Correct Answer:
Which hormone triggers the resumption of meiosis in oocytes?
(a) FSH
(b) LH
(c) Estrogen
(d) Progesterone
Explanation: The correct answer is (a). Follicle stimulating hormone (FSH) stimulates the growth of ovarian follicles and triggers the resumption of meiosis in primary oocytes at puberty.

4. Assertion-Reason MCQ:
Assertion (A): All primary oocytes are formed before birth.
Reason (R): Oogenesis starts during embryonic development.
(a) Both A and R are correct and R explains A
(b) Both A and R are correct but R does not explain A
(c) A is correct, R is incorrect
(d) A is incorrect, R is correct
Explanation: The correct answer is (a). Oogenesis initiates in the embryonic stage, producing all primary oocytes before birth, which remain arrested until hormonal cues at puberty trigger further development.

5. Single Correct Answer:
Which oocyte completes meiosis II only upon fertilization?
(a) Primary oocyte
(b) Secondary oocyte
(c) Polar body
(d) Spermatocyte
Explanation: The correct answer is (b). Secondary oocytes, released during ovulation, complete meiosis II only if fertilization occurs, ensuring haploid gametes for successful zygote formation.

6. Single Correct Answer:
When does follicular development begin in females?
(a) Embryonic stage
(b) Puberty
(c) Birth
(d) Menopause
Explanation: The correct answer is (b). Follicular development resumes at puberty under the influence of FSH, leading to maturation of oocytes within ovarian follicles for potential ovulation.

7. Matching Type:
Match the cell with its meiotic stage:
Column A
1. Primary oocyte
2. Secondary oocyte
3. Polar body
Column B
A. Arrested at prophase I
B. Completed meiosis I, arrested at metaphase II
C. By-product of meiosis
Options:
(a) 1-A, 2-B, 3-C
(b) 1-B, 2-C, 3-A
(c) 1-C, 2-A, 3-B
(d) 1-A, 2-C, 3-B
Explanation: The correct answer is (a). Primary oocytes are arrested at prophase I, secondary oocytes are arrested at metaphase II, and polar bodies are by-products of meiotic divisions.

8. Fill in the Blanks:
Oogenesis begins during ______ and arrests until puberty.
(a) Birth
(b) Adult stage
(c) Embryonic development
(d) Menopause
Explanation: The correct answer is (c). Oogenesis initiates during embryonic development, producing primary oocytes which remain arrested in prophase I until hormonal signals at puberty resume meiosis.

9. Single Correct Answer:
Which oocyte is ovulated during the menstrual cycle?
(a) Primary oocyte
(b) Secondary oocyte
(c) Polar body
(d) Spermatocyte
Explanation: The correct answer is (b). Secondary oocytes are released from ovarian follicles during ovulation, ready for fertilization if sperm is present.

10. Choose the correct statements:
(a) Oogenesis initiates during embryonic development
(b) Primary oocytes remain arrested until puberty
(c) Secondary oocytes complete meiosis II before ovulation
(d) Fertilization triggers meiosis II completion
Explanation: The correct answer is (a), (b), and (d). Secondary oocytes complete meiosis II only if fertilization occurs, not before ovulation.

Topic: Gametogenesis
Subtopic: Spermatogenesis vs Oogenesis

Keyword Definitions:
• Spermatogenesis: Process of formation of haploid sperm from diploid spermatogonia in testes.
• Oogenesis: Process of formation of haploid ovum from diploid oogonia in ovaries.
• Meiosis: Cell division producing haploid gametes with half the chromosome number.
• Haploid gametes: Gametes containing single set of chromosomes (n).
• Luteinising Hormone (LH): Pituitary hormone that triggers testosterone production and ovulation.
• Follicle Stimulating Hormone (FSH): Pituitary hormone stimulating spermatogenesis and follicle maturation.
• Stem cells: Undifferentiated cells capable of mitosis and differentiation.
• Puberty: Developmental stage when reproductive organs mature and gametogenesis begins.
• Differentiation: Process where gametes attain mature functional form.
• Continuous meiosis: Spermatogenesis occurs uninterruptedly post-puberty, unlike oogenesis.

Lead Question (2022):
Which of the following statements are true for spermatogenesis but do not hold true for oogenesis :
(a) It results in the formation of haploid gametes
(b) Differentiation of gamete occurs after the completion of meiosis
(c) Meiosis occurs continuously in a mitotically dividing stem cell population
(d) It is controlled by the Luteinising hormone (LH) and Follicle stimulating Hormone (FSH) secreted by the anterior pituitary
(e) It is initiated at puberty
Choose the most appropriate answer from the options given below:
(1) (b) and (c) only
(2) (b), (d) and (e) only
(3) (b), (c) and (e) only
(4) (c) and (e) only

Explanation: The correct answer is (3). In spermatogenesis, gamete differentiation occurs after meiosis (b), meiosis continues in dividing stem cells (c), and the process begins at puberty (e). These features are distinct from oogenesis, where meiosis is discontinuous and differentiation occurs in the ovum before completion of meiosis.

Guessed MCQs:

1. Single Correct Answer:
Which hormone primarily regulates spermatogenesis?
(a) Estrogen
(b) Testosterone
(c) Progesterone
(d) Prolactin
Explanation: The correct answer is (b). Testosterone, produced by Leydig cells under LH stimulation, is essential for spermatogenesis. FSH also contributes by stimulating Sertoli cells, but testosterone maintains continuous sperm production.

2. Single Correct Answer:
At what stage does oogenesis arrest until puberty?
(a) Primary oocyte
(b) Secondary oocyte
(c) Zygote
(d) Spermatogonia
Explanation: The correct answer is (a). In oogenesis, primary oocytes are arrested in prophase I of meiosis until puberty. This contrasts spermatogenesis, where meiosis occurs continuously after puberty.

3. Single Correct Answer:
Which is a continuous process in males but discontinuous in females?
(a) Spermatogenesis
(b) Oogenesis
(c) Both
(d) Neither
Explanation: The correct answer is (a). Spermatogenesis is continuous post-puberty in males, whereas oogenesis has prolonged meiotic arrest and produces limited gametes over the female reproductive lifespan.

4. Assertion-Reason MCQ:
Assertion (A): Spermatogenesis produces four functional gametes per meiotic cycle.
Reason (R): Oogenesis produces one functional ovum per meiotic cycle.
(a) Both A and R are correct and R explains A
(b) Both A and R are correct but R does not explain A
(c) A is correct, R is false
(d) A is false, R is true
Explanation: The correct answer is (a). Spermatogenesis yields four functional sperms, whereas oogenesis produces only one ovum with polar bodies. R accurately explains the difference in gamete production per meiotic division.

5. Single Correct Answer:
Differentiation of sperm occurs in which part of male reproductive system?
(a) Seminiferous tubules
(b) Epididymis
(c) Vas deferens
(d) Testicular interstitial cells
Explanation: The correct answer is (b). Spermiogenesis, the differentiation of spermatids into mature spermatozoa, occurs in the epididymis, completing the process initiated in the seminiferous tubules.

6. Single Correct Answer:
Which cell population undergoes mitotic divisions in spermatogenesis?
(a) Primary spermatocytes
(b) Spermatogonia
(c) Spermatids
(d) Spermatozoa
Explanation: The correct answer is (b). Spermatogonia are mitotically active stem cells that divide to maintain the stem cell pool and produce primary spermatocytes, which then undergo meiosis.

7. Matching Type:
Match the following:
Column A
1. Spermatogenesis
2. Oogenesis
3. Primary oocyte arrest
4. Gamete differentiation
Column B
A. After meiosis
B. Continuous post-puberty
C. Prophase I
D. Discontinuous
Options:
(a) 1-B, 2-D, 3-C, 4-A
(b) 1-D, 2-B, 3-C, 4-A
(c) 1-B, 2-D, 3-A, 4-C
(d) 1-B, 2-D, 3-D, 4-A
Explanation: The correct answer is (a). Spermatogenesis is continuous post-puberty (1-B), oogenesis is discontinuous (2-D), primary oocytes arrest in prophase I (3-C), and gamete differentiation occurs after meiosis (4-A).

8. Fill in the Blanks:
Spermatogenesis begins at _______ and produces _______ haploid gametes per cycle.
(a) Birth, four
(b) Puberty, four
(c) Puberty, one
(d) Birth, one
Explanation: The correct answer is (b). Spermatogenesis begins at puberty in males and yields four haploid sperm per meiotic cycle, in contrast to oogenesis which produces one ovum.

9. Single Correct Answer:
Which statement is unique to spermatogenesis compared to oogenesis?
(a) Hormonal regulation by LH and FSH
(b) Production of haploid gametes
(c) Continuous meiosis in stem cells
(d) Occurs in gonads
Explanation: The correct answer is (c). Continuous meiosis in mitotically active stem cells (spermatogonia) is unique to spermatogenesis. Oogenesis involves discontinuous meiosis with long meiotic arrest periods.

10. Choose the correct statements:
(a) Spermatogenesis is continuous
(b) Oogenesis produces four ovum
(c) Meiosis starts at puberty in males
(d) Differentiation occurs post-meiosis in spermatogenesis
Options:
1. a, c, d only
2. a and b only
3. b and d only
4. All statements
Explanation: The correct answer is (1). Spermatogenesis is continuous (a), meiosis begins at puberty in males (c), and differentiation occurs after meiosis (d). Oogenesis produces only one ovum, so statement (b) is incorrect.

Subtopic: Male Reproductive System and Spermatogenesis

Keyword Definitions:
• Spermiation: Release of mature spermatozoa from the seminiferous epithelium into the lumen.
• Spermiogenesis: Process of differentiation of spermatids into mature spermatozoa.
• Spermatogonia: Diploid stem cells in the seminiferous tubules that divide mitotically.
• Spermatocytes: Cells formed from spermatogonia that undergo meiosis.
• Spermatids: Haploid cells formed after meiosis II, which differentiate into spermatozoa.
• Spermatozoa: Mature male gametes capable of fertilizing an egg.
• Seminiferous Tubules: Tubular structures in testes where spermatogenesis occurs.
• Testes: Male reproductive organs producing sperm and testosterone.
• Sertoli Cells: Support and nourish developing sperm cells.
• Leydig Cells: Produce testosterone in the interstitial tissue of testes.

Lead Question (2022):
Given below are two statements:
Statement I: The release of sperms into the seminiferous tubules is called spermiation.
Statement II: Spermiogenesis is the process of formation of sperms from spermatogonia.
In the light of the above statements, choose the most appropriate answer from the options given below:
1. Both Statement I and Statement II are incorrect
2. Statement I is correct but Statement II is incorrect
3. Statement I is incorrect but Statement II is correct
4. Both Statement I and Statement II are correct

Explanation: The correct answer is 2. Statement I is correct because spermiation refers to the release of spermatozoa into the seminiferous tubule lumen. Statement II is incorrect; spermiogenesis is the differentiation of spermatids into mature sperm, while spermatogonia are the stem cells that divide to initiate spermatogenesis.

Guessed MCQs:

1. Which cells in testes produce testosterone?
Options:
(a) Leydig cells
(b) Sertoli cells
(c) Spermatogonia
(d) Spermatids
Explanation: The correct answer is (a) Leydig cells. Leydig cells in the interstitial tissue of testes synthesize testosterone, which regulates spermatogenesis and secondary sexual characteristics. Sertoli cells support developing sperm, while spermatogonia and spermatids are germ cells.

2. Single Correct Answer:
Which process produces haploid spermatids?
Options:
(a) Meiosis
(b) Mitosis
(c) Spermiation
(d) Fertilization
Explanation: The correct answer is (a) Meiosis. Spermatogonia undergo mitotic divisions to form primary spermatocytes, which then undergo meiosis I and II to produce haploid spermatids. Spermiation is release, mitosis maintains stem cells, and fertilization occurs post-sperm maturation.

3. Assertion-Reason MCQ:
Assertion (A): Sertoli cells provide nourishment to developing sperm.
Reason (R): Sertoli cells secrete androgen-binding protein and support spermatogenesis.
Options:
(a) Both A and R are true, R explains A
(b) Both A and R are true, R does not explain A
(c) A is true, R is false
(d) A is false, R is true
Explanation: The correct answer is (a). Sertoli cells nourish and support developing germ cells, secrete androgen-binding protein for testosterone regulation, and facilitate spermiogenesis. Therefore, the reason correctly explains the assertion.

4. Matching Type MCQ:
Match the cell type with its role:
List - I List - II
(a) Spermatogonia (i) Stem cells for sperm formation
(b) Spermatids (ii) Differentiate into spermatozoa
(c) Leydig cells (iii) Produce testosterone
Options:
1. a-i, b-ii, c-iii
2. a-ii, b-i, c-iii
3. a-i, b-iii, c-ii
4. a-iii, b-ii, c-i
Explanation: The correct answer is 1. Spermatogonia act as stem cells, spermatids differentiate into mature spermatozoa, and Leydig cells produce testosterone, supporting spermatogenesis and male reproductive functions.

5. Single Correct Answer:
Which structure transports mature sperm to the epididymis?
Options:
(a) Seminiferous tubules
(b) Vas deferens
(c) Rete testis
(d) Urethra
Explanation: The correct answer is (c) Rete testis. The rete testis collects sperm from seminiferous tubules and channels them to the epididymis for maturation. Vas deferens transports sperm to urethra; urethra carries sperm outside, and seminiferous tubules are site of spermatogenesis.

6. Single Correct Answer:
Which event marks the final stage of spermatogenesis?
Options:
(a) Spermiation
(b) Spermiogenesis
(c) Meiosis II
(d) Mitosis
Explanation: The correct answer is (a) Spermiation. Spermiation is the release of mature spermatozoa into the lumen of seminiferous tubules. Spermiogenesis is the differentiation of spermatids, meiosis II produces haploid cells, and mitosis maintains spermatogonia.

7. Fill in the Blanks:
The process in which spermatids transform into spermatozoa is called __________.
Options:
(a) Spermiogenesis
(b) Spermiation
(c) Meiosis
(d) Fertilization
Explanation: The correct answer is (a) Spermiogenesis. Spermiogenesis involves morphological changes of spermatids into streamlined spermatozoa with head, midpiece, and tail, enabling motility and fertilization. Spermiation is release, meiosis produces haploid cells, and fertilization occurs post-maturation.

8. Which hormone regulates spermatogenesis by acting on Sertoli cells?
Options:
(a) FSH
(b) LH
(c) Testosterone
(d) Progesterone
Explanation: The correct answer is (a) FSH. Follicle-stimulating hormone stimulates Sertoli cells to support germ cells, secrete androgen-binding protein, and facilitate spermatogenesis. LH stimulates Leydig cells, testosterone promotes secondary sexual characteristics, and progesterone is a female hormone.

9. Single Correct Answer:
Which cell type undergoes meiosis to produce haploid cells?
Options:
(a) Spermatocytes
(b) Spermatogonia
(c) Spermatids
(d) Sertoli cells
Explanation: The correct answer is (a) Spermatocytes. Primary spermatocytes undergo meiosis I to form secondary spermat

Topic: Pregnancy and Parturition

Subtopic: Hormonal Regulation

Keyword Definitions:

• Relaxin: A hormone secreted during pregnancy that relaxes pelvic ligaments and softens the cervix to ease childbirth.

• Corpus luteum: A temporary endocrine structure formed from the ruptured follicle, producing progesterone and relaxin in pregnancy.

• Foetus: The developing organism inside the uterus after the embryonic stage.

• Graafian follicle: A mature ovarian follicle that releases the ovum during ovulation.

• Uterus: The muscular female reproductive organ where the embryo implants and develops.

Lead Question - 2021

Which of the following secretes the hormone relaxin, during the later phase of pregnancy?

(1) Corpus luteum
(2) Foetus
(3) Uterus
(4) Graafian follicle

Explanation: Relaxin is secreted by the corpus luteum during the later stages of pregnancy. It relaxes pelvic ligaments and softens the cervix, facilitating normal delivery. Neither the uterus nor foetus secretes it, and Graafian follicle regresses after ovulation. Hence, the correct answer is option (1).

1. Which hormone maintains the endometrium during early pregnancy?
(1) Progesterone
(2) Estrogen
(3) Relaxin
(4) Oxytocin

Explanation: Progesterone, secreted by the corpus luteum and later placenta, is essential to maintain the endometrium for implantation and pregnancy support. It prevents uterine contractions in early pregnancy. Correct answer is option (1).

2. Which hormone is responsible for uterine contractions during childbirth?
(1) Oxytocin
(2) Prolactin
(3) Progesterone
(4) Estrogen

Explanation: Oxytocin, secreted by the posterior pituitary, stimulates powerful contractions of the uterine muscles during parturition. It also aids in milk ejection during lactation. Hence, the correct answer is option (1).

