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Samacheer Kalvi 12th Biology Chapter 13 Exercise Solutions

Tamil Nadu Class 12 Biology Chapter 13 Reproductive Health exercise solutions — contraception, STDs, infertility, ART (IVF, GIFT, ICSI), and exam tips.

Updated 25 May 202615 min read

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Chapter 13 — Reproductive Health Exercise Solutions

Reproductive health covers practical applications. Know the full form of all abbreviations (IVF, GIFT, ZIFT, ICSI, IUD, STI).

How to Use This Page

  • Read the Key Concepts table first — it gives you a quick overview of all important terms and definitions you must remember.
  • Work through each section in order — start with MCQs, then Fill in the Blanks, True or False, Match the Following, short answers, and detailed answers.
  • Check your answers using the bold/correct options provided. For open-ended questions, compare your wording with the model answers.
  • Review Common Mistakes to Avoid before every exam — these are the most frequent errors students make.
  • Use the Exam Checklist in the last section as a final revision tool to ensure you have covered every topic.

Key Concepts (Quick Recap)

TermDefinition
Reproductive healthPhysical, mental, and social well-being in matters related to the reproductive system
ContraceptionDeliberate prevention of pregnancy using natural, barrier, hormonal, IUD, or surgical methods
IUD (Intrauterine Device)Device inserted into the uterus to prevent implantation or fertilisation (e.g. Copper-T, LNG-20)
Combined oral contraceptive pillPill containing oestrogen and progesterone that prevents ovulation
VasectomySurgical method in males — cutting and tying the vas deferens to prevent sperm transport
TubectomySurgical method in females — cutting and tying the fallopian tubes to prevent egg transport
IVF (In Vitro Fertilisation)Fertilisation of egg and sperm outside the body in a culture dish
GIFT (Gamete Intra Fallopian Transfer)Transfer of egg and sperm directly into the fallopian tube for in vivo fertilisation
ZIFT (Zygote Intra Fallopian Transfer)Transfer of zygote (fertilised egg) into the fallopian tube
ICSI (Intra Cytoplasmic Sperm Injection)Direct injection of a single sperm into the cytoplasm of an ovum
STI (Sexually Transmitted Infection)Infection transmitted through sexual contact (e.g. gonorrhoea, syphilis, HIV)
AmniocentesisPrenatal diagnostic technique — analysis of amniotic fluid cells for genetic disorders
MTP (Medical Termination of Pregnancy)Legal and safe termination of pregnancy under the MTP Act (1971)
InfertilityInability to conceive after one year of regular unprotected intercourse

Contraception — Classification

Natural methods (no devices):

  • Periodic abstinence (avoid sex during fertile period — ovulation ±2 days)
  • Coitus interruptus (withdrawal)
  • Lactational amenorrhoea (breastfeeding suppresses ovulation — effective up to 6 months)

Barrier methods:

  • Male condom (latex), Female condom — also prevent STIs
  • Diaphragm, cervical cap — used with spermicides

IUDs (Intrauterine Devices):

  • Non-medicated: Lippes loop
  • Copper IUD: Copper-T (Cu-T 380A) — copper ions toxic to sperm
  • Hormonal IUD: LNG-20 (levonorgestrel) — thickens cervical mucus

Hormonal methods:

  • Combined oral contraceptive pills (oestrogen + progesterone)
  • Progestin-only pills (mini-pill)
  • Emergency contraception — high-dose hormone within 72 hours

Surgical (permanent):

  • Vasectomy — cutting/tying vas deferens (male)
  • Tubectomy (tubal ligation) — cutting/tying fallopian tubes (female)

Assisted Reproductive Technologies (ART)

TechniqueFull FormProcedure
IVFIn Vitro FertilisationFertilisation outside body; embryo transferred
ETEmbryo TransferTransfer of embryo into uterus
GIFTGamete Intra Fallopian TransferEgg + sperm placed in fallopian tube
ZIFTZygote Intra Fallopian TransferZygote placed in fallopian tube
ICSIIntra Cytoplasmic Sperm InjectionSingle sperm injected into egg
IUIIntra Uterine InseminationProcessed sperm injected into uterus
AIArtificial InseminationSemen deposited in reproductive tract

STI Prevention

  • Use condoms consistently — effective against most STIs.
  • Mutual monogamy reduces risk.
  • Vaccines: HPV vaccine (Gardasil) prevents cervical cancer; Hepatitis B vaccine.
  • Early diagnosis and treatment prevent complications.
  • Avoid sharing needles (HIV, Hepatitis B, C).

