Human Reproduction And Reproductive Health Class 12 Biology Chse

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questions with their answers, specifically tailored for Class 12 CHSE Biology students on the chapter "Human Reproduction and Reproductive Health".

Chapter: Human Reproduction and Reproductive Health

Multiple Choice Questions (MCQ)

1. Which of the following is the site of spermatogenesis? a) Epididymis b) Vas deferens c) Seminiferous tubules d) Rete testis Answer: c) Seminiferous tubules

2. The primary female sex organ is the: a) Uterus b) Ovary c) Fallopian tube d) Vagina Answer: b) Ovary

3. The release of a mature ovum from the ovary is called: a) Fertilization b) Implantation c) Ovulation d) Menstruation Answer: c) Ovulation

4. The menstrual phase of the menstrual cycle is caused by: a) High levels of estrogen and progesterone b) Low levels of LH and FSH c) Low levels of estrogen and progesterone d) High levels of LH and FSH Answer: c) Low levels of estrogen and progesterone

5. Fertilization in humans typically occurs in the: a) Uterus b) Ovary c) Vagina d) Fallopian tube (ampulla) Answer: d) Fallopian tube (ampulla)

6. The structure that provides nutrients to the developing embryo during pregnancy is the: a) Amniotic fluid b) Umbilical cord c) Placenta d) Yolk sac Answer: c) Placenta

7. Implantation is the embedding of the blastocyst in the: a) Ovary b) Fallopian tube c) Endometrium of the uterus d) Cervix Answer: c) Endometrium of the uterus

8. The hormone responsible for the vigorous contractions of the uterus during parturition is: a) Progesterone b) Estrogen c) Oxytocin d) Relaxin Answer: c) Oxytocin

9. Which of the following is a barrier method of birth control? a) Oral contraceptive pills b) Intra-uterine devices (IUDs) c) Diaphragm d) Vasectomy Answer: c) Diaphragm

10. Surgical method of contraception in males is called: a) Tubectomy b) Vasectomy c) Hysterectomy d) Ovariectomy Answer: b) Vasectomy

11. Which STD is caused by a bacterium? a) HIV/AIDS b) Genital Herpes c) Gonorrhea d) Warts Answer: c) Gonorrhea

12. Amniocentesis is a technique used for: a) Sex determination only b) Fetal sex determination and chromosomal abnormalities c) Treating infertility d) Birth control Answer: b) Fetal sex determination and chromosomal abnormalities

13. In IVF (In Vitro Fertilization), the zygote or early embryo is transferred into the: a) Uterus b) Fallopian tube c) Ovary d) Vagina Answer: a) Uterus

14. The first milk produced by the mother after childbirth, rich in antibodies, is called: a) Serum b) Lymph c) Colostrum d) Plasma Answer: c) Colostrum

15. GIFT (Gamete Intra Fallopian Transfer) involves the transfer of: a) Zygote into the fallopian tube b) Embryo into the fallopian tube c) Ovum and sperm into the fallopian tube d) Ovum and sperm into the uterus Answer: c) Ovum and sperm into the fallopian tube

Short Answer Questions (2-3 marks)

1. Name the accessory ducts of the male reproductive system. Answer: Rete testis, Vasa efferentia, Epididymis, Vas deferens, Ejaculatory duct, Urethra.

2. What are the functions of Leydig cells and Sertoli cells in the testis? Answer: * Leydig cells (Interstitial cells): Synthesize and secrete androgens (male hormones like testosterone). * Sertoli cells (Nurse cells): Provide nourishment to the developing spermatozoa and secrete some factors helpful in spermatogenesis.

3. Briefly explain the process of oogenesis. Answer: Oogenesis is the process of formation of a mature female gamete (ovum). It begins in the fetal ovary with oogonia (germ cells) undergoing mitosis to form primary oocytes. These enter meiosis I but arrest at prophase I. At puberty, under hormonal influence, a primary oocyte completes meiosis I, forming a large secondary oocyte and a tiny first polar body. The secondary oocyte arrests at metaphase II. Upon sperm entry, it completes meiosis II, forming a large ovum and a second polar body.

