Q10
1 markMCQSection A

The number of chromosomes in a cell division is halved. This kind of cell division is observed in:

How do Organisms Reproduce?
Sexual Reproduction — Meiosis and Germ Cells

Options

(A)Only testis
(B)Only ovary
(C)Ovary and testis both
(D)All cells of the body
Official Answer

C

meiosistestisovarygerm-cellschromosome number halved

Hint

Think about which two organs make the sperm and the egg — the text calls this halving division 'meiosis' and links it to germ-cell formation.

Quick Oral Answer

Both the testis and the ovary contain special germ-cell lineages that undergo meiosis, halving the chromosome number, so that fertilisation restores the normal chromosome count in the new individual.

Analysis & Explanation

The chapter explains: "many multi-cellular organisms have found... to have special lineages of cells in specialised organs in which only half the number of chromosomes and half the amount of DNA as compared to the nonreproductive body cells [are present]. This is achieved by a process of cell division called meiosis." In humans, these germ-cells (sperms and eggs) are formed specifically in the testis (male) and ovary (female).


  • (A) Only testis — incorrect. This ignores that the female reproductive organ, the ovary, also produces germ-cells (eggs) through the same halving (meiotic) division.
  • (B) Only ovary — incorrect. Similarly, this ignores that sperm formation in the testis also involves this reductional division.
  • (C) Ovary and testis both — correct. Both organs contain the specialised germ-cell lineages where meiosis halves the chromosome number, so that when the male and female gametes fuse during fertilisation, the normal (full) chromosome number is restored in the zygote.
  • (D) All cells of the body — incorrect. Ordinary body (somatic) cells divide by mitosis, which keeps the chromosome number constant, not halved; only the specialised reproductive-organ cell lineages undergo the chromosome-halving division.

Common Mistakes

  1. 1Believing meiosis occurs in all body cells like ordinary growth-related cell division
  2. 2Thinking only the male or only the female organ undergoes this halving, not both

Interesting Facts

This halving is essential bookkeeping: since sexual reproduction combines DNA from two parents, halving the chromosome number in germ-cells before fertilisation prevents the DNA content from doubling every generation.

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2025?

This question carries 1 mark in the CBSE Class 10 Science 2025 examination.

Which chapter does this question come from in Science?

This question is from the chapter "How do Organisms Reproduce?" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Sexual Reproduction — Meiosis and Germ Cells" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2025 paper?

This is a MCQ question from Section A in the CBSE Class 10 Science 2025 paper.