The high-frequency trap in this topic is contraceptive method category confusion — NEET questions present a specific method and ask you to classify it by mechanism. Students who memorise names without sorting by mechanism lose marks here.
Birth control methods are grouped by how they prevent pregnancy:
Natural/traditional methods — periodic abstinence (rhythm method: avoiding coitus from day 10–17 of a 28-day cycle), coitus interruptus (withdrawal), lactational amenorrhoea (effective up to 6 months post-partum if fully breastfeeding).
Barrier methods — physically block sperm from reaching the ovum. Examples: male condom, female condom, diaphragm, cervical cap, vault. Condoms also protect against STIs.
IUDs (Intra-Uterine Devices) — placed inside the uterus; three subtypes:
Hormonal methods — oral pills (Mala-N, Saheli/centchroman), injectable progestogens, implants (Norplant). They inhibit ovulation and alter cervical mucus.
Surgical methods (sterilisation) — vasectomy (male: vas deferens cut/tied), tubectomy (female: fallopian tubes cut/tied). Highly effective, essentially irreversible.
Medical termination of pregnancy (MTP): MTP, or induced abortion, is the intentional termination of a pregnancy before full term. Nearly 45-50 million MTPs are performed worldwide each year, about one-fifth of all conceived pregnancies. Because of emotional, ethical, religious and social concerns, countries debate whether to legalise it; the Government of India legalised MTP in 1971 under strict conditions meant to prevent misuse. MTPs help end unwanted pregnancies from unprotected coitus, contraceptive failure, or rape, and are also medically necessary when continuing the pregnancy would endanger the mother or the foetus. MTPs are relatively safe up to the first trimester (12 weeks); second-trimester abortions carry much higher risk. NCERT flags two concerning trends: many MTPs are performed illegally by unqualified quacks, which is unsafe and can be fatal, and amniocentesis is sometimes misused to determine foetal sex, followed by illegal, sex-selective MTP of female foetuses (NCERT Class 12 Biology, Chapter 3, page 46).
Watch-out: Copper IUDs do NOT work by hormonal action. Their mechanism is physical + chemical (Cu²⁺ ions). Confusing CuT with hormonal IUDs is a direct mark-loss trap (NCERT Class 12 Biology Chapter 3, page 44).
Select an option to see the explanation. Wrong answers show why your choice was tempting — and name the exact trap it exploits.
Regular combined oral contraceptive pills are taken daily for 21 days of the cycle, whereas emergency contraceptive pills (progestogen–estrogen combination) are effective only if taken within 72 hours after a single act of coitus. Why does the emergency pill need this narrow time window while the regular pill does not?
Answer: B. Regular pills sustain progestogen/progestogen–estrogen levels daily across the cycle to continuously inhibit ovulation and alter cervical mucus, while emergency pills (or IUDs) given within 72 hours of coitus act as a rescue dose to disrupt ovulation or implantation before fertilisation/implantation can be completed — beyond that window the biological opportunity has passed (NCERT Class 12 Biology Chapter 3, page 45).
Why A is wrong: IUDs, not oral pills, work by physically blocking/trapping sperm inside the uterus; both regular and emergency pills act hormonally, not as a physical barrier (trap: mixing IUD and pill mechanisms).
Why C is wrong: Phagocytosis of sperm in the uterus is the copper IUD mechanism, not the mechanism of hormonal pills — regular or emergency (trap: mixing IUD and pill mechanisms).
Why D is wrong: The 72-hour window has a biological basis — the rescue hormone dose must act before fertilisation/implantation is complete; it is not an arbitrary manufacturer precaution (trap: dismissing the physiological cause).
Saheli, the non-steroidal oral contraceptive pill, contains:
Answer: A. Saheli contains centchroman, a non-steroidal SERM developed by CDRI, Lucknow (NCERT Class 12 Biology Chapter 3, page 45).
Why B is wrong: B — Progesterone-estrogen combination describes conventional oral pills (Mala-N), not Saheli (trap: contraceptive type confusion).
Why C is wrong: C — Levonorgestrel is the hormone in emergency contraceptive pills and LNG-20 IUD, not in Saheli (trap: confusing hormonal methods with non-steroidal ones).
