Section A 146 marks)
Answer all the questions in the spaces provided on the
1
Figure 1.0 shows the set to an epesumed to me
the affect of a biological catalyst at the decomposion
a) Predict that would be thereof
increasing the member of potato dimos in Some of
Hydrogen perdide.
peroxide to produce uygen.
nesing the pricture of Sem of hydrogen perde wath
five polato disos.
le) Suggest two other characteristics of a biological analysis not demonstrated in (a) and (b) of this question.
Answers
Answer:
nvestigating an enzyme-controlled reaction: catalase and hydrogen peroxide concentration
Class practical or demonstration
Hydrogen peroxide (H2O2) is a by-product of respiration and is made in all living cells. Hydrogen peroxide is harmful and must be removed as soon as it is produced in the cell. Cells make the enzyme catalase to remove hydrogen peroxide.
This investigation looks at the rate of oxygen production by the catalase in pureed potato as the concentration of hydrogen peroxide varies. The oxygen produced in 30 seconds is collected over water. Then the rate of reaction is calculated.
Lesson organisation
You could run this investigation as a demonstration at two different concentrations, or with groups of students each working with a different concentration of hydrogen peroxide. Individual students may then have time to gather repeat data. Groups of three could work to collect results for 5 different concentrations and rotate the roles of apparatus manipulator, result reader and scribe. Collating and comparing class results allows students to look for anomalous and inconsistent data.
Apparatus and Chemicals
For each group of students:
Pneumatic trough/ plastic bowl/ access to suitable sink of water
Conical flask, 100 cm3, 2
Syringe (2 cm3) to fit the second hole of the rubber bung, 1
Measuring cylinder, 100 cm3, 1
Measuring cylinder, 50 cm3, 1
Clamp stand, boss and clamp, 2
Stopclock/ stopwatch
For the class – set up by technician/ teacher:
Hydrogen peroxide, range of concentrations, 10 vol, 15 vol, 20 vol, 25 vol, and 30 vol, 2 cm3 per group of each concentration (Note 1)
Pureed potato, fresh, in beaker with syringe to measure at least 20 cm3, 20 cm3 per group per concentration of peroxide investigated (Note 2)
Rubber bung, 2-holed, to fit 100 cm3 conical flasks – delivery tube in one hole (connected to 50 cm rubber tubing)
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