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CBSE Class 12 Chemistry Chapter 10 Biomolecules Worksheet with Answers

Biomolecules form the chemical foundation of all living systems, and Chapter 10 in NCERT Class 12 Chemistry explores carbohydrates, proteins, vitamins, and nucleic acids in depth. This worksheet is structured to give you focused 90-minute practice covering every topic from monosaccharides to DNA structure. Print it, attempt it under timed conditions, then check the detailed answer key at the end to identify gaps and strengthen your board exam readiness.

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Key takeaways

✓Complete worksheet covering carbohydrates, proteins, vitamins, and nucleic acids as per NCERT Class 12 Chemistry syllabus
✓90-minute difficulty level suitable for board exam preparation with progressive question complexity
✓Six multiple-choice questions test foundational understanding of biomolecule classification and properties
✓Five short-answer questions require explanations of enzyme action, vitamin deficiencies, and structural differences
✓Three HOTS long-answer questions demand deep conceptual clarity on glycosidic linkages, protein structures, and DNA-RNA differences
✓Case-study question integrates real-world applications of biomolecules in nutrition and medicine
✓Complete answer key with step-by-step explanations ensures self-assessment and concept reinforcement

Chapter 10 Biomolecules: Quick Recap

Chapter 10 Biomolecules introduces four major classes of biological macromolecules. Carbohydrates are polyhydroxy aldehydes or ketones, classified as monosaccharides (glucose, fructose), oligosaccharides (sucrose, maltose), and polysaccharides (starch, cellulose, glycogen). Proteins are polymers of alpha-amino acids linked by peptide bonds; their structures range from primary (sequence) to quaternary (multi-subunit assemblies). Enzymes are biological catalysts with remarkable specificity. Vitamins are organic compounds required in trace amounts, categorized as fat-soluble (A, D, E, K) or water-soluble (B-complex, C). Nucleic acids—DNA and RNA—are polymers of nucleotides, each comprising a nitrogenous base, pentose sugar, and phosphate group. DNA stores genetic information with a double-helix structure, while RNA plays roles in protein synthesis. Understanding structural formulas, functional group identification, and biomolecule classification is critical for CBSE board success.

Carbohydrates: monosaccharides, disaccharides, polysaccharides; reducing vs non-reducing sugars
Proteins: amino acids, peptide linkage, primary to quaternary structures, denaturation, enzymes
Vitamins: fat-soluble (A, D, E, K) and water-soluble (B, C); deficiency diseases
Nucleic acids: DNA (double helix, A-T & G-C pairing) and RNA (single strand, uracil instead of thymine)

Worksheet Details: Difficulty Level and Time

This worksheet is calibrated at moderate-to-high difficulty, mirroring the 2025 CBSE Class 12 Chemistry board exam pattern for Chapter 10. It is designed for a 90-minute timed practice session, which replicates the portion of time you would allocate to Biomolecules in a full three-hour board paper. Section A and B questions are foundational and should take 20-25 minutes combined. Section C matching or true-false items test recall and take roughly 10 minutes. Section D short-answer questions (2-3 marks each) require concise explanations and chemical structures, budgeting 25-30 minutes. Section E long-answer and HOTS questions (5 marks each) demand detailed mechanistic or comparative answers, allocating 25 minutes. The case-study question integrates theory with application and merits 10 minutes. Use the answer key only after completing all sections to simulate real exam discipline and build time-management skills crucial for scoring above ninety percent in CBSE 12 Chemistry.

Difficulty: Moderate-to-high, aligned with CBSE board exam standards
Suggested time: 90 minutes under exam conditions
Section-wise time: A+B (25 min), C (10 min), D (30 min), E (25 min), Case (10 min)
Answer key provided at the end with step-by-step explanations

Section A: Multiple Choice Questions (1 mark each)

Multiple-choice questions assess your grasp of definitions, structural features, and functional classifications within Biomolecules. Each question has four options; choose the single best answer. These six MCQs cover carbohydrate nomenclature, protein structure terminology, vitamin solubility, nucleotide components, enzyme specificity, and glycosidic linkage types. They mirror the objective-type items that frequently appear in CBSE board papers and competitive entrance tests. Practicing MCQs sharpens your ability to eliminate wrong options quickly and reinforces NCERT language. Aim to complete this section in under 8 minutes, leaving time to revisit any doubtful questions. Remember that even one-mark questions require precise recall of NCERT definitions and examples, so review your Class 12 Chemistry notes on carbohydrates, proteins, vitamins, and nucleic acids before attempting this section to maximize accuracy and confidence during the actual board examination.

