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Q1. Describe three ways in which fertilisation of the human ovum by a sperm can be prevented.

Solution

Fertilisation of the human ovum by a sperm can be prevented by the following methods: (a) Condoms made of thin rubber or latex sheath act as barriers. These are used to cover the penis in the male or vagina and cervix in females. (b) Diaphragm, cervical caps and vaults are barriers made of rubber which are introduced in the female reproductive tract to cover the cervix. (c) Spermicidal creams, jellies and foams are introduced in the vagina to kill sperms. 

Q2. Mention any two events which are inhibited by the intake of oral contraceptive pills to prevent pregnancy in humans.

Solution

Two events which are inhibited by the intake of oral contraceptive pills to prevent pregnancy in humans are ovulation and implantation. 

Q3. What is amniocentesis? Why has the government imposed a statutory ban in spite of its importance in the medical field?

Solution

Amniocentesis is a foetal sex determination test based on the chromosomal pattern in the amniotic fluid surrounding the developing embryo. Amniocentesis is used for sex determination which most people get done to kill the female foetus. Therefore, it has been banned. 

Q4. How do surgical procedures prevent conception in humans? Mention the way it is achieved in human males.

Solution

Surgical procedures block gamete transport and thereby prevent conception. In human males, the sterilisation procedure is called vasectomy, i.e. a small part of the vas deferens is removed or tied up through a small incision on the scrotum. 

Q5. Describe the different methods of embryo transfer.

Solution

An embryo is transferred into the uterus or fallopian tube of the females in the following ways: (i) The zygote or embryo with up to 8 blastomeres is transferred into the fallopian tube. This is called zygote intra-fallopian transfer (ZIFT). (ii) An embryo with more than 8 blastomeres is transferred into the uterus. This is called intra-uterine transfer (IUT). 

Q6. A mother of a one-year-old daughter wanted to space her second child. Her doctor suggested Copper T. Explain its contraceptive actions.

Solution

Copper T is an ideal contraceptive device for human females because (i) Cu ions released suppress sperm motility and the fertilising capacity of sperms. (ii) They increase phagocytosis of sperms within the uterus.

Q7. Write a note on chorionic villus sampling (CVS).

Solution

Chorionic villus sampling (CVS) is a new technique which can be used during the 8th to 10th week of pregnancy when abortion is safe for the woman. For CVS, cells are sucked into a catheter passed through the vagina and cervix. This technique provides a mass of rapidly dividing foetal cells, thus facilitating the examination of chromosomal disorders. 

Q8. Expand ZIFT and RTI.  

Solution

ZIFT: Zygote Intra-Fallopian Transfer RTI: Reproductive Tract Infection

Q9. Why is tubectomy considered a contraceptive method?

Solution

Tubectomy involves cutting a piece of the fallopian tube and tying its ends. This way, the sperms are not able to reach the egg and it acts as a contraceptive method. 

Q10. STDs are a threat to reproductive health. Describe any two such diseases and suggest preventive measures.

Solution

Diseases or infections which are transmitted through sexual intercourse with infected persons are called sexually transmitted diseases or STDs. Gonorrhoea caused by Neisseria gonorrhoeae (bacteria) and Hepatitis B caused by Hepatitis B virus are examples of sexually transmitted diseases. STDs can be prevented by following some simple practices: (i) Avoid sexual contact with HIV-infected people. (ii) Avoid using syringes, needles, razors and toothbrushes used by AIDS patients. (iii) Blood should be tested properly for HIV before blood donation. (iv) Breastfeeding should be avoided by an HIV-infected mother. (v) Addiction of drugs should be avoided.

Q11. Briefly explain IVF and ET. What are the conditions in which these methods are advised?

Solution

IVF refers to in vitro fertilisation and ET refers to embryo transfer. Gametes from the male and female are collected hygienically and induced to fuse in the laboratory set up under simulated conditions. The zygote formed is collected and is introduced into the uterus of a host or surrogate mother at the appropriate time (secretory phase). Early embryos (up to 8 cells) are generally transferred to the fallopian tube, whereas embryos with more than 8 cells are transferred to the uterus. 

Q12. Describe vasectomy and tubectomy with diagrams.

Solution

Vasectomy and tubectomy are permanent methods of contraception. They are also known as sterilisation techniques. These methods are generally advised to the male or female partner as a terminal method to prevent any more pregnancies. It blocks gamete transport and thereby prevents conception. In vasectomy, a small part of the vas deferens is removed and then tied up through a small incision on the scrotum.       In tubectomy, a small part of the fallopian tube is removed and then tied up through a small incision in the abdomen or through the vagina. These techniques are highly effective, but their reversibility is poor.      