4. Define menstrual cycle. Mention its average duration. Answer: The menstrual cycle is the cyclic series of changes that occur in the female reproductive system (especially the uterus and ovary) of primates, preparing the uterus for possible pregnancy. If pregnancy does not occur, the uterine lining sheds. Its average duration is 28 days.

5. Name the hormones involved in the regulation of the menstrual cycle. Answer: Gonadotropin-releasing hormone (GnRH), Follicle-stimulating hormone (FSH), Luteinizing hormone (LH), Estrogen, and Progesterone.

6. What is capacitation in relation to sperm? Answer: Capacitation is the physiological maturation process that sperm undergo in the female reproductive tract, which enables them to fertilize an egg. It involves changes in the sperm membrane that allow for the acrosome reaction and hyperactivated motility.

7. Describe the process of implantation. Answer: Implantation is the process by which the blastocyst (early embryo) attaches and embeds itself into the endometrium (inner lining) of the uterus, typically around 6-7 days after fertilization. This marks the beginning of pregnancy.

8. What is the significance of the placenta? Answer: The placenta is a temporary organ that forms during pregnancy and connects the mother and fetus. Its significance lies in facilitating the supply of oxygen and nutrients to the embryo/fetus, removing carbon dioxide and excretory wastes from the fetus, acting as an endocrine gland (producing hormones like hCG, progesterone, estrogen), and providing immunity to the fetus.

9. Define parturition. Which hormone is primarily responsible for it? Answer: Parturition is the process of childbirth, involving the expulsion of the fully developed fetus from the uterus at the end of pregnancy. The hormone primarily responsible for initiating and strengthening uterine contractions during parturition is Oxytocin.

10. What is colostrum? Why is it important for a newborn baby? Answer: Colostrum is the yellowish fluid secreted by the mammary glands during the initial few days of lactation, soon after childbirth. It is important because it is rich in antibodies (especially IgA), which provide passive immunity to the newborn, protecting them from various infections. It also contains essential nutrients.

11. List any two sexually transmitted diseases (STDs) and their causative agents. Answer: * Syphilis: Treponema pallidum (bacterium) * Gonorrhea: Neisseria gonorrhoeae (bacterium) * HIV/AIDS: Human Immunodeficiency Virus (HIV) * Genital Herpes: Herpes Simplex Virus (HSV) Type 2

12. Why is reproductive health important? Answer: Reproductive health is important to ensure a state of complete physical, mental, and social well-being in all matters relating to the reproductive system, at all stages of life. It includes safe and responsible sexual behavior, prevention of STDs, access to family planning, and maternal and child health care, contributing to a healthy society.

13. What is Medical Termination of Pregnancy (MTP)? When is it usually advised? Answer: Medical Termination of Pregnancy (MTP), also known as induced abortion, is the intentional or voluntary termination of pregnancy before the full term. It is usually advised in cases where continuation of pregnancy could be harmful to the mother's life, or to the fetus (e.g., severe abnormalities), or in cases of rape or contraceptive failure.

14. Explain the purpose of amniocentesis. What is its legal status in India for sex determination? Answer: The purpose of amniocentesis is to analyze the fetal cells present in the amniotic fluid to detect chromosomal abnormalities (e.g., Down's syndrome), genetic disorders, and some metabolic disorders in the fetus. In India, amniocentesis for sex determination is legally banned under the Pre-Conception and Pre-Natal Diagnostic Techniques (PCPNDT) Act, 1994, to prevent female feticide.

15. What is infertility? Name two Assisted Reproductive Technologies (ARTs) used to treat it. Answer: Infertility is the inability to conceive or produce offspring despite unprotected sexual cohabitation. Two Assisted Reproductive Technologies (ARTs) are: * In Vitro Fertilization (IVF) * Zygote Intra Fallopian Transfer (ZIFT) * Gamete Intra Fallopian Transfer (GIFT) * Intra Cytoplasmic Sperm Injection (ICSI)

Long Answer Questions (5-6 marks)

1. Describe the microscopic anatomy of a human testis and ovary. Explain the process of spermatogenesis and oogenesis, highlighting the key differences between them.

