Biomolecules — Class 11 MCQs with Answers
Class 11 CBSE Biology · Chapter 9
90 practice questions · 30 Easy · 30 Medium · 30 Hard · Updated
Practise the most important Class 11 CBSE Biology questions from Chapter 9, "Biomolecules". You get 9 timed quizzes made from 90 NCERT-based MCQs, with answers and explanations. The questions are split into 30 Easy, 30 Medium and 30 Hard. Warm up on the basics, then move on to the exam-level questions that set top scorers in CBSE & Maharashtra HSC Board exams, MHT-CET and NEET UG apart.
To score well in "Biomolecules", focus on diagrams, key terms and knowing NCERT line by line. Each MCQ here is timed and uses exam-style marking (+4 correct, −1 wrong, 0 skipped). This trains you to stay accurate under time pressure, as real papers need. Every question has a short explanation, so a wrong answer becomes a quick lesson. It is the fastest way to fix gaps before a test.
Use this chapter for focused revision. Start with the Easy set to check your basics on Biomolecules, then move to Medium and Hard to practise applying them. Your accuracy, streaks and XP save automatically. This chapter also adds to your overall Class 11 Biology mastery score. 14 sample questions are solved in full below, with the answer and a worked explanation. Sign in free to start practising.
Key concepts: Biomolecules (Class 11 Biology)
Living cells are built from a small set of biomolecules. This chapter surveys carbohydrates, proteins, lipids and nucleic acids, their monomers and bonds, then turns to enzymes — protein catalysts whose activity, governed by active sites and inhibitors, follows predictable temperature, pH and substrate relationships.
- Analysis of biomolecules
- Acid-insoluble macromolecules (proteins, nucleic acids, polysaccharides) form the biomacromolecule pool; acid-soluble small metabolites under 1000 Da make the other pool.
- Amino acids
- Building blocks of proteins with amino, carboxyl, hydrogen and R groups on one carbon; the twenty standard types are zwitterionic and differ only in their side chain.
- Proteins and peptide bond
- Amino acids link by peptide bonds into polypeptides; proteins are the most abundant biomolecule, acting as enzymes, transporters, receptors, hormones and antibodies.
- Protein structure levels
- Primary is the amino-acid sequence, secondary the helix or sheet folding, tertiary the 3-D shape, and quaternary the assembly of subunits, as in haemoglobin.
Biomolecules — important questions & MCQs with answers (Class 11 Biology)
14 solved questions from this chapter's difficulty levels, each with its answer and explanation. The other 76 are timed and scored when you sign in.
- Q1Easy
Building blocks of proteins:
A.GlucoseB.NucleotidesC.Amino acids✓ CorrectD.Fatty acidsAnswer: C. Amino acids
Explanation: Proteins are built entirely from the 20 standard amino acids joined by peptide bonds. Glucose is the monomer of carbohydrates and nucleotides build nucleic acids, not proteins.
- Q2Easy
Biomolecules can be separated into acid-soluble and acid-insoluble pools by?
A.CentrifugationB.Chromatography onlyC.ElectrophoresisD.Trichloroacetic acid treatment then filtration✓ CorrectAnswer: D. Trichloroacetic acid treatment then filtration
Explanation: Grinding tissue in trichloroacetic acid and filtering separates biomolecules: the filtrate holds small acid-soluble molecules while the residue holds acid-insoluble macromolecules.
- Q3Easy
Most enzymes are chemically?
A.CarbohydratesB.LipidsC.Proteins✓ CorrectD.Nucleic acidsAnswer: C. Proteins
Explanation: Most enzymes are proteins whose 3-D shape forms the active site; a minority of catalytic RNAs called ribozymes are the exception, not the rule.
- Q4Easy
Glucose is a:
A.LipidB.DisaccharideC.PolysaccharideD.Monosaccharide✓ CorrectAnswer: D. Monosaccharide
Explanation: Glucose is a single sugar unit (C6H12O6), so it is a monosaccharide. A disaccharide like sucrose links two such units, and a polysaccharide like starch links thousands.
- Q5Easy
Which is NOT a micromolecule?
A.Amino acidB.Protein✓ CorrectC.SugarD.NucleotideAnswer: B. Protein
Explanation: Proteins are macromolecules that end up in the acid-insoluble residue after TCA treatment. Amino acids, sugars and nucleotides are the small acid-soluble micromolecules.
- Q6Easy
Catalytic RNA molecules are called?
A.Ribozymes✓ CorrectB.CoenzymesC.ApoenzymesD.IsozymesAnswer: A. Ribozymes
Explanation: Ribozymes are RNA molecules with catalytic activity, such as the rRNA that forms peptide bonds in ribosomes. Coenzymes and prosthetic groups are cofactors, not catalysts themselves.
- Q7Medium
Three-dimensional folding of a polypeptide is termed?
A.Primary structureB.Secondary structureC.Quaternary structureD.Tertiary structure✓ CorrectAnswer: D. Tertiary structure
Explanation: Tertiary structure is the overall 3-D folding of a single polypeptide chain, stabilised by hydrogen, ionic, disulfide and hydrophobic bonds -- distinct from quaternary structure, which needs multiple chains.
- Q8Medium
Acid-soluble pool of a cell contains predominantly?