Q1. Which of the following is a non-reducing sugar? (a) Glucose (b) Fructose (c) Sucrose (d) Maltose
Q2. The secondary structure of protein is stabilized by: (a) Peptide bonds (b) Hydrogen bonds (c) Disulfide bridges (d) Ionic bonds
Q3. Vitamin B12 contains which metal ion? (a) Iron (b) Cobalt (c) Zinc (d) Copper
Q4. In DNA, adenine pairs with thymine through how many hydrogen bonds? (a) One (b) Two (c) Three (d) Four
Q5. Enzymes are chemically: (a) Carbohydrates (b) Lipids (c) Proteins (d) Nucleic acids
Q6. The linkage present in polysaccharides is called: (a) Peptide linkage (b) Glycosidic linkage (c) Ester linkage (d) Phosphodiester linkage

Section B: Fill in the Blanks (1 mark each)

Fill-in-the-blank questions test your ability to recall precise NCERT terminology and key facts without the crutch of multiple options. This section contains five statements with missing terms related to carbohydrate classification, amino acid properties, vitamin deficiency diseases, nucleotide structure, and enzyme action. Write the exact word or phrase that best completes each sentence. Accuracy in spelling matters, especially for chemical names like 'deoxyribose' or 'peptide.' These questions often appear in the board exam as one-mark rapid-fire items, so practice writing answers neatly and legibly. Budget approximately 6-7 minutes for this section. Reviewing NCERT Class 12 Chemistry notes on Biomolecules will help you internalize definitions such as 'glycosidic linkage,' 'denaturation,' and 'codon.' Consistent practice of fill-in-the-blank items builds the muscle memory required to recall technical vocabulary instantly under examination pressure, boosting both speed and accuracy in the CBSE board paper.

Q7. Starch is a polymer of __________ units.
Q8. The bond formed between two amino acids is called a __________ bond.
Q9. Deficiency of Vitamin D causes __________.
Q10. RNA contains the sugar __________ instead of deoxyribose.
Q11. The phenomenon of loss of biological activity of proteins due to heat or chemicals is called __________.

Section C: Match the Following (1 mark each pair)

Matching exercises reinforce connections between biomolecule types and their specific properties, examples, or functions. In this section you will find two columns: Column A lists five biomolecule-related terms or structures, and Column B provides corresponding examples, deficiency diseases, or structural features. Draw lines or write the correct pairs (for example, A-iv, B-ii) to demonstrate your understanding. This format is popular in CBSE Class 12 Chemistry Chapter 10 questions because it efficiently tests breadth of knowledge across carbohydrates, proteins, vitamins, and nucleic acids in a compact format. Allocate roughly 8-10 minutes to this section. Carefully read each item in both columns before matching to avoid careless errors. Cross-check that each answer in Column B is used exactly once. Matching questions reward systematic revision of NCERT tables and summary boxes, so refer back to your Class 12 Chemistry notes to ensure you can instantly link terms like 'cellulose' with 'beta-1,4-glycosidic linkage' or 'Vitamin C' with 'scurvy,' thereby securing these straightforward marks confidently in your board examination.

Section D: Short Answer Questions (2-3 marks each)

Short-answer questions require you to explain concepts, write structural formulas, or differentiate between related terms in 30-50 words. This section contains five questions worth 2-3 marks each, covering enzyme specificity and lock-and-key model, differences between DNA and RNA, vitamin deficiency diseases, reducing versus non-reducing sugars with examples, and the structure of a nucleotide. Each answer should be concise yet complete, using NCERT language and including chemical structures or diagrams where asked. Allocate approximately 25-30 minutes to this section, spending 5-6 minutes per question. Practice writing answers in point form to save time and improve clarity. For example, when asked to differentiate DNA and RNA, present a tabular comparison of sugar type, bases, strand count, and function. Reviewing NCERT Class 12 Chemistry solutions and Class 12 Chemistry notes will help you frame model answers that match the board's marking scheme. Well-structured short answers demonstrate depth of understanding and secure you full marks even when the question permits brief responses, making this section a high-yield scoring opportunity in the CBSE board exam.

