Skip to content

(a) What are the hydrolysis… (Class 12 Chemistry 2023, Q30)

questionbuddy.in/q/cbse-12-chemistry-2023-56-1-1-q30-hydrolysis-products-lactose-maltose-give

ChemistryCBSE Class 12 · Board exam 2023, set 56/1/1 · 3 marks · Short answer

CBSE Class 12 Chemistry 2023: question 30

Set in the CBSE Class 12 board exam of 2023, paper 56/1/1, section C, question 30, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q30 · 3 marks · Short answerBiomolecules

(a) What are the hydrolysis products of (i) Lactose, (ii) Maltose ?
(b) Give the basic structural difference between starch and cellulose.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 56/1/1.

Hints

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

Hint 1

Lactose is milk sugar; it contains a sugar other than glucose.

Hint 2

Maltose is malt sugar made of identical units.

Hint 3

Compare the anomeric form (α or β) of glucose in starch and in cellulose.

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)(i) Lactose on hydrolysis gives β-D-galactose and β-D-glucose.

    1 mark

  2. (a)(ii) Maltose on hydrolysis gives two molecules of α-D-glucose.

    1 mark

  3. (b) Starch is a polymer of α-D-glucose: amylose is a linear chain with C1–C4 α-glycosidic links, and amylopectin is branched with C1–C6 links. Cellulose is a linear, unbranched polymer of β-D-glucose joined by C1–C4 β-glycosidic linkages.

    1 mark

Answer: (a)(i) Galactose + glucose; (ii) glucose + glucose; (b) starch = α-D-glucose polymer, cellulose = β-D-glucose polymer

Where the marks are

  • Lactose → glucose + galactose (1 mark)
  • Maltose → two glucose units (1 mark)
  • Starch made of α-glucose, cellulose of β-glucose (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 paper2023 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.