Catalase is an enzyme that catalyses the breakdown of hydrogen peroxide to form water and oxygen. You are going to investigate 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. Read all the instructions but DO NOT DO THEM until you have drawn a table for your results in the space provided in $$\(1(\mathrm{a})(\mathrm{i})\)$$. You should use the safety equipment provided while you are doing the practical work. Step 1 Label one test-tube $$\(\mathbf{P}\)$$ and the other test-tube $$\(\mathbf{A}\)$$. Step 2 Put the potato cylinder onto the white tile. Use the scalpel and ruler to measure and cut the potato cylinder so that it is 2 cm in length. Step 3 Cut the 2 cm cylinder into five equal pieces. Each piece should be approximately 4 mm in length, as shown in Fig. 1.1. cut to form five pieces Fig. 1.1 Step 4 Put all five potato pieces into test-tube $$\(\mathbf{P}\)$$. Place the test-tube in the test-tube rack. Step 5 Repeat steps 2 to 4 using the apple cylinder and the test-tube labelled $$\(\mathbf{A}\)$$. Step 6 Use the syringe to put $$\(15 \mathrm{~cm}^{3}\)$$ of hydrogen peroxide solution into test-tube $$\(\mathbf{P}\)$$. Step 7 Start the stop-clock and wait for five minutes. Step 8 After five minutes, place the ruler against the outside of test-tube $$\(\mathbf{P}\)$$. Measure the height of the foam. Record this measurement in your table in 1(a)(i). Step 9 Repeat steps 6 to 8 with test-tube $$\(\mathbf{A}\)$$. Prepare a table to record your results. (ii) State a conclusion for your results. ....................................................................................................................................... . ....................................................................................................................................... . ................................................................................................................................. (iii) State the independent variable in this investigation. ....................................................................................................................................... . ................................................................................................................................. (iv) State two variables that were kept constant in this investigation. 1 .................................................................................................................................... 2 .................................................................................................................................... (v) Identify one possible source of error in step 8 and describe an improvement to the method that would eliminate this error. error in step 8 ................................................................................................................ ....................................................................................................................................... . ....................................................................................................................................... . improvement ................................................................................................................. ....................................................................................................................................... . ....................................................................................................................................... . (vi) Identify one safety hazard when carrying out this investigation and describe how the risk of this hazard could be reduced. safety hazard ................................................................................................................. ....................................................................................................................................... . ....................................................................................................................................... . method of reducing risk ................................................................................................. ....................................................................................................................................... . ....................................................................................................................................... .

Answer:

Knowledge points:

Solution: