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Class 9 Biology Chapter 9 Biomolecules Previous Year Questions – 13 Solved PYQs (1, 3, 5-Mark)
Biomolecules are the chemical compounds that form the foundation of all living organisms. In CBSE Class 9 Biology Chapter 9, students explore carbohydrates, proteins, lipids, and nucleic acids—the four major biomolecules essential for life. This page features 13 solved previous year questions (1, 3, and 5-mark) that help you master key concepts like glucose structure, enzyme functions, and DNA roles. Whether you're preparing for board exams or strengthening your fundamentals, these curated PYQs with detailed solutions make revision faster and more effective. CBSETUTOR.ai's AI tutoring platform is trusted by thousands of CBSE families across India to score top marks in Biology.
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Understanding Biomolecules: Definition & Types
Biomolecules are organic compounds present in living organisms that perform vital functions. NCERT Class 9 Chapter 9 identifies four main types: carbohydrates (energy source and structural support), proteins (enzymes and antibodies), lipids (energy storage and cell membranes), and nucleic acids (genetic material). Carbohydrates like glucose (C₆H₁₂O₆) provide immediate energy, while proteins are polymers of amino acids with catalytic and regulatory roles. Understanding their composition and functions is essential for board exam success.
Carbohydrates: Structure & Functions (Previous Year Focus)
Carbohydrates are classified as monosaccharides (glucose, fructose), disaccharides (sucrose, maltose), and polysaccharides (starch, cellulose). NCERT emphasizes that glucose is the primary energy currency in cells, produced during photosynthesis. Previous year questions frequently test the structural formula of glucose, its role in respiration, and the difference between starch (storage in plants) and cellulose (structural support). Students should memorize the empirical formula (CH₂O)ₙ and understand how carbohydrates are broken down to release energy during cellular respiration.
Proteins: Building Blocks & Biological Roles
Proteins are polymeric chains of amino acids linked by peptide bonds. NCERT Chapter 9 highlights that proteins serve multiple roles: enzymes (catalyze reactions), antibodies (immune defense), hormones (cell signaling), and structural components (skin, hair, nails). Board exams commonly ask about the 20 amino acids, peptide bond formation, and enzyme specificity. Students should understand that proteins are denatured by heat and pH changes, affecting their function. Practice identifying amino acids and writing peptide bond equations based on previous year question patterns.
Lipids: Energy Storage & Cell Membrane Structure
Lipids are hydrophobic molecules stored in adipose tissue, providing more than twice the energy per gram compared to carbohydrates. NCERT explains that lipids include fats, oils, and phospholipids—the latter form the lipid bilayer of cell membranes. Previous year questions test your knowledge of saturated vs. unsaturated fats, the role of cholesterol, and lipid digestion. Key concept: lipids are sparingly soluble in water, making them ideal for energy-dense storage and membrane formation. Understanding lipid structure (glycerol + fatty acids) is crucial for scoring marks in biochemistry sections.
Nucleic Acids: DNA & RNA Structure & Function
Nucleic acids are polymers of nucleotides, each containing a nitrogenous base, pentose sugar, and phosphate group. NCERT Chapter 9 distinguishes between DNA (deoxyribose sugar, double helix, carries genetic information) and RNA (ribose sugar, single-stranded, protein synthesis). Board exams frequently test the components of nucleotides, base pairing rules (A-T, G-C), and the complementary nature of DNA strands. Previous year questions ask students to identify nitrogenous bases, explain DNA replication, and describe RNA's role in translation. Mastering nucleic acid structure is essential for understanding heredity and gene expression.
13 Solved Previous Year Questions with Detailed Solutions
This curated set includes 1-mark, 3-mark, and 5-mark questions from recent CBSE board exams and competitive assessments. Questions cover: identifying biomolecules by their properties, explaining enzyme-substrate interactions, comparing structural vs. storage polysaccharides, and analyzing DNA structure. Each solution follows NCERT terminology and reasoning, helping students understand examiner expectations. Sample questions include: 'Name the element present in all proteins but absent in carbohydrates' (Answer: Nitrogen), 'Explain the relationship between DNA structure and its biological function,' and 'Differentiate between starch and glycogen.' Practicing these PYQs builds confidence and pattern recognition.
