A-LevelBiologyBiological molecules9700/21 · May/June 2020 · Q16 Marks

Answer all questions. 1 Fig. 1.1 shows five biological molecules. [Figure 1.1]

(a)State the name of the bond in molecule A indicated by the arrow.[1]
(b)Molecule B is described as a saturated fatty acid. State why molecule B is described as a saturated fatty acid.[1]
(c)Molecule D is a polymer. State the name of the monomer that is used to synthesise this polymer.[1]
(d)State the letter of the molecule that could be formed during the hydrolysis of a polypeptide.[1]
(e)State the letter of the molecule that forms part of the cell surface membranes of eukaryotic cells.[1]
(f)Molecule A and molecule C dissolve in water. Molecule B does not dissolve in water. Explain why molecule A and molecule C dissolve in water, but molecule B does not dissolve in water.[1]

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Mark scheme

Marking points from the official mark scheme (May/June 2020). The mark or mark type is shown in brackets.

[1] glycosidic;
[1] any one from: no double, bond / bonds, in hydrocarbon chain ; each carbon (atom) in the hydrocarbon chain is bonded to two hydrogen atoms ; there is, a full complement / maximum number, of hydrogen atoms on the hydrocarbon chain; A aliphatic chain for hydrocarbon chain A hydrogens for hydrogen atoms
[1] ẞ-glucose / beta-glucose ; R B-glucose
[1] C;
[1] E;
[1] any one from: A and C are, polar / hydrophilic; A has many, OH / hydroxyl groups B is, non-polar / hydrophobic; A has, only one OH/no groups, that interact with water

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