NEET Previous Year Questions (2016-2025): Human Reproduction | Biology Class 12 PDF Download

Ans: A.
The Fallopian tubes, also known as oviducts or uterine tubes, are structures in the female reproductive system that stretch from the uterus to the ovaries. These tubes play a crucial role in the journey of the egg from the ovary to the uterus. The primary components of the Fallopian tubes include the infundibulum, ampulla, and isthmus:
When examining the options provided, Option A mentions the "Uterine fundus". The fundus is actually the top part of the uterus, situated above the openings of the Fallopian tubes into the uterine cavity. The fundus of the uterus is not a part of the Fallopian tubes; instead, it is a region of the uterus itself. Therefore, the correct answer is: Option A: Uterine fundus

Ans: C.
To answer this question correctly, we need to evaluate the facts around each statement individually before making a comparison:
Statement I: The presence or absence of hymen is not a reliable indicator of virginity.
This statement is true. The hymen is a thin, elastic membrane located at the entrance to the vagina. Contrary to common belief, the hymen is not an impermeable barrier that is always torn when virginity is lost via sexual intercourse. It can vary greatly in shape and size from person to person. Some girls are born without a hymen, some have small hymenal tissue, and others have hymens that are very elastic. Moreover, the hymen can be stretched or torn during a variety of non-sexual activities such as tampon use, physical exercise (e.g., biking, gymnastics), or medical examinations. Therefore, the state of the hymen is not a definite indicator of virginity, making statement I true.
Statement II: The hymen is torn during the first coitus only.
This statement is false. As previously mentioned, the hymen can be stretched or torn by activities that are not sexual in nature. Additionally, many women may not experience tearing of the hymen at all during their first sexual intercourse. In cases where the hymen is more elastic or resilient, it may not tear during sexual activity. Furthermore, there are practices and surgeries, such as hymenoplasty, that can restore or create a hymen-like structure, indicating that the hymen can be altered multiple times throughout a woman's life. Thus, the claim that the hymen is torn only during the first coitus is incorrect.
Based on the explanations provided:
Option C (Statement I is true but Statement II is false) is the correct answer.

Ans: A.
Sol: The correct answer is option no. (A) as

Role of Hormones and Cells in Spermatogenesis:

FSH (Follicle-stimulating hormone) acts on the Sertoli cells to promote spermatogenesis (the production of sperm).

Leydig cells are responsible for producing testosterone, which supports the process of spermatogenesis.

Spermiogenesis is the final stage of spermatogenesis where spermatids mature into sperm.

Ans: A.
Assertion A states that breast-feeding during the initial period of infant growth is recommended by doctors to bring up a healthy baby. This statement is indeed correct. Breast-feeding is universally recommended by health professionals because mother's milk contains the perfect balance of nutrients essential for the newborn's growth and development. Additionally, breastfeeding promotes better health outcomes for the mother and infant, strengthening the immune system of the baby.
Reason R explains that colostrum, the first form of milk produced immediately following the delivery of the newborn, contains several antibodies absolutely essential to develop resistance for the newborn baby. This statement is also correct. Colostrum is rich in immunoglobulins, particularly IgA, which provide passive immunity to the baby by forming a protective layer in the baby's intestine, thereby preventing infection.
Since both Assertion A and Reason R are correct, and Reason R directly explains why breastfeeding is beneficial — particularly highlighting the role of colostrum in providing immunity which is crucial for the newborn's health, the correct option herein is:
Option A: Both A and R are correct and R is the correct explanation of A.

Ans: (c)
 (a) Testosterone: A steroid hormone produced in the testes and adrenal glands, involved in male characteristics.
(b) Progesterone: A steroid hormone important for regulating the menstrual cycle and maintaining pregnancy. 
(c) Glucagon: Not a steroid hormone; it is a peptide hormone produced by the pancreas that raises blood glucose levels. 
(d) Cortisol: A steroid hormone produced by the adrenal glands, involved in stress response and metabolism.

Ans: (d)
C. Seminiferous tubules: Site of sperm production in the testes. 
B. Rete testis: Network of tubules that collect sperm from seminiferous tubules. 
D. Vasa efferentia: Tubes that carry sperm from the rete testis to the epididymis. 
F. Epididymis: Site where sperm mature and are stored. 
A. Vas deferens: Duct that transports sperm from the epididymis to the ejaculatory duct. 
E. Urethra: Final pathway for sperm to exit the body.

Ans: (c)
A. After 4 weeks: II. Heart is formed. 
B. After 12 weeks: IV. External genital organs are well developed. 
C. After 24 weeks: I. Eye-lids separate and eyelashes are formed. 
D. After 8 weeks: III. Limbs and digits are developed.

Ans: (c)
(A) FSH acts on ovarian follicles but not on Leydig cells; Leydig cells are stimulated by LH. 
(R) The statement about ovarian follicles secreting estrogen is true.