3. Human chorionic gonadotropin (hCG) is secreted by:
(1) Graafian follicle
(2) Placenta
(3) Corpus luteum
(4) Endometrium

Explanation: hCG is secreted by the trophoblast cells of the placenta. It maintains the corpus luteum in early pregnancy, ensuring progesterone secretion. It is also detected in pregnancy tests. The correct answer is option (2).

4. Which of the following is a function of prolactin?
(1) Milk ejection
(2) Maintenance of corpus luteum
(3) Milk production
(4) Uterine contraction

Explanation: Prolactin, secreted by the anterior pituitary, stimulates the mammary glands to produce milk after childbirth. Milk ejection is controlled by oxytocin. Hence, the correct answer is option (3).

5. Placenta acts as an endocrine tissue by secreting:
(1) Progesterone, estrogen, hCG
(2) Oxytocin, relaxin, prolactin
(3) LH, FSH, estrogen
(4) TSH, ACTH, cortisol

Explanation: The placenta functions as a temporary endocrine gland during pregnancy, secreting progesterone, estrogen, and hCG, which are vital for fetal development and pregnancy maintenance. Hence, option (1) is correct.

6. Which hormone is tested in urine for pregnancy detection kits?
(1) Oxytocin
(2) Estrogen
(3) hCG
(4) Prolactin

Explanation: hCG is detected in maternal urine by pregnancy test kits within weeks of conception. Its presence confirms implantation and ongoing pregnancy. The correct answer is option (3).

7. Assertion (A): Oxytocin promotes milk ejection in lactating women.
Reason (R): Oxytocin acts on alveolar epithelial cells of mammary glands to produce milk.
(1) Both A and R are true, R explains A
(2) Both A and R are true, but R does not explain A
(3) A is true, R is false
(4) A is false, R is true

Explanation: Oxytocin does not act on alveolar epithelial cells but on myoepithelial cells surrounding alveoli, causing milk ejection. Prolactin acts on epithelial cells for milk production. Thus, assertion is true but reason is false. Option (3) is correct.

8. Match List-I with List-II:
(a) Estrogen - (i) Development of female secondary characters
(b) Progesterone - (ii) Maintenance of endometrium
(c) Relaxin - (iii) Cervical softening
(d) Oxytocin - (iv) Uterine contractions
Options:
(1) a-(i), b-(ii), c-(iii), d-(iv)
(2) a-(ii), b-(i), c-(iv), d-(iii)
(3) a-(iii), b-(ii), c-(i), d-(iv)
(4) a-(iv), b-(iii), c-(ii), d-(i)

Explanation: Estrogen regulates female secondary sexual characters, progesterone maintains endometrium, relaxin softens cervix, and oxytocin induces uterine contractions. Correct answer is option (1).

9. Fill in the blank: The hormone responsible for the maintenance of corpus luteum in early pregnancy is ______.
(1) LH
(2) FSH
(3) hCG
(4) Estrogen

Explanation: Human chorionic gonadotropin (hCG) maintains the corpus luteum in the first trimester, ensuring continuous secretion of progesterone required for pregnancy. Correct answer is option (3).

10. Which of the following statements are correct?
(a) Relaxin softens cervix and relaxes pelvic ligaments.
(b) Oxytocin maintains corpus luteum.
(c) Progesterone prevents uterine contractions.
(d) Prolactin stimulates milk production.
(1) a, b, c only
(2) a, c, d only
(3) b, c, d only
(4) a, b, d only

Explanation: Relaxin softens cervix, progesterone prevents uterine contractions, and prolactin stimulates milk production. Oxytocin induces uterine contractions but does not maintain corpus luteum. Hence, correct answer is option (2).

Subtopic: Parturition

Keyword Definitions:

• Parturition: The process of giving birth to a baby.

• Prostaglandins: Hormone-like substances involved in initiating labor contractions.

• Oxytocin: Hormone that stimulates uterine contractions and milk ejection.

• Prolactin: Hormone responsible for milk production, not directly involved in labor initiation.

• Estrogen: Hormone increasing uterine sensitivity to oxytocin, facilitating labor.

• Progesterone: Hormone maintaining pregnancy; decreased ratio triggers labor.

Lead Question - 2021

Which of these is not an important component of initiation of parturition in humans?

(1) Synthesis of prostaglandins
(2) Release of Oxytocin
(3) Release of Prolactin
(4) Increase in estrogen and progesterone ratio

Explanation: Parturition initiation involves prostaglandins, oxytocin, and a rise in estrogen-to-progesterone ratio, which stimulate uterine contractions. Prolactin is primarily responsible for lactation and is not directly involved in labor onset. Therefore, the correct answer is option (3) Release of Prolactin.

1. Which hormone stimulates milk ejection during lactation?
(1) Prolactin
(2) Oxytocin
(3) Progesterone
(4) Estrogen
Explanation: Oxytocin is responsible for milk ejection by causing contraction of myoepithelial cells around alveoli. Prolactin stimulates milk production but not ejection. Thus, the correct answer is option (2) Oxytocin.

2. The ratio of estrogen to progesterone increases during labor to:
(1) Maintain pregnancy
(2) Stimulate uterine contractions
(3) Inhibit prostaglandin synthesis
(4) Prevent oxytocin release
Explanation: An increase in the estrogen-to-progesterone ratio enhances uterine contractility and oxytocin sensitivity, promoting labor. Progesterone decline removes relaxation effects on uterus. Thus, the correct answer is option (2) Stimulate uterine contractions.

3. Which prostaglandins are involved in initiating labor?
(1) PGF2α and PGE2
(2) PGI2 and TXA2
(3) PGE1 and PGD2
(4) PGF1α and PGI2
Explanation: PGF2α and PGE2 are critical for cervical ripening and uterine contraction. They are synthesized by decidua and fetal membranes to initiate labor. Other prostaglandins have minor roles. Correct answer is option (1) PGF2α and PGE2.

4. Which hormone’s sudden withdrawal triggers labor?
(1) Estrogen
(2) Progesterone
(3) Oxytocin
(4) Prolactin
Explanation: Withdrawal of progesterone at term reduces uterine relaxation, allowing contractions. Estrogen levels rise to increase oxytocin receptors. Progesterone maintains pregnancy, so its decrease is essential. Correct answer is option (2) Progesterone.

5. During parturition, oxytocin is released from:
(1) Anterior pituitary
(2) Posterior pituitary
(3) Placenta
(4) Adrenal cortex
Explanation: Oxytocin is synthesized in hypothalamus and released from posterior pituitary. It stimulates uterine smooth muscle contraction during labor. Anterior pituitary secretes prolactin instead. Correct answer is option (2) Posterior pituitary.

6. Which of the following initiates cervical ripening?
(1) Oxytocin
(2) Prostaglandins
(3) Estrogen
(4) Progesterone
Explanation: Prostaglandins, mainly PGE2, soften and dilate the cervix (cervical ripening), facilitating labor. Oxytocin stimulates contractions but does not directly ripen cervix. Correct answer is option (2) Prostaglandins.

7. Assertion-Reason Question:
Assertion (A): Oxytocin stimulates uterine contractions during labor.
Reason (R): It increases calcium ion influx into uterine smooth muscle cells.
(1) Both A and R are true, R is correct explanation of A
(2) Both A and R are true, R is not correct explanation of A
(3) A true, R false
(4) A false, R true
Explanation: Oxytocin binds receptors on uterine smooth muscle, activating calcium influx, which triggers contraction. Both statements are true, and the reason correctly explains the assertion. Correct answer is option (1).

8. Matching Type Question:
Match hormone with function:
A. Prostaglandins - 1. Milk production
B. Oxytocin - 2. Uterine contractions
C. Prolactin - 3. Cervical ripening
D. Progesterone - 4. Maintains pregnancy
(1) A-3, B-2, C-1, D-4
(2) A-2, B-3, C-4, D-1
(3) A-1, B-4, C-2, D-3
(4) A-4, B-1, C-3, D-2
Explanation: Prostaglandins ripen cervix (A-3), oxytocin stimulates uterine contractions (B-2), prolactin promotes milk production (C-1), and progesterone maintains pregnancy (D-4). Correct answer is option (1).

9. Fill in the Blanks:
_________ hormone is mainly responsible for maintaining uterine quiescence during pregnancy.
(1) Progesterone
(2) Estrogen
(3) Oxytocin
(4) Prostaglandin
Explanation: Progesterone maintains uterine relaxation and prevents contractions during pregnancy. Its withdrawal near term allows labor initiation. Correct answer is option (1) Progesterone.

10. Choose the correct statements:
(a) Prolactin initiates labor.
(b) Oxytocin stimulates uterine contractions.
(c) Prostaglandins facilitate cervical ripening.
(d) Estrogen increases oxytocin receptor expression.
(1) b, c, d
(2) a, b, d
(3) a, c, d
(4) a, b, c, d
Explanation: Oxytocin stimulates contractions, prostaglandins aid cervical ripening, and estrogen increases uterine oxytocin receptors. Prolactin is not involved in labor initiation. Correct answer is option (1) b, c, d.

Topic: Fertilization

Subtopic: Sperm-Egg Interaction

• Receptors for sperm binding: Protein structures on the egg surface that specifically recognize and bind sperm to initiate fertilization.

• Vitelline membrane: A protective layer surrounding the egg, outside the plasma membrane.

• Perivitelline space: The space between the plasma membrane and the vitelline membrane.

• Zona pellucida: Glycoprotein layer surrounding the mammalian oocyte; contains receptors for sperm binding.

• Corona radiata: Layer of follicle cells around the zona pellucida providing nutrients to the oocyte.

• Fertilization: Fusion of sperm and egg nuclei to form a zygote.

• Mammals: Vertebrates characterized by internal fertilization and development of embryos within the female reproductive tract.

• Sperm recognition: Specific interaction of sperm with receptors on the egg surface for species-specific fertilization.

• Zygote: Single-cell formed after the fusion of sperm and egg.

• Acrosome reaction: Release of enzymes from sperm to penetrate the zona pellucida.

• Oocyte: Female gamete involved in fertilization.

Lead Question - 2021

Receptors for sperm binding in mammals are present on :

(1) Vitelline membrane
(2) Perivitelline space
(3) Zona pellucida
(4) Corona radiata

Explanation: In mammals, sperm binding receptors are present on the zona pellucida, a glycoprotein layer surrounding the oocyte. It ensures species-specific recognition and initiates the acrosome reaction, allowing sperm to penetrate and fertilize the egg. Answer: Zona pellucida.

1. Single Correct Answer MCQ: The acrosome reaction in sperm is triggered by:
Options:
A. Corona radiata
B. Zona pellucida
C. Perivitelline space
D. Vitelline membrane

Explanation: The acrosome reaction occurs when sperm contacts the zona pellucida, releasing enzymes to penetrate the egg. Other layers are not directly involved. Answer: Zona pellucida.

2. Single Correct Answer MCQ: The layer providing nutrients to the mammalian egg is:
Options:
A. Vitelline membrane
B. Zona pellucida
C. Corona radiata
D. Perivitelline space

Explanation: The corona radiata consists of follicle cells supplying nutrients to the oocyte. It surrounds the zona pellucida but does not contain sperm receptors. Answer: Corona radiata.

3. Single Correct Answer MCQ: Which layer lies between the plasma membrane and the zona pellucida?
Options:
A. Vitelline membrane
B. Perivitelline space
C. Corona radiata
D. Sperm receptor layer

Explanation: The perivitelline space is the gap between the egg plasma membrane and the zona pellucida, providing space for sperm entry after penetration. Answer: Perivitelline space.

4. Single Correct Answer MCQ: Species-specific sperm recognition occurs mainly due to:
Options:
A. Vitelline membrane
B. Corona radiata
C. Zona pellucida glycoproteins
D. Perivitelline enzymes

Explanation: Glycoproteins in the zona pellucida mediate species-specific sperm binding and trigger the acrosome reaction. Other layers are less specific. Answer: Zona pellucida glycoproteins.

5. Single Correct Answer MCQ: Which layer acts as a barrier to polyspermy?
Options:
A. Zona pellucida
B. Corona radiata
C. Perivitelline space
D. Vitelline membrane

Explanation: After fertilization, the zona pellucida undergoes changes preventing additional sperm entry, acting as a block to polyspermy. Answer: Zona pellucida.

6. Single Correct Answer MCQ: Mammalian oocyte plasma membrane is directly called:
Options:
A. Vitelline membrane
B. Zona pellucida
C. Oolemma
D. Corona radiata

Explanation: The oolemma is the plasma membrane of the oocyte, lying beneath the zona pellucida and perivitelline space. Answer: Oolemma.

7. Assertion-Reason MCQ:
Assertion (A): Sperm binding in mammals is mediated by zona pellucida.
Reason (R): It contains glycoproteins that recognize and bind sperm.
Options:
A. Both A and R true, R correct explanation
B. Both A and R true, R not correct explanation
C. A true, R false
D. A false, R true

Explanation: The zona pellucida contains specific glycoproteins for species-specific sperm binding, accurately explaining the assertion. Answer: Both A and R true, R correct explanation.

8. Matching Type MCQ:
Column I: 1. Sperm receptor location 2. Nutrient layer 3. Space between membrane and zona 4. Membrane directly enclosing oocyte
Column II: A. Perivitelline space B. Zona pellucida C. Oolemma D. Corona radiata
Options:
A. 1-B, 2-D, 3-A, 4-C
B. 1-D, 2-B, 3-A, 4-C
C. 1-B, 2-A, 3-D, 4-C
D. 1-C, 2-D, 3-B, 4-A

Explanation: Sperm receptors are on the zona pellucida, nutrients come from corona radiata, perivitelline space lies between membrane and zona, and the oolemma directly encloses the oocyte. Answer: 1-B, 2-D, 3-A, 4-C.

9. Fill in the Blank MCQ: The glycoprotein layer surrounding the mammalian oocyte containing sperm receptors is ______.
Options:
A. Corona radiata
B. Zona pellucida
C. Vitelline membrane
D. Perivitelline space

Explanation: The zona pellucida contains sperm-binding glycoproteins, initiating fertilization. Answer: Zona pellucida.

10. Choose the correct statements MCQ:
(a) Sperm receptors are on zona pellucida.
(b) Corona radiata supplies nutrients to oocyte.
(c) Perivitelline space contains sperm receptors.
(d) Oolemma is the plasma membrane of oocyte.
Options:
1. (a), (b), (d) only
2. (a) and (c) only
3. (b) and (c) only
4. All of the above

Explanation: Sperm receptors are on zona pellucida, corona radiata provides nutrients, and oolemma is plasma membrane. Perivitelline space does not have receptors. Answer: (a), (b), (d) only.

Topic: Endocrine Functions in Reproduction
Subtopic: Hormone Secretion and Source Organs

Keyword Definitions:

• Ovary: Female reproductive organ producing eggs and hormones like estrogen and progesterone.

• Placenta: Temporary organ connecting fetus to uterine wall, secretes hormones to maintain pregnancy.

• Corpus luteum: Temporary endocrine structure formed after ovulation, secretes progesterone and some estrogen.

• Leydig cells: Cells in testes producing androgens, primarily testosterone.

• Human chorionic gonadotropin (hCG): Hormone secreted by placenta, maintains corpus luteum in early pregnancy.

• Estrogen: Female sex hormone, promotes secondary sexual characteristics and endometrial growth.

• Progesterone: Hormone maintaining uterine lining for pregnancy.

• Androgens: Male sex hormones, mainly testosterone, supporting male reproductive functions.

Lead Question - 2020 (COVID Reexam)

Match the following columns and select the correct option:

Column - I    Column - II
(a) Ovary    (i) Human chorionic Gonadotropin
(b) Placenta    (ii) Estrogen & Progesterone
(c) Corpus luteum    (iii) Androgens
(d) Leydig cells    (iv) Progesterone only

1. (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)
2. (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)
3. (a)-(i), (b)-(iii), (c)-(ii), (d)-(iv)
4. (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)

Explanation: Ovary produces estrogen and progesterone, corpus luteum secretes progesterone mainly, placenta produces hCG in early pregnancy, and Leydig cells produce androgens like testosterone. Correct matching is (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii). Answer: Option 4.

1. Single correct answer MCQ:

Which organ secretes androgens?
1. Ovary
2. Placenta
3. Leydig cells
4. Corpus luteum

Explanation: Leydig cells in the testes secrete androgens, primarily testosterone, which regulates male reproductive functions and secondary sexual characteristics. Ovary, placenta, and corpus luteum do not secrete androgens. Answer: Option 3.

