Class 12 Chemistry — Chapter 5: Biomolecules

Chapter 5: Biomolecules is a chapter in Class 12 Chemistry (Part 2), part of the CBSE NCERT curriculum followed by over 25 million students across India. This chapter covers 7 topics including Introduction and Definition of Carbohydrates, Classification of Carbohydrates, Classification of Monosaccharides. BrainWeave provides free AI-powered explanations — by voice or text, in Hindi or English — with no signup required.

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What you'll learn

▸Introduction and Definition of Carbohydrates

polyhydroxy aldehydepolyhydroxy ketonesaccharideshydrates of carbonoptically active
▸Classification of CarbohydratesCore concept

monosaccharidesoligosaccharidespolysaccharideshydrolysisnon-sugars
▸Classification of Monosaccharides

aldoseketosealdohexoseketopentosetriose
▸Preparation of Glucose

sucrosestarchhydrolysiscane sugardilute acid
▸Open-Chain Structure of GlucoseCore concept

n-hexanegluconic acidsaccharic acidpentaacetateoxime
▸D/L Configuration of CarbohydratesCore concept

D-glucoseL-glucoseglyceraldehydeconfigurationasymmetric carbon
▸Limitations of the Open-Chain Structure of GlucoseCore concept

Schiff's testpentaacetatecyclic structurefree aldehydeNaHSO₃

Chapter Summary

Understand the chemical definition of carbohydrates as optically active polyhydroxy aldehydes or ketones, or compounds that produce such units on hydrolysis. Differentiate the modern definition from the older 'hydrates of carbon' concept.

Classify carbohydrates based on their hydrolysis products into monosaccharides, oligosaccharides (e.g., disaccharides), and polysaccharides. Understand the key differences in their properties, such as taste and complexity.

Further classify monosaccharides based on the number of carbon atoms (triose, tetrose, pentose, hexose) and the type of functional group present (aldose for aldehyde, ketose for ketone).

Learn the two primary methods for the preparation of glucose: the laboratory method from the hydrolysis of sucrose and the commercial method from the hydrolysis of starch.

Understand the chemical evidence that establishes the open-chain structure of glucose. This includes reactions confirming the straight six-carbon chain (with HI), the carbonyl group (with NH₂OH, HCN), the aldehyde group (with Br₂ water), five -OH groups (acetylation), and a primary alcohol group (oxidation to saccharic acid).

Understand the concept of relative configuration in carbohydrates, specifically the D and L notations. Learn how this configuration is assigned by comparing the position of the -OH group on the lowest asymmetric carbon atom to that of glyceraldehyde.

Identify the experimental observations that the open-chain structure of glucose fails to explain, such as its inability to give Schiff's test and form an addition product with NaHSO₃, which points towards the existence of a cyclic structure.

Practice Questions from this Chapter

Tap "Get Solution" on any question to ask our AI tutor.

Explain carbohydrate types simply. Get Solution →
Describe how glucose powers cells. Get Solution →
Identify essential biomolecule roles. Get Solution →
What are carbohydrates that cannot be hydrolyzed further to give a simpler unit called? Get Solution →
The hydrolysis of one molecule of sucrose yields which two monosaccharides? Get Solution →
Chemically, carbohydrates are defined as optically active polyhydroxy aldehydes or what other type of compound? Get Solution →
Which polysaccharide is hydrolyzed commercially to obtain glucose? Get Solution →
Based on its functional group and number of carbon atoms, glucose is classified as a(n) ____. Get Solution →

Did you know?

💡 Our bodies contain more protein than any other molecule except water.
💡 Cellulose, a type of sugar, is the most abundant organic polymer on Earth.
💡 Chitin, which makes up insect exoskeletons, is actually a complex carbohydrate.
💡 The human brain consumes about 20% of your daily sugar energy.
💡 Sugars like glucose can be converted into useful plastics by certain microbes.

Frequently Asked Questions

How many topics are covered in this chapter?

This chapter covers 7 key topics: Introduction and Definition of Carbohydrates, Classification of Carbohydrates, Classification of Monosaccharides, Preparation of Glucose, Open-Chain Structure of Glucose, and more. The BrainWeave AI tutor explains each one with examples.

Is Chapter 5: Biomolecules important for board exams?

Yes — Class 12 is a CBSE board exam year, and every NCERT chapter is part of the syllabus. Use BrainWeave's AI tutor to master this chapter, then practice with the auto-generated quizzes and mind maps.

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Related Chapters

Chapter 4: Amines

Chapter 1: Haloalkanes and Haloarenes

Chapter 2: Alcohols, Phenols and Ethers

Chapter 3: Aldehydes, Ketones and Carboxylic Acids

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