Q13. Within what age group are sexually transmitted diseases (STDs) reported to be very high? Mention three practices to avoid them.

Solution

In the age group of 15-24 years, STDs are reported to be very high. Following are the three practices to avoid them: (i) Avoid sex with unknown partners or multiple partners. (ii) Always use condoms during coitus. (iii) In case of any doubt, medical help should be taken for early detection. 

Q14. What are the assisted reproductive techniques practised to help infertile couples? Describe any three techniques.

Solution

Infertile couples can be assisted to have children through certain special techniques called assisted reproductive techniques (ART), which are as follows: (i) Test-tube baby programme: In this method, ova from the wife/donor (female) and sperms from the husband/donor (males) are collected and induced to form a zygote under simulated conditions in the laboratory. This process is called in vitro fertilisation (IVF). The baby produced by conceiving in a culture dish and nursing in the uterus is called a test-tube baby. The test-tube baby programme involves either ZIFT (zygote intra-fallopian transfer) in which the zygote or the early embryo (up to the 8 blastomere stage) is transferred into the fallopian tube of females or IUT (intra uterine transfer) in which the embryo with more than 8 blastomeres is transferred into the uterus to complete further development of the zygote or embryo. (ii) Gamete intra-fallopian transfer (GIFT): It is a method used in females who cannot produce ova but can provide a suitable environment for fertilisation and further development of the embryo in the oviducts. (iii) Intra-cytoplasmic sperm injection (ICSI): In intra-cytoplasmic sperm injection (ICSI), a sperm is directly injected into the ovum placed in a nutrient broth. (iv) Artificial insemination (AI): Artificial insemination is used in those females where the husband is either unable to inseminate the female or has very low sperm counts in the ejaculates. In such cases, the semen of the husband/donor male is first collected and is then artificially introduced either in the vagina or in the uterus (intra-uterine insemination or IUI) of the female.

Q15. Expand the following: (i) ART (ii) GIFT (iii) ICSI (iv) RTI (v) lUI

Solution

(i) ART: Assisted Reproductive Technology (ii) GIFT: Gamete Intra-Fallopian Transfer (iii) ICSI: Intra-Cytoplasmic Sperm Injection (iv) RTI: Reproductive Tract Infections (v) lUI: Intra-Uterine Insemination 

Q16. How do the following contraceptives act to prevent unwanted pregnancy in human females? (i) Intra-uterine devices (IUDs) (ii) Saheli

Solution

(i) Intra-uterine devices are inserted in the uterus through the vagina and are presently available as non-mediated IUDs, copper-releasing IUDs and hormone-releasing IUDs. They increase phagocytosis of sperms within the uterus and the Cu ions released suppress sperm mobility along with the fertilising capacity of the sperms. On the other hand, hormone-releasing IUDs make the uterus unsuitable for implantation and the cervix hostile to sperms. (ii) Saheli is an oral contraceptive for females containing a non-steroidal preparation. It is a 'once a week' pill with few side-effects and high contraceptive value. 

Q17. Describe three ways in which fertilisation of the human ovum by a sperm can be prevented.

Solution

Fertilisation of the human ovum by a sperm can be prevented by the following methods: (a) Condoms made of thin rubber or latex sheath act as barriers. These are used to cover the penis in males or vagina and cervix in females. (b) Diaphragm, cervical caps and vaults are barriers made of rubber which are introduced in the female reproductive tract to cover the cervix. (c) Spermicidal creams, jellies and foams are introduced in the vagina to kill sperms. 

Q18. Describe the lactational amenorrhea method of birth control.

Solution

Lactational amenorrhea is based on the principle that during the period of intense lactation after parturition, the menstrual cycle or ovulation does not occur.

Q19. The present population growth rate in India is alarming. Suggest ways to check it.  

Solution

Ways to check population growth: (i) By increasing marriageable age (ii) By promoting the use of birth control measures (iii) By educating people about the consequences of uncontrolled population growth 

Q20. Describe the various methods of birth control.

Solution

The methods of birth control are divided into the following categories: (i) Natural/traditional methods: These are natural methods which work on the principle of avoiding the meeting of the ovum and the sperm. It includes periodic abstinence, coitus interruptus and lactational amenorrhea. (ii) Barrier methods: These methods prevent the contact of the sperm and the ovum by using barriers. Such methods are available for both males and females. These include condoms, diaphragms, cervical caps, vaults, spermicidal creams, jellies and foams. (iii) Intra-uterine devices: These devices are inserted by doctors in the uterus through the vagina. There are three types of IUDs available which include non-medicated IUDs, copper-releasing IUDs and hormone-releasing IUDs. (iv) Oral contraceptive: This involves uptake of hormonal preparations of either progestogen or progestogen-oestrogen combinations in the form of pills. (v) Injections and implants: Progestogen or progestogen-oestrogen combination can also be used by females as injections or implants under the skin. (vi) Surgical methods: These are terminal and permanent methods which block the transport of gametes, thereby preventing conception. This is achieved by vasectomy in males and tubectomy in females. 

