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

Testing for biological molecules — practice question

Fig. 2.1 presents the molecular structure of a triglyceride molecule.
(a(i))[1]

Draw a circle around one ester bond in Fig. 2.1.

(a(ii))[2]

Name the type of reaction used to make a triglyceride from its components. State the number of water molecules formed in this reaction. Type of reaction ............................................. Number of water molecules produced .............................................

(b(i))[1]

Underline all the terms from the list that are used to describe these lipases: macromolecule, extracellular enzyme, fibrous protein, polysaccharide.

(b(ii))[1]

Calculate the time taken for the pH to fall from pH 6.6 to pH 6.3.

(b(iii))[4]

Explain the results shown in Fig. 2.2.

(b(iv))[2]

The scientists repeated the experiment using a higher concentration of lipase. All other variables were kept constant. Predict how a rise in the concentration of the lipase would affect the results of the experiment.

(ii)[1]

Calculate the time taken for the pH to fall from pH 6.6 to pH 6.3.

(iii)[4]

Explain the results shown in Fig. 2.2.

(iv)[2]

The scientists repeated the experiment using a higher concentration of lipase. All other variables were kept constant. Predict how a rise in the concentration of the lipase would affect the results of the experiment.

Worked solution & mark scheme

This 18-mark question has a full step-by-step worked solution and mark scheme. One marking point: Circle any one correct bond (reject if the C=O double bond is included)

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