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Select the incorrect match… (Class 12 Biology 2024, Q4)

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BiologyCBSE Class 12 · Board exam 2024, set 57/1/1 · 1 mark · MCQ

CBSE Class 12 Biology 2024: question 4

Set in the CBSE Class 12 board exam of 2024, paper 57/1/1, section A, question 4, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q4 · 1 mark · MCQPrinciples of Inheritance and Variation

Select the incorrect match from the following :

Human Karyotype – Characters

  1. (A)45 + XX – Broad palm with characteristic palm crease
  2. (B)44 + XXY – Overall feminine development
  3. (C)44 + XO – Sterile females as ovaries are rudimentary
  4. (D)44 + XY – Normal male

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 57/1/1.

Hints

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

Hint 1

Name the syndrome that goes with each karyotype.

Hint 2

A person with a Y chromosome is phenotypically male.

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. 44 + XXY is Klinefelter's syndrome. The person is a sterile male showing gynaecomastia, not an overall female, so the match in (B) is incorrect.

    1 mark

  2. The other options are correct matches: 45 + XX (trisomy 21) is Down's syndrome, 44 + XO is Turner's syndrome, and 44 + XY is a normal male.

Answer: (B)

Where the marks are

  • Identifies the Klinefelter match as incorrect (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 paper2024 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.