Reproduction MCQ Test - Zoology, Class 12 - Class 12 MCQ

Lytic Enzyme Present in Semen: Hyaluronidase

The lytic enzyme present in semen is hyaluronidase.

Explanation:

• Hyaluronidase is an enzyme that breaks down hyaluronic acid, a substance that helps hold cells together in the extracellular matrix.


• It is present in various body fluids and tissues, including semen.


• In semen, hyaluronidase plays a role in the liquefaction of semen after ejaculation.


• It helps in the dispersion of sperm cells by breaking down the hyaluronic acid present in the cervical mucus, allowing the sperm to swim freely towards the egg.


• Thus, hyaluronidase aids in the fertilization process.

Therefore, the correct answer is option D: hyaluronidase.

Progesterone hormone is secreted by:
The correct answer is C: corpus luteum in ovaries.
Explanation:
Progesterone is a hormone that plays a crucial role in the female reproductive system. It is primarily secreted by the corpus luteum in the ovaries. Here is a detailed explanation:
- Corpus Luteum: The corpus luteum is a temporary structure that forms in the ovary after the release of an egg during ovulation. It develops from the ruptured follicle and is responsible for producing progesterone.
- Function of Progesterone: Progesterone prepares the uterus for pregnancy and helps maintain a healthy pregnancy if fertilization occurs. It promotes the thickening of the uterine lining (endometrium) in preparation for implantation of a fertilized egg. If pregnancy does not occur, the corpus luteum breaks down, leading to a drop in progesterone levels.
- Other Sources of Progesterone: Apart from the corpus luteum, progesterone is also produced in smaller amounts by the adrenal glands and placenta during pregnancy.
In conclusion, the progesterone hormone is primarily secreted by the corpus luteum in the ovaries.

Sertoli cells are involved in:
Nutrition of sperms:
- Sertoli cells provide nutritional support to developing sperm cells.
- They produce and secrete various substances such as androgen-binding protein (ABP), transferrin, and inhibin, which are important for the maturation and nourishment of sperm cells.
- ABP helps in the concentration of testosterone in the seminiferous tubules, which is necessary for the development of sperm cells.
- Transferrin helps in the uptake of iron by developing sperm cells, which is essential for their growth and metabolism.
- Inhibin regulates the production of follicle-stimulating hormone (FSH) by the pituitary gland, which further influences the production of sperm cells.
Development of sex organs:
- Sertoli cells play a crucial role in the development of male sex organs.
- During embryonic development, Sertoli cells secrete antimullerian hormone (AMH), which causes regression of the Mullerian ducts, preventing the formation of female reproductive structures.
- They also secrete factors that promote the differentiation and growth of the male reproductive structures, such as the epididymis, vas deferens, and seminal vesicles.
Regulation of spermatogenesis:
- Sertoli cells provide structural and functional support to developing sperm cells.
- They form tight junctions with each other, creating the blood-testis barrier, which isolates the developing sperm cells from the immune system and allows the creation of a specialized microenvironment for spermatogenesis.
- Sertoli cells also phagocytose defective or excess germ cells, ensuring the quality control of sperm production.
- They secrete factors that regulate the process of spermatogenesis, such as growth factors, hormones, and signaling molecules.
In conclusion, Sertoli cells are involved in the nutrition of sperm cells, development of male sex organs, and regulation of spermatogenesis. They play a crucial role in supporting and nourishing developing sperm cells and creating a suitable environment for their maturation.

