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The given graph shows the… (Class 12 Biology 2025, Q7)

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BiologyCBSE Class 12 · Board exam 2025, set 57/7/1 · 1 mark · MCQ

CBSE Class 12 Biology 2025: question 7

Set in the CBSE Class 12 board exam of 2025, paper 57/7/1, section A, question 7, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q7 · 1 mark · MCQCompetency-basedEvolution

The given graph shows the range of variation among population members, for a trait determined by multiple genes. If this population is subjected to disruptive selection for several generations, which of the following distributions is most likely to result ?
Choose the correct option :

  1. (A)Broad, low, flattened bell-shaped curve
  2. (B)Narrow, tall, single-peaked curve
  3. (C)Curve with two peaks (bimodal) with a dip in the middle
  4. (D)Skewed curve with single peak towards the right

Figure in the paper: Given graph: Population (y-axis) vs trait range (x-axis), a normal bell-shaped curve with a single central peak. Options (A)-(D) are population curves: (A) broad low flattened arch, (B) narrow tall single peak, (C) two peaks with a dip between, (D) single peak skewed to the right. Option texts are described from the figures. See it in the official paper.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 57/7/1.

Hints

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

Hint 1

Which individuals are favoured in disruptive selection?

Hint 2

What happens to the middle of the curve if the mean value is selected against?

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. Disruptive selection favours individuals at both extremes and acts against the average form.

  2. Over several generations two peaks form at the extremes, with a dip in the middle (a bimodal curve). Hence (C).

    1 mark

Answer: (C)

Where the marks are

  • Disruptive selection gives a bimodal curve (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Evolution, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 57/7/1: 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.