10th Class Chemistry Chapter 13 Notes | Get Now

10th Class Chemistry Chapter 13 Notes cover Unit 13 “Biochemistry,” a scoring chapter that deals with the chemistry of living organisms. This unit explains carbohydrates, proteins, lipids, nucleic acids, and vitamins in detail. These 10th Class Chemistry Chapter 13 Notes are designed to help Matric students understand each concept clearly and prepare effectively for their board exams.

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Biochemistry connects classroom chemistry with everyday biology, which makes it interesting but also detailed. That’s why these 10th Class Chemistry Chapter 13 Notes are organized following the exact textbook pattern of Long Questions, Short Questions, and MCQs, so students can revise efficiently before exams.

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What Is Biochemistry?

Biochemistry is the branch of chemistry that studies the chemical composition and reactions of living organisms. It covers macromolecules like carbohydrates, proteins, lipids, and nucleic acids that are essential for life processes.

Carbohydrates: Structure and Classification

A major portion of these 10th Class Chemistry Chapter 13 Notes focuses on carbohydrates, which are polyhydroxy aldehydes or ketones with the general formula Cₙ(H₂O)ₙ.

Carbohydrates are classified into three types:

• Monosaccharides – simplest sugars (3–9 carbon atoms) that cannot be hydrolyzed, such as glucose and fructose
• Oligosaccharides – give 2 to 9 units of monosaccharides on hydrolysis, such as sucrose
• Polysaccharides – macromolecular carbohydrates like starch and cellulose, made of hundreds to thousands of monosaccharide units

Glucose and Fructose

Glucose is a pentahydroxy aldehyde, while fructose is a pentahydroxy ketone. Both share the same molecular formula, C₆H₁₂O₆, but differ in structure.

Hydrolysis of Sucrose

On hydrolysis, sucrose (C₁₂H₂₂O₁₁) breaks down into one unit of glucose and one unit of fructose using dilute HCl and heat.

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Beneficial Aspects of Carbohydrates

These 10th Class Chemistry Chapter 13 Notes also explain how carbohydrates benefit the human body:

1. Regulate blood sugar levels and prevent hypoglycemia
2. Provide nutrients for intestinal bacteria that aid digestion
3. Dietary fibre keeps the bowel functioning properly
4. Help lower cholesterol and regulate blood pressure
5. Protect muscles from cramping

Proteins and Amino Acids

Proteins are highly complicated nitrogenous compounds made up of amino acids, containing carbon, hydrogen, oxygen, nitrogen, and sulphur. They are polymers formed when amino acids link through peptide linkage.

Sources and Uses of Proteins

• Animal sources – meat, chicken, fish, eggs (used as food)
• Enzymes – protein catalysts that speed up body reactions and are used as drugs
• Hides – used to make leather for shoes and jackets
• Bones – produce gelatin when heated, used in bakery items
• Plant sources – pulses and beans used as food

Amino Acids

Amino acids have the general formula R–CH(NH₂)–COOH. There are 20 amino acids in total, out of which 10 can be synthesized by the human body (non-essential), while the remaining 10 must come from diet (essential amino acids).

Lipids: Oils and Fats

Lipids are macromolecules made up of fatty acids. They are classified into oils and fats, both of which are esters of long-chain carboxylic (fatty) acids with glycerol.

Difference Between Oils and Fats

• Oils – liquid at room temperature; triglycerides of unsaturated fatty acids
• Fats – solid at room temperature; triglycerides of saturated fatty acids

Sources and Uses of Lipids

• Animal fats are found in adipose tissue and used to make butter and ghee
• Plant oils like sunflower, coconut, and corn oil are used for cooking
• Marine oils like cod liver oil are used as medicine
• Fats and oils are also a source of vitamins A, D, and E

Hydrogenation of Vegetable Oil

Vegetable oils (unsaturated triesters) are converted into vegetable ghee (saturated triester) through hydrogenation using a nickel catalyst at 250–300°C. A similar process at 200°C produces margarine.

