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Select the option that… (Class 12 Biology SQP 2026-27, Q4)

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BiologyCBSE Class 12 · Sample paper, session 2026-27 · 1 mark · MCQ

CBSE Class 12 Biology sample paper 2026-27: question 4

From the official CBSE sample question paper for 2026-27, section A, question 4, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q4 · 1 mark · MCQCompetency-basedEvolution

Select the option that gives the correct description of the process of natural selection with respect to the length of the neck of the giraffe.

  1. (A)Stabilising selection as giraffes with longer neck lengths are selected further.
  2. (B)Disruptive selection as giraffes with smaller and longer neck lengths are selected.
  3. (C)Directional selection as giraffes with longer neck lengths are selected.
  4. (D)Stabilising selection as giraffes with medium neck lengths are selected.

Figure in the paper: Bell-shaped curve graph: x-axis 'Neck length in giraffe', y-axis 'Number of giraffes'; the curve peaks at medium neck length and falls at both extremes. See it in the official paper.

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2026-27.

Hints

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

Hint 1

Which neck length gave an advantage in feeding?

Hint 2

Ask whether the average moved to one end, stayed in the middle, or split towards both ends.

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. In giraffes, individuals with longer necks could reach higher foliage, so they survived and reproduced more.

  2. Over generations the mean neck length shifted towards one extreme, the longer side. This is directional selection. Option (C).

    1 mark

Answer: (C) Directional selection

Where the marks are

  • Identifies directional selection favouring longer necks (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 paperSample paper 2026-27: 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.