CBSE Class 12 Biology Revision Notes Chapter 4

Class 12 Biology Chapter 4 Notes

Class 12 Biology Chapter 4 explains Reproductive Health. Through this chapter, the students would be able to learn about the problems and strategies related to reproductive health, population explosion and birth control, medical termination of pregnancy, sexually transmitted diseases and infertility. 

Class 12 Biology Chapter 4 Notes cover all the topics and give students a detailed explanation prepared by the subject experts  at Extramarks by following the latest CBSE stated rules and regulations. Chapter 4 Biology Class 12 Notes provide students with an easy way to study, revise, and reduce the burden of exams on the students. The Extramarks academic team has created these Notes by referring to the NCERT textbook and other related sources.

Students may register on Extramarks to access the Class 12 Biology Chapter 4 Notes and CBSE Class 12 Syllabus. Along with the Syllabus, students may also refer to CBSE Revision Notes,  CBSE Sample Papers, CBSE Important Questions, CBSE Extra Questions, and CBSE past years’  question papers.

Key Topics Covered In Class 12 Biology Chapter 4 Notes

Following are the topics included in Class 12 Biology Chapter 4 Notes:

• Reproductive Health, Problems  And Strategies.
• Population Stabilisation and Birth control.
• Medical Termination of Pregnancy(MTP).
• Sexually Transmitted Infections(STIs).
• Infertility.

For every concept included in Class 12 Biology Chapter 4 Notes, explanatory  notes prepared by the subject expert at Extramarks are provided below: 

Reproductive Health:

As covered in the Class 12 Biology Chapter 4 Notes, the term reproductive health refers to healthy reproductive organs with regular functions. However, it also includes the social and emotional aspects of reproduction as well. According to the World Health Organisation (WHO), total well-being in all aspects of reproduction, i.e., emotional, physical, social and behavioural, refers to reproductive health.

How to maintain reproductive health:

A society with people having functionally and physically normal reproductive organs and regular behaviour can be said to have good reproductive health.

 Emotional interactions with them in all sex-related aspects can maintain the reproductive health. of society.

Problems and Strategies in Attaining Total Reproductive Health:

• To accomplish total reproductive health as a social goal, India was amongst the first countries globally who initiated action plans and programmes at a national level. 
• Programmenamed ‘family planning’ was initiated in 1951. After that, Improved programmes consisting of more expansive reproduction-related areas are currently in operation, known as ‘Reproductive and Child Health Care (RCH) programme’.
• Non-governmental and governmental agencies have taken various steps to create awareness about reproductive aspects. With the help of audio-visuals and print media, these agencies provide support and facilities for building up a reproductively healthy society.
• Parents, teachers, other close relatives and friends also have a significant role in disseminating the same information. 
• The awareness of sex education in schools should also be encouraged to provide the correct information to young people and discourage them from having misconceptions about sex-related matters.
• Good information about reproductive organs, adolescence and related changes, sexually transmitted diseases (STD), safe and hygienic sexual practices, AIDS, etc., would help people, especially those in the adolescent age group, to have a healthy reproductive life.
• Educating people, especially sexually active couples and young adults, about available birth control options (contraceptives), care of pregnant mothers, then the postnatal care of the mother and child, equal opportunities for the male and the female child, the importance of breastfeeding etc., would deal with bringing up socially conscious, healthy and educated families.
• The realisation of problems due to uncontrolled population growth, social evils like sex abuse and sex-related crimes, etc., needs to be dealt with. The programme aims to make citizens take up necessary actions and thereby build up a socially healthy and responsible society.
• Successful execution of various action plans to achieve reproductive health needs substantial infrastructural facilities, material support and professional expertise. These are essential to providing medical support and care for reproduction-related issues like contraception, menstrual problems, pregnancy, delivery, STDs, abortions, infertility, etc.
• Implementation of new strategies and better techniques from time to time are also required to furnish more efficient care and assistance to people. 
• Statutory ban on amniocentesis test for sex-determination to legally check the increasing menace of female foeticides, a huge number of child immunisation, etc., are some programmes that merit mention in this connection.
• In the amniocentesis test, some of the amniotic fluid of the developing foetus is taken out to analyse the cells of the foetus and dissolved substances. This method is used to test for the presence of certain genetic disorders such as down syndrome, haemophilia, sickle-cell anaemia, etc., and determine the survivability of the foetus.