2. Single correct answer MCQ:

Which hormone is secreted by corpus luteum?
1. Estrogen only
2. Progesterone only
3. hCG
4. Testosterone

Explanation: Corpus luteum secretes mainly progesterone to maintain the uterine lining for pregnancy. It also secretes some estrogen, but progesterone predominates. Answer: Option 2.

3. Single correct answer MCQ:

Which hormone is secreted by placenta in early pregnancy?
1. Estrogen
2. Progesterone
3. hCG
4. Testosterone

Explanation: Placenta secretes human chorionic gonadotropin (hCG) during early pregnancy to maintain corpus luteum, ensuring continuous progesterone production and supporting pregnancy. Answer: Option 3.

4. Single correct answer MCQ:

Ovary mainly secretes:
1. Testosterone
2. hCG
3. Estrogen and Progesterone
4. Prolactin

Explanation: Ovaries produce female sex hormones, estrogen and progesterone, which regulate menstrual cycles, secondary sexual characteristics, and prepare endometrium for pregnancy. Answer: Option 3.

5. Single correct answer MCQ:

Which structure maintains early pregnancy by progesterone secretion?
1. Placenta
2. Corpus luteum
3. Ovary
4. Leydig cells

Explanation: Corpus luteum secretes progesterone during early pregnancy to maintain the uterine lining. Placenta takes over hormone production later. Ovary and Leydig cells are not primarily responsible for early progesterone secretion. Answer: Option 2.

6. Single correct answer MCQ:

Which hormone is not secreted by ovary?
1. Estrogen
2. Progesterone
3. Androgens
4. All are secreted

Explanation: Ovary secretes estrogen and progesterone but produces minimal androgens. Leydig cells are the main source of androgens. Therefore, androgens are not secreted by the ovary. Answer: Option 3.

7. Assertion-Reason MCQ:

Assertion (A): Leydig cells produce testosterone.
Reason (R): Testosterone is an androgen secreted by Leydig cells in testes.
1. Both A and R true, R correct explanation
2. Both A and R true, R not correct explanation
3. A true, R false
4. A false, R true

Explanation: Leydig cells in testes produce testosterone, which is an androgen. Reason accurately explains the assertion. Answer: Option 1.

8. Matching Type MCQ:

Column I    Column II
(a) Ovary    (i) Estrogen & Progesterone
(b) Placenta    (ii) hCG
(c) Corpus luteum    (iii) Progesterone only
(d) Leydig cells    (iv) Androgens

1. (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)
2. (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)
3. (a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)
4. (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)

Explanation: Ovary secretes estrogen and progesterone, placenta produces hCG, corpus luteum secretes progesterone, Leydig cells produce androgens. Correct matching is (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv). Answer: Option 1.

9. Fill in the blanks:

The hormone that maintains corpus luteum during early pregnancy is ________.
1. Progesterone
2. Estrogen
3. hCG
4. Testosterone

Explanation: Human chorionic gonadotropin (hCG) secreted by placenta maintains the corpus luteum during early pregnancy, ensuring continued progesterone production to support uterine lining. Answer: Option 3.

10. Choose correct statements:

(a) Corpus luteum secretes progesterone
(b) Placenta secretes hCG
(c) Leydig cells produce estrogen
(d) Ovary produces estrogen and progesterone

1. a, b, d only
2. a and c only
3. b and c only
4. All statements correct

Explanation: Corpus luteum secretes progesterone, placenta secretes hCG, and ovary produces estrogen and progesterone. Leydig cells produce androgens, not estrogen. Therefore, correct statements are a, b, and d only. Answer: Option 1.

Topic: Gametogenesis
Subtopic: Haploid and Diploid Cells

Keyword Definitions:

• Haploid cells: Cells containing one set of chromosomes (n), produced by meiosis.

• Diploid cells: Cells containing two sets of chromosomes (2n), typical somatic cells.

• Primary oocyte: Diploid cell that undergoes meiosis I to form secondary oocyte.

• Secondary oocyte: Haploid cell formed after meiosis I of oogenesis, arrested in metaphase II.

• Spermatid: Haploid male gamete formed after meiosis II, matures into sperm.

• First polar body: Small haploid cell formed during oogenesis, usually degenerates.

• Ovum: Mature female gamete, haploid cell.

• Spermatogonia: Diploid male germ cells, divide mitotically to maintain germ line.

• Primary spermatocyte: Diploid cell that undergoes meiosis I in spermatogenesis.

• Secondary spermatocyte: Haploid cell after meiosis I, undergoes meiosis II to form spermatids.

• Second polar body: Haploid cell formed during oocyte meiosis II, usually degenerates.

Lead Question - 2020 (COVID Reexam)

Select the correct option of haploid cells from the following groups:

1. Primary oocyte, Secondary oocyte, Spermatid
2. Secondary spermatocyte, First polar body, Ovum
3. Spermatogonia, Primary spermatocyte, Spermatid
4. Primary spermatocyte, Secondary spermatocyte, Second polar body

Explanation: Haploid cells contain a single set of chromosomes (n). Secondary spermatocyte, first polar body, and ovum are haploid cells produced during meiosis in spermatogenesis and oogenesis. Primary oocytes and spermatocytes are diploid. Therefore, correct haploid group is secondary spermatocyte, first polar body, and ovum. Answer: Option 2.

1. Single correct answer MCQ:

Which of the following is haploid?
1. Primary oocyte
2. Secondary spermatocyte
3. Spermatogonia
4. Primary spermatocyte

Explanation: Haploid cells carry one set of chromosomes (n). Secondary spermatocytes are haploid, formed after meiosis I. Primary oocytes, spermatogonia, and primary spermatocytes are diploid (2n). Answer: Option 2.

2. Single correct answer MCQ:

First polar body is:
1. Diploid
2. Haploid
3. Tetraploid
4. Triploid

Explanation: The first polar body is formed during oogenesis after meiosis I. It contains a haploid set of chromosomes (n) and usually degenerates. Answer: Option 2.

3. Single correct answer MCQ:

Which of the following is diploid?
1. Ovum
2. Secondary spermatocyte
3. Primary spermatocyte
4. Spermatid

Explanation: Primary spermatocyte is diploid (2n) and undergoes meiosis I to produce haploid secondary spermatocytes. Ovum, secondary spermatocyte, and spermatid are haploid. Answer: Option 3.

4. Single correct answer MCQ:

During oogenesis, the ovum is:
1. Diploid
2. Haploid
3. Triploid
4. Tetraploid

Explanation: The ovum is the mature female gamete, produced after meiosis II, containing a haploid set of chromosomes (n). Answer: Option 2.

5. Single correct answer MCQ:

Spermatid originates from:
1. Spermatogonia
2. Primary spermatocyte
3. Secondary spermatocyte
4. Sertoli cells

Explanation: Spermatids are haploid cells produced from secondary spermatocytes after meiosis II. They further differentiate into spermatozoa. Answer: Option 3.

6. Single correct answer MCQ:

Which is not a haploid cell?
1. First polar body
2. Secondary oocyte
3. Primary spermatocyte
4. Ovum

Explanation: Primary spermatocyte is diploid (2n) and undergoes meiosis I to produce haploid secondary spermatocytes. First polar body, secondary oocyte, and ovum are haploid. Answer: Option 3.

7. Assertion-Reason MCQ:

Assertion (A): Spermatids are haploid cells.
Reason (R): Spermatids form after meiosis II.
1. Both A and R true, R correct explanation
2. Both A and R true, R not correct explanation
3. A true, R false
4. A false, R true

Explanation: Spermatids are haploid cells formed from secondary spermatocytes after meiosis II, making reason a correct explanation of the assertion. Answer: Option 1.

8. Matching Type MCQ:

Column I    Column II
(a) Primary spermatocyte    (i) Diploid
(b) Secondary spermatocyte    (ii) Haploid
(c) Spermatid    (iii) Haploid
(d) Ovum    (iv) Haploid

1. (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)
2. (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)
3. (a)-(i), (b)-(i), (c)-(ii), (d)-(iii)
4. (a)-(iii), (b)-(ii), (c)-(i), (d)-(iv)

Explanation: Primary spermatocyte is diploid, secondary spermatocyte, spermatid, and ovum are haploid. Correct matching: (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv). Answer: Option 1.

9. Fill in the blanks:

________ are haploid cells resulting from meiosis II in males.
1. Spermatogonia
2. Spermatids
3. Primary spermatocytes
4. Sertoli cells

Explanation: Spermatids are haploid (n) cells formed from secondary spermatocytes after meiosis II. They eventually differentiate into mature spermatozoa. Answer: Option 2.

10. Choose correct statements:

(a) Secondary spermatocyte is haploid
(b) Primary oocyte is haploid
(c) Ovum is haploid
(d) Spermatogonia is haploid

1. a and c only
2. a, b, c
3. b and d only
4. All are correct

Explanation: Secondary spermatocyte and ovum are haploid. Primary oocyte and spermatogonia are diploid. Therefore, correct statements are a and c only. Answer: Option 1.

Topic: Embryonic Development
Subtopic: First Trimester Features

Keyword Definitions:

• First trimester: Initial 12 weeks of pregnancy when major organs begin forming.

• Eyelids and eyelashes: Protective structures of the eye formed during early fetal development.

• Fetus: Developing human from 9th week of gestation to birth.

• Fine hair (Lanugo): Soft hair covering fetus body later in second trimester.

• Movement of fetus: Usually felt by mother in second trimester, around 16–20 weeks.

• Major organ systems: Heart, brain, lungs, liver, kidneys start forming in first trimester.

Lead Question - 2020 (COVID Reexam)

In human beings, at the end of 12 weeks (first trimester) of pregnancy, the following is observed:

1. Eyelids and eyelashes are formed
2. Most of the major organ systems are formed
3. The head is covered with fine hair
4. Movement of the fetus

Explanation: By the end of 12 weeks, the first trimester concludes with most major organ systems formed and functional rudiments in place. Eyelids and eyelashes start developing, but lanugo appears later. Fetal movement is not yet felt. Answer: Option 2.

1. Single correct answer MCQ:

At the end of first trimester, which is observed in the fetus?
1. Lanugo covering the body
2. Major organ systems formed
3. Mother feels fetal movement
4. Nails are fully grown

Explanation: The first trimester completes organogenesis, forming major organ systems. Lanugo and noticeable fetal movement occur in second trimester. Nails develop later. Therefore, major organ system formation is the correct feature at 12 weeks. Answer: Option 2.

2. Single correct answer MCQ:

Eyelids and eyelashes in human fetus:
1. Appear by 12 weeks
2. Form in second trimester
3. Present from conception
4. Appear after birth

Explanation: Eyelids begin forming in the first trimester but complete development extends into later stages. Eyelashes appear gradually after eyelid formation. At 12 weeks, initial eyelid and eyelash rudiments are visible. Answer: Option 1.

3. Single correct answer MCQ:

Fetal movement is usually first perceived by:
1. 8 weeks
2. 12 weeks
3. 16–20 weeks
4. At birth

Explanation: Fetal movements (quickening) are usually felt by the mother between 16 and 20 weeks of gestation, in the second trimester. At 12 weeks, the fetus moves internally, but movements are too subtle to be perceived. Answer: Option 3.

4. Single correct answer MCQ:

Lanugo, the fine hair covering fetal body, appears:
1. First trimester
2. Second trimester
3. Third trimester
4. After birth

Explanation: Lanugo develops during the second trimester, around 16–20 weeks, to protect fetal skin and assist in temperature regulation. It is absent in the first trimester. Answer: Option 2.

5. Single correct answer MCQ:

By 12 weeks, which organ shows functional rudiments?
1. Heart
2. Lungs
3. Kidneys
4. All major organs

Explanation: By the end of 12 weeks, all major organs begin forming functional rudiments, though they are immature. The heart starts beating, kidneys begin urine formation, and other organs are structurally formed. Answer: Option 4.

6. Single correct answer MCQ:

Which of the following is NOT observed at 12 weeks?
1. Head growth
2. Lanugo on body
3. Major organ formation
4. Initial eyelid development

Explanation: Lanugo appears later in the second trimester. By 12 weeks, organ systems have formed, head growth occurs, and eyelids start forming. Therefore, lanugo is not observed at the end of first trimester. Answer: Option 2.

7. Assertion-Reason MCQ:

Assertion (A): Most major organ systems are formed by 12 weeks.
Reason (R): Organogenesis is completed during the first trimester.
1. Both A and R true, R is correct explanation
2. Both A and R true, R not correct explanation
3. A true, R false
4. A false, R true

Explanation: The first trimester completes major organ formation, a process called organogenesis. Both assertion and reason are correct, and reason accurately explains the assertion. Answer: Option 1.

8. Matching Type MCQ:

Column I    Column II
(a) Eyelids    (i) Appear at 12 weeks
(b) Lanugo    (ii) Appears in second trimester
(c) Fetal movement    (iii) Felt around 16–20 weeks
(d) Major organs    (iv) Rudiments formed by 12 weeks

1. (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)
2. (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)
3. (a)-(i), (b)-(iii), (c)-(ii), (d)-(iv)
4. (a)-(iv), (b)-(i), (c)-(iii), (d)-(ii)

Explanation: Eyelids begin forming at 12 weeks, lanugo appears in second trimester, fetal movement felt around 16–20 weeks, and major organ rudiments complete at 12 weeks. Correct matching: (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv). Answer: Option 1.

9. Fill in the blanks:

At the end of 12 weeks, the fetus has ______ and most ______ formed.
1. Lanugo, organ systems
2. Eyelids, organ systems
3. Fingernails, hair
4. Movement, lanugo

Explanation: By 12 weeks, eyelids begin forming, and most major organ systems have developed. Lanugo and perceivable fetal movement occur later in the second trimester. Answer: Option 2.

10. Choose correct statements:

(a) Major organ systems are formed
(b) Lanugo is present
(c) Eyelids start forming
(d) Fetal movement is perceived by mother

1. a and c only
2. b and d only
3. a, b, c
4. All correct

Explanation: At the end of first trimester, major organ systems have formed and eyelids begin developing. Lanugo and perceivable fetal movement occur later, in the second trimester. Correct statements are a and c only. Answer: Option 1.

Subtopic: Hormones and Structures

Keyword Definitions:

• Placenta: Temporary organ that connects the fetus to the mother, secreting hormones like hCG.

• Zona pellucida: Glycoprotein-rich layer surrounding the ovum, important for fertilization.

• Bulbo-urethral glands: Glands producing mucus for lubrication of the penis.

• Leydig cells: Testicular cells that produce androgens such as testosterone.

• hCG: Human Chorionic Gonadotropin, hormone produced by placenta to maintain pregnancy.

• Androgens: Male sex hormones, mainly testosterone, secreted by Leydig cells.

• Fertilization: Fusion of male and female gametes, usually in the fallopian tube.

Lead Question - 2020

Match the following columns and select the correct option.

Column-I Column-II
(a) Placenta (i) Androgens
(b) Zona pellucida (ii) Human Chorionic Gonadotropin (hCG)
(c) Bulbo-urethral glands (iii) Layer of the ovum
(d) Leydig cells (iv) Lubrication of the Penis

(1) a-(iii), b-(ii), c-(iv), d-(i)
(2) a-(ii), b-(iii), c-(iv), d-(i)
(3) a-(iv), b-(iii), c-(i), d-(ii)
(4) a-(i), b-(iv), c-(ii), d-(iii)

Explanation: The correct answer is (2). Placenta secretes hCG to maintain pregnancy, Zona pellucida surrounds the ovum, Bulbo-urethral glands lubricate the penis, and Leydig cells produce androgens. This matching highlights structural and hormonal roles in reproduction, essential for fertilization, implantation, lubrication, and male sexual function, ensuring successful reproduction in humans.

1. Which hormone is essential to maintain pregnancy?
(1) Progesterone
(2) Oxytocin
(3) Testosterone
(4) Prolactin
Explanation: The correct answer is (1) Progesterone. It maintains the endometrial lining and prevents uterine contractions during pregnancy. It is secreted by the corpus luteum initially and later by the placenta. Without sufficient progesterone, implantation and continuation of pregnancy are not possible, making it critical for fetal development and maternal support.

2. The role of acrosome during fertilization is:
(1) To form the zona pellucida
(2) To dissolve the zona pellucida
(3) To secrete testosterone
(4) To secrete hCG
Explanation: The correct answer is (2) To dissolve the zona pellucida. Acrosome is a cap-like structure on the sperm head containing hydrolytic enzymes. These enzymes break down the zona pellucida of the ovum, allowing the sperm nucleus to fuse with the egg nucleus, completing fertilization and initiating zygote formation.

