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Answer the following. (Class 12 Chemistry SQP 2023-24, Q21)

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ChemistryCBSE Class 12 · Sample paper, session 2023-24 · 2 marks · Very short answer

CBSE Class 12 Chemistry sample paper 2023-24: question 21

From the official CBSE sample question paper for 2023-24, section B, question 21, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q21 · 2 marks · Very short answerBiomolecules

Answer the following.

  1. (a)

    DNA fingerprinting is used to determine paternity of an individual. Which property of DNA helps in the procedure?

    0 marks
  2. (b)

    What structural change will occur when a native protein is subjected to change in pH?

    0 marks

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2023-24.

Hints

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

Hint 1

What about a person's DNA is different from everyone else's, yet shared with the parents?

Hint 2

A pH change breaks the weak bonds that hold a protein's folded shape.

Hint 3

Which level of protein structure is held by peptide bonds, and which by hydrogen bonds?

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) DNA replicates and passes faithfully from parents to offspring, and the sequence of bases in each person's DNA is unique. Matching the child's DNA pattern with that of the parents therefore establishes paternity.

    1 mark

  2. (b) A change in pH denatures the protein. Hydrogen bonds are broken, so the globules unfold and the helices uncoil, destroying the secondary and tertiary structures. The primary structure (sequence of amino acids) stays intact, but the protein loses its biological activity.

    1 mark

Answer: (a) Unique base sequence of DNA, passed on by replication from parents; (b) Denaturation – 2° and 3° structures destroyed, 1° structure intact

Where the marks are

  • Unique base sequence of DNA inherited from parents via replication (1 mark)
  • Denaturation: secondary and tertiary structures destroyed, primary structure retained (1 mark)

Revise the chapter

  • Chapter: Biomolecules (notes, formulas, where marks are lost and every past question)
Practise this chapterBoard-style questions from Biomolecules, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2023-24: 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.