Ans: (a)
Statement I is true as the degeneration of the corpus luteum leads to a drop in progesterone, causing the endometrium to disintegrate. -
Statement II is also true as cyclic menstruation indicates a normal reproductive phase in females.

Ans: (c)
(A) is true as ovulation typically occurs around the 14th day of the cycle. 
(R) correctly explains that the LH surge induces ovulation.

Ans: (a)

• A-II: Mons pubis is a fatty cushion of cells covered by skin and hair.
• B-III: Clitoris is a tiny finger-like structure located above the labia minora.
• C-IV: Hymen is a thin membrane-like structure that partially covers the vaginal opening.
• D-I: Labia majora are fleshy folds of tissue that surround the vaginal opening.

Ans: (a)

• A-III: Parturition refers to the foetal ejection reflex during childbirth.
• B-IV: The placenta is responsible for the secretion of the hormone hCG.
• C-I: Colostrum contains several antibodies that are crucial for newborn babies.
• D-II: Fimbriae are involved in the collection of ovum after ovulation.

Ans: A.
Option (a) is the correct answer to this question because statement I and statement II both are correct. Vas deferens receives a duct from seminal vesicle and opens into urethra as the ejaculatory duct. The cavity of cervix is called cervical canal which along with vagina forms the birth canal.

Ans: D.
The correct answer is option (d) as first menstrual cycle that begins at puberty is called menarche.
Cyclic menstruation is an indicator of normal reproductive phase and extends between menarche and menopause.
In primates, cyclical changes during reproduction are called menstrual cycle.

Ans: (b)
Option (b) is the correct answer because both Assertion and Reason are true.
Implantation is embedding of the blastocyst into endometrium of uterus.
Correct explanation of reason is Corpus luteum secretes large amount of progesterone which is essential for maintenance of endometrium of uterus. In absence of fertilisation, the corpus luteum degenerates hence the decrease in the level of progesterone hormone will cause disintegration of endometrium leading to menstruation.

Ans: (c)
(B) Gonadotropin releasing hormone from hypothalamus: This hormone initiates the process by stimulating the anterior pituitary gland to release gonadotropins.
(E) Gonadotropins from anterior pituitary gland: These include LH and FSH, which are crucial for the regulation of gonadal function.
(A) Gonadotropin LH stimulates synthesis and secretion of Androgen: LH acts on Leydig cells in the testes to produce androgens, which are essential for male gametogenesis.
(C) Androgen stimulates spermatogenesis: The androgens produced promote the development of sperm cells from spermatogonia.
(D) Gonadotropin FSH helps in the process of spermiogenesis: FSH supports the maturation of sperm cells into fully developed spermatozoa.

Ans: (b)
Statement I:  is incorrect because the primary follicles, when surrounded by more layers of granulosa cells and a theca, are called secondary follicles. However, the secondary follicles then transform into tertiary follicles, which is characterized by a fluid-filled cavity called antrum. 
Statement II:  is correct as the Graafian follicle does rupture to release the secondary oocyte from the ovary, a process known as ovulation. 
So, the correct answer is Option B : Statement I is incorrect but Statement II is true.

Ans: (a)

• The process of spermatogenesis occurs in testis, in which the immature male germ cells or spermatogonia are converted to sperms. 
• The spermatogonia present on the inside wall of seminiferous tubules undergoes mitosis. 
• Some spermatogonia periodically undergo meiosis. These spermatogonia are called as primary spermatocytes (2n). 
• A primary spermatocyte completes the first meiotic division and forms secondary spermatocytes (n). 
• The secondary spermatocytes undergo the second meiotic division to produce spermatids.
• The spermatids are then, transformed into spermatozoa or sperms by the process called spermiogenesis. 
• After spermiogenesis, sperm heads become embedded in the Sertoli cells. These spermatozoa are finally released from the seminiferous tubules by the process called spermiation.

Ans: D
Oogenesis starts at embryonic development stage in females. 

Process of Oogenesis

Ans: A.
Concept:

• The process of formation of the male gamete (sperm) is called spermatogenesis.
• The process of formation of the female gamete (ovum) is called oogenesis.

Explanation:

Let us see some similarities and differences between oogenesis and spermatogenesis:

So, the correct answer is option A .

Ans: D.
Option (d) is the correct answer because one primary spermatocyte produces two secondary spermatocytes by meiosis I and one secondary spermatocyte produces two spermatozoa via meiosis 2. So, 200 million secondary spermatocytes will produce 400 million spermatozoa.

Ans: (d)
Option (d) is the correct answer because the components of mammary gland (from proximal to distal) is:
(c) → (e) → (a) → (d) → (b)
Alveoli→Mammarytubules→Mammaryduct→Mammaryampulla→Lactiferousduct
Each mammary lobule is composed of a number of alveoli which open into mammary tubules. The tubules of each lobule join to form a mammary duct. Near the nipple, mammary ducts expand to form mammary ampullae where some milk is stored before going to lactiferous duct which is present at distal end through which milk is sucked out.