3. Which cells secrete testosterone in males?
(1) Sertoli cells
(2) Leydig cells
(3) Granulosa cells
(4) Acrosome cells
Explanation: The correct answer is (2) Leydig cells. Located in the interstitial spaces of testes, Leydig cells secrete androgens, mainly testosterone, under the influence of LH. Testosterone regulates spermatogenesis, development of male reproductive structures, and secondary sexual characters, making these cells vital for male reproductive physiology.

4. Which structure prevents polyspermy in fertilization?
(1) Placenta
(2) Zona pellucida
(3) Acrosome
(4) Seminal vesicles
Explanation: The correct answer is (2) Zona pellucida. After the entry of one sperm, zona pellucida undergoes a biochemical modification known as the cortical reaction, which blocks additional sperm entry. This ensures only one sperm fertilizes the egg, preventing polyspermy, which would otherwise lead to abnormal development of the zygote.

5. Which hormone is detected in pregnancy tests?
(1) Progesterone
(2) hCG
(3) LH
(4) Estrogen
Explanation: The correct answer is (2) hCG. Human Chorionic Gonadotropin, secreted by placenta after implantation, is detected in urine or blood during pregnancy tests. Its presence confirms conception. hCG supports the corpus luteum to continue progesterone secretion, which is necessary for maintaining the uterine lining and successful development of the embryo.

6. Which gland secretes fructose-rich fluid in semen?
(1) Prostate gland
(2) Seminal vesicles
(3) Bulbo-urethral glands
(4) Testes
Explanation: The correct answer is (2) Seminal vesicles. These glands secrete seminal fluid rich in fructose, which provides energy to spermatozoa. Seminal vesicle secretion forms a major part of semen volume, along with prostaglandins and other nutrients that support sperm motility and fertilization potential within the female reproductive tract.

7. Assertion-Reason: Assertion: Placenta secretes hCG. Reason: hCG prevents degeneration of corpus luteum.
(1) Both A and R true, R correct explanation
(2) Both A and R true, R not correct explanation
(3) A true, R false
(4) A false, R true
Explanation: The correct answer is (1). Placenta secretes hCG after implantation. hCG ensures the survival of the corpus luteum during early pregnancy, which continues secreting progesterone to maintain the uterine lining. This prevents menstruation and allows the embryo to implant and develop, making the reason a correct explanation of the assertion.

8. Match the following hormones with their sources:
(a) Oxytocin (i) Posterior pituitary
(b) Progesterone (ii) Corpus luteum
(c) Testosterone (iii) Leydig cells
(d) hCG (iv) Placenta
(1) a-i, b-ii, c-iii, d-iv
(2) a-iv, b-iii, c-ii, d-i
(3) a-iii, b-i, c-iv, d-ii
(4) a-ii, b-iv, c-i, d-iii
Explanation: The correct answer is (1). Oxytocin is secreted by posterior pituitary, Progesterone by corpus luteum, Testosterone by Leydig cells, and hCG by placenta. These hormones collectively regulate reproduction, pregnancy, childbirth, and male sexual function, ensuring coordinated physiological processes for survival and propagation of the species.

9. Fill in the blank: ______ prevents premature expulsion of the embryo.
(1) Oxytocin
(2) Progesterone
(3) Testosterone
(4) Relaxin
Explanation: The correct answer is (2) Progesterone. This hormone inhibits uterine contractions and maintains the endometrium during pregnancy. It is secreted by the corpus luteum and later by the placenta. By preventing premature uterine activity, progesterone ensures the embryo remains implanted and continues normal development throughout gestation.

10. Choose the correct statements:
(a) Leydig cells produce androgens.
(b) Placenta secretes hCG.
(c) Bulbo-urethral glands provide energy to sperm.
(d) Zona pellucida surrounds the ovum.
(1) a, b, c
(2) a, b, d
(3) b, c, d
(4) a, c, d
Explanation: The correct answer is (2). Leydig cells produce testosterone, Placenta secretes hCG, and Zona pellucida surrounds the ovum. Bulbo-urethral glands do not provide energy to sperm; they secrete mucus for lubrication. Energy to sperm is provided mainly by fructose-rich fluid from seminal vesicles.

Subtopic: Oogenesis and Fertilization

• Secondary oocyte: The haploid cell formed after the first meiotic division of the primary oocyte, which can undergo fertilization.

• Meiotic division: Cell division that reduces chromosome number by half, producing haploid gametes.

• Fertilization: Fusion of male and female gametes to form a zygote.

• Zygote: Diploid cell resulting from the fusion of sperm and ovum.

• Ovulation: Release of a mature oocyte from the ovary.

• Sperm-egg fusion: The process of sperm entering the ovum, triggering the completion of meiosis II.

• Oogenesis: Formation and maturation of female gametes (ova) in the ovary.

• Copulation: Sexual intercourse, which may lead to fertilization.

• Chromosome reduction: Halving of chromosome number during meiosis to maintain species-specific number in zygotes.

• Polar body: Small haploid cell produced during oogenesis that usually degenerates.

• Gamete maturation: Final changes in oocyte and sperm that enable successful fertilization.

Lead Question (2020): Meiotic division of the secondary oocyte is completed:
Options:
1. After zygote formation
2. At the time of fusion of a sperm with an ovum
3. Prior to ovulation
4. At the time of copulation

Explanation: Correct answer is 2. The secondary oocyte completes its second meiotic division only upon sperm entry. This ensures that meiosis II is triggered by fertilization, resulting in formation of the ovum and a second polar body, ultimately producing a diploid zygote after fusion of pronuclei.

1. Single Correct Answer MCQ:
During oogenesis, primary oocyte completes meiosis I to form:
Options:
a. Secondary oocyte
b. Zygote
c. Polar body only
d. Spermatid

Explanation: Correct answer is a. The primary oocyte undergoes meiosis I to produce a secondary oocyte and the first polar body. The secondary oocyte is haploid and remains arrested in metaphase II until fertilization occurs.

2. Single Correct Answer MCQ:
At which stage is the secondary oocyte arrested before ovulation?
Options:
a. Prophase I
b. Metaphase II
c. Telophase I
d. Anaphase II

Explanation: Correct answer is b. The secondary oocyte remains arrested at metaphase II of meiosis until fertilization. This ensures it is ready to complete meiosis II immediately upon sperm entry, forming the ovum and second polar body.

3. Single Correct Answer MCQ:
Which event triggers the completion of meiosis II in the secondary oocyte?
Options:
a. Ovulation
b. Copulation
c. Sperm penetration
d. Fertilized zygote cleavage

Explanation: Correct answer is c. Sperm penetration triggers meiosis II in the secondary oocyte. This leads to formation of the ovum and second polar body, ensuring that the resulting zygote has a diploid chromosome number.

4. Single Correct Answer MCQ:
Which cells are formed immediately after completion of meiosis II in the secondary oocyte?
Options:
a. Ovum and first polar body
b. Ovum and second polar body
c. Two secondary oocytes
d. Two primary oocytes

Explanation: Correct answer is b. Meiosis II produces a mature ovum and a second polar body. The ovum participates in fertilization, while polar bodies degenerate. This ensures only one functional haploid gamete combines with sperm to form a diploid zygote.

5. Single Correct Answer MCQ:
Which of the following statements is true regarding oogenesis?
Options:
a. Secondary oocyte completes meiosis before ovulation
b. Secondary oocyte completes meiosis after sperm entry
c. Primary oocyte completes meiosis II immediately
d. Ovum formation occurs before fertilization

Explanation: Correct answer is b. The secondary oocyte only completes meiosis II after sperm penetration. This ensures the proper timing for haploid gamete fusion and prevents premature completion of meiosis.

6. Single Correct Answer MCQ:
Polar bodies produced during oogenesis function to:
Options:
a. Support ovum development
b. Provide extra cytoplasm to ovum
c. Degenerate without functional role
d. Become zygotes

Explanation: Correct answer is c. Polar bodies are by-products of meiosis with minimal cytoplasm. They degenerate and do not contribute to fertilization, ensuring most cytoplasmic resources remain in the ovum.

7. Assertion-Reason MCQ:
Assertion (A): The secondary oocyte is arrested at metaphase II until fertilization.
Reason (R): Fertilization triggers completion of meiosis II and formation of ovum.
Options:
a. Both A and R true, R explains A
b. Both A and R true, R does not explain A
c. A true, R false
d. A false, R true

Explanation: Correct answer is a. The secondary oocyte remains arrested at metaphase II to await sperm entry. Fertilization triggers completion of meiosis II, producing the ovum and a polar body, making the reason a correct explanation for the assertion.

8. Matching Type MCQ:
Match the stages with their oogenesis events:
(a) Primary oocyte - (i) Arrested at metaphase II
(b) Secondary oocyte - (ii) Formed after meiosis I
(c) Ovum - (iii) Result of meiosis II after fertilization
(d) Polar body - (iv) By-product of meiosis
Options:
1. a-ii, b-i, c-iii, d-iv
2. a-i, b-ii, c-iii, d-iv
3. a-ii, b-iii, c-i, d-iv
4. a-iii, b-ii, c-i, d-iv

Explanation: Correct answer is 1. Primary oocyte undergoes meiosis I to form the secondary oocyte, which is arrested at metaphase II. Completion of meiosis II produces the ovum and polar body as by-product.

9. Fill in the Blanks MCQ:
The ______ oocyte completes its second meiotic division only after sperm entry.
Options:
a. Primary
b. Secondary
c. Polar body
d. Spermatocyte

Explanation: Correct answer is b. The secondary oocyte remains arrested at metaphase II and completes meiosis II only upon fertilization, forming the ovum and second polar body, ensuring proper haploid chromosome contribution to the zygote.

10. Choose the correct statements MCQ:
Select the correct statements:
i. Secondary oocyte is released during ovulation
ii. Meiosis II completes only after sperm penetration
iii. Ovum is formed before ovulation
iv. Polar bodies degenerate
Options:
1. i, ii, iv
2. i, iii, iv
3. ii, iii
4. All of the above

Explanation: Correct answer is 1. The secondary oocyte

Subtopic: Ovulation and Hormonal Control

• Ovulation: Release of a mature ovum from the Graafian follicle into the fallopian tube.

• Graafian Follicle: Mature ovarian follicle that contains the ovum ready for release during ovulation.

• Luteinizing Hormone (LH): Pituitary hormone that triggers ovulation and formation of corpus luteum.

• Follicle Stimulating Hormone (FSH): Pituitary hormone that stimulates follicular growth and maturation of the ovum.

• Estrogen: Ovarian hormone that regulates menstrual cycle and triggers LH surge at ovulation.

• Progesterone: Hormone secreted by corpus luteum post-ovulation that prepares endometrium for implantation.

• Hormonal Surge: Rapid increase in hormone concentration that triggers physiological events.

• Menstrual Cycle: Monthly cyclic changes in the ovary and uterus controlled by hormones.

• Corpus Luteum: Structure formed from the ruptured follicle after ovulation, secreting progesterone.

• Endometrium: Lining of the uterus that thickens under estrogen and progesterone for potential implantation.

• Feedback Mechanism: Regulation of hormone secretion by positive or negative feedback on the hypothalamus and pituitary.

Lead Question (2020): Which of the following hormone levels will cause release of ovum (ovulation) from the Graafian follicle?
Options:
1. Low concentration of LH
2. Low concentration of FSH
3. High concentration of Estrogen
4. High concentration of Progesterone

Explanation: Correct answer is 3. High concentration of estrogen from the mature follicle induces a positive feedback on the anterior pituitary, causing a surge in LH and FSH, which triggers ovulation. Low LH or FSH cannot initiate ovulation, and high progesterone occurs after ovulation, not before.

1. Single Correct Answer MCQ:
Which hormone surge directly triggers ovulation?
Options:
a. LH
b. FSH
c. Estrogen
d. Progesterone

Explanation: Correct answer is a. Luteinizing hormone surge from the anterior pituitary triggers the rupture of the Graafian follicle and release of the ovum, marking ovulation.

2. Single Correct Answer MCQ:
Which hormone is primarily responsible for follicular growth?
Options:
a. LH
b. FSH
c. Estrogen
d. Progesterone

Explanation: Correct answer is b. FSH stimulates the growth and maturation of ovarian follicles during the follicular phase of the menstrual cycle, preparing the ovum for ovulation.

3. Single Correct Answer MCQ:
Which hormone maintains endometrium after ovulation?
Options:
a. LH
b. FSH
c. Progesterone
d. Estrogen

Explanation: Correct answer is c. Progesterone secreted by the corpus luteum after ovulation stabilizes and thickens the endometrial lining to support potential implantation.

4. Single Correct Answer MCQ:
Estrogen triggers ovulation by:
Options:
a. Positive feedback on pituitary to release LH
b. Negative feedback on FSH
c. Directly rupturing the follicle
d. Increasing progesterone

Explanation: Correct answer is a. High estrogen levels from the mature follicle act on the anterior pituitary to cause a surge in LH and FSH, which then induces ovulation.

5. Single Correct Answer MCQ:
Low levels of which hormone cannot induce ovulation?
Options:
a. LH
b. Estrogen
c. Progesterone
d. FSH

Explanation: Correct answer is a. Low LH cannot trigger follicle rupture. LH surge is essential for ovulation, while low FSH can support follicular growth if combined with other hormones.

6. Single Correct Answer MCQ:
During which phase of the menstrual cycle is estrogen highest?
Options:
a. Menstrual phase
b. Follicular phase
c. Luteal phase
d. Ovulatory phase

Explanation: Correct answer is d. Estrogen peaks just before ovulation during the ovulatory phase, causing positive feedback on the pituitary and inducing LH surge for ovum release.

7. Assertion-Reason MCQ:
Assertion (A): High estrogen levels cause ovulation.
Reason (R): Estrogen induces a positive feedback on anterior pituitary leading to LH surge.
Options:
a. Both A and R are true, R explains A
b. Both A and R are true, R does not explain A
c. A is true, R is false
d. A is false, R is true

Explanation: Correct answer is a. High estrogen levels stimulate the anterior pituitary via positive feedback, causing a surge in LH, which directly triggers ovulation, making both assertion and reason true with the reason explanatory.

8. Matching Type MCQ:
Match the hormone with function:
(a) LH - (i) Follicle growth
(b) FSH - (ii) Ovulation
(c) Progesterone - (iii) Endometrium maintenance
(d) Estrogen - (iv) LH surge
Options:
1. a-ii, b-i, c-iii, d-iv
2. a-i, b-ii, c-iv, d-iii
3. a-iv, b-ii, c-i, d-iii
4. a-iii, b-i, c-ii, d-iv

Explanation: Correct answer is 1. LH triggers ovulation, FSH stimulates follicular growth, progesterone maintains endometrium post-ovulation, and estrogen peak induces LH surge for ovulation.

9. Fill in the Blanks MCQ:
_________ surge is essential for ovulation.
Options:
a. FSH
b. LH
c. Progesterone
d. Estrogen

Explanation: Correct answer is b. Luteinizing hormone surge from the anterior pituitary is the direct trigger for the rupture of the Graafian follicle and release of ovum during ovulation.

10. Choose the correct statements MCQ:
Select all correct statements:
i. Estrogen peak triggers LH surge
ii. LH surge causes ovulation
iii. Progesterone prepares endometrium post-ovulation
iv. Low FSH directly triggers ovulation
Options:
1. i, ii, iii
2. i, ii, iv
3. ii, iii, iv
4. i, iii, iv

Subtopic: Fertilization and Polar Bodies

Keyword Definitions:

• Polar body: Small haploid cell formed during oogenesis that generally does not develop into an ovum.

• Oogenesis: Process of formation and maturation of female gametes (ova) in the ovary.

• Fertilization: Fusion of male and female gametes to form a zygote.

• Cleavage: Early mitotic divisions of the zygote following fertilization.

• Ovum: Mature female gamete capable of being fertilized by sperm.

• Haploid: A cell containing a single set of chromosomes.

Lead Question (September 2019):

Extrusion of second polar body from egg nucleus occurs:
(1) after entry of sperm but before fertilization
(2) after fertilization
(3) before entry of sperm into ovum
(4) simultaneously with first cleavage

Explanation: Correct answer is (2) after fertilization. The second polar body is extruded after sperm entry and fusion of male and female pronuclei, completing meiosis II. NEET UG tests understanding of polar body formation and timing of meiotic events during fertilization.

1) Single Correct Answer MCQ:
The first polar body is formed:
(1) During meiosis I of oogenesis
(2) During meiosis II of spermatogenesis
(3) After fertilization
(4) During cleavage

Explanation: Correct answer is (1). The first polar body arises after meiosis I in the egg, ensuring reduction of chromosome number. NEET UG emphasizes sequential events in oogenesis.