Nucleic Acids: DNA and RNA

Nucleic acids are long-chain molecules made up of nucleotides, each consisting of a nitrogenous base, a pentose sugar, and a phosphate group. Nucleic acids are classified into:

• DNA (Deoxyribonucleic acid)
• RNA (Ribonucleic acid)

Structure and Function of DNA

DNA’s double helix structure was discovered by J. Watson and F. Crick in 1953. It stores and passes genetic information from generation to generation, determining how proteins are synthesized from amino acids.

Function of RNA

RNA is synthesized by DNA to transmit genetic information. It receives, reads, and decodes instructions to synthesize new proteins, which is why RNA is called a “messenger.”

Vitamins: Types and Importance

These 10th Class Chemistry Chapter 13 Notes also explain the role of vitamins in daily life. Vitamins are organic substances the body cannot synthesize, so they must come from diet.

Fat-Soluble Vitamins

Vitamins A, D, E, and K dissolve in fats. If taken in excess, they accumulate in the body and may cause disease, such as bone pain from excess vitamin D.

Water-Soluble Vitamins

Vitamin B-complex and vitamin C dissolve in water. These are rapidly excreted from the body, so they are less likely to cause toxicity even in higher amounts.

Sources and Importance of Key Vitamins

• Vitamin A – found in dairy, eggs, fish; maintains epithelium health; deficiency causes night blindness
• Vitamin D – found in fish liver, dairy; formed in skin through sunlight; helps calcium absorption for healthy bones

Enzymes and Their Commercial Uses

Enzymes are proteins produced by living cells that catalyze biochemical reactions with high specificity and efficiency. Commercial uses include:

• Fermentation of molasses to produce ethanol
• Detergents that break down fats, starch, and protein stains
• Purification of fruit juices
• Bread making using amylase enzymes
• Dairy industry for cheese and yogurt production

Important Short Questions to Remember

These 10th Class Chemistry Chapter 13 Notes highlight commonly asked short questions, including:

• Why monosaccharides are called reducing sugars
• Difference between essential and non-essential amino acids
• What is meant by denaturing of proteins
• Why rancid butter has a foul smell (due to butanoic acid)
• Components of nucleotides in DNA

MCQs Practice

This chapter ends with 71 multiple-choice questions covering carbohydrates, proteins, lipids, vitamins, and nucleic acids. Practicing these MCQs alongside the 10th Class Chemistry Chapter 13 Notes strengthens conceptual clarity for objective-type papers.

Tips to Prepare This Chapter Effectively

• Memorize the general formulas of carbohydrates, amino acids, and triglycerides.
• Focus on the structures of glucose and fructose, as they are frequently asked.
• Understand the difference between DNA and RNA functions.
• Revise fat-soluble and water-soluble vitamins with their sources and deficiency diseases.
• Practice past MCQs to build exam confidence.

FAQs

Q1. What are 10th Class Chemistry Chapter 13 Notes about?
These notes cover Biochemistry, including carbohydrates, proteins, lipids, nucleic acids (DNA and RNA), enzymes, and vitamins, following the official Matric Chemistry syllabus with long questions, short questions, and MCQs.

Q2. What is the general formula of carbohydrates?
The general formula of carbohydrates is Cₙ(H₂O)ₙ. They are classified as monosaccharides, oligosaccharides, and polysaccharides based on the number of sugar units they contain.

Q3. What is the difference between DNA and RNA?
DNA stores and passes genetic information across generations through its double helix structure, while RNA reads and decodes this information to direct the synthesis of new proteins in the cell.

Q4. Where can I download 10th Class Chemistry Chapter 13 Notes?
Students can access and download complete 10th Class Chemistry Chapter 13 Notes, including long questions, short questions, and MCQs, directly from TaleemWorld.com for free exam preparation.

Q5. Why are monosaccharides called reducing sugars?
Monosaccharides like glucose and fructose are called reducing sugars because they are reducing in nature and cannot be hydrolyzed further, unlike disaccharides and polysaccharides.

Q6. What is the difference between oils and fats?
Oils are liquid at room temperature and are triglycerides of unsaturated fatty acids, while fats are solid at room temperature and are triglycerides of saturated fatty acids.