Proteins are natural polymers.

1. (a)Name one other natural polymer.[1]
2. (b)Describe how proteins can be hydrolysed to amino acids.[2]
3. (c)The structure of the amino acid alanine is shown. H | H2N-C - COOH | CH3 Alanine can be polymerised to form poly(alanine). Draw the partial structure of poly(alanine) to show two repeat units.[2]
4. (d)The structure of the amino acid serine is shown. H | H2N-C - COOH | CH2OH Serine can form polymers with amide linkages. Serine can also form polymers with a different linkage. Name this linkage and explain how it is formed. linkage explanation[2]
5. (e)(i)Paper chromatography can be used to separate a mixture of amino acids. The apparatus used is shown. [Diagram: lid, chromatography paper, baseline, solvent] Why should the baseline be drawn in pencil and not in ink?[1]
6. (e)(ii)When the separation of the amino acids is complete, the chromatography paper is sprayed with a locating agent. Explain why.[1]
7. (e)(iii)The diagram shows the chromatography paper after it has been sprayed with a locating agent. [Diagram: solvent front, S spot, baseline] Calculate the R_f_ value of the amino acid labelled S.[1]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.