Catalase is an enzyme that catalyses the breakdown of hydrogen peroxide to form water and oxygen. A student investigated the activity of catalase in tissues from two different plants. The oxygen produced during the breakdown of hydrogen peroxide forms a foam. The height of the foam can be used as a measure of the activity of the catalase present in plant tissue. The student used this method: Step 1 Label one test-tube $$\(\mathbf{P}\)$$ and another test-tube $$\(\mathbf{A}\)$$. Step 2 Cut a cylinder of tissue from a potato and a cylinder of tissue from an apple. Step 3 Cut a potato cylinder into five equal pieces. Each piece should be approximately 4 mm in length, as shown in Fig. 1.1. Step 4 Put all five potato pieces into test-tube $$\(\mathbf{P}\)$$. Place the test-tube in a test-tube rack. Step 5 Repeat steps 3 and 4 using the apple cylinder and the test-tube labelled $$\(\mathbf{A}\)$$. Step 6 Use a syringe to put $$\(15 \mathrm{~cm}^{3}\)$$ of hydrogen peroxide solution into test-tube $$\(\mathbf{P}\)$$. Step 7 Start a stop-clock and wait for five minutes. Step 8 After five minutes, place a ruler against the outside of test-tube $$\(\mathbf{P}\)$$ and measure the maximum height of the foam. Step 9 Repeat steps 6 to 8 with test-tube $$\(\mathbf{A}\)$$ and the pieces of apple. Fig. 1.2 shows a diagram of test-tube $$\(\mathbf{P}\)$$ and test-tube $$\(\mathbf{A}\)$$ in step 8 and step 9 . Amylase is an enzyme that catalyses the breakdown of starch to form reducing sugars. Plan an investigation to determine the effect of temperature on the rate of breakdown of starch by amylase. ............................................................................................................................................... . ............................................................................................................................................... . ............................................................................................................................................... . ............................................................................................................................................... . ............................................................................................................................................... . ............................................................................................................................................... . ............................................................................................................................................... . ............................................................................................................................................... . ............................................................................................................................................... . ............................................................................................................................................... . ............................................................................................................................................... . ............................................................................................................................................... . .........................................................................................................................................

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