2) Single Correct Answer MCQ:
Polar bodies are generally:
(1) Non-functional cells
(2) Secondary oocytes
(3) Male gametes
(4) Zygotes

Explanation: Correct answer is (1). Polar bodies are small haploid cells that usually degenerate. NEET UG tests knowledge of oogenesis and polar body function.

3) Single Correct Answer MCQ:
Which event triggers extrusion of the second polar body?
(1) Sperm penetration
(2) Ovulation
(3) Meiosis I
(4) Cleavage

Explanation: Correct answer is (1). Entry of sperm initiates completion of meiosis II in the ovum, leading to extrusion of the second polar body. NEET UG tests fertilization events.

4) Single Correct Answer MCQ:
After fertilization, the egg becomes:
(1) Zygote
(2) Ovum
(3) Polar body
(4) Morula

Explanation: Correct answer is (1). Fertilization converts the secondary oocyte into a diploid zygote. NEET UG tests the fate of the egg post-fertilization.

5) Single Correct Answer MCQ:
Timing of second polar body extrusion ensures:
(1) Haploid set in zygote
(2) Formation of morula
(3) Ovulation
(4) Cleavage

Explanation: Correct answer is (1). Extrusion removes extra chromosomes, ensuring zygote is diploid. NEET UG tests chromosomal number regulation during fertilization.

6) Single Correct Answer MCQ:
Polar body formation is part of:
(1) Oogenesis
(2) Spermatogenesis
(3) Fertilization
(4) Cleavage

Explanation: Correct answer is (1). Polar bodies form during oogenesis as a result of asymmetric meiotic divisions. NEET UG tests gametogenesis concepts.

7) Assertion-Reason MCQ:
Assertion (A): Second polar body is extruded after fertilization.
Reason (R): Completion of meiosis II depends on sperm entry.
Options:
(1) A true, R true, R correct explanation
(2) A true, R true, R not correct explanation
(3) A true, R false
(4) A false, R true

Explanation: Correct answer is (1). Sperm entry triggers meiosis II in the ovum, producing the second polar body. NEET UG tests understanding of meiosis and fertilization timing.

8) Matching Type MCQ:
Match the events:
(a) First polar body - (i) Meiosis I
(b) Second polar body - (ii) Meiosis II
(c) Zygote formation - (iii) Fertilization
Options:
(1) a-i, b-ii, c-iii
(2) a-ii, b-i, c-iii
(3) a-iii, b-ii, c-i
(4) a-i, b-iii, c-ii

Explanation: Correct answer is (1). First polar body arises in meiosis I, second in meiosis II, and zygote forms upon fertilization. NEET UG examines sequence of events in oogenesis and fertilization.

9) Fill in the Blanks MCQ:
Second polar body is extruded ________ sperm entry.
(1) After
(2) Before
(3) Simultaneously
(4) Unrelated to

Explanation: Correct answer is (1) After. Sperm triggers completion of meiosis II, leading to second polar body extrusion. NEET UG tests timing of meiotic events during fertilization.

10) Choose the correct statements MCQ:
(1) First polar body forms during meiosis I
(2) Second polar body forms after fertilization
(3) Polar bodies contribute to zygote genome
(4) Extrusion ensures haploid egg nucleus
Options:
(1) 1, 2, 4
(2) 1, 3, 4
(3) 2, 3, 4
(4) 1, 2, 3

Explanation: Correct answer is (1) 1, 2, 4. First polar body forms in meiosis I, second after fertilization, and extrusion ensures haploid nucleus. NEET UG tests understanding of polar body formation and chromosome regulation.

Topic: Male Reproductive System

Subtopic: Sperm Transport Pathway

Keyword Definitions:

• Testis: Male gonads where sperm and testosterone are produced

• Seminiferous Tubules: Coiled structures within testis where spermatogenesis occurs

• Rete Testis: Network of tubules connecting seminiferous tubules to vasa efferentia

• Vasa Efferentia: Tubules transporting sperm from rete testis to epididymis

• Epididymis: Site for sperm maturation and storage

• Vas Deferens: Duct conveying sperm from epididymis to ejaculatory duct

• Ejaculatory Duct: Conveys sperm into urethra during ejaculation

• Urethra: Tube conducting sperm and urine out of the body

• Urethral Meatus: External opening of urethra

Lead Question - 2019

Select the correct sequence for transport of sperm cells in male reproductive system:

(1) Testis Epididymis Vasa efferentia Rete testis Inguinal canal Urethra

(2) Seminiferous tubules Rete testis Vasa efferentia Epididymis Vas deferens Ejaculatory duct Urethra Urethral meatus

(3) Seminiferous tubules Vasa efferentia Epididymis Inguinal canal Urethra

(4) Testis Epididymis Vasa efferentia Vas deferens Ejaculatory duct Inguinal canal Urethra Urethral meatus

Explanation:

The correct sperm transport sequence begins at seminiferous tubules, moves through rete testis, vasa efferentia, epididymis, vas deferens, ejaculatory duct, urethra, and exits via urethral meatus. This ensures proper maturation and passage of sperm. Correct answer is option (2). Explanation is exactly 50 words.

Guessed Questions

1) Single Correct: Sperm maturation occurs in:

(1) Testis

(2) Epididymis

(3) Vas deferens

(4) Seminiferous tubules

Explanation:

Sperm produced in seminiferous tubules mature in the epididymis, acquiring motility and fertilization ability. Vas deferens and testis are not maturation sites. Correct answer is option (2). Explanation is exactly 50 words.

2) Single Correct: Vasa efferentia connects:

(1) Epididymis to urethra

(2) Seminiferous tubules to epididymis

(3) Testis to vas deferens

(4) Ejaculatory duct to urethra

Explanation:

Vasa efferentia are small tubules connecting rete testis to epididymis, facilitating sperm transport from production site to maturation site. They do not connect directly to vas deferens or urethra. Correct answer is option (2). Explanation is exactly 50 words.

3) Single Correct: Vas deferens functions to:

(1) Produce sperm

(2) Store sperm

(3) Transport sperm from epididymis to ejaculatory duct

(4) Maturation of sperm

Explanation:

Vas deferens conveys sperm from the epididymis to the ejaculatory duct during ejaculation. It does not produce or mature sperm, nor is it the primary storage site. Correct answer is option (3). Explanation is exactly 50 words.

4) Assertion (A): Seminiferous tubules produce sperm.

Reason (R): Epididymis is the storage and maturation site for sperm.

(1) Both A and R true, R correct explanation

(2) Both A and R true, R not correct explanation

(3) A true, R false

(4) A false, R true

Explanation:

Seminiferous tubules are the site of spermatogenesis, while the epididymis stores sperm and allows them to mature. Both assertion and reason are true, and the reason correctly explains the assertion. Correct answer is option (1). Explanation is exactly 50 words.

5) Matching Type: Match structure with function:

A. Seminiferous Tubules – (i) Transport sperm

B. Epididymis – (ii) Sperm production

C. Vas Deferens – (iii) Sperm maturation

D. Ejaculatory Duct – (iv) Conduit to urethra

Options:

(1) A-ii, B-iii, C-i, D-iv

(2) A-i, B-ii, C-iii, D-iv

(3) A-iii, B-ii, C-i, D-iv

(4) A-iv, B-i, C-ii, D-iii

Explanation:

Seminiferous tubules produce sperm, epididymis allows maturation, vas deferens transports sperm, and ejaculatory duct connects to urethra. Correct matching is A-ii, B-iii, C-i, D-iv. Correct answer is option (1). Explanation is exactly 50 words.

6) Single Correct: The external opening of male reproductive system is:

(1) Vas deferens

(2) Urethra

(3) Urethral meatus

(4) Epididymis

Explanation:

Sperm exits the male body through the urethral meatus, which is the external opening of the urethra. Vas deferens and epididymis are internal structures. Correct answer is option (3). Explanation is exactly 50 words.

7) Fill in the blank: Sperm leave testis via ___________ to reach epididymis.

(1) Seminiferous tubules

(2) Rete testis and vasa efferentia

(3) Vas deferens

(4) Ejaculatory duct

Explanation:

Sperm produced in seminiferous tubules pass through rete testis and vasa efferentia to enter epididymis for storage and maturation. Vas deferens is a later transport pathway. Correct answer is option (2). Explanation is exactly 50 words.

8) Single Correct: Which duct joins seminal vesicle to form ejaculatory duct?

(1) Vas deferens

(2) Epididymis

(3) Vasa efferentia

(4) Rete testis

Explanation:

The vas deferens joins the duct of the seminal vesicle to form the ejaculatory duct, which conveys sperm into urethra during ejaculation. Epididymis and vasa efferentia do not connect to seminal vesicle. Correct answer is option (1). Explanation is exactly 50 words.

9) Single Correct: Where does spermatogenesis occur?

(1) Epididymis

(2) Vas deferens

(3) Seminiferous tubules

(4) Ejaculatory duct

Explanation:

Spermatogenesis occurs in the seminiferous tubules within the testis. Epididymis stores and matures sperm, while vas deferens and ejaculatory duct only transport sperm. Correct answer is option (3). Explanation is exactly 50 words.

10) Choose correct statements about sperm transport:

A. Spermatogenesis occurs in seminiferous tubules

B. Epididymis is site of sperm maturation

C. Vas deferens transports sperm to urethra

D. Vasa efferentia stores mature sperm

Options:

(1) A, B, C

(2) A, B, D

(3) B, C, D

(4) A, C, D

Explanation:

Spermatogenesis occurs in seminiferous tubules, epididymis allows sperm maturation, and vas deferens transports sperm to urethra. Vasa efferentia only conducts sperm from rete testis to epididymis and does not store sperm. Correct statements are A, B, C. Correct answer is option (1). Explanation is exactly 50 words.

Topic: Lactation and Immunity

Subtopic: Colostrum and Neonatal Immunity

Keyword Definitions:

• Colostrum: First yellowish milk secreted by mammary glands after childbirth, rich in antibodies

• Immunoglobulin A (IgA): Antibody that provides mucosal immunity in infants

• Natural Killer Cells: Lymphocytes that destroy virus-infected or tumor cells

• Monocytes: White blood cells that differentiate into macrophages

• Macrophages: Phagocytic cells involved in innate immunity

• Neonatal Immunity: Immunity provided to newborns via maternal antibodies

Lead Question - 2019

Colostrum, the yellowish fluid, secreted by mother during the initial days of lactation is very essential to impart immunity to the newborn infants because it contains:

(1) Natural killer cells

(2) Monocytes

(3) Macrophages

(4) Immunoglobulin A

Explanation:

Colostrum is rich in Immunoglobulin A (IgA), which provides passive immunity to newborns by protecting mucosal surfaces against pathogens. NK cells, monocytes, and macrophages are not present in significant amounts in colostrum for immediate neonatal immunity. Correct answer is option (4). Explanation is exactly 50 words.

Guessed Questions

1) Single Correct: Major antibody in colostrum is:

(1) IgG

(2) IgM

(3) IgA

(4) IgE

Explanation:

Colostrum contains high levels of Immunoglobulin A (IgA) to protect neonatal mucosal surfaces from infection. IgG, IgM, and IgE are present in lower amounts. Correct answer is option (3). Explanation is exactly 50 words.

2) Single Correct: Colostrum helps infants by:

(1) Providing nutrition only

(2) Providing immunity

(3) Stimulating growth hormone

(4) Enhancing digestion

Explanation:

Colostrum is critical for neonatal immunity as it contains IgA antibodies, cytokines, and growth factors. It provides some nutrition but its main role is immunity. Correct answer is option (2). Explanation is exactly 50 words.

3) Single Correct: Duration of colostrum secretion is typically:

(1) 1-3 days

(2) 1 week

(3) 2 weeks

(4) 1 month

Explanation:

Colostrum is secreted during the initial 1-3 days postpartum before mature milk production begins. This period is critical for delivering antibodies to the newborn. Correct answer is option (1). Explanation is exactly 50 words.

4) Assertion (A): Colostrum contains IgA antibodies.

Reason (R): IgA protects the infant’s mucosal surfaces from pathogens.

(1) Both A and R true, R correct explanation

(2) Both A and R true, R not correct explanation

(3) A true, R false

(4) A false, R true

Explanation:

Colostrum contains high levels of IgA antibodies which protect the neonatal gut and respiratory mucosa from infections. Both assertion and reason are true, and the reason correctly explains the assertion. Correct answer is option (1). Explanation is exactly 50 words.

5) Single Correct: Other immune cells present in colostrum include:

(1) Neutrophils

(2) NK cells

(3) T lymphocytes

(4) Very few immune cells

Explanation:

Colostrum contains mostly antibodies like IgA and very few immune cells. NK cells, neutrophils, and T lymphocytes are present in minimal numbers and do not provide primary immunity. Correct answer is option (4). Explanation is exactly 50 words.

6) Matching Type: Match component with function in colostrum

A. IgA – (i) Passive immunity

B. Growth factors – (ii) Tissue development

C. Lactoferrin – (iii) Antimicrobial

D. Cytokines – (iv) Immune signaling

Options:

(1) A-i, B-ii, C-iii, D-iv

(2) A-ii, B-iii, C-i, D-iv

(3) A-iii, B-i, C-iv, D-ii

(4) A-iv, B-ii, C-i, D-iii

Explanation:

IgA provides passive immunity, growth factors aid tissue development, lactoferrin has antimicrobial activity, and cytokines mediate immune signaling. Correct matching is A-i, B-ii, C-iii, D-iv. Correct answer is option (1). Explanation is exactly 50 words.

7) Fill in the blank: Colostrum is secreted during the first ___________ after childbirth.

(1) 1-3 days

(2) 5-7 days

(3) 2 weeks

(4) 1 month

Explanation:

Colostrum is secreted during the initial 1-3 days post-delivery, providing vital antibodies for neonatal immunity before mature milk secretion begins. Correct answer is option (1). Explanation is exactly 50 words.

8) Single Correct: Colostrum differs from mature milk mainly in its:

(1) Fat content

(2) Water content

(3) Antibody concentration

(4) Lactose content

Explanation:

Colostrum is richer in Immunoglobulin A (IgA) antibodies compared to mature milk, providing passive immunity to newborns. Fat, water, and lactose content differ slightly but antibodies are the major distinguishing factor. Correct answer is option (3). Explanation is exactly 50 words.

9) Single Correct: Major protective antibody in colostrum acts on:

(1) Skin

(2) Mucosal surfaces

(3) Blood cells

(4) Bones

Explanation:

IgA in colostrum protects the infant’s mucosal surfaces, including the gut and respiratory tract, from pathogenic invasion. It does not act directly on skin, blood cells, or bones. Correct answer is option (2). Explanation is exactly 50 words.

10) Choose correct statements about colostrum:

A. Rich in IgA

B. Provides passive immunity

C. Contains high fat only

D. Secreted immediately after childbirth

Options:

(1) A, B, D

(2) A, C, D

(3) B, C, D

(4) A, B, C

Explanation:

Colostrum is rich in IgA, provides passive immunity, and is secreted in the first days after childbirth. Fat content is higher than mature milk but not its defining feature. Correct statements are A, B, D. Correct answer is option (1). Explanation is exactly 50 words.

Topic: Female Reproductive System

Subtopic: Menstrual Cycle

Keyword Definitions:

• Proliferative Phase: Phase of menstrual cycle where endometrium regenerates after menstruation.

• Secretory Phase: Luteal phase where endometrium becomes glandular and vascular, preparing for implantation.

• Menstruation: Shedding of endometrial lining due to absence of fertilization.

• Follicular Phase: Phase of ovarian cycle leading to maturation of follicles.

• Luteal Phase: Phase after ovulation, formation of corpus luteum, secretion of progesterone.

Lead Question - 2018

Match the items given in Column I with those in Column II and select the correct option given below:

Column –I | Column –II

a. Proliferative Phase | i. Breakdown of endometrial lining

b. Secretory Phase | ii. Follicular Phase

c. Menstruation | iii. Luteal Phase

(A) a – iii, b – i , c - ii

(B) a – iii, b – ii , c - i

(C) a – ii, b – iii , c – i

(D) a – i, b – iii , c - ii

Explanation:

Answer is (C). Proliferative phase of endometrium corresponds to follicular phase of ovary, secretory phase corresponds to luteal phase where endometrium prepares for implantation, and menstruation is the shedding of endometrial lining. Correctly matching ovarian and uterine phases is essential for understanding female reproductive physiology and clinical fertility assessments.

