Lesson 3.3.13.1

3.3.13.1 Amino acids Quiz: AQA Chemistry, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.3.13.1, Amino acids: 20 multiple choice questions for the AQA Chemistry (7405), Unit 3: Organic chemistry, written with Revision Ninja.

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The 20 questions

  1. What functional groups does an amino acid contain?

    • A ketone and a hydroxyl group, which are the functional groups in simple sugars
    • Two ester groups, which are the functional groups formed by the amino acid units
    • An amine group and a carboxylic acid group
    • A nitrile and a halogen, which are the functional groups in halogenated alkyl nitriles

  2. What is a zwitterion?

    • An ion with a permanent charge of +2, which forms when the amine is doubly protonated
    • An ion with both a positive and a negative group but a net charge of zero
    • A metal complex with two ligands, which is held together by coordinate bonds only
    • A molecule with no functional groups, which has no charged sites at any pH

  3. Which species does an amino acid form in strongly acidic solution?

    • A cation with -NH3+ and -COOH groups
    • An anion with -NH2 and -COO- groups
    • A dimer with two ester links
    • A neutral zwitterion with no charged groups

  4. Which species does glycine form in strongly alkaline solution?

    • H3N+CH2COOH, a cation that forms in strongly acidic solution with a positive charge
    • H2NCH2COO-, an anion with -NH2 and -COO- groups that forms in strongly alkaline solution
    • H2NCH2COO-, an anion with -NH2 and -COO-
    • H2NCH2COOH, a neutral molecule with both the amine and acid groups uncharged

  5. What is the net charge of an amino acid at its isoelectric point?

    • -1
    • Zero
    • +2
    • +1

  6. Which structure shows the zwitterion of alanine?

    • H2N-CH(CH3)-COOH
    • +H3N-CH(CH3)-COO-
    • H2N-CH(CH3)-COO-Na+
    • H3N+-CH(CH3)-COOH with Cl-

  7. What term describes a substance that can react with both acids and bases?

    • Catalytic
    • Chiral
    • Neutral
    • Amphoteric

  8. Why do amino acids have relatively high melting points compared with similar organic compounds?

    • They contain metal atoms that form strong metallic bonds between the molecules
    • Strong attractions between zwitterions, which behave like ionic salts
    • They have no intermolecular forces, so they dissolve easily in all solvents
    • They are always gases at room temperature, because they have very small molar masses

  9. What is the general formula of an alpha-amino acid?

    • RCOOCH3, which is the general formula of an ester formed from an acid and methanol
    • RCH2CHO, which is the general formula of an aldehyde with an alkyl side chain
    • RCH(NH2)COOH
    • RCONH2, which is the general formula of a primary amide with a single nitrogen atom

  10. What is the simplest amino acid?

    • Valine
    • Serine
    • Alanine
    • Glycine

  11. Why can amino acids form dipeptides?

    • They have both an amine group and a carboxylic acid group that can condense
    • They contain a triple bond between carbon atoms, which allows them to add together
    • They are metal salts that combine directly with each other to form a chain of ions
    • They have no reactive functional groups, so they cannot bond to each other at all

  12. What is the net charge of an amino acid when the solution pH is below its isoelectric point?

    • Zero
    • Positive
    • It depends only on the molar mass
    • Negative

  13. Why does the -NH2 group of an amino acid gain a proton in acid solution?

    • The amino group is negatively charged
    • The nitrogen lone pair acts as a base and accepts H+
    • The nitrogen loses its lone pair to the carboxyl group
    • The amino group is an acid that donates H+ easily

  14. What is the product when glycine reacts with hydrochloric acid?

    • H3N+CH2COOH Cl-
    • H2NCH2COO- Na+
    • H2NCH2COOCH3
    • H3N+CH2COO-

  15. What is the product when glycine reacts with sodium hydroxide?

    • H2NCH2COO- Na+ and water
    • NH2CH2COOH and sodium oxide
    • H3N+CH2COO- and hydrogen
    • H3N+CH2COOH and sodium chloride

  16. Why does a zwitterion exist as a stable form for an amino acid?

    • Zwitterions are only formed at very high temperature, when the protein is heated
    • The acid group transfers its proton to the amine, giving an internal salt
    • The molecule loses all its hydrogen atoms, which leaves a neutral carbon framework
    • Zwitterions contain a permanent covalent charge that is fixed to the carbon skeleton

  17. Which statement about amino acids is correct?

    • Amino acids contain only C=O groups
    • Amino acids are always solids with no optical activity
    • Amino acids other than glycine are chiral at the alpha carbon
    • All amino acids have a planar structure with no chiral centres

  18. In an alpha-amino acid, which group is attached to the carbon next to the carboxylic acid?

    • An amino group, -NH2
    • A nitrile group, -CN
    • A methyl ester group, -COOCH3
    • A hydroxyl group, -OH

  19. What is the net charge of an amino acid when the solution pH is above its isoelectric point?

    • Positive
    • Negative
    • It depends only on the molar mass
    • Zero

  20. Why is glycine the only common amino acid without a chiral centre?

    • Its alpha carbon carries two hydrogen atoms, so two of its groups are identical
    • It has a triple bond in its side chain, which makes the molecule non-planar and chiral
    • It has no alpha carbon at all, because the amine and acid groups are on the same carbon
    • It contains no carboxylic acid group, so the molecule cannot form a zwitterion

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