A scientist wants to determine how temperature affects photosynthesis? He sets up a controlled experiment in which he places small plants acquired from an aquarium store
into 3 separate test tubes. He pours 20 ml of cold water into one test tube, 20 mL of
room temperature water into the second test tube, and 20 mL of warm water into the
third test tube. He covers each test tube with a small latex balloon and measures the
circumference of each balloon after 2 days. What is the test (independent variable?
The three test tubes
The temperature of the water
The type of plants
The circumference of the balloon after 2 days