A.Proteins and nucleic acidsB.Amino acids, sugars, nucleotides✓ CorrectC.Lipids onlyD.PolysaccharidesAnswer: B. Amino acids, sugars, nucleotides
Explanation: The acid-soluble pool is the filtrate left after TCA precipitation, made up of small molecules like free amino acids, simple sugars and nucleotides; macromolecules stay in the residue.
- Q9Medium
Most enzymes are:
A.Nucleic acidsB.LipidsC.CarbohydratesD.Proteins✓ CorrectAnswer: D. Proteins
Explanation: Most enzymes are globular proteins whose folded shape creates the active site. A small class of RNA molecules called ribozymes also catalyse reactions, but proteins dominate.
- Q10Medium
α-helix of proteins is stabilised mainly by?
A.Peptide bondsB.Hydrogen bonds between C=O and N-H✓ CorrectC.Disulfide bondsD.Hydrophobic forcesAnswer: B. Hydrogen bonds between C=O and N-H
Explanation: The alpha-helix is held together by hydrogen bonds between the backbone C=O of one residue and the N-H of the residue four places ahead, not by side-chain interactions like disulfide bonds.
- Q11Medium
An essential amino acid is one that?
A.Is non-proteinB.Is required for protein function onlyC.Forms enzymesD.Cannot be synthesised by the body, must be ingested✓ CorrectAnswer: D. Cannot be synthesised by the body, must be ingested
Explanation: An amino acid is essential when the human body lacks the enzymes to synthesise it, so it must come from the diet -- lysine and methionine are classic examples. Non-essential amino acids are the ones the body CAN make internally, which is the usual mix-up.
- Q12Hard
Storage polysaccharide in animals:
A.StarchB.Glycogen✓ CorrectC.CelluloseD.ChitinAnswer: B. Glycogen
Explanation: Glycogen is the animal storage polysaccharide, stockpiled in liver and muscle. Starch plays that role in plants, while cellulose and chitin are structural, not storage, polysaccharides.
- Q13Hard
Assertion: Average composition of living tissue places water at the top by weight. Reason: Proteins are the most abundant macromolecule by weight.
A.Both true; R explains AB.A false, R trueC.A true, R falseD.Both true; R does NOT explain A✓ CorrectAnswer: D. Both true; R does NOT explain A
Explanation: Water being most abundant by weight and proteins being the most abundant macromolecule are both independently true, but the reason water dominates is its role as universal solvent, not protein content -- so R does not explain A.
- Q14Hard
Enzymes catalyse reactions by:
A.Lowering activation energy✓ CorrectB.Raising temperatureC.Adding more substrateD.Increasing pressureAnswer: A. Lowering activation energy
Explanation: Enzymes speed reactions by lowering the activation energy needed to reach the transition state, not by supplying extra energy or shifting the equilibrium point of the reaction.
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Start this chapter free →Biomolecules — FAQs
What are the key concepts in Class 11 Biology Biomolecules?+
Living cells are built from a small set of biomolecules. This chapter surveys carbohydrates, proteins, lipids and nucleic acids, their monomers and bonds, then turns to enzymes — protein catalysts whose activity, governed by active sites and inhibitors, follows predictable temperature, pH and substrate relationships. Key ideas include Analysis of biomolecules, Amino acids, Proteins and peptide bond, Protein structure levels.
What does Class 11 Biology Chapter 9 (Biomolecules) cover on XamBaaz?+
It has 90 NCERT-based MCQs on "Biomolecules": 30 Easy, 30 Medium and 30 Hard. Together they make 9 timed quizzes, and you never get the same set twice. Every question has an instant explanation. They help you prepare for CBSE & Maharashtra HSC Board exams, MHT-CET and NEET UG.
Are these "Biomolecules" questions free to practise?+
Yes. Sign in with Google to practise "Biomolecules" free. Full unlimited access is ₹999/year on a launch offer until 1 December 2026. No chapter is charged separately.
How should I revise "Biomolecules" for the exam?+
Start with the Easy quiz to check your basics, then try Medium and Hard to practise applying them. There are 9 timed quizzes on this chapter, so you can come back for a fresh set instead of one you have seen. Read each explanation, retry the questions you miss, and track your accuracy until it stays high.
Are these "Biomolecules" MCQs available with answers?+
Yes. 14 sample questions are shown here in full, each with the correct option and a step-by-step "Why" explanation. Sign in free with Google to start practising, with instant scoring.
Is there negative marking in the "Biomolecules" quizzes?+
Yes. The timed quizzes use exam-style marking: +4 for a right answer, −1 for a wrong one and 0 for a skip, the same negative marking as NEET UG. MHT-CET and CBSE board papers have no negative marking. Our mocks for those are scored their way.
What are the important questions from Biomolecules (Class 11 Biology)?+
The questions that matter most test Analysis of biomolecules, Amino acids, Proteins and peptide bond, Protein structure levels. This page shows 14 solved important MCQs with answers and explanations; all 90 questions on the chapter are available as timed quizzes once you sign in.
Is there an online quiz for Biomolecules?+
Yes — Class 11 Biology Biomolecules has timed online quizzes at Easy, Medium and Hard levels, with instant scoring and a worked explanation on every question. The first quiz on the chapter is free.