Answer:

Microscopic Anatomy of Testis: The human testis is covered by a dense fibrous capsule called the tunica albuginea. Each testis contains about 250 compartments called testicular lobules. Each lobule contains 1-3 highly coiled seminiferous tubules, which are the sites of sperm production (spermatogenesis). The seminiferous tubules are lined by two types of cells:

Spermatogonia:

Male germ cells that undergo meiosis to form spermatozoa.

Sertoli cells (Nurse cells):

Large, pyramid-shaped cells that provide nourishment to the developing sperm, remove waste, and secrete factors essential for spermatogenesis. Between the seminiferous tubules, in the interstitial spaces, are

interstitial cells (Leydig cells)

, which synthesize and secrete androgens (male hormones like testosterone).

Microscopic Anatomy of Ovary: The ovary is the primary female sex organ. Its outer region, the cortex, contains the ovarian follicles at various stages of development. The inner region is the medulla, which contains connective tissue, blood vessels, lymphatic vessels, and nerves. Each ovarian follicle consists of an ovum surrounded by follicular cells. These follicles grow from primordial follicles to primary, secondary, tertiary, and mature Graafian follicles. The Graafian follicle contains the secondary oocyte surrounded by zona pellucida and corona radiata. After ovulation, the ruptured follicle transforms into the Corpus Luteum.

Spermatogenesis vs. Oogenesis:

Feature	Spermatogenesis	Oogenesis
Site	Seminiferous tubules of testes	Ovaries
Onset	Puberty	Fetal stage (initiated), completes at puberty
Continuity	Continuous from puberty throughout life	Discontinuous, pauses at two stages
Gametes Produced	Four haploid, motile spermatozoa from one primary spermatocyte	One haploid, large ovum and 2-3 polar bodies from one primary oocyte
Polar Bodies	Not formed	Formed (2 or 3)
Size of Gamete	Small, motile	Large, non-motile
Cytokinesis	Equal	Unequal
Number of Cells	Millions produced daily	Limited number of oocytes (approx. 60,000-80,000 at puberty)

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Process of Spermatogenesis: It starts at puberty. Spermatogonia (diploid) in the seminiferous tubules undergo mitotic divisions to increase their number. Some spermatogonia develop into primary spermatocytes (diploid). These primary spermatocytes undergo Meiosis I to form two haploid secondary spermatocytes. Each secondary spermatocyte then undergoes Meiosis II to form two haploid spermatids. Finally, spermatids undergo spermiogenesis (differentiation) to transform into mature, motile spermatozoa.

Process of Oogenesis: It begins during fetal development. Oogonia (diploid) within the fetal ovary undergo mitosis to form millions of primary oocytes (diploid). These primary oocytes enter Meiosis I but arrest at prophase I. At puberty, under hormonal influence, a few primary oocytes mature. One primary oocyte completes Meiosis I, resulting in a large haploid secondary oocyte and a tiny haploid first polar body (unequal cytokinesis). The secondary oocyte proceeds to Meiosis II but arrests at metaphase II. Ovulation occurs with the release of this secondary oocyte. Meiosis II is completed only upon sperm entry, forming a large haploid ovum and a tiny haploid second polar body. The polar bodies eventually degenerate.

2. Discuss the various birth control methods available to humans, explaining their mechanisms and providing examples. Also, briefly explain the need for reproductive health and the common approaches to preventing sexually transmitted diseases (STDs).

Answer:

Birth Control Methods: Birth control methods, also known as contraception, are techniques used to prevent unwanted pregnancies. They vary in their effectiveness, mechanism, and reversibility.

Natural Methods:

Periodic Abstinence (Rhythm method): Avoiding coitus during the fertile period of the menstrual cycle (around days 10-17).