Corpus Luteum in Mammals
The corpus luteum is a temporary endocrine gland that develops in the ovary after the release of an egg during ovulation. It plays a crucial role in the female reproductive system.
Answer Choice: B - Ovary
The corpus luteum is specifically found in the ovaries of mammals. Here's a detailed explanation of why the correct answer is the ovary:
- The ovary is one of the main organs in the female reproductive system. It is responsible for producing and releasing eggs (oocytes) during the menstrual cycle.
- After ovulation, when the egg is released from the ovary, the remaining tissue in the ovary undergoes a transformation and forms the corpus luteum.
- The corpus luteum is a yellowish structure that secretes hormones, primarily progesterone, which is essential for maintaining the uterus lining and preparing it for possible pregnancy.
- If fertilization and implantation occur, the corpus luteum continues to produce progesterone to support early pregnancy. However, if fertilization does not occur, the corpus luteum degenerates and is eventually replaced by scar tissue called the corpus albicans.
- The presence of the corpus luteum and its hormone secretion is a crucial part of the reproductive cycle in mammals, ensuring proper preparation of the uterus for potential implantation and pregnancy.
Therefore, the corpus luteum is found in the ovary of mammals.

Testosterone is secreted by Leydig cells.
Testosterone is a hormone that plays a crucial role in the development and maintenance of male reproductive tissues and secondary sexual characteristics. It is primarily secreted by the Leydig cells, which are located in the interstitial tissue of the testes.
Leydig cells:
- Leydig cells are found in the testes, specifically in the interstitial tissue surrounding the seminiferous tubules.
- They are responsible for producing and secreting testosterone.
- The secretion of testosterone is regulated by luteinizing hormone (LH) from the pituitary gland.
Function of testosterone:
- Testosterone is essential for the development of male reproductive organs, such as the testes and prostate.
- It promotes the growth and maturation of sperm cells.
- Testosterone is responsible for the development of secondary sexual characteristics in males, such as facial and body hair, deepening of the voice, and increased muscle mass.
- It also plays a role in the regulation of libido (sex drive) and overall energy levels.
Sertoli cells and seminiferous tubules:
- Sertoli cells are found within the seminiferous tubules of the testes.
- They provide support and nourishment to developing sperm cells.
- Sertoli cells do not secrete testosterone.
Conclusion:
In summary, testosterone is primarily secreted by Leydig cells, which are located in the interstitial tissue of the testes. These cells play a crucial role in the production of testosterone, which is essential for male reproductive function and the development of secondary sexual characteristics. Neither Sertoli cells nor seminiferous tubules secrete testosterone.

The most important component of oral contraceptive is progesterone. Here's a detailed explanation:
Oral Contraceptives:
- Oral contraceptives, also known as birth control pills, are hormonal medications that are taken by mouth to prevent pregnancy.
- They contain synthetic versions of the hormones progesterone and estrogen, which are naturally produced by the ovaries.
Importance of Progesterone:
- Progesterone is one of the key hormones involved in the menstrual cycle and pregnancy.
- It plays a crucial role in preparing the uterus for implantation of a fertilized egg and maintaining pregnancy.
- In the context of oral contraceptives, progesterone is the most important component because it helps prevent pregnancy by:
- Thickening the cervical mucus, making it difficult for sperm to reach the egg.
- Inhibiting the release of follicle-stimulating hormone (FSH) from the pituitary gland, which prevents the development of mature eggs.
- Preventing ovulation, the release of eggs from the ovaries.
Other Components:
- Estrogen is another important component of oral contraceptives, but it is not the most crucial one.
- Estrogen helps regulate the menstrual cycle and supports the actions of progesterone.
- It also helps prevent ovulation and plays a role in maintaining the integrity of the uterine lining.
- Other components, such as LH (luteinizing hormone), GH (growth hormone), and thyroxine, do not have a direct role in oral contraceptives.
In conclusion, while oral contraceptives contain various components, the most important one is progesterone. Progesterone helps prevent pregnancy by thickening cervical mucus, inhibiting the release of FSH, and preventing ovulation. Estrogen and other components play supporting roles in regulating the menstrual cycle and maintaining the uterine lining.