• Research on various reproduction-related areas is encouraged and supported by governmental and non-governmental agencies to find new methods to attain reproductive health or improve existing ones. 
• ‘Saheli’–a new oral contraceptive for females–was developed by scientists at Central Drug Research Institute (CDRI) in Lucknow, India.

These problems and strategies have been covered in more depth in our Class 12 Biology Chapter 4 Notes. Students can register on the Extramarks website and get access to our chapter notes.

Indications of improved reproductive health in the society:

• Better awareness about sex-related matters.
• Increased number of medically assisted deliveries.
• Better postnatal care leads  to decreased maternal and infant maternal mortality rates.
• More couples with small families.
• Early detection and cure of STDs and overall increased medical facilities for all sex-related problems, etc.

Population Stabilisation And Birth Control:

Population Explosion:

Development in various areas significantly improved the quality of life of the people in the last century. However, increased health facilities and better living conditions had an explosive impact on the growth of the population.

The world population expanded from 2 billion to 6 billion at the end of the last century and reached 7.2 billion in 2011. In India, our population, approximately 350 million at our independence, reached close to the one billion mark by 2000 and crossed 1.2 billion in May 2011.

Causes of Population Explosion: 

Probable reasons behind the population increase as discussed in our Class 12 Biology Chapter 4 Notes could be:

•  A rapid decline in the death rate.
•  Reduction in the maternal and infant mortality rate.         

•  Increase in the number of people of reproducible age.

Such a fast growth rate could lead to the scarcity of essential requirements, i.e., food, shelter, and clothing, despite significant development in those areas. However, we could decrease the population growth rate through our Reproductive Child Health (RCH) programme. Since it was only marginal, the government was forced to take serious measures to check this population growth rate.

Methods to control population growth:

The most important way to overcome this problem is to motivate people to keep smaller families using various contraceptive methods. Many couples, mostly the young, urban ones, have even adopted a ‘one child norm’.

• Statutory raising of the marriageable age of the female to 18 years and that of males to 21 years.
• Incentives are given to couples with small families.

Contraception and contraceptive methods:

Contraception refers to birth control, and contraceptives are designed to prevent unwanted pregnancies. A good contraceptive should be readily available, user-friendly, easy, effective and reversible with no or negligible side effects. It also should in no way intervene with the sexual act of the user. Contraceptive methods could be broadly grouped into the following categories as given in our Class 12 Biology Chapter 4 Notes:

• Natural/Traditional.
• Barrier.
• IUDs.
• Oral contraceptives.
• Injectables and Implants.
• Surgical methods.

1. Natural or Traditional method:

• Natural methods work on avoiding chances of ovum and sperm meeting. Periodic abstinence is a method in which the couples abstain from coitus from day 10 to 17 of the menstrual cycle when ovulation in females could be expected. During this period, chances of fertilisation are very high, and it is called the fertile period. Therefore, by abstaining from coitus, conception could be prevented during this period.

• Coitus interruptus or withdrawal is another method in which the male partner withdraws his penis from the vagina just before ejaculation to prevent insemination.
• The lactational amenorrhea (absence of ovulation and menstruation) method is based on ovulation and, therefore, the menstrual cycle does not occur during the period of heavy lactation. Hence, as long as the mother breastfeeds the child fully, the conception chances are almost zero. However, this kind of conception has been reported to be effective only up to six months after parturition. As no medicines or devices are used, side effects are almost nil. Chances of failure, though, in this method are also high.