Q12. Explain the lock-and-key model of enzyme action. (2 marks)
Q13. Differentiate between DNA and RNA on the basis of sugar and bases present. (3 marks)
Q14. Name two fat-soluble vitamins and the deficiency disease caused by each. (2 marks)
Q15. What are reducing sugars? Give two examples. (2 marks)
Q16. Draw the structure of a nucleotide and label its three components. (3 marks)

Section E: Long Answer and HOTS Questions (5 marks each)

Long-answer and higher-order thinking questions assess your ability to integrate concepts, compare structures, and provide detailed mechanistic explanations. This section presents three five-mark questions on glycosidic linkages in starch and cellulose with structural implications, the hierarchy of protein structure from primary to quaternary with examples of bonds at each level, and a comprehensive comparison of DNA and RNA covering structure, function, location, and stability. Each answer should be 100-150 words, well-organized into sub-points or short paragraphs, and supported by chemical structures or diagrams where appropriate. Budget 25 minutes total, roughly 8 minutes per question. HOTS questions often ask you to 'explain why' or 'compare and contrast,' so go beyond rote definitions to demonstrate conceptual clarity. For instance, when discussing starch versus cellulose, note that both are glucose polymers but differ in glycosidic linkage (alpha versus beta), which affects digestibility and physical properties. Refer to NCERT Class 12 Chemistry notes and Class 12 Chemistry solutions to practice model answers. Mastery of long-answer questions distinguishes top scorers in the CBSE board exam, as these items test depth, coherence, and the ability to communicate chemistry clearly.

Q17. Explain the difference between starch and cellulose in terms of glycosidic linkage. Why can humans digest starch but not cellulose? (5 marks)
Q18. Describe the four levels of protein structure (primary, secondary, tertiary, quaternary) with examples of bonds stabilizing each. (5 marks)
Q19. Compare DNA and RNA under the following headings: sugar present, nitrogenous bases, number of strands, location in cell, stability, and function. (5 marks)

Section F: Case-Study Question (4 marks)

Case-study questions integrate real-world scenarios with chapter concepts, testing your ability to apply theoretical knowledge to practical situations. This four-mark item presents a short passage about nutrition, disease, or biotechnology involving biomolecules, followed by sub-questions that probe understanding of carbohydrates, proteins, vitamins, or nucleic acids in context. For example, a case on diabetes may ask you to identify the biomolecule involved (glucose), explain why it is a reducing sugar, and describe the role of insulin (a protein hormone). Allocate 10 minutes to read the passage carefully, underline key facts, and answer each sub-question precisely. Case studies reward students who can bridge textbook theory and everyday applications, a skill increasingly emphasized in the CBSE board exam pattern. Practice similar passages from NCERT Class 12 Chemistry exemplars and previous years' board papers. Writing clear, direct answers that reference the passage demonstrates analytical ability and ensures you capture full marks. Use CBSETUTOR.ai to upload case-study screenshots and get instant, step-by-step breakdowns, helping you master this high-value question format efficiently at just ₹999 per month for all classes with a three-day free trial.

Answer Key with Explanations

The answer key below provides correct responses and brief explanations for every question in Sections A through F. Use it only after completing the entire worksheet to simulate real exam conditions. Each MCQ answer is followed by a one-line rationale referencing NCERT concepts. Fill-in-the-blank answers are given with the exact term expected. Matching pairs are listed explicitly. Short-answer model responses include key points and structural formulas where required. Long-answer solutions are outlined in bullet form, highlighting the main arguments and examples you should include. The case-study solution breaks down each sub-question logically. Cross-check your answers against this key, award yourself marks honestly, and identify topics that need revision. If you scored below seventy percent, revisit the corresponding NCERT sections and Class 12 Chemistry notes, then re-attempt weak areas. Consistent practice with self-assessment builds confidence and ensures you walk into the CBSE board exam fully prepared to tackle any Biomolecules question with precision and speed.