Causes of Infertility

CauseIn MalesIn Females
HormonalLow testosterone, FSH/LH imbalancePCOS, anovulation
StructuralVas deferens blockageFallopian tube blockage
Sperm qualityLow count (oligospermia), poor motility—
Uterine—Fibroids, endometriosis

I. Choose the Best Answer (MCQs)

1. Which of the following is a barrier method of contraception? (a) Copper-T (b) Condom (c) Oral pill (d) Vasectomy

2. The full form of ICSI is: (a) Intra Cervical Sperm Injection (b) Intra Cytoplasmic Sperm Integration (c) Intra Cytoplasmic Sperm Injection (d) Intra Cytoplasmic Sperm Implantation

3. Which IUD releases copper ions that are toxic to sperm? (a) Lippes loop (b) Copper-T (c) LNG-20 (d) Progestasert

4. In which ART technique are both egg and sperm directly transferred into the fallopian tube? (a) IVF (b) ZIFT (c) GIFT (d) IUI

5. Emergency contraceptive pills should be taken within: (a) 24 hours (b) 48 hours (c) 72 hours (d) 7 days

6. The causative organism of syphilis is: (a) Neisseria gonorrhoeae (b) Treponema pallidum (c) HIV (d) Human papillomavirus

7. Lactational amenorrhoea is effective as contraception up to: (a) 1 month (b) 3 months (c) 6 months (d) 12 months

8. Amniocentesis is a technique used for: (a) Contraception (b) Fertilisation (c) Prenatal diagnosis of genetic disorders (d) Embryo transfer

9. Which of the following is a sexually transmitted viral disease? (a) Gonorrhoea (b) Syphilis (c) Genital herpes (d) Trichomoniasis

10. Tubectomy involves cutting and tying the: (a) Vas deferens (b) Ureter (c) Urethra (d) Fallopian tubes

11. The MTP Act in India was enacted in: (a) 1961 (b) 1971 (c) 1981 (d) 1991

II. Fill in the Blanks

1. The full form of GIFT is Gamete Intra Fallopian Transfer. 2. Copper-T releases copper ions that are toxic to sperm and prevent fertilisation. 3. The combined oral contraceptive pill contains oestrogen and progesterone hormones. 4. In vasectomy, the vas deferens is cut and tied to prevent the passage of sperm. 5. The first test tube baby was born through the IVF technique. 6. Amniocentesis is a prenatal diagnostic technique that analyses amniotic fluid cells. 7. Gonorrhoea is caused by the bacterium Neisseria gonorrhoeae. 8. The HPV vaccine is called Gardasil and prevents cervical cancer. 9. Lactational amenorrhoea works because breastfeeding suppresses ovulation. 10. IUI stands for Intra Uterine Insemination, where processed sperm is placed directly into the uterus.

III. True or False (with corrections for false statements)

1. True. Copper-T is an intrauterine device that prevents implantation and fertilisation.

2. False. — Oral contraceptive pills prevent ovulation, not fertilisation. They primarily inhibit the release of the egg from the ovary.

3. True. Genital herpes is caused by Herpes Simplex Virus type 2 (HSV-2).

4. False. — GIFT transfers gametes (egg and sperm) into the fallopian tube, not a zygote. ZIFT transfers a zygote.

5. True. Vasectomy is a permanent method of contraception in males.

6. False. — Acquired characters are not relevant to contraceptive choice, but more importantly, lactational amenorrhoea is effective only up to 6 months postpartum, not indefinitely.

