RowQ
The Vault
RowQ
The Vault
CBSE Class 12 Biology · 11 questions · 26 marks
Reproductive health means far more than the absence of disease — it covers physical, emotional, and social well-being in all matters relating to reproduction. This chapter looks at India's reproductive and child health programmes, the range of contraceptive methods and how each one works, the medical and legal position on abortion, sexually transmitted infections, and the assisted reproductive technologies offered to infertile couples. Answering well here depends on knowing the exact mechanism behind each method rather than just its name.
Which contraceptive method, apart from preventing pregnancy, also gives protection against sexually transmitted infections?
Answer
Condom is correct — it is a barrier that covers the genitalia during intercourse, so it prevents both sperm from reaching the ovum and the exchange of body fluids that transmits infections such as HIV, gonorrhoea, and syphilis. A Copper-T acts inside the uterus, pills act hormonally, and tubectomy blocks the fallopian tubes, so none of these offers any barrier against infection.
Copper-releasing intrauterine devices such as CuT prevent pregnancy mainly because the released Cu²⁺ ions:
Answer
Suppress sperm motility and fertilising capacity is correct — copper ions released steadily into the uterine cavity make the environment hostile to sperm so that fertilisation is unlikely, while the device itself also increases phagocytosis of sperm and makes the endometrium less suitable for implantation. Copper IUDs do not act on the hypothalamus, do not block the tubes, and do not target the corpus luteum.
In which assisted reproductive technique is a single sperm injected directly into the cytoplasm of an ovum in the laboratory?
Answer
ICSI, intracytoplasmic sperm injection, is correct — it is used when sperm count or motility is so poor that sperm cannot fertilise the ovum on their own, so a single sperm is injected directly into the ovum to form a zygote. GIFT transfers an ovum into the fallopian tube of another female, ZIFT transfers an early embryo into the fallopian tube, and IUI is the introduction of semen into the uterus.
Which of the following statements about a vasectomy is correct?
Answer
A small part of the vas deferens is cut or tied, so sperm cannot reach the urethra is correct — vasectomy is a male sterilisation procedure in which the duct carrying sperm from the epididymis is interrupted through a small incision in the scrotum. The testes remain intact and continue to secrete testosterone, so secondary sexual characters and sexual function are unaffected; the option describing blocked fallopian tubes refers to tubectomy in females.
Assertion (A): Sterilisation techniques such as vasectomy and tubectomy are regarded as terminal methods of contraception. Reason (R): These procedures block the transport of gametes, and reversal is difficult and often unsuccessful.
Answer
Both A and R are true and R is the correct explanation of A — vasectomy interrupts the vas deferens and tubectomy interrupts the fallopian tubes, so gametes can no longer be transported. Because surgical restoration of these ducts frequently fails to restore fertility, the methods are counselled as permanent and are therefore classed as terminal methods, recommended only for couples who are certain they want no further children.
What is lactational amenorrhoea, and why is it not a reliable method of contraception beyond about six months after childbirth?
Answer
Lactational amenorrhoea is the absence of the menstrual cycle during the period of intense, exclusive breast-feeding after childbirth. High prolactin levels associated with frequent suckling suppress the hormonal signals needed for follicle maturation and ovulation, so pregnancy is unlikely while it lasts. It is unreliable beyond roughly six months because as breast-feeding becomes less frequent or supplementary feeds are introduced, ovulation can resume without warning. Since ovulation returns before the first period after childbirth, a woman may become pregnant before she has any sign that her cycles have restarted.
Name any three sexually transmitted infections along with their causative organisms, and state two general consequences of leaving such infections untreated.
Answer
Three examples are: gonorrhoea, caused by the bacterium Neisseria gonorrhoeae; syphilis, caused by the bacterium Treponema pallidum; and AIDS, caused by the human immunodeficiency virus (HIV). Chlamydiasis, caused by Chlamydia trachomatis, is another common example. If left untreated, such infections can spread to the upper reproductive tract and cause pelvic inflammatory disease, ectopic pregnancy, stillbirth, or scarring of the tubes leading to infertility or complete sterility. Certain infections such as HIV and hepatitis B can also be transmitted from an infected mother to her foetus or newborn, and untreated systemic infections may go on to damage other organs.
Medical termination of pregnancy is legal in India, yet it is described as being misused. Explain this statement.
Answer
MTP was legalised in 1971 with strict conditions so that unwanted pregnancies — for example those arising from failure of contraception, from rape, or those that endanger the health of the mother or the foetus — could be terminated safely by qualified doctors instead of through unsafe illegal procedures. The misuse arises when the procedure is used to terminate a normal, healthy pregnancy after illegal determination of the sex of the foetus, resulting in female foeticide. This distorts the sex ratio of the population, and it is the reason sex determination of a foetus is prohibited by law in India.