Withdrawal (Coitus interruptus): Male withdraws penis from the vagina just before ejaculation.

Lactational Amenorrhea: Absence of menstruation during intense lactation (post-delivery), which can naturally prevent conception for up to 6 months.

Barrier Methods:

Prevent the meeting of sperm and ovum.

Condoms (Male and Female): Thin rubber sheaths used to cover the penis or line the vagina/cervix. They also protect against STDs.

Diaphragms, Cervical Caps, and Vaults: Reusable rubber barriers inserted into the female reproductive tract to cover the cervix, used with spermicides.

Intra-Uterine Devices (IUDs):

Devices inserted by a doctor into the uterus.

Non-medicated IUDs: (e.g., Lippes Loop) increase phagocytosis of sperm.

Copper-releasing IUDs: (e.g., CuT, Cu7, Multiload 375) release copper ions that suppress sperm motility and fertilizing capacity.

Hormone-releasing IUDs: (e.g., Progestasert, LNG-20) make the uterus unsuitable for implantation and the cervix hostile to sperm.

Oral Contraceptives (Pills):

Combined Pills: Contain small doses of estrogen and progesterone. They inhibit ovulation and alter cervical mucus to prevent sperm entry.

Progesterone-only Pills (Mini-pills): Primarily alter cervical mucus and uterine lining.

Emergency Contraceptives: High doses of progestogens or a combination, taken within 72 hours of unprotected coitus.

Injectables and Implants:

Hormonal preparations (progestogen or combination) administered as injections or small implants under the skin. They are effective for longer periods.

Surgical Methods (Sterilization):

Permanent methods for both males and females.

Vasectomy (Male): Small incision made on the scrotum, and a small part of the vas deferens is cut or tied to prevent sperm from reaching the semen.

Tubectomy (Female): Small incision made in the abdomen or through the vagina, and a small part of the fallopian tube is cut or tied to prevent the ovum from reaching the uterus.

Need for Reproductive Health: Reproductive health is crucial for individual well-being and societal progress. Its importance stems from:

Preventing unwanted pregnancies: Leads to population control and reduces illegal abortions.

Reducing maternal and infant mortality: Through proper prenatal and postnatal care.

Preventing and managing STDs: Protects individuals from severe health consequences, including infertility and cancer.

Promoting safe and responsible sexual behavior: Helps individuals make informed choices about their sexual health.

Addressing infertility issues: Provides options for couples struggling to conceive.

Empowering individuals with reproductive choices: Allows people to decide if, when, and how many children to have.

Prevention of Sexually Transmitted Diseases (STDs): STDs (also known as STIs or VD) are infections transmitted primarily through sexual contact. Common approaches for prevention include:

Abstinence: The most effective way to prevent STDs is to avoid sexual contact.

Monogamous relationships: Being in a mutually faithful relationship with an uninfected partner.

Using barrier contraceptives: Consistent and correct use of condoms (male and female) can significantly reduce the risk of transmission.

Avoiding multiple partners: Reduces exposure to various infections.

Avoiding sharing needles: Especially for intravenous drug users, as some STDs (like HIV, Hepatitis B) can spread through contaminated blood.

Early detection and treatment: Prompt diagnosis and complete treatment of STDs in infected individuals and their partners can prevent further spread and complications.

Education and Awareness: Spreading awareness about STDs, their modes of transmission, symptoms, and prevention methods is crucial.

Vaccination: Vaccines are available for some STDs, such as HPV (Human Papillomavirus) and Hepatitis B.

Combined Pills: Contain small doses of estrogen and progesterone. They inhibit ovulation and alter cervical mucus to prevent sperm entry.

Progesterone-only Pills (Mini-pills): Primarily alter cervical mucus and uterine lining.

Emergency Contraceptives: High doses of progestogens or a combination, taken within 72 hours of unprotected coitus.

Injectables and Implants: Hormonal preparations (progestogen or combination) administered as injections or small implants under the skin. They are effective for longer periods.