A1. (c) Sucrose — non-reducing because the anomeric carbons of glucose and fructose are involved in glycosidic linkage.
A2. (b) Hydrogen bonds — alpha-helix and beta-pleated sheets are stabilized by H-bonds between C=O and N-H groups.
A3. (b) Cobalt — Vitamin B12 (cyanocobalamin) contains a cobalt ion at its core.
A4. (b) Two — Adenine and thymine pair via two hydrogen bonds; guanine and cytosine pair via three.
A5. (c) Proteins — Enzymes are biological catalysts composed of amino acid chains.
A6. (b) Glycosidic linkage — the C-O-C bond between monosaccharide units in polysaccharides.
A7. Glucose (or alpha-D-glucose units).
A8. Peptide bond (or peptide linkage).
A9. Rickets (in children) or osteomalacia (in adults).
A10. Ribose.
A11. Denaturation.
Match: A-ii, B-v, C-i, D-iv, E-iii.
A12. The lock-and-key model states that the enzyme's active site (lock) has a complementary shape to the substrate (key). Only the specific substrate fits, ensuring high specificity of enzyme action.
A13. DNA contains deoxyribose sugar; RNA contains ribose. DNA has bases A, G, C, T; RNA has A, G, C, U. DNA is double-stranded; RNA is single-stranded. DNA stores genetic info; RNA is involved in protein synthesis.
A14. Vitamin A causes night blindness; Vitamin D causes rickets. (Both are fat-soluble.)
A15. Reducing sugars contain a free aldehyde or ketone group that can reduce Fehling's or Benedict's reagent. Examples: glucose, fructose, maltose.
A16. A nucleotide consists of: (i) nitrogenous base (purine or pyrimidine), (ii) pentose sugar (ribose or deoxyribose), (iii) phosphate group. [Draw and label structure.]
A17. Starch has alpha-1,4-glycosidic linkages; cellulose has beta-1,4-linkages. Humans possess enzymes (amylase) to break alpha-linkages but lack cellulase for beta-linkages, so starch is digestible but cellulose is not. Cellulose acts as dietary fiber.
A18. Primary: sequence of amino acids linked by peptide bonds. Secondary: alpha-helix or beta-sheet stabilized by H-bonds. Tertiary: 3D folding stabilized by disulfide bridges, H-bonds, ionic & hydrophobic interactions (e.g. myoglobin). Quaternary: multiple polypeptides (e.g. hemoglobin with four subunits).
A19. DNA: deoxyribose sugar, bases A-T-G-C, double helix, mainly nucleus, stable. RNA: ribose sugar, bases A-U-G-C, single strand, nucleus & cytoplasm, less stable, involved in protein synthesis and gene expression.
Case: (i) Vitamin C (ascorbic acid). (ii) Water-soluble. (iii) Acts as antioxidant and is essential for collagen synthesis. (iv) Water-soluble vitamins are not stored in the body and are excreted, so daily intake is necessary.

How CBSETUTOR.ai Helps You Master Biomolecules

CBSETUTOR.ai offers a twenty-four-by-seven AI tutor designed specifically for CBSE students from Class 6 to 12. For Chapter 10 Biomolecules, you can upload photos of tricky structural formulas, enzyme diagrams, or case-study passages and receive instant step-by-step solutions in simple language. The platform covers the entire NCERT Class 12 Chemistry syllabus, ensuring you have on-demand support for carbohydrates, proteins, vitamins, and nucleic acids any time doubt strikes. At a flat ₹999 per month for all classes, it is far more affordable than traditional tuition, and the three-day free trial lets you test-drive the AI tutor risk-free. Whether you need clarification on glycosidic linkages, peptide bond formation, or DNA-RNA structural differences, CBSETUTOR.ai delivers clear explanations aligned to CBSE marking schemes. Students across India use it to reinforce Class 12 Chemistry notes, practice additional worksheets, and build the confidence required to excel in board exams and competitive entrances. Try it today and experience personalized, instant chemistry help that fits your study schedule.

