Biology 5090/31 — May/June 2015

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

questions

marks

minutes

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

Q119MMicroscopy and Biological DrawingExperimental ContextsObservations and MeasurementsAnalysis, Conclusions and EvaluationPlanning Experiments and InvestigationsUse of Techniques, Apparatus and MaterialsFree sample

You are provided with several bean seeds which have been soaked in water.

(a)

Carefully cut one of the beans vertically into two halves. In the space below, make a drawing of one of the halves. On your drawing, label the cotyledon and the testa.

(b)

Catalase is an enzyme found in many different tissues. Catalase breaks down hydrogen peroxide, forming water and oxygen.

You are required to carry out an experiment to compare the amounts of catalase in the cotyledons and testa of a bean seed.

Put $5\text{ cm}^3$ of hydrogen peroxide into each of two test-tubes.
Carefully separate the testa from the cotyledons of a bean seed.
Keeping the testa and the cotyledons separate, cut both into small pieces.
Add the pieces of testa to one test-tube containing hydrogen peroxide and the pieces of cotyledon to the other test-tube containing hydrogen peroxide.
Observe any changes in the test-tubes for two minutes.

(i)

Record your observations in Table 1.1.

Table 1.1

part of bean seed	observations
testa
cotyledons

(ii)

State what you conclude about the amount of catalase in the testa and in the cotyledons from your observations in Table 1.1.

______

(iii)

Suggest an explanation for the difference in the amount of catalase found in the testa and in the cotyledons.

______

(iv)

Suggest one way in which this experiment could be improved.

______

(c)

Using another soaked bean seed, carry out a test to show whether its testa and its cotyledons contain starch.

(i)

Describe how you carried out this test.

______

(ii)

After completing this test, state your conclusions.

______

(d)

Cereal grains, such as maize and barley, store carbohydrates.

An investigation was carried out to measure the activity of the enzyme amylase in barley grains during germination.

The results are shown in Table 1.2.

Table 1.2

germination / days	amylase activity / arbitrary units
0	0.2
2	0.8
4	2.0
6	3.0
8	8.0
10	6.5

(i)

Construct a line graph of the data in Table 1.2 on the grid below.
Join your points with ruled, straight lines.

Fig. 1.1

(ii)

Use your graph to find the amylase activity after 5 days of germination.

______ arbitrary units

(iii)

Suggest the role of amylase in germinating barley grains.

______

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2 more questions

Q2Microscopy and Biological Drawing · Experimental Contexts · Planning Experiments and Investigations14M
Q3Experimental Contexts7M

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