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Answer the following. (Science 2025 31/6/1 Q35b)

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ScienceCBSE Class 10 · Board exam 2025, set 31/6/1 · 5 marks · Long answer

CBSE Class 10 Science 2025: question 35(b)

Set in the CBSE Class 10 board exam of 2025, paper 31/6/1, 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 answerHow do Organisms Reproduce?

Answer the following.

  1. (a)

    Name the part performing following functions in human female reproductive system :

    0 marks
  2. (i)

    production of eggs

    0 marks

  3. OR

    (ii)

    site of fertilization

    0 marks

  4. OR

    (iii)

    site of implantation

    0 marks

  5. OR

    (iv)

    entry of the sperms

    0 marks
  6. (b)

    What changes are observed in the uterus : (i) subsequent to implantation of zygote and (ii) if an egg does not get fertilized ?

    0 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 31/6/1.

Hints

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

Hint 1

Follow the egg's path: where it is made, where it meets sperm, where the embryo settles, and where sperm enter.

Hint 2

After implantation, think about how the embryo gets food and oxygen from the mother.

Hint 3

If no embryo arrives, what happens to the thickened lining that was prepared for it?

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. (a)(i) Production of eggs: ovary

    ½ mark

  2. (a)(ii) Site of fertilisation: oviduct (fallopian tube)

    ½ mark

  3. (a)(iii) Site of implantation: uterus

    ½ mark

  4. (a)(iv) Entry of sperms: vagina

    ½ mark

  5. (b)(i) After implantation, the zygote keeps dividing and forms the embryo.

    ½ mark

  6. The thickened uterine lining, rich in blood vessels, nourishes the developing embryo.

    ½ mark

  7. A special tissue called the placenta develops. Through it the embryo receives glucose and oxygen from the mother's blood, and its wastes are passed into the mother's blood for removal.

    ½ mark

  8. (b)(ii) If the egg is not fertilised, the egg lives for about a day and the thick, spongy uterine lining is no longer needed. The lining slowly breaks down and comes out through the vagina as blood and mucus, along with the unfertilised egg. This is menstruation, which occurs roughly every month and lasts about 2–8 days.

    1½ marks

Answer: (a) (i) Ovary (ii) Oviduct/fallopian tube (iii) Uterus (iv) Vagina; (b)(i) lining thickens and nourishes the embryo, placenta forms; (ii) lining breaks down and is shed as blood and mucus (menstruation).

Where the marks are

  • Four correct parts named (½ × 4 = 2 marks)
  • Changes after implantation: zygote/embryo develops, thick vascular lining nourishes it, placenta forms (½ × 3 = 1½ marks)
  • Uterine lining breaks down and comes out as blood and mucus – menstruation (1½ marks)

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 paper2025 board paper, set 31/6/1: 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.