Edexcel IGCSE Biology 2.9 Food Tests Questions

Practise safe sample preparation, positive colour changes and fair control of heating, timing and volumes.

Exam points

describe Benedict's, iodine, Biuret and emulsion tests with their positive colour changes
interpret food-test results to identify glucose, starch, protein or fat in a sample
control temperature, sample/reagent volumes and heating time during a fair food-test practical

[Maximum number: 2]

Pineapple juice contains a protease called bromelain.
A student uses this method to investigate the digestion of solid gelatine protein by bromelain.
- place solid gelatine protein into a test tube up to a height of 5 cm
- mix $5 \mathrm{~cm}^{3}$ pineapple juice with $1 \mathrm{~cm}^{3}$ of pH 4 buffer
- place $1 \mathrm{~cm}^{3}$ of the pineapple juice and buffer solution on top of the gelatine
- leave for one hour in a water bath set to $37^{\circ} \mathrm{C}$
- measure the height of the solid gelatine and use it to calculate the volume of gelatine that has been digested

Repeat the method three more times.
The diagram shows part of the student's method.

Figure for Question Edexcel IGCSE Biology 2.9 Food Tests Questions question 1 — Edexcel IGCSE Biology

Describe how to test for the presence of protein.

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Edexcel IGCSE Biology 2.9 Food Tests Questions question 1