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Which one of the following… (Class 12 Biology 2023, Q1)

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BiologyCBSE Class 12 · Board exam 2023, set 57/1/1 · 1 mark · MCQ

CBSE Class 12 Biology 2023: question 1

Set in the CBSE Class 12 board exam of 2023, paper 57/1/1, section A, question 1, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q1 · 1 mark · MCQPrinciples of Inheritance and Variation

Which one of the following processes results in the production of recombinants in future generations ?
(i) Mutation
(ii) Independent assortment during meiosis I
(iii) Independent assortment during meiosis II
(iv) Crossing over of bivalents

  1. (A)(iv) only
  2. (B)(ii) and (iv)
  3. (C)(i), (ii) and (iii)
  4. (D)(i), (ii), (iii) and (iv)

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 57/1/1.

Hints

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

Hint 1

Recombination means new combinations of genes that already exist in the parents.

Hint 2

Which meiotic events reshuffle homologous chromosomes or exchange segments between them?

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. Recombinants (new combinations of parental genes) arise from independent assortment of homologous chromosomes in meiosis I and from crossing over between non-sister chromatids of bivalents in prophase I.

    1 mark

  2. Mutation produces new alleles rather than recombining existing ones, and meiosis II only separates sister chromatids, so (i) and (iii) are excluded. Answer: (ii) and (iv).

Answer: (ii) and (iv), option (B)

Where the marks are

  • Chooses (ii) and (iv) (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Principles of Inheritance and Variation, one at a time, marked against the answer key and marking points.Back to the full paper2023 board paper, set 57/1/1: 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.