18.1 Studying Viruses and Prokaryotes

CHAPTER 18OPTIONS FOR INQUIRYUse these inquiry-based labs and online activities to deepen yourunderstanding of viruses and prokaryotes.DESIGN YOUR OWN INVESTIGATIONUsing Bacteria to Break Down OilSome types of bacteria have enzymes that can breakdown oil and are used by scientists to help clean up anoil spill. Some types of drain cleaners contain bacteriathat work in the same way to clear drain pipes. In thislab, you will test the effectiveness of different types ofenzymatic drain cleaners at breaking down cooking oil.SKILLS Designing Experiments, ConcludingPROBLEM Which enzymatic drain cleaner is mosteffective at breaking down oil?MATERIALS• 4 10-mL test tubes with caps• 6 cm masking tape• marker• test tube rack• 5 plastic droppers• 3 10-mL graduated cylinders• 2 mL cooking oil• 2 mL 0.02% tetrazoliumindicator solution• 2 mL each of three types ofenzymatic drain cleanerPROCEDURE1. Label four test tubes A, B, C, and D.2. Determine a procedure for your experiment, usingsmall amounts of the materials. Decide whichmaterials and how much of each will be placed ineach test tube. You will test the effectiveness ofeach type of drain cleaner at breaking down cooking oil. Each class group will use adifferent type of oil. The tetrazolium indicator solution turns pink when oil is brokendown.3. Identify the independent and dependent variables in your experiment. Identify thecontrols and constants in your experiment. Develop an operational definition of yourdependent variable.4. Get approval from your teacher to carry out your experiment. Wear gloves.5. Use a separate dropper for the oil, the tetrazolium solution, and each type of draincleaner. Once they are prepared, place the caps on the test tubes and gently swirl thetest tubes to thoroughly mix solutions.6. Observe your test tubes every day for at least five days. Record your data in a table likethe one below. Day 0 represents the observations you make immediately after yourtest tubes have been prepared.TABLE 1. DRAIN CLEANER EFFECTIVENESSDay Tube A Tube B Tube C Tube D01ANALYZE AND CONCLUDE1. Analyze Which drain cleaner was most effective at breaking down the oil?2. Compare Compare your results to those of other groups in the class that used differenttypes of cooking oil. Which type of oil was broken down most effectively?3. Conclude Which drain cleaner would you buy? Explain.566 Unit 6: Classification and Diversity