Biology 5090/31 — October/November 2023

Cambridge O-Level · Practical Test · worked solutions for every part, with the mark scheme

questions

marks

minutes

Topics Experimental Contexts · Observations and Measurements · Analysis, Conclusions and Evaluation · Use of Techniques, Apparatus and Materials · Planning Experiments and Investigations · Microscopy and Biological Drawing

Q120MExperimental ContextsObservations and MeasurementsAnalysis, Conclusions and EvaluationUse of Techniques, Apparatus and MaterialsPlanning Experiments and InvestigationsFree sample

Hydrogen peroxide is a toxic waste product found in cells. Catalase, an enzyme present in cells, breaks down hydrogen peroxide to produce water and oxygen.

\text{hydrogen peroxide} \xrightarrow{\text{catalase}} \text{water} + \text{oxygen}

When potato tissue is added to a solution of hydrogen peroxide in a test-tube the catalase in the potato cells causes bubbles of oxygen to be produced. If some detergent is added to the hydrogen peroxide solution the oxygen bubbles are trapped to produce a layer of bubbles that rises up the test-tube. The height of this layer of bubbles indicates how much catalase activity there has been.

You are going to investigate the activity of the catalase in potato tissue. As hydrogen peroxide may cause damage to eyes, wear eye protection while you do this investigation.

You are provided with a piece of potato and three large test-tubes that are labelled A, B and C. Each test-tube contains $5\text{ cm}^3$ of hydrogen peroxide solution.

Add $1\text{ cm}^3$ of detergent to the hydrogen peroxide solution in test-tubes A, B and C.
Mark the height of the liquid in each test-tube using the marker pen.
Cut three pieces of potato measuring $10\text{ mm} \times 10\text{ mm} \times 10\text{ mm}$ .
Add one of these pieces of potato to test-tube A. It will sink to the bottom of the hydrogen peroxide solution.
Immediately start timing (0 minutes) and observe the piece of potato.

(a)

(i)

Bubbles of oxygen will rise to the surface and form a layer at the top of the hydrogen peroxide solution.

Measure the height of this layer at 2, 4 and 6 minutes from the start and record these measurements in Table 1.1. The height of the layer of bubbles should be measured from the top of the hydrogen peroxide solution to the top of the layer of bubbles as shown in Fig. 1.1.

Fig. 1.1

Cut the second piece of potato into four equal parts.

Add these four parts to test-tube B.
Immediately start timing and observe the pieces of potato.
Measure the height of the layer of bubbles that forms at the top of the hydrogen peroxide solution at 2, 4 and 6 minutes from the start and record these in Table 1.1.

Cut the third piece of potato into eight equal parts.

Add these eight parts to test-tube C.
Immediately start timing and observe the pieces of potato.
Measure the height of the layer of bubbles that forms at the top of the hydrogen peroxide solution at 2, 4 and 6 minutes from the start and record these in Table 1.1.

Table 1.1

______	height of layer of bubbles / $\text{mm}$
	test-tube A	test-tube B	test-tube C
2
4
6

(ii)

Enter the missing heading in Table 1.1.

(iii)

Cutting the potato pieces into smaller parts increases the surface area of the potato.

Describe the effect of increasing the surface area of the potato and explain what caused this effect.

description = ______
explanation = ______

(iv)

Describe two possible sources of error in your investigation and explain why these may affect the results.

1 description = ______
explanation = ______
2 description = ______
explanation = ______

(b)

A student investigated the activity of catalase in potato by measuring the volume of oxygen produced. They added cubes of potato to hydrogen peroxide solution in the apparatus shown in Fig. 1.2.

Fig. 1.2

(i)

Name the piece of apparatus labelled D.

______

(ii)

Design an investigation to determine the effect of temperature on the activity of catalase in potato.

Use the apparatus shown in Fig. 1.2.

The rest of this paper

2 more questions

Q2Observations and Measurements · Experimental Contexts · Analysis, Conclusions and Evaluation · Planning Experiments and Investigations10M
Q3Microscopy and Biological Drawing · Experimental Contexts · Use of Techniques, Apparatus and Materials10M

Loading the full paper…