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Placed below are case… (Class 12 Biology SQP 2023-24, Q31a)

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BiologyCBSE Class 12 · Sample paper, session 2023-24 · 5 marks · Long answer

CBSE Class 12 Biology sample paper 2023-24: question 31(a)

From the official CBSE sample question paper for 2023-24, section E, question 31(a), for 5 marks. Try it first; the hints and our step-by-step solution are below.

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

Placed below are case studies of some couples who were not able to have kids. These couples are not ready for adoption or taking gametes from donors. After thoroughly examining the cases, which Assisted Reproductive Technology will you suggest to these couples as a medical expert? Explain briefly with justification of each case.

CoupleTest reports of Female partnerTest reports of male partner
Couple 1Normal reportsNormal sperms in testes, Missing connection in epididymis and Vas deferens
Couple 2Blockage in the fallopian tubeNormal reports
Couple 3Normal reportsPoor semen parameters in terms of count, motility and morphology
Couple 4low ovarian reserveNormal reports
Couple 5Sterilization in maleMorphologically abnormal sperms

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2023-24.

Hints

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

Hint 1

For each couple, find which step of natural conception fails: sperm delivery, gamete meeting, or sperm quality.

Hint 2

Remember the difference between ZIFT (≤8 blastomeres, tube) and IUT (>8 blastomeres, uterus).

Hint 3

Which technique injects a single sperm directly into an ovum?

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. Couple 1: Sperms are normal in the testes, but there is no connection through the epididymis or vas deferens, so the semen has no sperms.

    • ART: Collect sperms surgically from the testis/epididymis and fertilise the ovum by IVF (or ICSI).
    • Then transfer the embryo by ZIFT (zygote or embryo up to 8 blastomeres into the fallopian tube) or IUT (embryo with more than 8 blastomeres into the uterus).
    1 mark

  2. Couple 2: The female's blocked fallopian tube prevents sperm and ovum from meeting at the site of fertilisation.

    • ART: IVF followed by IUT (test-tube baby). The embryo with more than 8 blastomeres goes directly into the uterus, bypassing the blocked tube.
    1 mark

  3. Couple 3: The male's sperms have poor count, motility and morphology.

    • ART: ICSI (intracytoplasmic sperm injection). A selected sperm is injected directly into the ovum in the lab, and the embryo is then transferred.
    • If only the count were low, artificial insemination (IUI) could be tried.
    1 mark

  4. Couple 4: The female has low ovarian reserve and the male is normal.

    • ART: Stimulate the ovaries to recover the few available ova, then perform IVF with the partner's sperm.
    • Transfer the embryo by ZIFT (up to 8 blastomeres) or IUT (more than 8 blastomeres).
    1 mark

  5. Couple 5: The female has poor ovarian reserve and the male has morphologically abnormal sperms.

    • ART: Select the best ova and normal-looking sperms, and perform ICSI by injecting a sperm directly into each ovum.
    • Then transfer the embryo (ZIFT/IUT).
    1 mark

Answer: Couple 1: sperm retrieval + IVF/ICSI, then ZIFT/IUT; Couple 2: IVF + IUT; Couple 3: ICSI; Couple 4: IVF + ZIFT/IUT; Couple 5: ICSI.

Where the marks are

  • Couple 1: IVF with sperms from testis/epididymis, ZIFT/IUT with reason (1 mark)
  • Couple 2: IVF followed by IUT, bypassing the blocked tube (1 mark)
  • Couple 3: ICSI for poor semen parameters (1 mark)
  • Couple 4: IVF followed by ZIFT/IUT (1 mark)
  • Couple 5: ICSI with selected sperms/ova (1 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 paperSample paper 2023-24: 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.