Purpose of tubectomy is to prevent:
There are several options for contraception, and tubectomy is one of them. Tubectomy is a surgical procedure that involves blocking or sealing the fallopian tubes to prevent fertilization and pregnancy. Here are the key points explaining the purpose of tubectomy:
- Fertilization: The primary purpose of tubectomy is to prevent fertilization, which is the process of the sperm and egg joining together to form an embryo. By blocking or sealing the fallopian tubes, tubectomy prevents the sperm from reaching the egg, thus preventing fertilization.
- Coitus: Tubectomy does not prevent coitus, which refers to sexual intercourse. It only affects the fertilization process by blocking the passage of sperm to the egg.
- Egg formation: Tubectomy does not directly affect egg formation. It focuses on preventing the fertilization process by blocking the fallopian tubes.
- Embryonic development: Tubectomy does not directly impact embryonic development. It prevents the fertilization of the egg, so there is no embryo formed in the first place.
In conclusion, the purpose of tubectomy is to prevent fertilization by blocking or sealing the fallopian tubes. It does not affect coitus, egg formation, or embryonic development.

Answer:
The hormone progesterone is secreted by the corpus luteum.
Explanation:

• Corpus aorta: The corpus aorta is not involved in the secretion of progesterone. It is a term that does not exist in anatomy.


• Corpus albicans: The corpus albicans is a structure that forms from the degeneration of the corpus luteum. It does not secrete progesterone.


• Corpus luteum: The corpus luteum is a temporary endocrine structure that forms in the ovary after ovulation. It secretes progesterone, which is important for maintaining pregnancy and preparing the uterus for implantation.


• Corpus callosum: The corpus callosum is a large bundle of nerve fibers that connects the two hemispheres of the brain. It is not involved in the secretion of progesterone.

Therefore, the correct answer is option C: Corpus luteum.

The male and female urinogenital organs in rabbits
The male and female urinogenital organs in rabbits differ in their structures and functions. One of the following parts is present in males but not in females:
Vasa deferens
- The vasa deferens is a tubular structure that is part of the male reproductive system.
- It is responsible for carrying sperm from the testes to the urethra for ejaculation.
- This structure is absent in females.
The other options mentioned are present in both male and female rabbits:
Urethra
- The urethra is a tube that connects the urinary bladder to the external opening.
- In males, it also serves as a passage for semen during ejaculation.
- In females, it serves as a passage for urine.
Fallopian tube
- The fallopian tubes, also known as oviducts, are part of the female reproductive system.
- They are responsible for capturing the released eggs from the ovaries and providing a site for fertilization.
- The fertilized egg then travels through the fallopian tube to the uterus for implantation.
Vagina
- The vagina is a muscular canal that connects the cervix to the external opening.
- It is the site of sexual intercourse and also serves as the birth canal during childbirth.
- The vagina is present in both male and female rabbits.
In conclusion, the correct answer is option D: Vasa deferens. This structure is present in males but not in females.

Bidder's canal is present in male frogs.
Bidder's canal is a structure found in the reproductive system of male frogs. It is also known as the mesonephric duct or Wolffian duct. Here are some key points to understand Bidder's canal:
1. Definition: Bidder's canal is a tubular structure that runs parallel to the ureter in the male frog's reproductive system.
2. Origin: Bidder's canal develops from the mesonephric duct during the embryonic development of male frogs.
3. Function: Bidder's canal serves as a passageway for the transportation of sperm from the testes to the cloaca during mating.
4. Location: Bidder's canal is located in the mesonephros, which is a temporary kidney-like structure in the male frog's reproductive system.
5. Characteristics: Bidder's canal is lined with ciliated epithelial cells that help in the movement of sperm towards the cloaca.
6. Sexual Dimorphism: Bidder's canal is found exclusively in male frogs, indicating sexual dimorphism in their reproductive system.
In conclusion, Bidder's canal is present in male frogs and plays a crucial role in the transportation of sperm during mating.

