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Answer the following. (Class 10 Science 2026, Q14)

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ScienceCBSE Class 10 · Board exam 2026, set 31/2/1 · 3 marks · Short answer

CBSE Class 10 Science 2026: question 14

Set in the CBSE Class 10 board exam of 2026, paper 31/2/1, section A, question 14, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q14 · 3 marks · Short answerHeredity

Answer the following.

  1. (a)

    Giving two examples, justify the statement that the sex of the offspring in all animals is not always genetically determined.

    0 marks
  2. (b)

    Differentiate between the sex chromosomes of male and female human beings.

    0 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 31/2/1.

Hints

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

Hint 1

Think of animals where an environmental factor, not genes, decides the sex.

Hint 2

For humans, compare the 23rd pair of chromosomes in males and females.

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) Example 1: In a few reptiles, the temperature at which the fertilised eggs are kept decides whether the animal developing from the egg will be male or female.

    1 mark

  2. (a) Example 2: In snails, individuals can change sex. So sex is not always fixed by genes.

    1 mark

  3. (b) Males have a mismatched pair of sex chromosomes, XY, in which Y is smaller than X. Females have a perfect pair, XX, with both X chromosomes of the same size.

    1 mark

Answer: (a) Temperature-dependent sex determination in some reptiles; sex change in snails. (b) Male: XY (mismatched, Y smaller); Female: XX (matched pair).

Where the marks are

  • Example of reptiles where egg temperature decides sex (1 mark)
  • Example of snails changing sex (1 mark)
  • Difference: male XY mismatched pair vs female XX perfect pair (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Heredity, one at a time, marked against the answer key and marking points.Back to the full paper2026 board paper, set 31/2/1: 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.