A Biology student wants to know if putting aspirin in the soil will make a rose plant grow more quickly. She buys two rose plants and places 1 tablet of aspirin in the soil of each plant. Plant A Plant B

Each day, she gives the plants the same amount of fresh water (0.5 liter). The plants receive the same amount of sunlight each day (12 hours). 1. Identify this experiment as controlled or uncontrolled, and explain your answer. Use the term “M.V.” in your answer. 12 hours 0.5 liter 12 hours 0.5 liter Plant A Plant B 1 tablet

At the advice of her Biology teacher, the student re-designs the experiment. She puts aspirin in the soil of plant A only. She gives both plants the same amount of sunlight each day (12 hours). Plant B receives 0.5 liter of water daily, while plant A receives 1 liter of water daily to help dissolve the aspirin. 12 hours 1 liter 12 hours 0.5 liter 2. Identify this experiment as controlled or uncontrolled, and explain your answer. Use the term “M.V.” Plant A Plant B 1 tablet

3. In the re-designed experiment, plant A grew TWICE as fast as plant B. Based on the data, the student concludes that her hypothesis was supported; aspirin does seem to help roses grow faster. Explain to the student why she is getting false results. Use the term M.V. in your answer. 12 hours 1 liter 12 hours 0.5 liter Plant A Plant B 1 tablet

4. Re-design the student’s experiment to make it controlled. (2-3 sentences; brief description of how you would do it). Plant A Plant B

5. What is the RV in your experiment? Explain why it is the RV. Plant A Plant B

6. What is the MV in your experiment? Explain why it is the MV. Plant A Plant B

7. List three variables that must be controlled in this experiment. Plant A Plant B

8. Identify Dr. Sayer’s experiment as controlled or uncontrolled, and explain why. In the L-Dopa experiment, Dr. Sayer first administers 200 mg of the drug in orange juice; he then administers 1500 mg of the drug in milk.