Causes of Abortion in Ladies
There are several factors that can cause abortion in ladies. These include:
Bacteria:
- Certain bacterial infections can lead to abortion in ladies.
- Bacteria such as Chlamydia trachomatis, Mycoplasma hominis, and Ureaplasma urealyticum have been associated with abortion.
- These bacteria can cause infections in the reproductive system, leading to complications that may result in abortion.
Viruses:
- Certain viral infections can also cause abortion in ladies.
- Viruses such as Rubella (German measles), Cytomegalovirus (CMV), and Herpes simplex virus (HSV) have been linked to abortion.
- These viruses can cross the placenta and infect the developing fetus, leading to complications and possible abortion.
Mycoplasma:
- Mycoplasma infections can also be a cause of abortion in ladies.
- Mycoplasma genitalium and Mycoplasma pneumoniae have been associated with abortion.
- These bacteria can cause infections in the reproductive system, leading to complications that may result in abortion.
None of these:
- This option implies that none of the mentioned factors (viruses, bacteria, mycoplasma) are the cause of abortion in ladies.
- However, it is important to note that there are various other factors that can contribute to abortion, such as hormonal imbalances, genetic abnormalities, structural abnormalities of the uterus, and certain medications.
In conclusion, the correct answer is option B: Bacteria.

Accessory sexual character in female is promoted by estrogen.
Estrogen is a hormone that plays a crucial role in the development and maintenance of female reproductive system and secondary sexual characteristics. It is primarily produced by the ovaries, but small amounts are also produced by the adrenal glands and fat tissues. Estrogen is responsible for the following accessory sexual characteristics in females:
1. Development of breasts: Estrogen stimulates the growth of mammary glands, leading to the development of breasts during puberty.
2. Growth of pubic and axillary hair: Estrogen promotes the growth of hair in the pubic and axillary regions. It also influences the texture and pigmentation of this hair.
3. Widening of hips: Estrogen contributes to the widening of the pelvic bones, allowing for childbirth.
4. Softening of skin: Estrogen helps maintain the elasticity and moisture of the skin, giving it a soft and smooth appearance.
5. Distribution of subcutaneous fat: Estrogen influences the deposition of fat in specific areas of the body, such as the breasts, hips, and thighs.
6. Regulation of menstrual cycle: Estrogen plays a key role in the regulation of the menstrual cycle, including the development and shedding of the uterine lining.
Overall, estrogen is essential for the development and maintenance of female secondary sexual characteristics and reproductive function.

Sertoli cells in the testis:
Sertoli cells are specialized cells found in the seminiferous tubules of the testis. They play a crucial role in the development and maturation of spermatozoa. Here are some key points about Sertoli cells:
1. Nurse cells: Sertoli cells are often referred to as nurse cells because they provide physical and nutritional support to developing sperm cells.
2. Structural support: Sertoli cells form a structural framework within the seminiferous tubules, providing support to developing germ cells.
3. Blood-testis barrier: Sertoli cells create a barrier between the bloodstream and developing germ cells, known as the blood-testis barrier. This barrier helps protect developing germ cells from harmful substances and immune responses.
4. Hormone secretion: Sertoli cells secrete various hormones and growth factors that are essential for the development and maturation of germ cells. These hormones include follicle-stimulating hormone (FSH), androgen-binding protein (ABP), and inhibin.
5. Phagocytosis: Sertoli cells are involved in the removal of excess cytoplasm and residual bodies during sperm maturation through a process called phagocytosis.
6. Support of spermatozoa: Sertoli cells provide physical support to mature spermatozoa within the seminiferous tubules until they are released into the lumen.
In conclusion, Sertoli cells are nurse cells found in the testis that provide structural support, nutritional support, hormone secretion, and phagocytic activity for the development and maturation of spermatozoa.

