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Biomolecules & Polymers

Carbohydrates, proteins, nucleic acids, polymers

Key Concepts
  • Carbohydrates: polyhydroxy aldehydes/ketones; monosaccharides (glucose), disaccharides (sucrose), polysaccharides (starch)
  • Proteins: polymers of amino acids linked by peptide bonds; 4 levels of structure
  • Lipids: fats and oils — triesters of glycerol and fatty acids
  • Nucleic acids: DNA (deoxyribose, A-T-G-C) and RNA (ribose, A-U-G-C)
  • Enzymes: biological catalysts; highly specific; denatured by heat and extreme pH
Important Formulae
Glucose molecular formula C₆H₁₂O₆
Peptide bond formation −COOH + H₂N− → −CO−NH− + H₂O
Quick Tips
  • In DNA: A pairs with T (2 H-bonds); G pairs with C (3 H-bonds).
  • Sucrose = glucose + fructose; maltose = glucose + glucose; lactose = glucose + galactose.
  • Essential amino acids cannot be synthesised by the body — must come from diet (e.g., lysine, leucine).
Sample Practice Questions

  1. Nucleotide consists of a nitrogenous base, a sugar and:

    • Amino group
    • Phosphate group
    • Hydroxyl group
    • Carbonyl group
    Show answer

    Answer: Phosphate group

  2. DNA double helix is held together by:

    • Covalent bonds between bases
    • Hydrogen bonds between base pairs
    • Ionic bonds
    • Van der Waals forces only
    Show answer

    Answer: Hydrogen bonds between base pairs

  3. The alpha-helix and beta-pleated sheet are examples of protein:

    • Primary structure
    • Secondary structure
    • Tertiary structure
    • Quaternary structure
    Show answer

    Answer: Secondary structure

  4. The monomer unit of proteins is:

    • Glucose
    • Amino acid
    • Nucleotide
    • Fatty acid
    Show answer

    Answer: Amino acid

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Practice Questions

Practice 20 randomly selected NEET questions on Biomolecules & Polymers. Answers are revealed after each question.

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