7. True. HIV/AIDS is transmitted through sexual contact, blood transfusion, and from mother to child.

8. False. — Tubectomy is performed in females (fallopian tubes), not males. Vasectomy is performed in males.

IV. Match the Following

Column AColumn B
1. Copper-T(d) Copper-releasing IUD
2. IVF(f) Fertilisation outside the body
3. Vasectomy(a) Cutting of vas deferens
4. Gonorrhoea(g) Neisseria gonorrhoeae
5. LNG-20(c) Hormone-releasing IUD
6. ZIFT(e) Zygote transferred to fallopian tube
7. Syphilis(b) Treponema pallidum
8. GIFT(h) Gametes transferred to fallopian tube

V. Answer Briefly (2-mark)

1. What is reproductive health?
Answer

Reproductive health refers to the complete physical, mental, and social well-being of individuals in all matters relating to the reproductive system. It is not merely the absence of disease but includes the ability to have a satisfying and safe sex life, the capability to reproduce, and the freedom to decide if, when, and how often to do so.

2. Differentiate between GIFT and ZIFT.
Answer

GIFT (Gamete Intra Fallopian Transfer) involves transferring both the egg and sperm directly into the fallopian tube, where fertilisation occurs naturally inside the body. ZIFT (Zygote Intra Fallopian Transfer) involves fertilising the egg outside the body first, then transferring the resulting zygote into the fallopian tube. The key difference is that GIFT transfers gametes while ZIFT transfers a zygote.

3. What are the advantages of barrier methods of contraception?
Answer

Barrier methods such as condoms and diaphragms prevent pregnancy by physically blocking sperm from reaching the egg. Their major advantage is that they also provide protection against sexually transmitted infections including HIV. They do not involve hormonal side effects and are easily available without prescription. However, they must be used consistently and correctly every time.

4. List any four sexually transmitted infections and their causative organisms.
Answer

(i) Gonorrhoea — caused by Neisseria gonorrhoeae (bacterium), (ii) Syphilis — caused by Treponema pallidum (bacterium), (iii) Genital herpes — caused by Herpes Simplex Virus type 2 (virus), (iv) HIV/AIDS — caused by Human Immunodeficiency Virus (retrovirus).

5. What is amniocentesis? Why has its use been regulated?
Answer

Amniocentesis is a prenatal diagnostic technique in which a small amount of amniotic fluid is withdrawn from the uterus and analysed for chromosomal abnormalities and genetic disorders in the foetus. Its use has been regulated because it has been misused for sex determination, leading to female foeticide, which is illegal under the PCPNDT Act in India.

6. Define infertility. Name any two causes each in males and females.
Answer

Infertility is the inability of a couple to conceive after one year of regular unprotected intercourse. In males: (i) Low sperm count (oligospermia), (ii) Blockage of vas deferens. In females: (i) Polycystic Ovarian Syndrome (PCOS) leading to anovulation, (ii) Blockage of fallopian tubes.

VI. Answer in Detail (5-mark)

1. Describe the various methods of contraception with examples.
Answer

Contraception methods are classified as follows:

  • Natural methods: Periodic abstinence (avoiding intercourse during fertile window around ovulation), coitus interruptus (withdrawal before ejaculation), and lactational amenorrhoea (breastfeeding suppresses ovulation, effective up to 6 months postpartum). These have higher failure rates.
  • Barrier methods: Male condoms (latex sheath), female condoms, diaphragms, and cervical caps used with spermicidal creams. They physically block sperm entry and also protect against STIs.
  • Intrauterine Devices (IUDs): Non-medicated (Lippes loop), copper-releasing (Copper-T — copper ions are toxic to sperm and suppress sperm motility), and hormone-releasing (LNG-20 — thickens cervical mucus and suppresses sperm activity).
  • Hormonal methods: Combined oral contraceptive pills (oestrogen + progesterone — prevent ovulation), progestin-only pills, injections (Depo-Provera), and emergency contraceptive pills (high-dose hormones within 72 hours of unprotected intercourse).
  • Surgical (permanent) methods: Vasectomy in males (cutting and tying the vas deferens) and tubectomy in females (cutting and tying the fallopian tubes). These are irreversible in most cases.
2. Explain the various Assisted Reproductive Technologies (ART) with their procedures.
Answer

