Starch consists of two polysaccharides:

• Amylose: Water-soluble linear polymer constituting about $15 - 20\%$ of starch.
• Amylopectin: Water-insoluble branched polymer constituting the remaining $80 - 85\%$ of starch.

Proteins are classified into two major structural classes:

• Globular proteins: Polypeptide chains fold into spherical shapes and are soluble in water (e.g. Insulin, Albumin; Statements A and C).
• Fibrous proteins: Polypeptide chains run parallel and are held together by hydrogen and disulphide bonds, forming insoluble fibre-like structures (e.g. Keratin in hair/nails, Myosin in muscles; Statements B and D).

The secondary structure of proteins (both $\alpha$-helix and $\beta$-pleated sheet) is specifically maintained and stabilised by regular hydrogen bonds formed between the carbonyl oxygen ($-\text{C}=\text{O}$) of one peptide link and the amino hydrogen ($-\text{NH}-$) of another.

Standard single-letter IUPAC symbols for amino acids:

• Lysine: Code is K $\rightarrow$ (III)
• Tryptophan: Code is W $\rightarrow$ (I)
• Tyrosine: Code is Y $\rightarrow$ (IV)
• Glutamine: Code is Q $\rightarrow$ (II)
  Correct match: (A)-(III), (B)-(I), (C)-(IV), (D)-(II).