Upload structural formulas or diagrams from Biomolecules and get instant AI explanations
Covers all NCERT Class 12 Chemistry chapters, including detailed solutions for Chapter 10
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Tips to Maximize Your Worksheet Practice

To extract full value from this worksheet, treat it as a mock test: print it, set a ninety-minute timer, and work in a quiet space without notes. Attempt every section in order, resisting the urge to peek at the answer key. This discipline mirrors real board exam conditions and trains time management. After completing all questions, score yourself honestly using the answer key and tally marks section-wise. Identify patterns—did you lose marks in MCQs due to careless reading, or in long answers due to incomplete explanations? Revisit those NCERT sections and rework similar questions from Class 12 Chemistry solutions. Make flashcards for definitions (denaturation, glycosidic linkage, codon) and structural formulas (nucleotide, peptide bond). Practice drawing diagrams neatly, as board examiners award marks for clear, labeled structures. Repeat this worksheet after a week to measure improvement. Pair worksheet practice with concept videos or AI-powered doubt solving on CBSETUTOR.ai for a blended learning approach that covers theory, application, and self-assessment comprehensively, ensuring you approach the CBSE board exam with confidence and clarity.

Simulate exam conditions: print, timer, no notes
Complete all sections before checking answers to build endurance
Identify weak areas from your score breakdown and revise targeted NCERT topics
Practice drawing and labeling structures neatly for maximum marks
Reattempt the worksheet after one week to track progress and reinforce learning

Frequently asked questions

What topics are covered in CBSE Class 12 Chemistry Chapter 10 Biomolecules?+

Chapter 10 covers carbohydrates (monosaccharides, disaccharides, polysaccharides), proteins (amino acids, peptide bonds, enzyme action), vitamins (fat-soluble and water-soluble), and nucleic acids (DNA and RNA structure and function) as per the NCERT syllabus.

How much time should I spend on this Biomolecules worksheet?+

Allocate a full 90 minutes under timed conditions. Section A and B take roughly 25 minutes, Section C 10 minutes, Section D 30 minutes, Section E 25 minutes, and the case-study 10 minutes, mirroring actual board exam pacing.

Are the answers provided with explanations?+

Yes, the complete answer key at the end includes correct answers and brief explanations for every MCQ, fill-in-the-blank, matching, short-answer, long-answer, and case-study question, helping you understand mistakes and reinforce concepts.

What is the difficulty level of this worksheet?+

The worksheet is moderate-to-high difficulty, designed to match the CBSE Class 12 board exam standard for Chapter 10. It includes foundational recall questions and HOTS items that test deep conceptual understanding and application skills.

Can this worksheet help me score above 90 percent in boards?+

Yes, regular practice of structured worksheets like this one builds speed, accuracy, and familiarity with question formats. Combined with thorough NCERT revision and doubt-solving via platforms like CBSETUTOR.ai, students can confidently target ninety-plus scores.

How do I use the answer key effectively?+

Attempt the entire worksheet first without referring to the key. Then check each answer, award marks honestly, and note topics where you lost marks. Revisit those NCERT sections, make notes, and rework similar questions to close gaps.

What is the difference between reducing and non-reducing sugars?+

Reducing sugars have a free aldehyde or ketone group that can reduce Fehling's or Benedict's reagent (e.g. glucose, fructose, maltose). Non-reducing sugars like sucrose have the anomeric carbons of both monosaccharides involved in the glycosidic bond, so no free carbonyl is available.

Why should I practice case-study questions for Biomolecules?+

Case-study questions test your ability to apply theoretical knowledge to real-world scenarios, a skill increasingly emphasized in CBSE board exams. They integrate multiple concepts and reward analytical thinking, making them high-value scoring opportunities.

How can CBSETUTOR.ai help with Chapter 10 doubts?+

CBSETUTOR.ai provides a 24×7 AI tutor where you can upload photos of structural formulas, enzyme diagrams, or case passages and get instant step-by-step solutions. At ₹999/month for all classes with a three-day free trial, it is an affordable, on-demand doubt-solving tool.

What are the key structural differences between DNA and RNA?+

DNA contains deoxyribose sugar and bases A, T, G, C; it is double-stranded and more stable. RNA has ribose sugar and bases A, U, G, C; it is single-stranded, less stable, and involved in protein synthesis and gene expression.

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