2. Barrier method:

• In barrier methods, sperms and ovum are prevented from meeting with the help of some barriers. Such methods are available for both females and males. Condoms are a kind of barrier made of thin rubber/ latex sheaths that are used to cover the penis in the male and vagina or cervix in the female partner just before coitus so that the ejaculated semen from penis would not enter the female reproductive tract. So, condoms can prevent conception. The use of condoms has increased in recent years due to the additional advantage of protecting the partners from contracting STDs and AIDS. Both type of male and the female condoms are disposable, can be self-inserted, and give the user privacy.
• Cervical caps, diaphragms and vaults are also barriers made of rubber inserted into the female reproductive tract to cover the cervix as a barrier during coitus. They prevent the fusion of sperms to the ovum by checking the entry of sperms through the cervix. These barriers are reusable. To increase contraceptive efficiency, spermicidal creams or jellies are used along these barriers.

3. IUDs:

• Intrauterine Devices (IUDs) are another effective and popular method. Doctors or expert nurses insert devices into the uterus through the vagina. 

These Intra-Uterine Devices (IUDs) are presently available as:

• The non-medicated IUDs (e.g., Lippes loop)- These IUDs increase phagocytosis of sperms within the uterus. 
• Copper releasing IUDs (CuT, Cu7, Multiload 375)-  Cu ions released decrease sperm motility and the fertilising capacity of sperms.
• Hormone-releasing IUDs (Progestasert, LNG-20)-  The hormone-releasing IUDs help make the uterus incompatible so that implantation cannot happen. It also makes the cervix hostile to sperms.

In India, IUDs are ideal and the most widely accepted contraceptives for females who want to delay pregnancy. Students can get more information about the IUD procedure via our Class 12 Biology Chapter 4 Notes.

4. Oral contraceptives:

Another contraceptive method used by females is oral intake of small doses of either progestogens or progestogen–estrogen combinations. Many tablets or pills are available for oral intake, which must be taken daily for 21 days, starting within the first five days of the menstruation. After seven days, when menstruation occurs, it has to be repeated in the same pattern till the female desires to prevent conception.

• Pills inhibit ovulation and implantation and alter the quality of cervical mucus to check the sperm’s entry.
• These pills are very effective with lesser side effects and are well accepted by females.

For Example, Saheli– an oral contraceptive for females, contains a non-steroidal preparation. It is a once-a-week pill with very few side effects and a high contraceptive value.

5. Injectable and Implants:

• Females can also use estrogen or progestogens as implants under the skin or injections. It is similar to pills, and their adequate periods are much longer.
• Administration of progestogens or progestogen-estrogen combinations or IUDs within 72 hours of coitus is very effective as emergency contraceptives. They could be used to avoid possible pregnancy due to unprotected intercourse. These are also known as Emergency Contraceptives.

6. Surgical Method:

Surgical methods are generally advised for the male/female partner as a terminal method (non-reversible) to prevent pregnancies. Surgical interference blocks gamete transport and thereby prevents conception.

7. Vasectomy: 

The sterilisation procedure in the male is called ‘vasectomy’. In this surgical procedure a small part of the vas deferens is removed and then tied up through a small incision on the scrotum. Students should refer to Extramarks Class 12 Biology Chapter 4 Notes for more details on how Vasectomy is done.

8. Tubectomy: 

The sterilisation procedure in the female is called ‘tubectomy’. A small part of the fallopian tube of the female is removed or tied up through a minor surgical procedure in the abdomen or through the vagina in a tubectomy procedure. These methods are highly effective, but their reversibility is very poor.

One should always consult with qualified medical professionals before selecting and using a suitable contraceptive. Contraceptives are not regular requirements for maintaining reproductive health. These methods prevent pregnancy or delay or space pregnancy for personal reasons.

The universal use of these methods has a significant role in checking the uncontrolled growth of the population. However, the possible side effects are nausea, abdominal pain, breakthrough

bleeding, irregular menstrual bleeding or even breast cancer etc.

MEDICAL TERMINATION OF PREGNANCY (MTP):

Voluntary pregnancy termination before full term is called medical termination of pregnancy (MTP) or induced abortion.

