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The image below shows… (Class 10 Science SQP 2024-25, Q35B)

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ScienceCBSE Class 10 · Sample paper, session 2024-25 · 5 marks · Long answer

CBSE Class 10 Science sample paper 2024-25: question 35(B)

From the official CBSE sample question paper for 2024-25, section D, question 35(B), for 5 marks. Try it first; the hints and our step-by-step solution are below.

Q35(B) · 5 marks · Long answerCompetency-basedHow do Organisms Reproduce?

The image below shows a developing fetus in the mother's womb. The developing fetus is connected to the placenta by means of umbilical cord. The Umbilical vein and artery run inside the umbilical cord.
(i) Name two substance that moves through the blood vessels. (1)
(ii) If the placenta has less villi how will it affect the baby's growth? (1)
(iii) Name the region where the embryo develops inside the female body. Explain how this region is adapted for nourishing the baby. (1)
(iv) Some of the fetal cells fall off into the amniotic fluid and can be collected by careful procedure. The cells were screened and found to contain XY chromosome. (2)
a) What is the sex of the foetus?
b) How is this prenatal sex determination misused?

(A version for visually impaired students is printed with the same parts without the image.)

Figure in the paper: Fetus in amniotic fluid connected by umbilical cord (with umbilical arteries and vein labelled) to the placenta; a syringe is shown drawing amniotic fluid. See it in the official paper.

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2024-25.

Hints

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

Hint 1

What does a growing baby need from its mother, and what must it get rid of?

Hint 2

Villi are like the folds of the small intestine. What do such folds increase?

Hint 3

Which sex chromosome decides that a child is a boy?

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) The umbilical vessels carry materials between mother and foetus.

    • Glucose and oxygen pass from mother to foetus.
    • Carbon dioxide and nitrogenous wastes pass from foetus to mother.

    Any two of these substances, e.g. glucose and oxygen.

    1 mark

  2. (ii) Villi give the placenta a large surface area for exchange. With fewer villi, the surface area is smaller. Less glucose and oxygen pass from mother to embryo, and wastes are removed less efficiently. The baby's growth would therefore be slow (retarded).

    1 mark

  3. (iii) The embryo develops in the uterus. To nourish the baby, the uterus develops a thick, spongy lining with a rich blood supply. The embryo is attached to this lining through the placenta, so nutrients and oxygen reach it easily.

    1 mark

  4. (iv)(a) The cells carry the XY sex chromosomes, i.e. a Y chromosome is present. The foetus is therefore a male child.

    1 mark

  5. (iv)(b) Some people use prenatal tests to find the sex of the foetus. If it is female, they get it aborted. This is female foeticide, which is illegal and lowers the sex ratio. For this reason, prenatal sex determination is banned by law.

    1 mark

Answer: (i) e.g. glucose and oxygen (also CO₂/wastes); (ii) smaller surface area for exchange, so slow growth of the baby; (iii) uterus, whose thick lining has a rich blood supply; (iv)(a) male, (iv)(b) misused for female foeticide

Where the marks are

  • Any two substances exchanged, e.g. glucose, oxygen, CO₂, wastes (1 mark)
  • Fewer villi means less surface area, less nutrient supply and slow growth (1 mark)
  • Names uterus and states its thick, blood-rich lining (1 mark)
  • Identifies the foetus as male (1 mark)
  • States misuse as female foeticide (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from How do Organisms Reproduce?, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2024-25: 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.