Why D is wrong: D — Copper ions are released by CuT/Multiload IUDs, not oral pills (trap: mixing IUD and pill mechanisms).
Which birth control method also provides protection against sexually transmitted infections?
Answer: D. Condoms (both male and female) act as physical barriers that prevent exchange of body fluids, thereby protecting against STIs including HIV (NCERT Class 12 Biology Chapter 3, page 44).
Why A is wrong: A — Copper-T is placed inside the uterus and does not block pathogen transmission at the point of contact (trap: assuming all contraceptives protect against STIs).
Why B is wrong: B — Oral pills alter hormonal cycles to prevent ovulation but offer zero barrier to pathogen entry (trap: assuming all contraceptives protect against STIs).
Why C is wrong: C — Tubectomy prevents egg transport but provides no physical barrier against pathogens (trap: assuming sterilisation = full protection).
The mechanism of action of copper-releasing IUDs includes:
Answer: C. Copper ions released from CuT/Multiload IUDs suppress sperm motility and increase phagocytosis of sperms in the uterus (NCERT Class 12 Biology Chapter 3, page 44).
Why A is wrong: A — GnRH suppression is the mechanism of hormonal pills/injections, not copper IUDs (trap: IUD mechanism confusion — attributing hormonal action to copper devices).
Why B is wrong: B — Thickening cervical mucus is the mechanism of hormone-releasing IUDs like LNG-20, not copper IUDs (trap: IUD mechanism confusion).
Why D is wrong: D — Endometrial removal is not the mechanism of any IUD; copper IUDs make the uterine environment hostile to sperm, not strip endometrium (trap: confusing mechanism with surgical curettage).
A couple wants a permanent contraceptive method. The male partner opts for surgery. Which structure is cut and tied in vasectomy?
Answer: B. In vasectomy, a small part of the vas deferens is removed or tied through a scrotal incision, preventing sperm from reaching the ejaculatory duct (NCERT Class 12 Biology Chapter 3, page 46).
Why A is wrong: A — The epididymis is the site of sperm maturation/storage; it is not the structure cut in vasectomy (trap: confusing duct anatomy sequence).
Why C is wrong: C — Seminiferous tubules are inside the testis where spermatogenesis occurs; surgical access would damage the testis (trap: confusing sperm production site with transport duct).
Why D is wrong: D — The ejaculatory duct is deep inside the body near the prostate; vasectomy targets the more accessible vas deferens in the scrotum (trap: confusing proximal vs distal ducts).
Lactational amenorrhoea as a method of contraception is effective up to a maximum of:
Answer: C. Lactational amenorrhoea is effective only up to 6 months post-partum when the mother is fully breastfeeding, as high prolactin suppresses ovulation during this period (NCERT Class 12 Biology Chapter 3, page 44).
Why A is wrong: A — 3 months is too conservative; NCERT states effectiveness up to 6 months, not just 3 (trap: underestimating the duration).
Why B is wrong: B — Beyond 6 months, ovulation may resume even with continued breastfeeding; this method becomes unreliable (trap: overestimating duration of amenorrhoea).
Why D is wrong: D — 24 months far exceeds the reliable window; menstrual cycles typically resume well before this (trap: confusing breastfeeding duration with contraceptive efficacy window).
A woman using the periodic abstinence (rhythm) method should avoid coitus during which days of a standard 28-day menstrual cycle?
Answer: B. Ovulation occurs around Day 14; considering sperm survival (~3 days) and ovum viability (~1 day), the fertile window spans approximately Day 10 to Day 17 (NCERT Class 12 Biology Chapter 3, pages 44–45).
Why A is wrong: A — Days 1–7 correspond to the menstrual and early follicular phase when ovulation has not yet occurred; this is generally a non-fertile window (trap: confusing menstrual bleeding days with the fertile period).
Why C is wrong: C — Days 18–25 fall in the post-ovulatory luteal phase when the ovum has already degenerated; this is an infertile window (trap: shifting the fertile window too late).
Why D is wrong: D — Days 21–28 are deep in the luteal phase approaching menstruation; no viable ovum is present (trap: confusing pre-menstrual phase with pre-ovulatory phase).
