Catalase is an enzyme found in plant and animal cells. It catalyses the breakdown of hydrogen peroxide to form water and oxygen.
The oxygen produced forms a foam. You can measure the height of the foam to determine catalase activity.
A student investigated catalase activity in cooked and uncooked potato tissue.
The student:
Step 1 | Cut two potato cylinders so that they were identical in shape and size |
Step 2 | Put 5 cm3 of 3 % hydrogen peroxide solution into a test-tube labelled cooked potato |
Step 3 | Put 5 cm3 of 3 % hydrogen peroxide solution into a test-tube labelled uncooked potato |
Step 4 | Put one of the potato cylinders into a beaker of hot water for five minutes |
Step 5 | Removed the potato cylinder from the hot water and put it into the test-tube labelled cooked potato |
Step 6 | Put the uncooked potato cylinder into the test-tube labelled uncooked potato |
Step 7 | Left the potato cylinders in the 3 % hydrogen peroxide solution for three minutes and then measured the height of the foam produced in each of the test-tubes. |
Fig. 1 shows the test-tubes after three minutes.
Fig. 1
(i)
Prepare a table to record your results.
Measure the height of the foam in each of the test-tubes in Fig. 1 Record these measurements in your table.
[3]
(ii)
Calculate the difference in the height of the foam produced by the cooked and uncooked potato after three minutes.
[1]
(iii)
State one conclusion for these results.
[1]
(i)
Identify the independent variable in this investigation.
[1]
(ii)
State why it is important that the two potato cylinders were identical in shape and size.
[1]
(iii)
State two other variables that were kept constant in this investigation.
[2]
Identify one possible source of error in the method used in this investigation.
A student stated that:
'Catalase activity is the same in all species of plants'
Plan an investigation to test this statement.
Potatoes contain starch. Starch can be broken down into reducing sugars.
Describe the tests to identify starch and reducing sugars and give the results of the positive tests.
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