Q21. What is meant by artificial insemination?  

Solution

Artificial insemination is a  technique by  which  the semen  collected from  the  husband or  a  healthy donor is artificially introduced either into the vagina  or into  the uterus of the female.

Q22. What is the significant role of MTP in human population?

Solution

MTP or Medical Termination of Pregnancy is done to get rid of unwanted pregnancies due to (i) Casual unprotected intercourse (ii) Failure of the contraceptive used during coitus (iii) Rape It is also essential in cases where continuation of pregnancy could pose a threat to the life of either the mother or foetus or both. 

Q23. Explain the zygote intra-fallopian transfer technique (ZIFT). How is intra-uterine transfer technique (IUT) different from it?

Solution

Zygote intra-fallopian transfer technique (ZIFT) is a technique in in vitro fertilisation where the zygote or early embryo with up to 8 blastomeres is transferred into the fallopian tube to complete its further development. Intra-uterine transfer (IUT) technique is different from ZIFT as the embryos with more than 8 blastomeres are transferred into the uterus in IUT. 

Q24. What are the commonly used barrier methods of contraception?

Solution

Condoms, diaphragms, cervical caps and vaults are the commonly used barrier methods of contraception. 

Q25. What do you mean by reproductive health? Mention the different ways in which people are made aware of the significance of reproductively healthy society.

Solution

Reproductive health means total well-being in all aspects of reproduction, i.e. physical, emotional, behavioural, social and physiological. Following measures are to be taken to make people aware of reproductively healthy society: (i) Providing infrastructural facilities and professional expertise to attain reproductive health. (ii) Educating people about birth control methods, care of pregnant mothers, importance of breast feeding, safe and hygienic sexual practices and safeguards against STDs. (iii) Introduction of sex education in schools to give proper information to young minds about sex-related aspects. (iv) Help of audio-visual and print-media to create awareness among people about reproduction-related aspects. (v) Awareness of problems due to population explosion, social evils such as sex abuse and sex-related crimes. (vi) Statutory ban on amniocentesis to legally check female foeticides. 

Q26. Describe the technique by which a genetic disorder in a developing foetus can be detected.

Solution

Amniocentesis is a technique by which a genetic disorder in a developing foetus can be detected. This is based on the chromosomal pattern in the amniotic fluid surrounding the developing embryo. The amniotic fluid contains cells and molecules shed by the foetus. The chromosomes of foetal cells can also be used to find out the sex of the foetus. So, if an abnormality is found, the mother should get the foetus aborted. 

Q27. How are assisted reproductive technologies helpful to humans? How are ZIFT and GIFT different from intra-uterine transfers? Explain.

Solution

The infertile couples could be assisted to have children through certain special techniques known as assisted reproductive technologies (ART). ZIFT: The zygote or early embryo with up to 8 blastomeres is transferred into the fallopian tube. This is called zygote intra-fallopian transfer (ZIFT). GIFT: Gamete intra-fallopian transfer is the transfer of an ovum collected from a donor into the fallopian tube of another female who cannot produce one but can provide a suitable environment for fertilisation and further development of the embryo. Intra-uterine transfer (IUT) refers to the introduction of an embryo with more than 8 blastomeres into the uterus of a female to complete its further development. 

Q28. Why intensely lactating mothers do not generally conceive? 

Solution

Intensely lactating mothers do not generally conceive due to the suppression of gonadotropins.

Q29. At the time of Independence, the population of India was 350 million, which exploded to over 1 billion by May 2000. List any two reasons for this rise in population and any two steps taken by the government to check this population explosion. 

Solution

Two reasons for increase in population are (i) A rapid decline in the death rate, maternal mortality rate and infant mortality rate. (ii) Increase in the number of people of reproducible age. Two steps for checking population explosion: (i) Statutory raising of marriageable age of females to 18 years and males to 21 years. (ii) Incentives given to couples with small families. 

Q30. In GIFT, gametes are transferred to the fallopian tube. Can gametes be transferred to the uterus to achieve the same result? Explain.

Solution

The uterine environment is not ideal for the survival of gametes. If directly transferred to the uterus, gametes will undergo degeneration or could be phagocytosed, and hence, viable zygotes would not be formed.