Which of the following statements about IUDs is correct?
i. Lippes loop is a hormone-releasing IUD.
ii. CuT releases copper ions that suppress sperm motility.
iii. LNG-20 releases levonorgestrel that thickens cervical mucus.
iv. All IUDs work by inhibiting ovulation.
Answer: B. Statement (ii) is correct — CuT releases Cu²⁺ ions that suppress sperm motility and increase phagocytosis. Statement (iii) is correct — LNG-20 releases levonorgestrel that thickens cervical mucus and makes the endometrium unreceptive (NCERT Class 12 Biology Chapter 3, page 44).
Why A is wrong: A — Statement (i) is wrong (Lippes loop is non-medicated/inert, not hormone-releasing) and statement (iv) is wrong (IUDs do NOT inhibit ovulation — that's the mechanism of hormonal pills). Trap: IUD mechanism confusion.
Why C is wrong: C — Statement (i) is incorrect; Lippes loop contains no medication. Including it invalidates this option (trap: assuming all IUDs release something).
Why D is wrong: D — Both (i) and (iv) are incorrect, so 'all of the above' fails (trap: conflating IUD subtypes into a single mechanism).
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Given
A NEET question presents four contraceptive methods and asks which one works by releasing copper ions that suppress sperm motility.
Options presented: (A) LNG-20, (B) Lippes loop, (C) Multiload 375, (D) Saheli.
Required
Identify the copper-releasing IUD from the list.
Concept
IUDs are classified by their mechanism: non-medicated (inert plastic), copper-releasing (Cu²⁺ ions), or hormone-releasing (progestogen). Copper-releasing types specifically use Cu²⁺ to suppress sperm motility and increase phagocytosis.
Formula
No formula applies; this is a classification question.
Substitution
• LNG-20 → hormone-releasing IUD (levonorgestrel). Eliminate.• Lippes loop → non-medicated/inert. Eliminate.• Multiload 375 → "375" refers to 375 mm² of copper surface area. Copper-releasing. Candidate.• Saheli → oral pill (centchroman). Eliminate.
Calculation
Direct classification; no arithmetic.
Final answer
(C) Multiload 375 — it is a copper-releasing IUD.
Common trap
Students confuse LNG-20 (hormone-releasing IUD) with copper IUDs because both are "IUDs." The key discriminator is the active agent: Cu²⁺ ions vs levonorgestrel. The number in "Multiload 375" and "CuT-380A" refers to copper surface area — a helpful mnemonic cue.
Similar NEET-style question
"Which of the following IUDs makes the uterine environment hostile to sperms by releasing ions?" — The answer pattern is the same: identify the copper-releasing device (CuT-380A or Multiload 375) vs non-medicated (Lippes loop) vs hormonal (LNG-20).
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Natural (rhythm, withdrawal, lactational amenorrhoea), barrier (condoms, diaphragm, IUDs — Cu releasing, hormonal — Mirena), oral (Mala-D, Saheli — non-steroidal), implants/injections, surgical (vasectomy, tubectomy).
-- NCERT Class 12 Biology, Ch. 3, p. 44These are the exact patterns that cause wrong answers in NEET. Each trap includes when it triggers and how to avoid it.
Category: Similar Terms
Hormonal: pills, implants. Barrier: condom, diaphragm. IUD: Cu releasing (CuT), hormonal (LNG-20). Surgical: vasectomy/tubectomy.
Question asks which category a specific method falls in.
Map by mechanism: hormone → pill/implant; physical block → barrier; uterine → IUD; permanent → surgical.
Root cause: concept gap
IUD mechanisms vary: copper IUDs (CuT) increase phagocytosis of sperm; hormonal IUDs (Mirena/LNG-20) thicken cervical mucus + suppress endometrium. Both reduce implantation.
More in Reproduction: 8 exam traps and mistakes · 1 question pattern from its other lessons.
7 questions from NEET 2021, 2022, 2023, 2024. Answers verified against NTA official keys.
Which of the following is not a natural/traditional contraceptive method?
Lippe’s loop is a type of contraceptive used as:
Which one of the following is an example of Hormone releasing IUD?
Page numbers are the ones printed in the current NCERT textbook (2023 rationalised edition), unless marked pre-2023. The books are free at ncert.nic.in.
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