ACT (Enhanced)ScienceMedium
A student is conducting an experiment to determine the effect of different types of music on plant growth. They set up three identical plant pots, each with the same type and amount of soil, plant seeds, and water. Pot A is exposed to classical music for 4 hours daily, Pot B to heavy metal music for 4 hours daily, and Pot C is kept in a quiet room with no music. All pots are exposed to the same amount of sunlight and kept at the same temperature. After 3 weeks, the height of each plant is measured. Which of the following is the most appropriate control for this experiment?
- APot A (Classical Music)
- BA fourth pot with no plant seeds, exposed to classical music.
- CPot C (Quiet Room)
- DPot B (Heavy Metal Music)
Show answer & explanationAnswer & explanation
Correct answer: C. Pot C (Quiet Room)
A control group is essential for comparison. Pot C, kept in a quiet room, represents the baseline condition where the independent variable (music) is absent. This allows the student to determine if any observed differences in growth are truly due to the music and not other factors.
Why the other options are wrong
- A. Pot A is an experimental group, testing the effect of classical music.
- B. A pot with no seeds would not provide information about plant growth, which is the dependent variable of interest.
- D. Pot B is an experimental group, testing the effect of heavy metal music.
Control Group
A group in an experiment that does not receive the treatment or manipulation being tested. It serves as a baseline for comparison, helping to isolate the effect of the independent variable.
- Identical to experimental groups in all aspects except the independent variable.
- Provides a standard for comparison.
- Helps to rule out confounding variables.
Memory trick: Controls Compare, Variables Change