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A cross between two tall pea… (Class 10 Science 2024, Q12)

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ScienceCBSE Class 10 · Board exam 2024, set 31/3/1 · 1 mark · MCQ

CBSE Class 10 Science 2024: question 12

Set in the CBSE Class 10 board exam of 2024, paper 31/3/1, section A, question 12, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q12 · 1 mark · MCQHeredity

A cross between two tall pea plants resulted in offsprings having a few dwarf plants. The gene-combination of the parental plants must be

  1. (A)Tt and Tt
  2. (B)Tt and tt
  3. (C)TT and tt
  4. (D)TT and Tt

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 31/3/1.

Hints

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

Hint 1

A dwarf plant must be homozygous recessive.

Hint 2

Where did each of the two t alleles come from?

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. Dwarf plants are tt, so each parent must give a t allele. Both parents are tall, so each must carry T as well. Each parent is therefore Tt.

  2. Tt × Tt gives TT : Tt : tt = 1 : 2 : 1, so about ¼ of the offspring are dwarf ('a few'). Option (A).

    1 mark

Answer: Tt and Tt, option (A)

Where the marks are

  • Concludes both parents are heterozygous Tt (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 paper2024 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.