Amylase is an enzyme found in the human body that catalyses the breakdown of starch into reducing sugars. Tea contains a chemical called tannin which affects amylase activity in the body. A student investigated the effect of tea on the enzyme amylase. The student used this method: Step 1 Label three test-tubes S1, S2 and S3. Step 2 Put $$\(2 \mathrm{~cm}^{3}\)$$ of starch suspension into all three test-tubes. Step 3 Label another three test-tubes A, AT and T. Step 4 Put $$\(2 \mathrm{~cm}^{3}\)$$ of amylase solution into test-tube $$\(\mathbf{A}\)$$ and $$\(2 \mathrm{~cm}^{3}\)$$ of amylase solution into test-tube AT. Step 5 Put $$\(2 \mathrm{~cm}^{3}\)$$ of tea into test-tube AT and $$\(2 \mathrm{~cm}^{3}\)$$ of tea into test-tube T. The test-tubes are shown in Fig. 1.1. Fig. 1.1 Step 6 Place all six test-tubes into a hot water-bath. Step 7 Use a marker pen to label three sections on a white tile, as shown in Fig. 1.2. Step 8 Add 10 drops of iodine solution to each section, as shown in Fig. 1.2. Fig. 1.2 Step 9 Start the stop-clock and pour the starch suspension in test-tube $$\(\mathbf{S} 1\)$$ into test-tube $$\(\mathbf{A}\)$$. Step 10 Use a pipette to immediately remove a drop of the mixture from test-tube $$\(\mathbf{A}\)$$ and place it onto the first drop of iodine solution in section $$\(\mathbf{A}\)$$ on the white tile. Return any mixture still in the pipette to test-tube $$\(\mathbf{A}\)$$. Step 11 Repeat step 10 every 30 seconds, until all 10 drops of iodine solution in section $$\(\mathbf{A}\)$$ have been used. Reset the stop-clock to zero. Step 12 Repeat steps 9 to 11 using test-tubes $$\(\mathbf{S 2}\)$$ and $$\(\mathbf{A T}\)$$ and section AT on the white tile. Step 13 Repeat steps 9 to 11 using test-tubes $$\(\mathbf{S 3}\)$$ and $$\(\mathbf{T}\)$$ and section $$\(\mathbf{T}\)$$ on the white tile. The student's results are shown in Fig. 1.3. key: - blue-black colour - yellow-brown colour Fig. 1.3 Fig. 1.4 Make a large drawing of the tea leaf shown in Fig. 1.4.

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