ACT (Enhanced)ScienceEasy
A student investigates the effect of temperature on the rate of enzyme activity. They set up three identical experiments, each containing the same enzyme and substrate concentration. Experiment 1 is conducted at 20°C, Experiment 2 at 37°C, and Experiment 3 at 50°C. The amount of product formed is measured after 10 minutes in each experiment. Which of the following is the independent variable in this investigation?
- ATemperature
- BTime
- CAmount of product formed
- DEnzyme concentration
Show answer & explanationAnswer & explanation
Correct answer: A. Temperature
The independent variable is the factor that is intentionally changed or manipulated by the experimenter. In this scenario, the student is varying the temperature across the three experiments to observe its effect.
Why the other options are wrong
- B. This is a controlled variable, kept constant across all experiments.
- C. This is the dependent variable, as its change is observed in response to the independent variable.
- D. This is a controlled variable, kept constant across all experiments.
Independent Variable
The variable in an experiment that is intentionally changed or manipulated by the researcher.
- It is the 'cause' in a cause-and-effect relationship.
- Its value is controlled by the experimenter.
- Often plotted on the x-axis of a graph.
Memory trick: IV (Independent Variable) is what I Vary.