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Mendel took garden pea… (Class 10 Science 2026, Q15a)

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ScienceCBSE Class 10 · Board exam 2026, set 31/1/1 · 4 marks · Short answer

CBSE Class 10 Science 2026: question 15(a)

Set in the CBSE Class 10 board exam of 2026, paper 31/1/1, section A, question 15(a), for 4 marks. Try it first; the hints and our step-by-step solution are below.

Q15(a) · 4 marks · Short answerHeredity

Mendel took garden pea plants with different characteristics, such as height to study the inheritance pattern of factors (genes). He crossed tall pea plant with short pea plant and obtained all the tall plants in the F1 generation. Answer the following questions:

  1. (a)

    Why only tall pea plants were observed in F1 progeny?

    1 mark
  2. (b)

    By which method did Mendel obtain F2 progeny?

    1 mark
  3. (c)(i)

    Write one difference between dominant and recessive trait.

    2 marks

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

Hints

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

Hint 1

Write the genotypes of the parents and of the F₁.

Hint 2

How did Mendel cross F₁ plants among themselves?

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) The tall parent (TT) gives T and the short parent (tt) gives t, so every F₁ plant is Tt. Tallness (T) is dominant over shortness (t), so all F₁ plants appear tall.

    1 mark

  2. (b) Mendel obtained the F₂ progeny by self-pollination of the F₁ tall plants.

    1 mark

  3. (c)(i) A dominant trait expresses itself even in the presence of the recessive factor, so it shows in both TT and Tt. A recessive trait is masked when the dominant factor is present; it shows only when both factors are recessive (tt).

    2 marks

Answer: (a) F₁ is Tt and tall is dominant over short; (b) self-pollination of F₁; (c)(i) dominant trait shows in TT and Tt, recessive shows only in tt.

Where the marks are

  • F₁ is Tt; tall is dominant (1 mark)
  • Self-pollination (1 mark)
  • Correct difference between dominant and recessive traits (2 marks)

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 31/1/1: 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.