Classify the contraceptive methods available to a couple and explain the mode of action of one method from each of the following groups: natural, barrier, intrauterine, hormonal, and surgical.
Answer
Contraceptive methods fall into five broad groups: natural or traditional methods, barrier methods, intrauterine devices, hormonal methods (oral pills and injectables or implants), and surgical sterilisation. Natural — periodic abstinence: the couple avoids intercourse from about day 10 to day 17 of the cycle, the period during which ovulation and therefore fertilisation are most likely. No device or chemical is used, but the method fails often because cycle length varies. Barrier — the condom: a thin sheath of rubber or latex covers the penis (or lines the vagina) so that semen is not deposited in the reproductive tract. The sperm and ovum are physically prevented from meeting, and the barrier additionally reduces transmission of sexually transmitted infections. Intrauterine — the copper-releasing IUD such as CuT: inserted into the uterus by a doctor, it releases Cu²⁺ ions that reduce sperm motility and fertilising capacity, while the device also raises phagocytosis of sperm within the uterus and makes the endometrium unsuitable for implantation. Hormonal — the oral pill: taken daily, the progestogen or progestogen-oestrogen combination suppresses the gonadotropin signals needed for ovulation, thickens cervical mucus so sperm cannot pass, and alters the endometrium so implantation is unlikely. Surgical — tubectomy: a small part of each fallopian tube is removed or tied through a small abdominal or vaginal incision, so the ovum can never reach the sperm. It is highly effective but should be regarded as permanent.
A couple has been unable to conceive for four years. Explain what infertility is, list the possible causes, and describe four assisted reproductive technologies that could be offered to them.
Answer
Infertility is the inability of a couple to achieve conception despite two or more years of unprotected cohabitation. The cause may lie with either partner, and medical evaluation of both is essential — socially it is often unfairly blamed on the woman alone. Causes include physical or anatomical problems such as blocked fallopian tubes or an obstructed vas deferens, congenital defects, hormonal or endocrine disorders that prevent ovulation or sperm production, immunological factors, infections including untreated sexually transmitted infections, and psychological factors. Four assisted reproductive technologies are as follows. In vitro fertilisation with embryo transfer: ova from the wife or a donor are fertilised by sperm in the laboratory under conditions mimicking the body. If an early embryo of up to 8 blastomeres is transferred into the fallopian tube, the procedure is called ZIFT; if an embryo at a later stage is transferred directly into the uterus, it is called IUT. GIFT, gamete intrafallopian transfer: an ovum collected from a donor is transferred into the fallopian tube of a woman who cannot produce her own ovum but can otherwise provide a suitable environment for fertilisation and development. ICSI, intracytoplasmic sperm injection: a single sperm is injected directly into the cytoplasm of an ovum in the laboratory to form a zygote. It is the option of choice when the male partner's sperm count or motility is very low. Artificial insemination (IUI): semen from the husband or a healthy donor is introduced into the vagina or directly into the uterus. It is used where the male has very low sperm count or where inability to inseminate is the problem. Adoption should also be counselled as a valuable option for couples who wish to raise a child.
A rural health worker in a district holds a counselling session. A newly married couple say they wish to delay their first child by about three years; a second couple already have two children and want no more; and a third couple, married for five years, report that they have been unable to conceive despite investigations showing that the wife ovulates normally while the husband has a very low sperm count. (a) Suggest one suitable reversible method for the first couple and state how it works. (b) Suggest a suitable method for the second couple and name the equivalent procedure in the other partner. (c) Name the assisted reproductive technique best suited to the third couple and justify your choice. (d) State one reason why counselling should stress that infertility is not always the woman's problem.
Answer
(a) An oral contraceptive pill or a copper-releasing IUD such as CuT would suit them, since both are reversible and can be discontinued when they wish to conceive. The pill's progestogen-oestrogen combination suppresses ovulation, thickens cervical mucus, and alters the endometrium; a CuT releases Cu²⁺ ions that suppress sperm motility and fertilising capacity. (b) Since they want no further children, sterilisation is appropriate. If the wife undergoes tubectomy, a small portion of each fallopian tube is removed or tied so the ovum cannot meet sperm; the equivalent procedure in the husband is vasectomy, in which a small portion of the vas deferens is removed or tied. (c) ICSI, intracytoplasmic sperm injection, is best suited. Because the wife ovulates normally, an ovum can be retrieved, and because the limiting factor is the husband's very low sperm count, injecting a single viable sperm directly into the ovum bypasses the need for large numbers of motile sperm to achieve fertilisation. (d) Investigation frequently shows the cause to lie with the male partner, as in the third couple here, or with both partners. Blaming the woman alone is scientifically wrong and causes her needless social distress, and it also delays the correct diagnosis and treatment of the actual cause.
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