A team of biochemists investigated the activity of the enzyme *lactase* under varying pH conditions. Four test tubes were prepared, each containing of a lactose substrate solution and of standardized lactase solution. Buffer solutions were added to adjust the pH in the test tubes to 3.0, 5.0, 7.0, and 9.0, respectively. All test tubes were placed in a water bath maintained at a constant temperature of for 15 minutes. The final concentration of glucose produced (measured in ) was determined for each test tube to quantify enzymatic activity.
Match each experimental component to its correct variable classification.
- The pH level of the buffer solution (3.0, 5.0, 7.0, or 9.0)Independent Variable
- The final concentration of glucose produced after 15 minutesDependent Variable
- The volume of lactose solution () and water bath temperature ()Controlled Variable
Answer
The pH level corresponds to the Independent Variable; the glucose concentration corresponds to the Dependent Variable; and the solution volume alongside incubation temperature correspond to the Controlled Variables.
In experimental design, the independent variable is the condition deliberately manipulated by the researcher (the pH levels). The dependent variable is the outcome being measured to assess the effect of that manipulation (glucose concentration produced). Controlled variables are the extraneous factors held constant across all trials (such as substrate volume and incubation temperature) to prevent confounding effects.
Step-by-Step Solution
Key Concept
Experimental design variable classification
Estimated Time:1m 50s