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JEE Main Chemistry: Amino acids Practice Questions

14 free multiple-choice questions on Amino acids (Biomolecules) for JEE Main Chemistry, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.

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  1. Q1. In the context of amino acids, which property is primarily determined by the R group attached to the alpha carbon?

    • AThe potential for hydrogen bonding
    • BThe type of bond in the backbone
    • CThe overall chain length
    • DThe pKa of the carboxyl group
    Show answer & explanation

    Correct answer: A — The potential for hydrogen bonding

    The nature and size of the R group significantly influence the physical properties, including hydrophobicity and the capacity for hydrogen bonding, which are crucial for protein folding.

  2. Q2. Amino acids that are essential for protein synthesis are known as:

    • AHydrophobic amino acids
    • BPolar amino acids
    • CNon-essential amino acids
    • DEssential amino acids
    Show answer & explanation

    Correct answer: D — Essential amino acids

    Essential amino acids are those that the human body cannot synthesize and must be obtained through diet for protein synthesis.

  3. Q3. Amino acids are primarily classified based on the nature of their side chain (R group). Which group corresponds to amino acids that are nonpolar?

    • AAmino groups
    • BAlkyl groups
    • CHydroxyl groups
    • DCarboxyl groups
    Show answer & explanation

    Correct answer: B — Alkyl groups

    Nonpolar amino acids possess side chains (R groups) that are hydrocarbon chains, making them relatively nonpolar. Alkyl groups represent these nonpolar chains.

  4. Q4. The peptide bond linkage that forms between amino acids is an example of which type of bond?

    • AHydrogen bond
    • BIonic bond
    • CVan der Waals interaction
    • DCovalent bond
    Show answer & explanation

    Correct answer: D — Covalent bond

    The peptide bond is an amide linkage, which is a strong covalent bond formed by dehydration synthesis.

  5. Q5. Which functional group is present in every α-amino acid?

    • A-OH
    • B-NH₂
    • C-COOH
    • D-C=O
    Show answer & explanation

    Correct answer: C — -COOH

    All α-amino acids possess a carboxyl group (-COOH), an amino group (-NH₂), and a central alpha-carbon.

  6. Q6. Which of the following amino acids is typically considered non-essential for human nutritional requirements?

    • AValine
    • BLysine
    • CGlycine
    • DLeucine
    Show answer & explanation

    Correct answer: C — Glycine

    Glycine is one of the few amino acids that is readily available in excess and is not strictly required for the body to synthesize, hence it is non-essential.

  7. Q7. Which of the following groups is present in all α-amino acids?

    • AA ketone group (-C=O)
    • BA carboxyl group (-COOH)
    • CAn ether linkage
    • DA hydroxyl group (-OH)
    Show answer & explanation

    Correct answer: B — A carboxyl group (-COOH)

    All amino acids share the defining structure of having an amino group (-NH2), a carboxyl group (-COOH), and a central α-carbon.

  8. Q8. Amino acids are characterized by which type of bonding within their structure?

    • AVan der Waals forces
    • BIonic bonds
    • CCovalent bonds
    • DHydrogen bonds
    Show answer & explanation

    Correct answer: C — Covalent bonds

    The backbone of an amino acid, including the alpha carbon and attached groups, is held together by strong covalent bonds.

  9. Q9. Amino acids are classified based on the nature of their side chains. Which group of amino acids contains non-polar hydrocarbon side chains?

    • ABasic amino acids
    • BPolar amino acids
    • CAcidic amino acids
    • DNon-polar amino acids
    Show answer & explanation

    Correct answer: D — Non-polar amino acids

    Amino acids are broadly classified based on their R group (side chain). Non-polar amino acids possess hydrocarbon side chains.

  10. Q10. Which part of the amino acid molecule contains the carboxyl group (-COOH)?

    • AAmino group (-NH2)
    • BCarboxyl group (-COOH)
    • CSide chain group (R group)
    • DAlpha carbon
    Show answer & explanation

    Correct answer: B — Carboxyl group (-COOH)

    The carboxyl group (-COOH) is the functional group attached to the carbon atom at position 1 in the standard representation of an amino acid structure.

  11. Q11. The α-amino acid structure is characterized by a central carbon atom bonded to which four groups?

    • ATwo -H atoms and two -H atoms
    • BOne -H atom, one -H atom, one -NH₂ group, and one -COOH group
    • COne -H atom, two -H atoms, one -NH₂ group, and one -R group
    • DTwo -H atoms, one -NH₂ group, one -COOH group, and one side chain (-R)
    Show answer & explanation

    Correct answer: D — Two -H atoms, one -NH₂ group, one -COOH group, and one side chain (-R)

    The α-carbon atom is bonded to -H, -H, -NH₂, and the R group (side chain).

  12. Q12. Which of the following characteristics is generally associated with amino acids that are highly non-polar?

    • ATendency to form strong dipole-dipole interactions
    • BHigh hydrophobicity
    • CAbility to participate in strong covalent bond formation
    • DHigh capacity for hydrogen bonding
    Show answer & explanation

    Correct answer: B — High hydrophobicity

    Non-polar groups exhibit high hydrophobicity, leading them to favor interactions with other non-polar groups rather than polar ones.

  13. Q13. The peptide bond formation between two amino acids is a process that occurs through which type of reaction?

    • AHydrolysis
    • BDehydration synthesis (Condensation)
    • COxidation
    • DReduction
    Show answer & explanation

    Correct answer: B — Dehydration synthesis (Condensation)

    The formation of a peptide bond involves the removal of a water molecule between the carboxyl group and the amino group of adjacent amino acids, which is a dehydration synthesis reaction.

  14. Q14. The R group of an amino acid determines its physical properties. Amino acids with non-polar R groups tend to be more:

    • APolar
    • BHydrophilic
    • CAcidic
    • DHydrophobic
    Show answer & explanation

    Correct answer: D — Hydrophobic

    Non-polar R groups interact poorly with water, leading to increased hydrophobicity (water-fearing nature).

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