Assisted Reproductive Technologies help couples overcome infertility:

  • IVF (In Vitro Fertilisation): The woman is given hormonal treatment (FSH) for superovulation to produce multiple eggs. Eggs are retrieved (oocyte pick-up) and fertilised with sperm in a culture dish outside the body. The resulting embryo is cultured for 2–5 days and then transferred into the uterus (embryo transfer). This is the basis of test tube baby technology.
  • GIFT (Gamete Intra Fallopian Transfer): Both egg and sperm are collected and directly placed into the fallopian tube using a laparoscope. Fertilisation occurs naturally inside the body. Suitable when the fallopian tubes are healthy.
  • ZIFT (Zygote Intra Fallopian Transfer): Egg and sperm are fertilised in vitro, and the resulting zygote (or early embryo) is transferred into the fallopian tube. Combines IVF fertilisation with natural tubal environment.
  • ICSI (Intra Cytoplasmic Sperm Injection): A single sperm is directly injected into the cytoplasm of an ovum using a micromanipulator. Used especially in cases of severe male infertility (low sperm count or poor motility).
  • IUI (Intra Uterine Insemination): Processed and concentrated sperm are directly deposited into the uterus around the time of ovulation. Used when sperm quality or cervical mucus is a factor.
  • AI (Artificial Insemination): Semen is deposited into the female reproductive tract. Can use the husband's sperm (AIH) or donor sperm (AID).
3. Discuss the major sexually transmitted infections, their causative organisms, and preventive measures.
Answer

Major STIs and their causative organisms:

  • Gonorrhoea: Caused by Neisseria gonorrhoeae (bacterium). Symptoms include painful urination and discharge. Can cause PID and infertility if untreated.
  • Syphilis: Caused by Treponema pallidum (bacterium). Progresses through primary (chancre), secondary (rash), and tertiary (organ damage) stages.
  • Genital herpes: Caused by Herpes Simplex Virus type 2 (HSV-2). Causes painful blisters; recurrent outbreaks are common.
  • Genital warts: Caused by Human Papillomavirus (HPV). Can lead to cervical cancer in women.
  • HIV/AIDS: Caused by Human Immunodeficiency Virus (retrovirus). Attacks CD4+ T-cells, destroying the immune system. Transmitted through sexual contact, blood, and mother-to-child.
  • Trichomoniasis: Caused by Trichomonas vaginalis (protozoan). Causes vaginitis in females.

Preventive measures: (i) Use condoms consistently and correctly, (ii) Practice mutual monogamy, (iii) Get vaccinated (HPV vaccine, Hepatitis B vaccine), (iv) Undergo regular STI screening, (v) Avoid sharing needles, (vi) Seek early diagnosis and treatment to prevent complications and further transmission.

4. What is MTP? Discuss the legal provisions and safe periods for MTP in India.
Answer

Medical Termination of Pregnancy (MTP) refers to the legal and safe termination of pregnancy. The MTP Act of 1971 (amended in 2021) governs this in India. Key provisions: (i) MTP is permitted up to 20 weeks of gestation on grounds including risk to the mother's life, grave physical/mental injury, risk of foetal abnormalities, and pregnancy resulting from contraceptive failure or rape. (ii) The 2021 amendment extended the upper limit to 24 weeks for special categories including survivors of sexual assault, rape, minors, and women with changed marital status. (iii) For pregnancies up to 20 weeks, the opinion of one registered medical practitioner is sufficient. (iv) Between 20–24 weeks, a board of two medical practitioners must approve. (v) MTP must be performed at a government-approved facility by a registered medical practitioner. Safe periods: First trimester (up to 12 weeks) is the safest. Second trimester carries higher risks of complications.