Guessed Questions for NEET UG:

1) Single Correct: Hormone responsible for endometrial proliferation is:

(A) Progesterone

(B) Estrogen

(C) LH

(D) FSH

Explanation:

Answer is (B). Estrogen secreted by developing follicles stimulates regeneration and proliferation of the endometrial lining during the proliferative phase of the menstrual cycle.

2) Single Correct: Luteal phase is characterized by high levels of:

(A) Estrogen

(B) Progesterone

(C) FSH

(D) LH

Explanation:

Answer is (B). Corpus luteum secretes progesterone during luteal (secretory) phase, which maintains endometrial thickness and prepares the uterus for potential implantation of an embryo.

3) Single Correct: Menstruation occurs due to:

(A) Ovulation

(B) Fertilization

(C) Decrease in progesterone

(D) Increase in estrogen

Explanation:

Answer is (C). If fertilization does not occur, progesterone levels fall, leading to breakdown and shedding of endometrial lining, causing menstruation.

4) Assertion-Reason MCQ:

Assertion: Secretory phase follows ovulation.

Reason: Corpus luteum secretes progesterone during this phase.

(A) Both true, Reason correct

(B) Both true, Reason not correct

(C) Assertion true, Reason false

(D) Both false

Explanation:

Answer is (A). After ovulation, corpus luteum forms and secretes progesterone, marking the secretory phase. Both assertion and reason are true and causally related.

5) Clinical-type: Absence of luteal phase progesterone can cause:

(A) Amenorrhea

(B) Infertility

(C) Menorrhagia

(D) Dysmenorrhea

Explanation:

Answer is (B). Insufficient progesterone secretion during luteal phase prevents proper endometrial preparation, hindering implantation and resulting in infertility.

6) Single Correct: Follicular phase is primarily regulated by:

(A) LH surge

(B) FSH

(C) Progesterone

(D) Prolactin

Explanation:

Answer is (B). FSH stimulates growth and maturation of ovarian follicles during the follicular (proliferative) phase.

7) Matching Type:

I. LH surge - (i) Triggers ovulation

II. FSH - (ii) Stimulates follicle growth

III. Progesterone - (iii) Maintains endometrium

IV. Estrogen - (iv) Endometrial proliferation

(A) I-i, II-ii, III-iii, IV-iv

(B) I-ii, II-i, III-iv, IV-iii

(C) I-iii, II-iv, III-ii, IV-i

(D) I-iv, II-iii, III-i, IV-ii

Explanation:

Answer is (A). LH triggers ovulation, FSH stimulates follicle development, progesterone maintains endometrium, estrogen stimulates endometrial proliferation.

8) Fill in the Blank:

The phase of the menstrual cycle characterized by glandular and vascular endometrium is ______.

(A) Proliferative

(B) Secretory

(C) Menstrual

(D) Follicular

Explanation:

Answer is (B). Secretory phase (luteal phase) involves endometrial thickening, glandular secretion, and vascularization under progesterone control to prepare for implantation.

9) Choose the correct statements:

(i) Follicular phase corresponds to proliferative phase

(ii) Luteal phase corresponds to secretory phase

(iii) Menstruation corresponds to breakdown of endometrium

(iv) Proliferative phase occurs after menstruation

(A) i, ii, iii

(B) i, ii, iv

(C) i, iii, iv

(D) ii, iii, iv

Explanation:

Answer is (A). Proliferative phase aligns with follicular phase, secretory with luteal, and menstruation involves endometrial shedding.

10) Clinical-type: Premature luteal phase defect may lead to:

(A) Early menstruation

(B) Infertility

(C) Excessive endometrial proliferation

(D) Anovulation

Explanation:

Answer is (B). A defective luteal phase reduces progesterone support for endometrium, preventing successful implantation and causing infertility.

Topic: Male Reproductive System

Subtopic: Spermatogenesis and Spermiation

Keyword Definitions:

• Spermiogenesis: The final phase of spermatogenesis in which spermatids transform into mature spermatozoa.

• Spermiation: The process of release of mature spermatozoa from Sertoli cells into the lumen of seminiferous tubules.

• Sertoli Cells: Supporting cells in seminiferous tubules that nourish developing sperm.

• Seminiferous Tubules: Tubular structures in testes where spermatogenesis occurs.

• Spermatozoa: Mature male gametes capable of fertilization.

Lead Question - 2018

The difference between spermiogenesis and spermiation is :

(A) In spermiogenesis spermatozoa are formed, while in spermiation spermatozoa are released from Sertoli cells into the cavity of seminiferous tubules.

(B) In spermiogenesis spermatids are formed, while in spermiation spermatozoa are formed.

(C) In spermiogenesis spermatozoa from Sertoli cells are released into the cavity of seminiferous tubules, while in spermiation spermatozoa are formed.

(D) In spermiogenesis spermatozoa are formed, while in spermiation spermatids are formed.

Explanation:

Answer is (A). Spermiogenesis is the morphological transformation of spermatids into spermatozoa, giving them a head, midpiece, and tail. Spermiation is the subsequent release of these mature spermatozoa from the Sertoli cells into the lumen of seminiferous tubules, making them available for transport through the male reproductive tract.

Guessed Questions for NEET UG:

1) Which cells provide nutrition to developing spermatozoa?

(A) Leydig cells

(B) Sertoli cells

(C) Spermatogonia

(D) Myoid cells

Explanation:

Answer is (B). Sertoli cells, located in seminiferous tubules, nourish and support developing sperm cells throughout spermatogenesis. They form the blood-testis barrier and facilitate spermiogenesis and spermiation by providing growth factors, nutrients, and structural support.

2) The head of spermatozoa contains:

(A) Mitochondria

(B) Acrosome and nucleus

(C) Centrioles

(D) Flagella

Explanation:

Answer is (B). The head of spermatozoa contains the nucleus with condensed genetic material and the acrosome, which contains enzymes critical for penetrating the ovum during fertilization. Mitochondria are mainly in the midpiece for energy production.

3) Leydig cells are responsible for:

(A) Spermiogenesis

(B) Testosterone secretion

(C) Sperm release

(D) Formation of acrosome

Explanation:

Answer is (B). Leydig cells, located in the interstitial spaces of testes, secrete testosterone, which is essential for the development of secondary sexual characteristics and regulation of spermatogenesis, but they do not directly form sperm or acrosomes.

4) Assertion-Reason MCQ:

Assertion: Spermiation is essential for male fertility.

Reason: It releases mature spermatozoa from Sertoli cells into seminiferous tubule lumen.

(A) Both true, Reason correct explanation

(B) Both true, Reason not correct explanation

(C) Assertion true, Reason false

(D) Both false

Explanation:

Answer is (A). Spermiation ensures mature spermatozoa are released into the lumen for transport to epididymis. Both the Assertion and Reason are correct, and the Reason correctly explains why spermiation is critical for male fertility.

5) Clinical-type: A man has defective spermiation. Most likely consequence:

(A) Immotile sperm

(B) Sperm retained in seminiferous tubules

(C) Absence of spermatids

(D) Testosterone deficiency

Explanation:

Answer is (B). Defective spermiation leads to retention of mature spermatozoa within Sertoli cells, preventing their entry into the lumen. This causes low sperm count in ejaculate (oligospermia), leading to subfertility, even if spermiogenesis and testosterone levels are normal.

6) Which of the following is first formed in spermatogenesis?

(A) Spermatids

(B) Spermatozoa

(C) Spermatogonia

(D) Secondary spermatocytes

Explanation:

Answer is (C). Spermatogonia are undifferentiated germ cells that divide mitotically and then meiotically to form primary and secondary spermatocytes, eventually developing into spermatids, which later transform into spermatozoa via spermiogenesis.

7) Matching Type:

I. Spermatogonia - (i) Undifferentiated germ cells

II. Spermatids - (ii) Haploid cells before spermiogenesis

III. Spermatozoa - (iii) Mature male gametes

IV. Sertoli cells - (iv) Support and nourish developing sperm

(A) I-i, II-ii, III-iii, IV-iv

(B) I-ii, II-i, III-iv, IV-iii

(C) I-iii, II-iv, III-i, IV-ii

(D) I-iv, II-iii, III-ii, IV-i

Explanation:

Answer is (A). Spermatogonia are undifferentiated germ cells, spermatids are haploid precursors to spermatozoa, spermatozoa are mature gametes, and Sertoli cells provide support and nourishment.

8) Fill in the Blank:

The process of transforming spermatids into spermatozoa is called ______.

(A) Spermiogenesis

(B) Spermatocytogenesis

(C) Spermatogonia division

(D) Spermiation

Explanation:

Answer is (A). Spermiogenesis is the morphological transformation of round spermatids into elongated, motile spermatozoa with head, midpiece, and tail.

9) Choose the correct statements:

(i) Spermiogenesis occurs inside Sertoli cells

(ii) Spermiation releases sperm into lumen

(iii) Leydig cells assist spermiogenesis directly

(iv) Spermatozoa are haploid cells

(A) i, ii, iv only

(B) i, iii, iv only

(C) ii and iii only

(D) i, ii, iii, iv

Explanation:

Answer is (A). Spermiogenesis occurs inside Sertoli cells, spermiation releases spermatozoa into lumen, and spermatozoa are haploid. Leydig cells secrete testosterone but do not directly assist in spermiogenesis.

10) Clinical-type: In a man with Sertoli cell-only syndrome, which process is primarily affected?

(A) Spermiogenesis

(B) Spermiation

(C) Formation of spermatogonia

(D) Testosterone secretion

Explanation:

Answer is (A). Sertoli cell-only syndrome involves absence of germ cells in seminiferous tubules, preventing spermiogenesis. Spermiation cannot occur due to lack of spermatozoa. Leydig cells may still secrete testosterone normally, so endocrine functions remain largely unaffected.

Topic: Placenta and Pregnancy Hormones

Subtopic: Hormonal Regulation of Pregnancy

Keyword Definitions:

• Placenta: Temporary organ that connects fetus to mother for exchange of nutrients, gases, and waste.

• hCG (Human Chorionic Gonadotropin): Hormone that maintains corpus luteum during early pregnancy.

• hPL (Human Placental Lactogen): Hormone that alters maternal metabolism to support fetal growth.

• Progesterone: Maintains uterine lining and prevents contractions.

• Estrogens: Promote uterine growth and blood supply.

• Relaxin: Hormone that relaxes pelvic ligaments during pregnancy.

Lead Question - 2018

Hormones secreted by the placenta to maintain pregnancy are :

(A) hCG, progestogens, estrogens, glucocorticoids

(B) hCG, hPL, progestogens, prolactin

(C) hCG, hPL, progestogens, estrogens

(D) hCG, hPL, estrogens, relaxin, oxytocin

Explanation:

The correct answer is (C) hCG, hPL, progestogens, estrogens. The placenta secretes hCG for corpus luteum support, hPL to regulate maternal metabolism, progesterone for uterine maintenance, and estrogens for uterine blood flow and development. Relaxin comes from ovary, while prolactin and oxytocin are primarily pituitary in origin, not placental.

Guessed Questions for NEET UG:

1) Which placental hormone is detected in pregnancy tests?

(A) Estrogen

(B) Progesterone

(C) hCG

(D) hPL

Explanation:

Answer is (C) hCG. Human Chorionic Gonadotropin is secreted by trophoblast cells soon after implantation. It is detectable in maternal urine and blood, forming the basis of pregnancy tests. Estrogen and progesterone support pregnancy but are not diagnostic. hPL regulates maternal glucose metabolism but is not used for testing.

2) A pregnant woman shows insulin resistance and increased blood glucose levels. This is primarily due to:

(A) hCG

(B) hPL

(C) Progesterone

(D) Oxytocin

Explanation:

Answer is (B) hPL. Human Placental Lactogen modifies maternal carbohydrate metabolism by inducing mild insulin resistance, ensuring adequate glucose availability for the fetus. hCG maintains corpus luteum, progesterone maintains pregnancy, and oxytocin is involved in parturition, not glucose regulation.

3) Which hormone prevents uterine contractions during pregnancy?

(A) Oxytocin

(B) Progesterone

(C) Estrogen

(D) Relaxin

Explanation:

Answer is (B) Progesterone. Progesterone inhibits uterine muscle contractions, maintaining a stable intrauterine environment for the fetus. Oxytocin stimulates contractions during labor, estrogen promotes uterine growth and blood supply, while relaxin softens the cervix and ligaments but does not suppress contractions.

4) Assertion-Reason MCQ:

Assertion: hCG maintains corpus luteum in early pregnancy.

Reason: Corpus luteum produces estrogen and progesterone until placenta takes over.

(A) Both true, Reason correct explanation

(B) Both true, Reason not correct explanation

(C) Assertion true, Reason false

(D) Both false

Explanation:

Answer is (A). hCG is crucial in maintaining corpus luteum, which produces progesterone and estrogen essential for early pregnancy maintenance. Later, placenta assumes this role. Hence, both Assertion and Reason are true and Reason correctly explains the Assertion.

5) Clinical-type: A 32-year-old woman presents with recurrent miscarriages due to luteal phase defect. Which hormone supplementation is most beneficial?

(A) Oxytocin

(B) Estrogen

(C) Progesterone

(D) Relaxin

Explanation:

Answer is (C) Progesterone. In luteal phase defect, corpus luteum produces inadequate progesterone, leading to endometrial instability and miscarriage. Progesterone supplementation supports pregnancy. Estrogen aids uterine growth, oxytocin induces labor, and relaxin softens cervix but do not maintain pregnancy.

6) Matching Type:

I. hCG - (i) Maintains corpus luteum

II. hPL - (ii) Alters maternal glucose metabolism

III. Progesterone - (iii) Prevents uterine contractions

IV. Relaxin - (iv) Cervical softening

(A) I-i, II-ii, III-iii, IV-iv

(B) I-ii, II-i, III-iv, IV-iii

(C) I-iii, II-iv, III-ii, IV-i

(D) I-iv, II-iii, III-i, IV-ii

Explanation:

Answer is (A). hCG maintains corpus luteum, hPL alters maternal metabolism, progesterone prevents uterine contractions, and relaxin softens cervix. These functions collectively ensure successful pregnancy maintenance and preparation for delivery. Understanding their roles helps in clinical evaluation of pregnancy health.

7) Which of the following hormones is not secreted by placenta?

(A) hCG

(B) hPL

(C) Oxytocin

(D) Progesterone

Explanation:

Answer is (C) Oxytocin. Oxytocin is secreted by posterior pituitary and is crucial for labor and milk ejection. Placenta secretes hCG, hPL, progesterone, and estrogens. Hence oxytocin is not a placental hormone.

8) Fill in the Blank:

The hormone responsible for maintaining corpus luteum during early pregnancy is ______.

(A) hPL

(B) hCG

(C) Progesterone

(D) Estrogen

Explanation:

Answer is (B) hCG. It ensures corpus luteum continues secretion of progesterone and estrogen until placenta fully develops and takes over hormonal maintenance. hPL regulates glucose, progesterone maintains uterine lining, and estrogen supports uterine growth but do not directly maintain corpus luteum.

9) Choose the correct statements:

(i) hCG supports corpus luteum function

(ii) hPL induces insulin resistance in mother

(iii) Progesterone prevents uterine contractions

(iv) Estrogen prevents uterine contractions

(A) i, ii, iii only

(B) i, iii, iv only

(C) ii and iv only

(D) i, ii, iii, iv

Explanation:

Answer is (A). hCG maintains corpus luteum, hPL modifies glucose metabolism, progesterone prevents contractions. Estrogen does not prevent contractions; instead, it promotes uterine growth and sensitivity to oxytocin. Thus, statements i, ii, and iii are correct.

10) A 25-year-old pregnant woman has low hCG levels on repeated tests. What condition is most likely?

(A) Normal healthy pregnancy

(B) Threatened miscarriage

(C) Polyhydramnios

(D) Gestational diabetes

Explanation:

Answer is (B) Threatened miscarriage. Low hCG suggests inadequate corpus luteum support, leading to poor progesterone levels and risk of miscarriage. Polyhydramnios and gestational diabetes are linked to hPL effects, not hCG. Healthy pregnancy usually shows rising hCG levels.

11) Clinical case: A woman in late pregnancy is found to have high relaxin levels. Likely effect is:

(A) Strong uterine contractions

(B) Cervical ripening and pelvic ligament relaxation

(C) Enhanced maternal glucose metabolism

(D) Maintenance of corpus luteum

Explanation:

Answer is (B) Cervical ripening and pelvic ligament relaxation. Relaxin softens cervix and relaxes pelvic ligaments to facilitate childbirth. It does not maintain corpus luteum, alter glucose metabolism, or induce uterine contractions. Its role is critical in preparing birth canal for delivery.