Explanation of Cryptorchidism:
Cryptorchidism is a condition in which the testis does not descend into the scrotal sac. Here is a detailed explanation of the condition:
Definition:
- Cryptorchidism is a congenital condition where one or both testes fail to fully descend into the scrotal sac.
Causes:
- The exact cause of cryptorchidism is unknown, but it is thought to be a result of abnormal hormonal or anatomical development.
- It may be due to a hormonal imbalance or a mechanical obstruction preventing the testes from descending properly.
Prevalence:
- Cryptorchidism is a common condition, affecting about 3% of full-term male infants and up to 30% of premature infants.
- It is more common in premature infants and those with low birth weight.
Effects:
- Undescended testes are at a higher risk of developing complications such as infertility, testicular cancer, and torsion.
- The absence of the testes in the scrotum may also affect the production of male hormones, leading to hormonal imbalances.
Treatment:
- Treatment for cryptorchidism typically involves surgical correction to bring the testes into the scrotal sac.
- The surgery is usually performed before the age of 1 to minimize the risk of complications and improve fertility outcomes.
Conclusion:
Cryptorchidism is a condition in which the testis does not descend into the scrotal sac. It is a common condition that can have long-term effects on fertility and hormone production. Early diagnosis and treatment are important to minimize the risk of complications.

The cellular layer that disintegrates and regenerates again and again in humans is the endometrium of the uterus.
The endometrium is the inner lining of the uterus, and it undergoes cyclic changes every month as part of the menstrual cycle. During each menstrual cycle, the endometrium thickens in preparation for possible implantation of a fertilized egg. If fertilization does not occur, the endometrium disintegrates and is shed during menstruation. After menstruation, the endometrium regenerates and begins to thicken again for the next cycle.
Key points:
- The endometrium of the uterus is the cellular layer that disintegrates and regenerates in humans.
- It undergoes cyclic changes as part of the menstrual cycle.
- The endometrium thickens in preparation for possible implantation of a fertilized egg.
- If fertilization does not occur, the endometrium disintegrates and is shed during menstruation.
- After menstruation, the endometrium regenerates and begins to thicken again for the next cycle.
This continuous process of disintegration and regeneration allows the endometrium to support the potential implantation of a fertilized egg and ensures the proper functioning of the reproductive system in females.

The functional maturation of sperms takes place in: Epididymis
The functional maturation of sperms refers to the process by which the sperm cells acquire the ability to fertilize an egg. This process occurs in the epididymis, which is a long, coiled tube located on the posterior surface of the testis. Here is a detailed explanation of why the epididymis is the site of sperm maturation:
Function of the Epididymis:
- The epididymis serves as a storage and maturation site for sperm cells.
- It provides a microenvironment that is conducive to the development and maturation of sperm.
Process of Sperm Maturation in the Epididymis:
1. Sperm Production in the Testes: Sperm cells are produced in the seminiferous tubules of the testes.
2. Immature Sperm in the Testes: The sperm cells produced in the testes are immature and lack the ability to swim or fertilize an egg.
3. Transport to the Epididymis: The immature sperm cells are transported from the testes to the epididymis through a series of ducts.
4. Maturation in the Epididymis: Once in the epididymis, the sperm cells undergo a process called capacitation, which involves changes in their membrane proteins and ion channels. This process enables the sperm cells to become motile and acquire the ability to fertilize an egg.
5. Storage in the Epididymis: The mature sperm cells are stored in the epididymis until they are ejaculated during sexual intercourse.
Importance of Sperm Maturation in the Epididymis:
- Sperm maturation in the epididymis is essential for the functional development of sperm cells.
- The maturation process allows sperm cells to acquire the ability to swim and navigate through the female reproductive tract.
- It also enables sperm cells to undergo the necessary biochemical and physiological changes required for fertilization.
In conclusion, the functional maturation of sperms takes place in the epididymis. This structure provides a microenvironment that supports the development and maturation of sperm cells, allowing them to acquire the ability to fertilize an egg.

Tubectomy

• Tubectomy is the surgical removal or cutting and ligation of the ends of the oviduct, also known as fallopian tubes.


• This procedure is performed in females as a form of permanent contraception to prevent pregnancy.


• The fallopian tubes are responsible for carrying the egg from the ovaries to the uterus. By blocking or removing them, fertilization of the egg by sperm is prevented.


• Tubectomy is considered a safe and effective method of contraception.


• It is usually performed under general anesthesia, and small incisions are made in the abdomen or through laparoscopy.


• The fallopian tubes are then cut, sealed, or blocked to prevent the passage of eggs.