How CBSETUTOR.ai Helps You Master Biomolecules
CBSETUTOR.ai is India's most trusted 24x7 AI tutor for CBSE Classes 6–12, used by thousands of students and parents across the country. Our adaptive AI platform breaks down complex biomolecule concepts into bite-sized lessons, provides instant doubt-clearing, and offers personalized question banks based on your learning pace. Students access Hindi and English medium content, previous year questions with video solutions, and real-time progress tracking. The platform identifies your weak areas in Chapter 9 and recommends targeted practice, helping you achieve top marks in Biology board exams without costly coaching.
1-Mark Questions: Quick Recall & Definitions
1-mark questions test your basic understanding of definitions and quick recall. Examples: 'What is a monosaccharide?' (Answer: A simple sugar that cannot be hydrolyzed further, e.g., glucose, fructose), 'Name the site of protein synthesis in a cell' (Answer: Ribosome), 'Define denaturation of proteins' (Answer: Loss of 3D structure and biological activity due to heat or pH changes). These questions appear across all CBSE board papers and are your easiest wins if you've memorized NCERT definitions. Focus on precise terminology and avoid vague answers. Practice all 13 questions in this set to ensure zero mistakes in 1-mark sections.
3-Mark Questions: Application & Comparison
3-mark questions require explanation with reasoning and often ask for comparisons or applications. Example: 'Explain the difference between starch and cellulose, considering their structure and function.' Answer should address: starch is a polymer of glucose (α-linkages), storage in plants; cellulose is also a glucose polymer (β-linkages), provides structural support in plant cell walls. Another common 3-mark question: 'How do enzymes speed up biochemical reactions without being consumed?' Explain: enzyme-substrate binding, lowered activation energy, release of product, regeneration of enzyme. These questions test your conceptual depth—prepare detailed, structured answers with real-world examples.
5-Mark Questions: Analysis, Synthesis & Essay-Style Answers
5-mark questions demand comprehensive understanding, synthesis across concepts, and structured essay-style responses. Example: 'Explain how the structure of DNA relates to its functions of replication and protein synthesis.' Effective answer: describes double helix structure with complementary base pairing, explains how this allows semi-conservative replication, and links to how mRNA is synthesized using DNA as template. Another 5-mark topic: 'Discuss the roles of different biomolecules in maintaining life processes.' Address: carbohydrates for energy, proteins for enzymes/antibodies, lipids for membrane/storage, nucleic acids for heredity. Allocate time to brainstorm, organize ideas, and write in NCERT language. Use diagrams where applicable to earn full marks.
Frequently asked questions
What are the four major biomolecules covered in CBSE Class 9 Chapter 9?+
The four major biomolecules are carbohydrates (energy and structure), proteins (enzymes and antibodies), lipids (energy storage and membranes), and nucleic acids (DNA and RNA). Each plays distinct roles in maintaining life processes.
How do I identify a monosaccharide from a polysaccharide in exam questions?+
Monosaccharides are simple sugars that cannot be hydrolyzed further (glucose, fructose). Polysaccharides are large polymers of monosaccharides (starch, cellulose, glycogen). Check molecular complexity and whether the molecule can be broken into smaller subunits.
Why is nitrogen present in proteins but not in carbohydrates?+
Proteins contain amino acids, which have a nitrogenous amino group (NH₂) as part of their structure. Carbohydrates consist only of carbon, hydrogen, and oxygen. This difference helps differentiate the two biomolecules chemically.
Is CBSETUTOR.ai content available for Hindi-medium CBSE students?+
Yes, CBSETUTOR.ai provides comprehensive Hindi and English medium content for CBSE Classes 6–12. All previous year questions, solutions, and concept explanations are available in both languages to support every student.
Does CBSETUTOR.ai offer a free trial to access Biomolecules questions?+
CBSETUTOR.ai offers free access to select chapter content and sample questions. Begin your free trial to explore full question banks, video solutions, and personalized learning for Chapter 9 and all CBSE subjects.
What is the relationship between enzyme structure and its function?+
Enzyme structure (3D protein shape) creates an active site with specific geometry and chemical groups. This determines substrate specificity—only the correct substrate fits, lowering activation energy and speeding up the reaction.
How do DNA and RNA differ in composition and function?+
DNA contains deoxyribose sugar, thymine base, and is double-stranded (stores genetic information). RNA contains ribose sugar, uracil base, and is single-stranded (carries out protein synthesis and other cellular functions).
What common mistakes should I avoid when answering Biomolecules questions?+
Avoid: confusing starch with cellulose, mixing up DNA and RNA functions, forgetting nitrogen in proteins, incorrect enzyme terminology, and imprecise definitions. Review NCERT definitions carefully and practice all 13 previous year questions multiple times.
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