Ans: B.
Option (b) is the correct answer because thyroxine is the main hormone that increases the basal metabolic rate in our body. A high metabolic rate is required during pregnancy, so levels of thyroxine increase in pregnant females along with other hormones such as cortisol, progesterone, etc.

Ans: B.

• Option B. is correct because zona pellucida has receptors for sperm binding (ZP3 receptors) in mammals.
• Corona radiata is a layer of radially arranged cells of membrana granulosa.
• Perivitelline space is present in between vitelline membrane and zona pellucida.

Ans: D.
Corpus luteum is formed in ovary after the ovulation and degenerates if pregnancy does not occur.
In later phase of pregnancy the corpus luteum secretes relaxin hormone.Relaxin dilates the cervix and helps in parturition. Graafian follicle, uterus and foetus has no role in relaxin secretion.

Ans: B.

• At the end of gestation, the completely developed foetus is expelled out. This process is called parturition.
• Parturition is controlled by a complex neuroendocrine mechanism.
• Estrogen and progesterone ratio increases as estrogen levels rise significantly.
• Prostaglandins, which stimulate uterine contractions are also produced that act on myometrium.
• Oxytocin, the main hormone, also called as birth hormone is released by maternal pituitary, which brings about strong uterine contractions.
• Prolactin is a lactation hormone that has no role in initiation of parturition.

Ans: B.
Placenta secretes human chorionic gonadotropin (hCG). Zona pellucida is a primary egg membrane secreted by the secondary oocyte. The secretions of bulbourethral glands help in lubrication of the penis Leydig cells synthesise and secrete testicular hormones called androgens.

Ans: B.
Meiotic division of secondary oocyte is completed after the entry of sperm in secondary oocyte which lead to the formation of a large ovum and a tiny 2nd polar body.

Ans: C.

• High level of estrogen will send positive feedback to anterior pituitary for release of LH.

• LH surge leads to ovulation.

• FSH, LH and estrogen are at peak level during mid of menstrual cycle (28 day cycle).

Ans: B.
Sperms enters into 2^o oocytes which breaks metaphase promoting factor and activates anaphase promoting complex which causes extrusion of second polar body by completing meiosis-II. 

Ans: (c)
The correct sequence for transport of sperm cells in male reproductive system is :
Seminiferous tubules → Rete testis → Vasa efferentia → Epididymis → Vas deferens → Ejaculatory duct → Urethra → Urethral meatus. 

Ans: C.
Placenta is temporary organ that helps in exchange of gases, nutrients and waste materials between mother and fetus. During pregnancy, placenta acts as an endocrine gland and secretes some hormones such as estrogen, progesterone, human chorionic gonadotropin (hCG), human placental lactogen (hPL), chorionic thyrotropin, chorionic corticotropin and relaxin.

Ans: D.

The spermatids are transformed into spermatozoa (sperms) by the process called spermiogenesis.
After spermiogenesis, sperm heads become embedded in the Sertoli calls, and are finally released from the seminiferous tubules by the process called spermiation.

Ans: (c)
Menstruation is a phase of bleeding by breakdown of endometrial long, Proliferate phase is follicular phase where as secretary phase is lacteal phase.

Ans: C.
At the pituitary, GnRH stimulates the synthesis and secretion of the gonadotropins, follicle-stimulating hormone (FSH), and luteinizing hormone (LH). These processes are controlled by the size and frequency of GnRH pulses, as well as by feedback from progesterone and estrogens. Lowfrequency GnRH pulses are required for FSH release, whereas high-frequency GnRH pulses stimulate LH pulses in a one to one manner

Ans: A.
Considering the female reproductive endocrinology, ovulation is the process of the monthly release of the viable oocyte from the ovary between the time of menarche and menopause. During this time, there is a surge in the production of LH and FSH, termed as gonadotropins, thereby initiating estradiol and progesterone secretion from the ovary. Both these hormones are very important for the menstrual cycle.

Ans: D.
In both females and males, inhibin inhibits FSH production. In females, FSH stimulates the secretion of inhibin from the granulosa cells of the ovarian follicles in the ovaries. In turn, inhibin suppresses FSH. In males, androgens stimulate inhibin production. It is secreted from the Sertoli cells, located in the seminiferous tubules inside the testes.

Ans: A.
The correct sequence for transport of sperm cells in male reproductive system is :
Seminiferous tubules → Rete testis → Vasa efferentia → Epididymis → Vas deferens → Ejaculatory duct → Urethra → Urethral meatus.

Ans: B.
Placenta is temporary organ that helps in exchange of gases, nutrients and waste materials between mother and fetus. During pregnancy, placenta acts as an endocrine gland and secretes some hormones such as estrogen, progesterone, human chorionic gonadotropin (hCG), human placenta] lactogen (liPL), chorionic thyrotropin, chorionic corticotropin and relaxin.