ATI TEAS (Test of Essential Academic Skills) Version 7ScienceMedium
A student is conducting an experiment to measure the effect of different pH levels on the activity of an enzyme. They prepare several solutions with varying pH values and add a fixed amount of enzyme and substrate to each. After a set time, they measure the product formed. In this experiment, what represents the independent variable?
- ATemperature of the solutions
- BAmount of product formed
- CpH level of the solutions
- DAmount of enzyme added
Show answer & explanationAnswer & explanation
Correct answer: C. pH level of the solutions
The independent variable is the factor that is intentionally changed or manipulated by the experimenter. In this scenario, the student is varying the pH levels to observe their effect, making pH the independent variable.
Why the other options are wrong
- A. Temperature would be a controlled variable, assumed to be kept constant in a well-designed experiment.
- B. The amount of product formed is the dependent variable, as it is the outcome being measured.
- D. The amount of enzyme added is a controlled variable, kept constant to ensure a fair test.
Independent Variable
The factor in an experiment that is intentionally changed or manipulated by the researcher to observe its effect on another variable.
- Also known as the 'manipulated variable'.
- Its value is controlled or chosen by the experimenter.
- It is plotted on the x-axis of a graph.
Memory trick: I Change D Measure.