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Answer the following. (Class 12 Biology 2026, Q31b)

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BiologyCBSE Class 12 · Board exam 2026, set 57/1/1 · 5 marks · Long answer

CBSE Class 12 Biology 2026: question 31(b)

Set in the CBSE Class 12 board exam of 2026, paper 57/1/1, section E, question 31(b), for 5 marks. Try it first; the hints and our step-by-step solution are below.

Q31(b) · 5 marks · Long answerCompetency-basedReproductive Health

Answer the following.

  1. (i)

    Case studies of some couples are given below. They were not able to have kids even though the parents were not taking any precautions. They also do not wish to adopt a child or take the help of donors. Study these cases and suggest an appropriate Assisted Reproductive Technology that could help them.
    Case I – Female – Normal Reports. Male – Normal sperms but no connection between epididymis and vas deferens. (1)
    Case II – Female – Normal eggs but Fallopian tube blocked. Male – Normal sperms. Male reports are normal. (1)
    Case III – Female – Normal Reports. Male – Low sperm count with less motility. (1)

    3 marks
  2. (ii)

    Copper releasing intrauterine devices are very effective and popular contraceptive devices. Name any two copper releasing IUDs. Write two reasons that make them effective contraceptives.

    2 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 57/1/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

In each case, locate the problem: sperm transport, egg transport, or sperm number and motility.

Hint 2

If the fallopian tube is blocked, the embryo must be placed where the blockage is bypassed.

Hint 3

For IUDs, think about what copper ions do to sperms and to uterine phagocytes.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. (i) Case I: the sperms are normal but cannot reach the ejaculate because the epididymis–vas deferens link is missing. Sperms can be retrieved and used in in vitro fertilization followed by ZIFT (embryo up to 8 blastomeres transferred into the fallopian tube). Alternatively, the collected semen can be used for artificial insemination / IUI. The female's reports are normal, so either is suitable.

    1 mark

  2. Case II: the eggs and sperms are normal but the fallopian tube is blocked, so fertilization cannot occur in the body. Suggested method: IVF followed by IUT (intra-uterine transfer of an embryo with more than 8 blastomeres into the uterus), which bypasses the tube.

    1 mark

  3. Case III: the male has a low sperm count with poor motility. Suggested method: ICSI (intra-cytoplasmic sperm injection, i.e. a sperm injected directly into the ovum in the laboratory) or artificial insemination / IUI with the husband's semen.

    1 mark

  4. (ii) Copper-releasing IUDs: CuT and Multiload 375 (also Cu7).

    1 mark

  5. They are effective because (1) they increase phagocytosis of sperms within the uterus, and (2) the Cu ions released suppress sperm motility and the fertilising capacity of sperms.

    1 mark

Answer: (i) Case I: IVF + ZIFT (or IUI/AI); Case II: IVF + IUT; Case III: ICSI (or AI/IUI); (ii) CuT, Multiload 375 (Cu7); they increase phagocytosis of sperms, and Cu ions suppress sperm motility and fertilising capacity

Where the marks are

  • Case I: IVF–ZIFT/IUT or IUI/AI (1 mark)
  • Case II: IVF followed by IUT (1 mark)
  • Case III: ICSI or AI/IUI (1 mark)
  • Any two copper IUDs (½ + ½ mark)
  • Two reasons: increased phagocytosis of sperms; Cu ions suppress sperm motility and fertilising capacity (½ + ½ mark)

Revise the chapter

Practise this chapterBoard-style questions from Reproductive Health, one at a time, marked against the answer key and marking points.Back to the full paper2026 board paper, set 57/1/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.