Biology 9700 · AS & A Level · Testing for biological molecules

Testing for biological molecules — practice question

Fig. 3.1 is a transmission electron micrograph of two neighbouring cells from a leaf.
(a(i))[3]

Cellulose is the principal polysaccharide found in plant cell walls. Describe the structure of cellulose.

(a(ii))[1]

State one visible feature in Fig. 3.1, apart from the cell wall, that shows the cells are plant cells.

(a(iii))[3]

Outline ATP’s role in a leaf cell.

(b)[2]

Fig. 3.2 shows two water molecules joined by a hydrogen bond. Explain how hydrogen bonding forms between water molecules.

(c)[2]

Suggest why water is a very good solvent for ions.

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: A polymer built from $\beta$-glucose units linked by glycosidic bonds

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