A biochemist investigated how varying the pH of a reaction mixture affects the rate of hydrogen peroxide () decomposition by the enzyme catalase. In each trial, the catalase concentration, total reaction volume, and incubation temperature () were held constant, while the volume of oxygen gas () produced per minute was measured across solutions ranging from to .
Match each experimental component from the study to its correct variable classification.
- pH of the reaction mixtureIndependent variable
- Volume of oxygen gas () produced per minuteDependent variable
- Incubation temperature and catalase concentrationControlled variable
Answer
The pH of the reaction mixture matches Independent variable; the volume of oxygen gas produced per minute matches Dependent variable; and incubation temperature and catalase concentration match Controlled variable.
In experimental design, the independent variable is the condition deliberately manipulated by the researcher (the pH of the solution). The dependent variable is the measured outcome that changes in response to the independent variable (the volume of oxygen gas produced per minute). Controlled variables are parameters kept constant across all trials (temperature and catalase concentration) to ensure a fair test.
Step-by-Step Solution
Key Concept
Identifying Independent, Dependent, and Controlled Variables