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Study the given chart showing… (Class 12 Biology 2026, Q24)

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BiologyCBSE Class 12 · Board exam 2026, set 57/5/1 · 3 marks · Short answer

CBSE Class 12 Biology 2026: question 24

Set in the CBSE Class 12 board exam of 2026, paper 57/5/1, section C, question 24, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q24 · 3 marks · Short answerCompetency-basedEvolution

Study the given chart showing evolution of plants. Answer the following questions :

(a) Identify the plant which acts as an immediate ancestor of both ferns and conifers.
(b) Name the nearest ancestors of flowering plants.
(c) Name the most primitive group of plants.
(d) Psilophyton provides common ancestry to which classes ?
(e) Name the common ancestor of psilophyton and seed ferns.
(f) Name the common ancestor of mosses and tracheophytes.

Figure in the paper: Flow chart with boxes: top row Moss, Ferns, Conifers, Flowering plants. Flowering plants arrow from Seed ferns; Seed ferns arrow from Psilophyton (via a side line). Ferns and Conifers arrows from Psilophyton. Psilophyton arrow from Tracheophyte ancestors, which arrow from Chlorophyte ancestors. Moss arrow comes directly from Chlorophyte ancestors. See it in the official paper.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 57/5/1.

Hints

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

Hint 1

Trace each arrow in the chart backwards, from the plant group to the box it comes from.

Hint 2

The box at the very bottom of the chart is the oldest. Find where branches split to get common ancestors.

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) Psilophyton is the immediate ancestor of both ferns and conifers.

    ½ mark

  2. (b) Seed ferns are the nearest ancestors of flowering plants.

    ½ mark

  3. (c) Chlorophyte ancestors are the most primitive group, at the base of the chart.

    ½ mark

  4. (d) Psilophyton gives common ancestry to ferns, conifers and seed ferns.

    ½ mark

  5. (e) Tracheophyte ancestors are the common ancestor of Psilophyton and seed ferns.

    ½ mark

  6. (f) Chlorophyte ancestors are the common ancestor of mosses and tracheophytes.

    ½ mark

Answer: (a) Psilophyton; (b) Seed ferns; (c) Chlorophyte ancestors; (d) Ferns, conifers, seed ferns; (e) Tracheophyte ancestors; (f) Chlorophyte ancestors

Where the marks are

  • (a) Psilophyton (½ mark)
  • (b) Seed ferns (½ mark)
  • (c) Chlorophyte ancestors (½ mark)
  • (d) Ferns, conifers and seed ferns (½ mark)
  • (e) Tracheophyte ancestors (½ mark)
  • (f) Chlorophyte ancestors (½ mark)

Revise the chapter

  • Chapter: Evolution (notes, formulas, where marks are lost and every past question)
Practise this chapterBoard-style questions from Evolution, one at a time, marked against the answer key and marking points.Back to the full paper2026 board paper, set 57/5/1: 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.