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Answer the following : (any… (Class 12 Chemistry 2024, Q27)

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ChemistryCBSE Class 12 · Board exam 2024, set 56/1/1 · 3 marks · Short answer

CBSE Class 12 Chemistry 2024: question 27

Set in the CBSE Class 12 board exam of 2024, paper 56/1/1, section C, question 27, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q27 · 3 marks · Short answerBiomolecules

Answer the following : (any three)

  1. (a)

    What is peptide linkage ?

    1 mark
  2. (b)

    What type of bonds hold a DNA double helix together ?

    1 mark
  3. (c)

    Which one of the following is a polysaccharide ? Sucrose, Glucose, Starch, Fructose

    1 mark
  4. (d)

    Give one example each for water-soluble vitamins and fat-soluble vitamins.

    1 mark

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 56/1/1.

Hints

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

Hint 1

Think of the bond formed by condensation of –COOH and –NH₂.

Hint 2

Base pairing in DNA involves N–H and O/N atoms; a polysaccharide is made of many monosaccharide units.

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) Peptide linkage is the amide (–CO–NH–) bond formed between the –COOH group of one α-amino acid and the –NH₂ group of another with loss of a water molecule.

    1 mark

  2. (b) The two strands of DNA are held together by hydrogen bonds between complementary bases (A=T with two, G≡C with three H-bonds).

    1 mark

  3. (c) Starch is the polysaccharide (sucrose is a disaccharide; glucose and fructose are monosaccharides).

    1 mark

  4. (d) Water-soluble: vitamin B or C; fat-soluble: vitamin A, D, E or K.

Answer: (a) –CO–NH– bond between amino acids; (b) hydrogen bonds; (c) starch; (d) e.g. vitamin C (water-soluble), vitamin A (fat-soluble)

Where the marks are

  • Peptide linkage as –CONH– bond joining two amino acids (1 mark)
  • Hydrogen bonding between base pairs (1 mark)
  • Starch (1 mark)
  • One water-soluble (B/C) and one fat-soluble (A/D/E/K) vitamin (1 mark) — any three parts counted

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 paper2024 board paper, set 56/1/1: 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.