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The graph given below shows… (Class 12 Biology 2023, Q17)

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BiologyCBSE Class 12 · Board exam 2023, set 57/5/1 · 2 marks · Very short answer

CBSE Class 12 Biology 2023: question 17

Set in the CBSE Class 12 board exam of 2023, paper 57/5/1, section B, question 17, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q17 · 2 marks · Very short answerCompetency-basedHuman Reproduction

The graph given below shows the number of primordial follicles per ovary in women at different ages. Study the graph and answer the questions that follow.

  1. (a)

    What is the average age of the women at the onset of menopause ?

    1 mark
  2. (b)

    At what age are maximum primordial follicles present in the ovary, according to the given graph ?

    1 mark

Figure in the paper: Scatter graph: x-axis Age (y) from 0 to 60 (marks at 10,20,30,40,50,60); y-axis Primordial follicles/ovary on a log scale (0,1,10,100,1000,10,000,100,000). Filled squares (premenopausal women, regular menses) cluster near 100,000 at young ages and decline with age; open squares (perimenopausal women, irregular menses for at least one year) lie around ages 40-55 at lower values; triangles (post menopausal women, no menses for at least one year) lie near 0-1 at ages about 45-55. See it in the official paper.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 57/5/1.

Hints

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

Hint 1

Menopause is the stage when menses stop and very few follicles remain. Look for where the triangles begin on the age axis.

Hint 2

For (b), find the highest filled square on the log-scale y-axis and read its age on the x-axis.

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) Read the age where the open squares (perimenopausal women) give way to the triangles (postmenopausal women, follicle count near 0–1). This happens at about 47 years, so the average age at the onset of menopause is about 47 years (roughly 45–49 years).

    1 mark

  2. (b) The filled squares reach their highest point, about 100,000 primordial follicles per ovary, in early childhood at about 6–8 years of age. After that the count falls steadily with age.

    1 mark

Answer: (a) About 47 years (45–49 years); (b) About 6–8 years of age

Where the marks are

  • States the average age at onset of menopause as about 47 years; any value from 45 to 49 is accepted (1 mark)
  • States the age of maximum primordial follicles as about 6–8 years (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Human Reproduction, one at a time, marked against the answer key and marking points.Back to the full paper2023 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.