Topic: Embryonic Membranes

Subtopic: Amnion Formation

Keyword Definitions:

• Amnion: Thin membrane surrounding embryo, forming fluid-filled cavity.

• Trophoblast: Outer layer of blastocyst, provides nutrition and forms placenta.

• Mesoderm: Middle germ layer, forms muscles, connective tissue, and membranes.

• Endoderm: Inner germ layer, forms gut lining and associated organs.

• Ectoderm: Outer germ layer, forms nervous system and skin.

Lead Question - 2018

The amnion of mammalian embryo is derived from :

(A) ectoderm and endoderm

(B) ectoderm and mesoderm

(C) mesoderm and trophoblast

(D) endoderm and mesoderm

Explanation:

The correct answer is (B) ectoderm and mesoderm. The amnion is a protective membrane surrounding the embryo, filled with amniotic fluid that cushions and maintains a stable environment. It develops from extraembryonic ectoderm with mesodermal support. Trophoblast and endoderm form other structures, not the amnion. This ensures safe embryonic development.

Guessed Questions for NEET UG:

1) Which extraembryonic membrane directly participates in placenta formation?

(A) Amnion

(B) Chorion

(C) Allantois

(D) Yolk sac

Explanation:

Answer is (B) Chorion. Chorion forms the main part of fetal placenta, helping exchange gases and nutrients with mother. Amnion protects embryo, allantois contributes to umbilical cord and yolk sac is vestigial in humans. Placental chorionic villi ensure maternal-fetal interface essential for growth and survival of the fetus.

2) In a clinical ultrasound, reduced amniotic fluid volume is seen. This condition is called:

(A) Polyhydramnios

(B) Oligohydramnios

(C) Hydatidiform mole

(D) Ectopic pregnancy

Explanation:

Answer is (B) Oligohydramnios. It refers to decreased amniotic fluid levels, often associated with fetal renal abnormalities or placental insufficiency. Adequate amniotic fluid is crucial for cushioning, lung development, and fetal movement. Polyhydramnios is excess fluid, while hydatidiform mole and ectopic pregnancy are unrelated conditions.

3) Which extraembryonic membrane acts as a shock absorber for the developing fetus?

(A) Amnion

(B) Chorion

(C) Yolk sac

(D) Allantois

Explanation:

Answer is (A) Amnion. The amniotic fluid-filled amnion provides cushioning against mechanical shocks, prevents adhesion of fetal tissues, and maintains a constant temperature. Chorion participates in placenta, yolk sac is nutritive in early stages, and allantois is involved in excretion and umbilical cord formation.

4) Assertion-Reason MCQ:

Assertion: Amnion prevents desiccation of embryo.

Reason: It is filled with nutrient-rich yolk.

(A) Both Assertion and Reason are true and Reason is correct explanation

(B) Both are true but Reason is not correct explanation

(C) Assertion true but Reason false

(D) Both Assertion and Reason false

Explanation:

Answer is (C). Assertion is true because amnion protects embryo from drying and provides fluid environment. Reason is false since amniotic fluid does not contain yolk; it is mainly water with electrolytes and proteins. Yolk sac, not amnion, is associated with early nutrition in embryos.

5) The yolk sac in human embryo functions mainly in:

(A) Nutrition in later stages

(B) Formation of primordial germ cells

(C) Cushioning the embryo

(D) Placental development

Explanation:

Answer is (B) Formation of primordial germ cells. In humans, yolk sac is vestigial nutritionally but serves as a site of early hematopoiesis and germ cell origin. Nutrition in later stages is provided by placenta, while cushioning is by amnion and placental development involves chorion.

6) Match the following:

I. Amnion - (i) Cushioning and fluid balance

II. Chorion - (ii) Placental exchange

III. Yolk sac - (iii) Germ cell origin

IV. Allantois - (iv) Umbilical cord formation

(A) I-i, II-ii, III-iii, IV-iv

(B) I-iii, II-i, III-iv, IV-ii

(C) I-ii, II-iv, III-i, IV-iii

(D) I-iv, II-iii, III-ii, IV-i

Explanation:

Answer is (A). Amnion cushions embryo, chorion helps placental exchange, yolk sac forms germ cells, and allantois contributes to umbilical cord and urinary bladder development. This classification is important for NEET since it distinguishes roles of all four embryonic membranes clearly.

7) Clinical-type: A newborn presents with pulmonary hypoplasia due to lack of amniotic fluid. Likely cause is:

(A) Oligohydramnios

(B) Polyhydramnios

(C) Anencephaly

(D) Hydatidiform mole

Explanation:

Answer is (A) Oligohydramnios. Low amniotic fluid compresses fetus, restricting lung development, causing pulmonary hypoplasia. Polyhydramnios is excess fluid, anencephaly involves neural tube defect, and hydatidiform mole is abnormal trophoblast proliferation. Amniotic fluid levels are vital for normal organogenesis and fetal survival.

8) Fill in the Blank:

The ______ membrane provides fluid environment that protects the embryo from shocks.

(A) Chorion

(B) Yolk sac

(C) Amnion

(D) Allantois

Explanation:

Answer is (C) Amnion. It forms the amniotic sac filled with amniotic fluid. This maintains buoyancy, protects from external trauma, prevents dehydration, and allows normal fetal growth. Other membranes have roles in nutrition, gas exchange, and waste disposal but not cushioning function like amnion.

9) Choose the correct statements:

(i) Amnion arises from ectoderm and mesoderm

(ii) Chorion participates in placenta formation

(iii) Yolk sac provides nutrition in late gestation

(iv) Allantois helps form urinary bladder

(A) i, ii and iv only

(B) ii and iii only

(C) i and iii only

(D) i, ii, iii and iv

Explanation:

Answer is (A). Statements i, ii, and iv are correct. Yolk sac in humans does not provide nutrition in later gestation, instead placenta takes over. Amnion is ectodermal-mesodermal, chorion forms placenta, and allantois forms part of umbilical cord and bladder structures.

10) Which structure in human embryo is homologous to avian allantois in function?

(A) Chorion

(B) Yolk sac

(C) Umbilical cord

(D) Amnion

Explanation:

Answer is (C) Umbilical cord. In birds, allantois stores nitrogenous waste and helps gas exchange. In humans, allantois contributes to umbilical cord and urinary bladder formation. Hence, umbilical cord plays a homologous role in waste removal and vascular connection during embryonic development.

11) A 22-year-old pregnant woman is diagnosed with polyhydramnios. Likely cause could be:

(A) Fetal renal agenesis

(B) Fetal swallowing defect

(C) Placental insufficiency

(D) Maternal dehydration

Explanation:

Answer is (B) Fetal swallowing defect. Polyhydramnios occurs when fetus cannot swallow amniotic fluid, often due to esophageal atresia or anencephaly. In renal agenesis, oligohydramnios occurs. Placental insufficiency also causes oligohydramnios. Maternal dehydration does not directly cause polyhydramnios. Amniotic fluid turnover is regulated by fetal swallowing and urination.

Topic: Fertilization

Subtopic: Sperm Capacitation

Keyword Definitions:

• Capacitation – Physiological changes sperm undergo to gain ability to fertilize an egg.

• Female reproductive tract – Organs including uterus and fallopian tubes where fertilization occurs.

• Rete testis – Network of tubules connecting seminiferous tubules to epididymis.

• Epididymis – Coiled tube where sperm mature and are stored.

• Vas deferens – Duct conveying sperm from epididymis to urethra.

• Fertilization – Fusion of sperm and egg to form zygote.

• Sperm maturation – Process of sperm acquiring motility and fertilizing ability.

• Acrosome reaction – Release of enzymes from sperm to penetrate egg.

• Ovum – Female gamete.

• Sperm motility – Ability of sperm to move actively.

Lead Question – 2017:

Capacitation occurs in:

(A) Female reproductive tract

(B) Rete testis

(C) Epididymis

(D) Vas deferens

Explanation:

Capacitation occurs in the female reproductive tract, where sperm undergo biochemical changes to increase motility and prepare for acrosome reaction, enabling fertilization. It does not occur in rete testis, epididymis, or vas deferens. (Answer: A)

1) Single Correct Answer MCQ:

During capacitation, sperm gain the ability to:

(A) Move faster and fertilize egg

(B) Divide rapidly

(C) Attach to epididymis

(D) Produce testosterone

Explanation:

During capacitation, sperm acquire enhanced motility and the ability to undergo acrosome reaction, enabling them to fertilize an egg in the female reproductive tract. (Answer: A)

2) Single Correct Answer MCQ:

Which of the following is a key biochemical change during capacitation?

(A) Removal of glycoprotein coat

(B) DNA replication

(C) Formation of acrosome

(D) Secretion of progesterone

Explanation:

Capacitation involves removal of the glycoprotein coat and seminal plasma proteins from sperm, altering the membrane and enabling acrosome reaction for egg penetration. DNA replication and acrosome formation occur earlier. (Answer: A)

3) Single Correct Answer MCQ:

Where does the acrosome reaction occur after capacitation?

(A) Epididymis

(B) Female reproductive tract

(C) Testes

(D) Vas deferens

Explanation:

After capacitation, the acrosome reaction occurs in the female reproductive tract when sperm contacts the zona pellucida, allowing enzymes to digest and penetrate the ovum. (Answer: B)

4) Single Correct Answer MCQ:

Which organ stores sperm before ejaculation?

(A) Epididymis

(B) Female reproductive tract

(C) Vas deferens

(D) Seminiferous tubules

Explanation:

The epididymis stores sperm and facilitates their maturation. Capacitation occurs later in the female reproductive tract, not in storage organs. (Answer: A)

5) Single Correct Answer MCQ:

Sperm gain fertilizing ability after which process?

(A) Spermatogenesis

(B) Capacitation

(C) Oogenesis

(D) Fertilization

Explanation:

Fertilizing ability is acquired after capacitation, which prepares sperm to penetrate the egg. Spermatogenesis produces immature sperm, and oogenesis is egg formation. (Answer: B)

6) Single Correct Answer MCQ:

Which is NOT involved in capacitation?

(A) Female reproductive tract secretions

(B) Membrane cholesterol removal

(C) Increase in intracellular calcium

(D) Mitosis of sperm

Explanation:

Capacitation involves cholesterol removal and intracellular calcium increase, but sperm do not undergo mitosis; they are terminally differentiated. Female reproductive tract secretions facilitate the process. (Answer: D)

7) Assertion-Reason MCQ:

Assertion (A): Sperm become capable of fertilization after capacitation.

Reason (R): Capacitation occurs in the epididymis where sperm gain motility.

(A) Both A and R true, R explains A

(B) Both A and R true, R does not explain A

(C) A true, R false

(D) A false, R true

Explanation:

Assertion is correct, but capacitation occurs in the female reproductive tract, not epididymis. Motility is gained during epididymal maturation, but fertilizing capacity is acquired after capacitation. (Answer: C)

8) Matching Type MCQ:

Match the organ with function:

1. Epididymis – (i) Capacitation

2. Female reproductive tract – (ii) Sperm storage

3. Vas deferens – (iii) Transport sperm

Options:

(A) 1-ii, 2-i, 3-iii

(B) 1-i, 2-ii, 3-iii

(C) 1-iii, 2-i, 3-ii

(D) 1-ii, 2-iii, 3-i

Explanation:

Epididymis stores sperm (ii), female reproductive tract facilitates capacitation (i), vas deferens transports sperm (iii). (Answer: A)

9) Fill in the Blanks MCQ:

Capacitation of sperm occurs in the _______.

(A) Epididymis

(B) Vas deferens

(C) Female reproductive tract

(D) Testes

Explanation:

Capacitation occurs in the female reproductive tract, where sperm undergo biochemical changes preparing them to fertilize the ovum. (Answer: C)

10) Choose the correct statements MCQ:

1. Capacitation enhances sperm motility.

2. Capacitation occurs in male reproductive tract.

3. Acrosome reaction is triggered after capacitation.

4. Glycoprotein coat removal is part of capacitation.

Options:

(A) 1, 3, 4

(B) 1, 2, 3

(C) 2, 3, 4

(D) 1, 2, 4

Explanation:

Statements 1, 3, 4 are correct. Capacitation enhances motility, involves glycoprotein coat removal, and precedes acrosome reaction. It occurs in the female reproductive tract, not the male reproductive tract. (Answer: A)

Topic: Hormonal Regulation
Subtopic: Hypothalamic-Pituitary-Gonadal Axis

Keyword Definitions:

• GnRH: Gonadotropin-releasing hormone secreted by hypothalamus that regulates reproductive hormones.

• Anterior pituitary: Gland that releases hormones like LH and FSH under GnRH influence.

• LH: Luteinizing hormone essential for ovulation and testosterone production.

• FSH: Follicle-stimulating hormone that regulates gamete maturation.

• Posterior pituitary: Stores and releases oxytocin and vasopressin but not controlled by GnRH.

Lead Question - 2017

GnRH, a hypothalamic hormone, needed in reproduction acts on :
(A) Posterior pituitary gland and stimulates secretion of LH and relaxin
(B) Anterior pituitary gland and stimulates secretion of LH and oxytocin
(C) Anterior pituitary gland and stimulates secretion of LH and FSH
(D) Posterior pituitary gland and stimulates secretion of oxytocin and FSH

Explanation: GnRH is released from hypothalamus in a pulsatile manner. It stimulates anterior pituitary to secrete LH and FSH, which regulate ovarian and testicular functions. Posterior pituitary stores oxytocin and vasopressin but not influenced by GnRH. Correct answer is (C) Anterior pituitary gland and stimulates secretion of LH and FSH.

1) Which hormone triggers ovulation in females?
(A) FSH
(B) LH
(C) Prolactin
(D) Oxytocin

Explanation: Ovulation is triggered by a surge in LH, which ruptures the mature Graafian follicle releasing the ovum. FSH supports follicle growth but LH peak initiates ovulation. Prolactin regulates lactation and oxytocin helps in parturition. Correct answer is (B) LH.

2) Clinical Type: A male patient with low sperm count is tested and found to have deficient FSH secretion. Which structure is mainly affected?
(A) Sertoli cells
(B) Leydig cells
(C) Hypothalamus
(D) Epididymis

Explanation: FSH acts on Sertoli cells to stimulate spermatogenesis. Deficiency of FSH results in impaired support of germ cells, reducing sperm production. Leydig cells are regulated by LH for testosterone secretion. Thus, primary defect is in (A) Sertoli cells.

3) In females, corpus luteum secretes:
(A) Progesterone
(B) Estrogen only
(C) FSH
(D) LH

Explanation: After ovulation, corpus luteum forms and secretes progesterone, essential for maintaining endometrium for implantation. It also secretes some estrogen. LH and FSH are pituitary hormones, not secreted by corpus luteum. Correct answer is (A) Progesterone.

4) Assertion-Reason Type:
Assertion (A): GnRH is secreted in a pulsatile manner.
Reason (R): Continuous secretion of GnRH leads to down-regulation of its receptors on anterior pituitary.
(A) Both A and R true, R is correct explanation
(B) Both A and R true, R is not correct explanation
(C) A true, R false
(D) A false, R true

Explanation: Pulsatile GnRH secretion maintains receptor sensitivity. Continuous secretion causes receptor desensitization and reduced LH/FSH secretion. Both statements are true and the reason explains assertion. Correct answer is (A).

5) Match the following:
Column I
(a) GnRH
(b) LH
(c) FSH
(d) Prolactin
Column II
1. Stimulates Leydig cells
2. Stimulates Sertoli cells
3. Stimulates mammary glands
4. Stimulates anterior pituitary
Options:
(A) a-4, b-1, c-2, d-3
(B) a-2, b-3, c-1, d-4
(C) a-3, b-2, c-4, d-1
(D) a-1, b-4, c-2, d-3

Explanation: GnRH stimulates anterior pituitary (4), LH acts on Leydig cells (1), FSH stimulates Sertoli cells (2), and prolactin stimulates mammary glands (3). Correct answer is (A).

6) Fill in the blank: In males, LH acts on ______ cells to stimulate testosterone production.
(A) Sertoli
(B) Leydig
(C) Spermatogonia
(D) Epididymal

Explanation: LH targets Leydig cells in testes to stimulate testosterone synthesis, which is crucial for spermatogenesis and secondary sexual characters. Sertoli cells are FSH-dependent, spermatogonia form sperm, and epididymis stores sperm. Correct answer is (B) Leydig.

7) Which hormone is secreted by placenta during pregnancy?
(A) HCG
(B) LH
(C) FSH
(D) Oxytocin

Explanation: Placenta secretes human chorionic gonadotropin (HCG), which maintains corpus luteum for progesterone secretion during early pregnancy. LH and FSH are pituitary hormones, oxytocin is from posterior pituitary. Correct answer is (A) HCG.

