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A pure pea plant having round… (Class 10 Science 2025, Q30)

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ScienceCBSE Class 10 · Board exam 2025, set 31/3/1 · 3 marks · Short answer

CBSE Class 10 Science 2025: question 30

Set in the CBSE Class 10 board exam of 2025, paper 31/3/1, section C, question 30, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q30 · 3 marks · Short answerHeredity

A pure pea plant having round (R), yellow (Y) seeds is crossed with another pure pea plant having wrinkled (r), green (y) seeds. Subsequently progeny is self-pollinated to obtain progeny.

  1. (a)

    What do the seeds of generation look like?

    1 mark
  2. (b)

    Give the possible combinations of traits in seeds of generation. Also give their ratio.

    1 mark
  3. (c)

    State the reason of obtaining seeds of new combination of traits in generation.

    1 mark

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 31/3/1.

Hints

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

Hint 1

Only the dominant traits show in F₁.

Hint 2

Draw a 4×4 checkerboard with gametes RY, Ry, rY, ry.

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) Cross RRYY × rryy gives all RrYy, so all seeds are round and yellow (round and yellow are dominant).

    1 mark

  2. (b) combinations: round yellow : round green : wrinkled yellow : wrinkled green = 9 : 3 : 3 : 1.

    1 mark

  3. (c) New combinations (round green, wrinkled yellow) appear because the two traits are inherited independently of each other (independent assortment).

    1 mark

Answer: (a) Round, yellow; (b) RY : Ry(green) : wrinkled yellow : wrinkled green = 9 : 3 : 3 : 1; (c) independent inheritance of traits

Where the marks are

  • F₁ all round yellow (1 mark)
  • Four combinations with 9:3:3:1 ratio (1 mark)
  • Independent inheritance/assortment of traits (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 paper2025 board paper, set 31/3/1: 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.