NCERT Class 12 Biology: Chapter – 4 Reproductive Health Part 6 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Question 2:

Discuss the mode of action and advantages/disadvantages of hormonal contraceptives.


Hormonal contraceptives are trusted devices to prevent conception.

The mode of action and advantages of hormonal contraceptives are as follows:

i. Oral administration of small doses of either progestogens or progestogen-estrogen combinations, mostly target to females, is known as pills. Pills inhibit ovulation and implantation as well as alter the quality of cervical mucus to prevent/retard entry of sperms. Pills are very effective, have lesser side effects and are well accepted by women.

Pills have to be taken daily for a period of 21 days preferably within the first 5 days of menstrual cycle. After a gap of 7 days (during which menstruation occurs) it has to be repeated in the same pattern.

ii. Progestogens alone or in combination with estrogen can also be used as injections or implants under the skin. Their effective periods are much longer.

iii. Administration of progestogens or progestogen-estrogen combinations or IUDs within 72 hours of coitus has been found to be very effective as an emergency contraceptive.

iv. Hormone-based contraceptive are completely reversible allowing pregnancy to occur on discontinued usage.

Disadvantages of hormonal contraceptives:

i. They can have many serious side effects.

ii. They can cause allergic reaction.

iii. They can sometimes damage the normal hormonal balance and later even if desired, pregnancy may not be achieved.

iv. They disturb the menstrual cycle so that level of menstrual flow can be either too low or high and lead to irregular menstruation cycles.

v. Hormonal balance is disturbed that may lead to nausea, abdominal pain, breakthrough bleeding, irregular menstrual bleeding or even breast cancer.

Question 3:

STDs are a threat to reproductive health. Describe any two such diseases and suggest preventive measures.


STDs are diseases or infections which are transmitted through sexual intercourse, they are also known as venereal diseases (VD) or reproductive tract infections (RTI) .

Gonorrhoea, syphilis, genital herpes, chlamydia, genital warts, trichomoniasis, hepatitis-B and AIDS are some of the common STDs.

i. Syphilis can infect sex organs and sometimes lips and mouth as well. They can spread from one person to another. It is caused by the spirochete Treponema palladium. At final stage the infected person chronic ulcers on many body parts and damage to internal parts.

ii. Gonorrhea most often affects the urethra, rectum or throat. In females, gonorrhea can also infect the cervix. It can also cause arthritis and/or eye infections. It is caused by a diplococcus bacterium Neisseria gonorrhoeae.

iii. Genital warts are contagious, fleshy growths in the genital or anal area. They are one of the most common types of STDs.

iv. AIDS (Acquired Immuno Deficiency Syndrome) is a set of symptoms caused by HIV (Human Immunodeficiency virus or Human T-cell leukaemia virus) virus in humans. The HIV virus does not directly affect sex organs as such but produce other set of symptoms in the body of infected person like it affects lymphocytes or macrophages, etc. AIDS is usually developed from infection after few months or can even take years. Diagnostic test for AIDS is ELISA (Enzyme Linked Immuno Sorbent Assay) . Western blot can be used as confirmatory test. The virus of AIDS is transferred via blood and semen.

v. Hepatitis-B is caused by Hepatitis-B virus. It is transmitted by blood transfusions or contaminated needles or body fluids (like semen, saliva, sweat, breast milk, etc) . As it can be transmitted by breast milk the baby lactating infected mother also gets infected. The infected mother can also transfer the disease to foetus via her placenta. It is incurable STD.

The preventive measures to avoid STDs are as follows:

i. Individuals should avoid sex with unknown partners/multiple partners՚ especially HIV-infected people.

ii. Individuals should use condoms during coitus if there are chances of STDs.

iii. And if in doubt individuals should go to a qualified doctor for early detection and thereby getting complete treatment if diagnosed.

iv. Individuals should not share injection, needles, razors, toothbrushes; etc with infected persons especially AIDS patients, which could also lead to STDs.

v. Diagnose blood before blood donation or blood transfusions.

vi. Infected mother should not be lactating infants.

vi. Infected pregnant mother should terminate her pregnancy.

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