• Tubectomy is a permanent form of contraception and is not easily reversible, so it is typically chosen by individuals who do not wish to have any more children.


• It does not affect a woman's hormonal balance or menstrual cycle.

Therefore, the surgical removal or cutting and ligation of the ends of the oviduct is known as tubectomy.

The follicle that ruptures at the time of ovulation promptly fills with blood, forming:

A: Corpus haemorrhagicum

B: Corpus luteum

C: Corpus albicans

D: Corpus callosum

Answer: a. Corpus haemorrhagicum
Detailed
When the follicle ruptures at the time of ovulation, it promptly fills with blood, forming a corpus haemorrhagicum. Here is a detailed explanation of the options:
A: Corpus haemorrhagicum:
- This is the correct answer. After ovulation, when the follicle ruptures, it fills with blood, forming a corpus haemorrhagicum. This structure is temporary and is an early stage in the formation of the corpus luteum.
- The corpus haemorrhagicum is responsible for the release of hormones such as progesterone, which is essential for the preparation of the uterus for possible implantation of a fertilized egg.
B: Corpus luteum:
- The corpus luteum is formed from the corpus haemorrhagicum. After the follicle ruptures and fills with blood, it undergoes changes and transforms into a corpus luteum.
- The corpus luteum produces hormones, primarily progesterone, which is important for the maintenance of a potential pregnancy.
C: Corpus albicans:
- The corpus albicans is the final stage of the corpus luteum. If fertilization does not occur, the corpus luteum degenerates and forms a scar tissue called the corpus albicans.
- The corpus albicans is a non-functional structure and eventually gets reabsorbed by the body.
D: Corpus callosum:
- The corpus callosum is a part of the brain that connects the left and right cerebral hemispheres. It is not related to the process of ovulation or the formation of the corpus haemorrhagicum.
In conclusion, the correct answer is A: Corpus haemorrhagicum, as it accurately describes the formation of the structure that fills with blood after follicle rupture during ovulation.

Estrogens Secretion in Mammals
The estrogens are secreted by the Graafian follicle, which is a mature ovarian follicle, during the menstrual cycle. The Graafian follicle is responsible for the production and release of the egg (ovum) during ovulation. The specific location of estrogen secretion within the Graafian follicle is as follows:
Internal Theca
- The internal theca cells are located within the Graafian follicle.
- These cells are responsible for producing and secreting androgens, which are precursors of estrogen.
- The androgens produced by the internal theca cells are converted into estrogen by the adjacent granulosa cells.
Zona Pellucida
- The zona pellucida is a glycoprotein layer surrounding the oocyte (immature egg) within the Graafian follicle.
- It acts as a protective barrier and is involved in sperm-egg interaction during fertilization.
- The zona pellucida does not secrete estrogens.
Corona Radiata
- The corona radiata is a layer of granulosa cells that surrounds the oocyte within the Graafian follicle.
- It plays a role in nourishing and protecting the oocyte.
- The corona radiata does not secrete estrogens.
External Theca
- The external theca cells are located outside the Graafian follicle.
- They are involved in the production and secretion of androgens, which are precursors of estrogen.
- The androgens produced by the external theca cells are converted into estrogen by the adjacent granulosa cells.
Therefore, the correct answer is Option B: Internal Theca.

Orchidectomy is the surgical removal of:
- Testes: Orchidectomy refers to the surgical removal of the testes, also known as castration. This procedure is commonly performed for medical reasons such as in the treatment of testicular cancer or gender reassignment surgery.
- Liver: Orchidectomy does not involve the surgical removal of the liver. The liver is a vital organ responsible for various metabolic functions in the body.
- Kidney: Orchidectomy does not involve the surgical removal of the kidney. The kidneys are responsible for filtering waste products from the blood and producing urine.
- Ovary: Orchidectomy does not involve the surgical removal of the ovary. Ovary removal is known as oophorectomy and is performed for various medical reasons such as in the treatment of ovarian cancer or as a part of gender reassignment surgery.
Therefore, the correct answer is D: Testes.