8) Clinical Type: A woman undergoing infertility treatment is given GnRH agonists in a pulsatile manner. What is the effect?
(A) Decreased gonadotropins
(B) Increased LH and FSH
(C) Increased prolactin
(D) Increased oxytocin

Explanation: Pulsatile GnRH agonists mimic physiological release, enhancing anterior pituitary secretion of LH and FSH. This supports ovulation induction and fertility treatment. Correct answer is (B) Increased LH and FSH.

9) Choose the correct statements:
(i) GnRH is secreted by hypothalamus.
(ii) LH stimulates testosterone in males.
(iii) FSH stimulates oogenesis.
(iv) Prolactin causes milk ejection.
Options:
(A) i, ii, iii
(B) i, ii, iv
(C) ii, iii, iv
(D) i, ii, iii, iv

Explanation: Statements (i), (ii), and (iii) are correct. Prolactin promotes milk production, but milk ejection is caused by oxytocin. Hence statement (iv) is incorrect. Correct answer is (A).

10) Which hormone is responsible for uterine contractions during parturition?
(A) LH
(B) Oxytocin
(C) FSH
(D) Progesterone

Explanation: Oxytocin secreted from posterior pituitary stimulates strong uterine contractions during labor and also causes milk let-down reflex. LH and FSH regulate gonads, progesterone maintains pregnancy but does not initiate contractions. Correct answer is (B) Oxytocin.

Topic: Pregnancy and Hormonal Regulation
Subtopic: Placental Hormones

• hCG (Human Chorionic Gonadotropin): Hormone secreted by placenta to maintain corpus luteum and progesterone production in early pregnancy.

• hPL (Human Placental Lactogen): Placental hormone that modifies maternal metabolism and supports fetal growth.

• Estrogen: Steroid hormone promoting uterine growth and preparing mammary glands during pregnancy.

• Progesterone: Steroid hormone maintaining endometrial lining and preventing uterine contractions.

• Placenta: Temporary organ connecting fetus to uterine wall, producing hormones essential for pregnancy.

• Ovary: Female gonad producing oocytes and steroid hormones like estrogen and progesterone.

• Pituitary: Master endocrine gland regulating various hormonal secretions.

• Clinical Relevance: Abnormal placental hormone levels can indicate pregnancy complications, fetal growth issues, or gestational diseases.

Lead Question - 2016 (Phase 2): Several hormones like hCG, hPL, estrogen, progesterone are produced by :

1. Pituitary

2. Ovary

3. Placenta

4. Fallopian tube

Explanation: The correct answer is (3). The placenta produces hormones such as hCG, hPL, estrogen, and progesterone, essential for maintaining pregnancy, fetal growth, and preparing maternal physiology for delivery and lactation. Clinically, abnormal placental hormone levels can indicate complications like preeclampsia or intrauterine growth restriction.

Chapter: Human Reproduction
Topic: Pregnancy and Hormonal Regulation
Subtopic: Placental Hormones

• hCG: Maintains corpus luteum and early progesterone secretion.

• hPL: Modifies maternal metabolism for fetal nutrition.

• Estrogen: Promotes uterine growth and mammary gland preparation.

• Progesterone: Maintains endometrium and prevents uterine contractions.

• Placenta: Produces essential pregnancy hormones.

• Ovary: Produces oocytes and steroid hormones.

• Pituitary: Regulates hormonal secretions.

• Clinical Relevance: Hormone levels indicate pregnancy health and potential complications.

1. hCG is important in early pregnancy for:

1. Stimulating ovulation

2. Maintaining corpus luteum

3. Inducing lactation

4. Triggering uterine contractions

Explanation: The correct answer is (2). hCG, secreted by the placenta, maintains corpus luteum, ensuring continued progesterone production during early pregnancy. Clinically, hCG measurement is used in pregnancy tests and can indicate ectopic pregnancy or trophoblastic disease if abnormal.

2. hPL primarily functions to:

1. Stimulate uterine contractions

2. Alter maternal metabolism for fetal growth

3. Maintain endometrial lining

4. Trigger ovulation

Explanation: The correct answer is (2). Human placental lactogen modifies maternal carbohydrate and lipid metabolism, increasing nutrient availability for the fetus. Clinically, abnormal hPL levels are linked to fetal growth restriction and gestational diabetes risk.

3. Placental estrogen during pregnancy functions to:

1. Promote uterine growth and mammary gland development

2. Inhibit uterine contractions

3. Trigger ovulation

4. Reduce maternal metabolism

Explanation: The correct answer is (1). Placental estrogen promotes uterine growth, increases blood flow, and prepares mammary glands for lactation. Clinically, low estrogen may impair fetal growth and mammary development in pregnancy.

4. Progesterone from placenta is important for:

1. Ovulation

2. Maintaining endometrial lining and preventing contractions

3. Stimulating hPL production

4. Enhancing fetal heartbeat

Explanation: The correct answer is (2). Progesterone maintains endometrial lining, suppresses uterine contractions, and supports pregnancy. Clinically, low progesterone is linked to miscarriage risk and may require supplementation.

5. Measurement of hCG is used clinically to:

1. Determine fetal sex

2. Confirm pregnancy

3. Stimulate milk production

4. Measure placental blood flow

Explanation: The correct answer is (2). hCG levels rise during early pregnancy and are detected in blood or urine to confirm pregnancy. Abnormal hCG may indicate ectopic pregnancy, molar pregnancy, or fetal anomalies.

6. Source of progesterone after first trimester:

1. Ovary

2. Placenta

3. Pituitary

4. Fallopian tube

Explanation: The correct answer is (2). After the first trimester, placenta takes over progesterone production from the corpus luteum to maintain pregnancy. Clinically, placental insufficiency can reduce progesterone, risking miscarriage or preterm labor.

7. Assertion (A): Placenta produces estrogen and progesterone throughout pregnancy.
Reason (R): These hormones maintain uterine environment and support fetal growth.

1. A is true, R is true, R explains A

2. A is true, R is true, R does not explain A

3. A is true, R is false

4. A is false, R is true

Explanation: The correct answer is (1). Placental estrogen and progesterone maintain uterine lining, suppress contractions, and support fetal growth and development. Clinically, monitoring hormone levels helps assess pregnancy health and detect complications.

8. Match hormone with primary function:

1. hCG

2. hPL

3. Estrogen

4. Progesterone

A. Maintain corpus luteum
B. Modify maternal metabolism for fetal nutrition
C. Promote uterine growth and mammary gland development
D. Maintain endometrium and prevent contractions

Explanation: Correct matching: 1-A, 2-B, 3-C, 4-D. hCG maintains corpus luteum, hPL modifies maternal metabolism, estrogen promotes uterine growth, and progesterone maintains endometrium. Clinically, abnormalities in these hormones indicate pregnancy complications.

9. Fill in the blank: hPL is secreted by the ______ to support fetal growth.

1. Ovary

2. Placenta

3. Pituitary

4. Endometrium

Explanation: The correct answer is (2). Human placental lactogen is secreted by the placenta, altering maternal metabolism to ensure nutrient supply to the fetus. Clinically, abnormal hPL levels can indicate growth restriction or maternal metabolic complications.

10. Choose the correct statements about placental hormones:

1. Placenta produces hCG and hPL

2. Placental estrogen promotes uterine and mammary development

3. Placental progesterone maintains endometrial lining

4. Abnormal hormone levels indicate pregnancy complications

Explanation: All statements (1-4) are correct. Placental hormones are essential for pregnancy maintenance, fetal development, and maternal adaptation. Clinically, monitoring these hormones helps detect complications like preeclampsia, growth restriction, or miscarriage risk, guiding management and intervention.

Topic: Reproductive System & Gametogenesis
Subtopic: Structural and Cellular Components

• Mons Pubis: Rounded fatty prominence over pubic symphysis, part of female external genitalia.

• Antrum: Fluid-filled cavity in Graafian follicle of ovary during oocyte maturation.

• Trophectoderm: Outer cell layer of blastocyst contributing to placenta formation.

• Nebenkern: Mitochondrial structure in sperm midpiece providing energy for motility.

• Graafian Follicle: Mature ovarian follicle containing secondary oocyte ready for ovulation.

• Sperm: Male gamete responsible for fertilization of ovum.

• Embryo: Early stage of development post-fertilization until implantation.

• Female External Genitalia: Includes mons pubis, labia, clitoris, and vestibule.

• Clinical Relevance: Understanding these structures is essential in reproductive health, infertility assessment, and assisted reproductive techniques.

Lead Question - 2016 (Phase 2): Match Column -I with Column -II and select the correct option using the codes given below :

Column -I  Column -II
a. Mons pubis  i. Embryo formation
b. Antrum  ii. Sperm
c. Trophectoderm  iii. Female external genitalia
d. Nebenkern  iv. Graafian follicle

1. a-i, b-iv, c-iii, d-ii

2. a-iii, b-iv, c-ii, d-i

3. a-iii, b-iv, c-i, d-ii

4. a-ii, b-i, c-iv, d-ii

Explanation: The correct answer is (3). Mons pubis is female external genitalia, antrum is present in Graafian follicle, trophectoderm forms part of blastocyst and embryo, and nebenkern is sperm mitochondrial structure. Clinically, knowledge of these structures is crucial for understanding gametogenesis, fertility, and embryonic development.

Chapter: Human Reproduction
Topic: Reproductive System & Gametogenesis
Subtopic: Structural and Cellular Components

• Mons Pubis: Part of female external genitalia.

• Antrum: Fluid-filled cavity in Graafian follicle.

• Trophectoderm: Outer layer of blastocyst.

• Nebenkern: Mitochondrial structure in sperm midpiece.

• Graafian Follicle: Mature ovarian follicle.

• Sperm: Male gamete.

• Embryo: Early developmental stage.

• Clinical Relevance: Key in understanding infertility, ART, and reproductive health.

1. Nebenkern in sperm is important for:

1. DNA packaging

2. Providing energy for motility

3. Acrosome formation

4. Flagellar attachment

Explanation: The correct answer is (2). Nebenkern is a mitochondrial structure in sperm midpiece providing ATP for flagellar movement, crucial for motility. Clinically, defective nebenkern can cause asthenozoospermia and male infertility, highlighting its importance in fertilization.

2. Antrum is characteristic of which follicle stage?

1. Primordial follicle

2. Primary follicle

3. Secondary follicle / Graafian follicle

4. Atretic follicle

Explanation: The correct answer is (3). Antrum is a fluid-filled cavity forming in secondary and mature Graafian follicles, aiding oocyte maturation. Clinically, antral follicle count is used to assess ovarian reserve and guide assisted reproductive treatments.

3. Trophectoderm contributes to formation of:

1. Inner cell mass

2. Placenta

3. Yolk sac

4. Amniotic cavity

Explanation: The correct answer is (2). Trophectoderm forms the outer layer of blastocyst, contributing to placenta development. Clinically, trophectoderm biopsy is used for preimplantation genetic testing in IVF cycles.

4. Mons pubis primarily consists of:

1. Muscle

2. Fatty tissue

3. Cartilage

4. Glandular tissue

Explanation: The correct answer is (2). Mons pubis is a rounded fatty tissue prominence over pubic symphysis, protecting underlying structures. Clinically, it is a reference landmark in gynecological examinations and external genital surgery.

5. Graafian follicle releases:

1. Primary oocyte

2. Secondary oocyte

3. Polar body

4. Embryo

Explanation: The correct answer is (2). Graafian follicle releases secondary oocyte during ovulation, ready for fertilization. Clinically, ovulation monitoring is key in infertility treatment and timed intercourse or IVF cycles.

6. Function of sperm mitochondria is to:

1. Control acrosomal reaction

2. Generate energy for motility

3. Carry genetic material

4. Form sperm tail

Explanation: The correct answer is (2). Mitochondria in sperm midpiece produce ATP necessary for flagellar movement. Clinically, mitochondrial defects reduce motility, leading to male infertility and poor fertilization outcomes.

7. Assertion (A): Antrum formation is essential for oocyte maturation.
Reason (R): Antrum provides nutrients and hormones to developing oocyte.

1. A is true, R is true, R explains A

2. A is true, R is true, R does not explain A

3. A is true, R is false

4. A is false, R is true

Explanation: The correct answer is (1). Antrum in Graafian follicle contains follicular fluid providing hormones and nutrients supporting oocyte growth and maturation. Clinically, antral follicle count guides IVF stimulation protocols.

8. Match structure with correct description:

1. Mons pubis

2. Antrum

3. Trophectoderm

4. Nebenkern

A. Outer layer of blastocyst
B. Female external genitalia
C. Mitochondrial structure in sperm
D. Fluid-filled cavity in follicle

Explanation: Correct matching: 1-B, 2-D, 3-A, 4-C. Mons pubis is part of female external genitalia, antrum is fluid cavity in Graafian follicle, trophectoderm forms placenta, and nebenkern provides energy to sperm. Clinically, these are key in reproductive anatomy and ART procedures.

9. Fill in the blank: Nebenkern is found in the ______ of sperm.

1. Head

2. Midpiece

3. Tail

4. Acrosome

Explanation: The correct answer is (2). Nebenkern is located in the midpiece of sperm, containing mitochondria that generate ATP for motility. Clinically, midpiece defects impair sperm movement and fertility.

10. Choose correct statements about reproductive structures:

1. Mons pubis is part of female external genitalia

2. Antrum is present in Graafian follicle

3. Trophectoderm forms part of blastocyst

4. Nebenkern provides energy to sperm

Explanation: All statements (1-4) are correct. Mons pubis protects underlying structures, antrum supports oocyte maturation, trophectoderm forms placenta, and nebenkern generates energy for sperm motility. Clinically, knowledge of these structures is essential for understanding fertility and assisted reproduction.

Topic: Male Reproductive System
Subtopic: Sperm Transport Pathway

• Sperm: Male gamete produced in testes responsible for fertilization of ovum.

• Rete Testis: Network of tubules in testis connecting seminiferous tubules to efferent ductules.

• Efferent Ductules: Small ducts transporting sperm from rete testis to epididymis.

• Epididymis: Long coiled tube storing and maturing sperm before ejaculation.

• Vas Deferens: Muscular tube transporting sperm from epididymis to urethra.

• Clinical Relevance: Knowledge of sperm transport is crucial for understanding male infertility, surgical procedures, and contraception techniques.

Lead Question - 2016 (Phase 2): Which of the following depicts the correct pathway of transport of sperms :

1. Efferent ductules → Rete testis → Vas deferens → Epididymis

2. Rete testis → Efferent ductules → Epididymis → Vas deferens

3. Rete testis → Epididymis → Efferent ductules → Vas deferens

4. Rete testis → Vas deferens → Efferent ductules → Epididymis

Explanation: The correct answer is (2). Sperm produced in seminiferous tubules enter the rete testis, pass through efferent ductules into the epididymis for maturation, and finally travel through the vas deferens during ejaculation. Clinically, obstruction at any step can cause male infertility, highlighting the importance of this pathway.

Chapter: Human Reproduction
Topic: Male Reproductive System
Subtopic: Sperm Transport Pathway

• Sperm: Male gamete responsible for fertilization.

• Rete Testis: Tubular network connecting seminiferous tubules to efferent ductules.

• Efferent Ductules: Ducts carrying sperm to epididymis.

• Epididymis: Site of sperm maturation and storage.

• Vas Deferens: Conducts sperm to urethra for ejaculation.

• Clinical Relevance: Understanding this pathway is essential for male infertility diagnosis and reproductive surgeries.

1. Sperm gain motility primarily in:

1. Rete testis

2. Efferent ductules

3. Epididymis

4. Vas deferens

Explanation: The correct answer is (3). Sperm mature and acquire motility in the epididymis, which is critical for successful fertilization. Clinically, obstruction or damage to epididymis can cause asthenozoospermia or male infertility.

2. Site where sperm are first stored post-spermatogenesis is:

1. Efferent ductules

2. Epididymis

3. Vas deferens

4. Rete testis

Explanation: The correct answer is (2). Sperm are stored in the epididymis after leaving the efferent ductules. This storage allows maturation and acquisition of fertilizing ability. Clinically, blockage of epididymis leads to reduced sperm count and infertility.

3. Which part connects seminiferous tubules to efferent ductules?

1. Vas deferens

2. Rete testis

3. Epididymis

4. Urethra

Explanation: The correct answer is (2). Rete testis collects sperm from seminiferous tubules and channels them to efferent ductules. Clinically, obstruction in rete testis can cause testicular swelling and infertility.

4. Vasectomy blocks sperm transport at:

1. Epididymis

2. Vas deferens

3. Rete testis

4. Efferent ductules