• Whether to legalise MTP or not is being debated in many countries due to ethical, social, emotional and religious issues involved in it. The government of India legalised MTP in 1971 with some strict conditions to avoid its misuse. 
• Such restrictions are more important to check illegal female foeticides, which are reported to be high in India.
• MTP is required to get rid of unwanted pregnancies due to casual unprotected intercourse or the malfunction of the contraceptives or rapes.
• MTPs are also essential for abnormal pregnancy, harmful or fatal to the fetus or mother.
• MTPs are considered relatively safe in the first trimester, i.e., up to 12 weeks of pregnancy. 
• There could be the misuse of amniocentesis for sex determination of the unborn child, and if the foetus is found to be female, it is followed by MTP- which is illegal. Such practices should be avoided because they are dangerous for both mother and foetus.

For further step-by-step understanding of the MTP, Students can refer to the Class 12 Biology Chapter 4 Notes.

Measures to be taken:

Effective counselling on the requirement to avoid unprotected coitus and the risk factors involved in illegal abortions and providing more health care facilities could reverse the mentioned unhealthy trend.

Students can refer to the Class 12 Biology Chapter 4 Notes drafted by subject experts of Extramarks along with other study materials for getting detailed information about important measures to be taken.

SEXUALLY TRANSMITTED INFECTIONS (STIs):

Infections or diseases which are passed on through sexual intercourse are collectively called sexually transmitted infections (STI) or reproductive tract infections (RTI), or venereal diseases (VD).

For Example, Gonorrhoea, syphilis, genital herpes, chlamydiosis, genital warts, trichomoniasis, hepatitis B and HIV leading to AIDS are common STIs. Among these, HIV infection is the most dangerous.

• Except for hepatitis B, genital herpes and HIV infections, other diseases are completely curable if detected early and treated adequately.
• Most of these early symptoms are minor and include itching, fluid discharge, slight pain, swellings, etc., in the genital region.
• Infected females may often be asymptomatic, and the absence of symptoms in the early stages leads to late detection of the disease, making it incurable for the Individuals. This could lead to later complications, including pelvic inflammatory diseases(PID), abortions, stillbirths, ectopic pregnancies, infertility, or even reproductive tract cancer.

Therefore, early detection, prevention and cure of these diseases are given prime consideration in reproductive healthcare programmes.

Simple principles to prevent STIs are given below:

•  Avoid sex with unknown partners/multiple partners.
•  Always try to use condoms during intercourse.
•  In case of doubt of infection, one should go to a qualified doctor for early detection and get complete treatment if diagnosed with an infection.

The information on STIs has been covered at length in Extramarks Class 12 Biology Chapter 4 Notes for students to get a full understanding of the topic.

INFERTILITY:

Reproductive health also includes the problem of infertility. As stated in the Class 12 Biology Chapter 4 Notes, the inability of parents to produce children despite the unprotected coitus is called infertility. 

The reasons leading to infertility can be physical, diseases, congenital, immunological, drugs, or even psychological. 

• In Indian society, mainly women are blamed for being childless, but more often than not, the problem lies in the males partners. 
• The diagnosis and treatment of some of these infertility disorders can be treated with the help of specialised health care units like infertility clinics. If these treatments are not effective, the couples can opt for a technique commonly known as Assisted Reproductive Technology (ART). 

Some of the essential processes involved in the treatment of infertility are as under. For further details about each of these processes students can refer to our Class 12 Biology Chapter 4 Notes:

• In-vitro Fertilisation (IVF): The process involves the fusion of gametes outside the partner’s body, mainly in the medical laboratories where the conditions that are similar to the body are maintained, followed by embryo transfer(ET). It is popularly known as the test tube baby programme.
• Zygote IntraFallopian Transfer (ZIFT): In this process, the transfer of the zygote or early embryo (up to eight blastomeres) into the fallopian tube of the female is done. 
• Intrauterine Transfer (IUT): It involves the transfer of embryos into the uterus of a female with more than eight blastomeres.
• Gamete Intra Fallopian Transfer (GIFT): This procedure involves the collection of the ovum from the donor female and is then introduced to the other female who cannot produce the ovum on her own, but the internal body conditions are suitable for the process of fertilisation and embryo development. 
• Intracytoplasmic Sperm injection (ICSI): In this specialised procedure, the sperms are directly injected into the female’s ovum, resulting in the laboratory’s embryo formation.
• Artificial insemination (AI) technique: This technique involves collecting semen consisting of sperm from either the husband or a healthy male donor and then injected into either the vagina or the uterus (IUI – intrauterine insemination) of the female body. 