Worked Examples

Example 1 — ART techniques (model answer)

IVF : fertilisation outside body; embryo transferred to uterus ("test-tube baby") ZIFT : ZYGOTE/early embryo transferred to fallopian tube GIFT : GAMETES (egg + sperm) transferred to fallopian tube ICSI : a single sperm injected directly into the ovum

Example 2 — Contraceptive methods classification

Barrier : condoms, diaphragm Hormonal : oral pills (prevent OVULATION) IUD : Cu-T (copper releasing) Surgical : vasectomy (male), tubectomy (female)

Example 3 — Why is reproductive health important? (model answer)

Reproductive health means physically, mentally, and socially healthy reproduction. Programmes promote awareness, contraception, prevention of STDs, and maternal–infant care — improving family planning and reducing population growth and disease.

Common Mistakes

  • Confusing GIFT (gamete — egg + sperm) with ZIFT (zygote — fertilised egg).
  • Saying oral contraceptives prevent fertilisation — they primarily prevent ovulation.
  • Not mentioning that vasectomy is reversible in some cases while tubectomy is generally considered permanent.

Common Mistakes to Avoid

  • ❌ Saying oral contraceptive pills prevent fertilisation → ✅ Oral contraceptive pills primarily prevent ovulation (release of egg from ovary).
  • ❌ Confusing GIFT and ZIFT → ✅ GIFT transfers gametes (egg + sperm) into the fallopian tube; ZIFT transfers a zygote (fertilised egg) into the fallopian tube.
  • ❌ Writing that vasectomy is performed in females → ✅ Vasectomy is performed in males (vas deferens); tubectomy is performed in females (fallopian tubes).
  • ❌ Stating that Copper-T is a hormonal IUD → ✅ Copper-T is a copper-releasing IUD; LNG-20 is the hormone-releasing IUD.
  • ❌ Saying ICSI stands for Intra Cytoplasmic Sperm Implantation → ✅ ICSI stands for Intra Cytoplasmic Sperm Injection — a single sperm is injected into the ovum.
  • ❌ Writing that STIs are only transmitted through sexual intercourse → ✅ STIs can also be transmitted through blood transfusion, shared needles, and mother-to-child (HIV, syphilis).
  • ❌ Confusing amniocentesis with contraception → ✅ Amniocentesis is a prenatal diagnostic technique for detecting genetic disorders; it is not a contraceptive method.
  • ❌ Saying lactational amenorrhoea works indefinitely → ✅ It is effective only up to 6 months of intensive breastfeeding postpartum.

Exam Checklist

  • [ ] Know all contraceptive methods with examples: natural, barrier, IUD, hormonal, surgical
  • [ ] Memorise full forms: IVF, GIFT, ZIFT, ICSI, IUI, AI, IUD, MTP, STI
  • [ ] Clearly distinguish GIFT (gametes) vs ZIFT (zygote) vs IVF (external fertilisation)
  • [ ] Know the mechanism of each IUD type: non-medicated, copper-releasing, hormone-releasing
  • [ ] List at least 5 STIs with their causative organisms (bacteria, virus, protozoan)
  • [ ] Remember: oral contraceptives prevent ovulation, not fertilisation
  • [ ] Know the MTP Act provisions and safe periods for termination
  • [ ] Explain amniocentesis and why its misuse (sex determination) is banned
  • [ ] Differentiate male and female infertility causes
  • [ ] Know the HPV vaccine name (Gardasil) and its role in preventing cervical cancer
  • [ ] Write the correct procedure steps for IVF in sequence
  • [ ] Remember: Copper-T is copper-releasing, LNG-20 is hormone-releasing

Frequently Asked Questions

Contraception methods: 1. Natural methods — periodic abstinence, coitus interruptus, lactational amenorrhoea. 2. Barrier methods — condoms (male/female), diaphragm, cervical cap, vaults. 3. IUDs — Copper-T, LNG-20 (hormonal). 4. Oral contraceptives — pills (oestrogen + progesterone). 5. Injections — Depo-Provera. 6. Surgical — vasectomy (male), tubectomy (female — permanent).