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Biomolecules — NEET Chemistry MCQs

30 questions written by hand against the NCERT chapter. Every wrong option is explained, not just the right one.

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Sample questions from this chapter

Which chemical description best defines carbohydrates?
  1. Optically active polyhydroxy aldehydes or ketones, or compounds yielding such units on hydrolysis ✓
  2. All compounds having the formula Cx(H2O)y
  3. Polymers made only from amino acids
  4. Hydrocarbons that dissolve in water
Answer: A. Functional groups and hydrolysis behaviour define carbohydrates, not a general empirical formula. The hydrate-of-carbon formula is the historical but overinclusive trap.
Why not B: Acetic acid fits a hydrate-of-carbon formula but is not a carbohydrate, while rhamnose is a carbohydrate that does not fit it.
Why not C: Amino-acid polymers are proteins.
Why not D: Carbohydrates contain oxygenated functional groups and are not defined as hydrocarbons.
Why do many amino acids have high melting points and appreciable water solubility?
  1. They are nonpolar hydrocarbons
  2. They exist only as neutral gas molecules
  3. They exist as ionic zwitterions containing NH3+ and COO- groups ✓
  4. They are metallic crystals
Answer: C. Internal proton transfer produces a dipolar zwitterion, strengthening electrostatic attractions and hydration. Treating the written NH2-CH(R)-COOH form as exclusively neutral misses this dominant form.
Why not A: Amino acids have polar amino and carboxyl-derived groups.
Why not B: In the solid state and often in solution they have charge-separated ionic forms.
Why not D: Their crystals are ionic molecular solids, not metallic lattices.
Glucose forms a pentaacetate on exhaustive acetylation. What does this most directly establish?
  1. Five hydroxyl groups are present ✓
  2. Five aldehyde groups are present
  3. A five-carbon chain is present
  4. Five glucose molecules are linked
Answer: A. Each acetyl group replaces the hydrogen of one OH, so formation of the pentaacetate demonstrates five hydroxyl groups. Equating five acetates with five carbons is the stoichiometric interpretation trap.
Why not B: Acetylation targets OH groups; glucose has only one carbonyl centre in its open form.
Why not C: Glucose has six carbons, and the number of acetate groups counts reactive hydroxyls rather than chain length.
Why not D: The product is a derivative of one glucose molecule, not an oligosaccharide.

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Other NEET Chemistry chapters

Some Basic Concepts of ChemistryStructure of AtomClassification of Elements and Periodicity in PropertiesChemical Bonding and Molecular StructureThermodynamicsEquilibrium

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Questions

How many NEET questions are there on Biomolecules?

This chapter test has 30 questions — 10 easy, 14 medium and 6 hard — all written against the NCERT Class 12 chapter.

Is this NEET Chemistry chapter test free?

Yes. Every chapter test is free with no login, and you get your all-India rank on every one. Nothing on the site is on sale right now.

Do the questions explain the wrong options?

Yes — every distractor carries its own explanation naming the specific misconception that makes a student pick it. That is the part most question banks skip, and it is the part that changes your next attempt.