These methods and techniques require incredibly high precision handling by specialised professionals and expensive instrumentation. Their benefits are not affordable to everyone. Emotional, social and religious factors are also deterrents to adopting these methods. 

Another good option for couples who desire a child is a legal adoption route, and it is one of the best methods for couples looking for parenthood.

Students can learn more about infertility from Extramarks Class 12 Biology Chapter 4 Notes.

Class 12 Biology Chapter 4 Notes: Exercises & Solutions

Extramarks provides education study materials for the full Biology Syllabus, where Class 12 students can get knowledge of every Chapter with ease. Subjects like Biology will become easy once students get access to the latest syllabus, chapter notes, question and answer solutions, etc. Students may register on Extramarks to access the Class 12 Biology Chapter 4 Notes any time from anywhere.

Class 12 Biology Chapter 4 Notes The Reproductive Health is prepared with a simple explanation. The Notes are based on the CBSE Syllabus and can benefit the students immensely. Students may access chapter-specific exercises and solutions by clicking on the links below. 

• Chapter 4: Exercise 4.1 Solutions
• Chapter 4: Exercise 4.2 Solutions 
• Chapter 4: Exercise 4.3 Solutions
• Chapter 4: Exercise 4.4 Solutions
• Chapter 4: Exercise 4.5 Solutions
• Chapter 4: Exercise 4.6 Solutions
• Chapter 4: Exercise 4.7 Solutions
• Chapter 4: Exercise 4.8 Solutions
• Chapter 4: Exercise 4.9 Solutions
• Chapter 4: Exercise 4.10 Solutions
• Chapter 4: Exercise 4.11 Solutions
• Chapter 4: Exercise 4.12 Solutions
• Chapter 4: Exercise 4.13 Solutions
• Chapter 4: Exercise 4.14 Solutions
• Chapter 4: Exercise 4.15 Solutions
• Chapter 4: Exercise 4.16 Solutions

The Class 12 Biology Chapter 4 Notes and study materials provided by Extramarks are prepared by experts and are 100% accurate and complete. Students may refer to these study materials to clear their doubts and better understand the respective Chapters. These study materials are focused on understanding Chapters included in the CBSE Class 12 textbooks, which can help students secure excellent marks in Class 12 examinations.

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• NCERT Solutions
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NCERT Exemplar Class 12 Biology

Biology requires regular studying and revisions. Class 12 Biology syllabus is extensive and it is recommended that students should solve a lot of questions. 

NCERT Exemplar for Class 12 Biology is a great resource for students to get a consolidated set of questions and solutions from past years’ exam papers. The Exemplar covers a variety of question forms such as short answer questions, long answer questions, multiple choice, etc. 

Extramarks team has developed step-by-step answer solutions and covered these as part of our Class 12 Biology Chapter 4 Notes study materials. The solved exemplar questions help students to develop higher thinking skills and problem solving capabilities. While solving these questions students will build a deeper understanding of the various topics covered in Chapter 4. Along with the exemplar solutions, our Class 12 Biology Chapter 4 notes also include additional study materials such as CBSE revision notes, past years’ question papers, etc.

Key Features of Class 12 Biology Chapter 4 Notes

The key features of Class 12 Biology Chapter 4 Notes provided by Extramarks are below:

• It follows CBSE Syllabus.
• These notes are prepared by experienced faculty at Extramarks.
• It provides a broad understanding of all the concepts.
• It is focused on preparing short and pointwise Notes. 
• It provides authentic knowledge in an easy language.
• It enhances time management skills.
• It provides quick revision of all the topics.

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