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A biologist is studying the effect of a new pesticide on a specific insect population. They set up three experimental plots: Plot A receives the full dose of the pesticide, Plot B receives a half dose, and Plot C receives no pesticide. All other environmental conditions (temperature, humidity, light) are kept identical across the plots. After one month, the insect population density in each plot is measured. What is the role of Plot C in this experiment?
- AIt serves as the independent variable.
- BIt functions as the control group.
- CIt represents experimental error.
- DIt acts as the variable group.
Show answer & explanationAnswer & explanation
Correct answer: B. It functions as the control group.
Plot C, receiving no pesticide, is used as a baseline for comparison. It allows the researchers to determine if the changes observed in Plots A and B are actually due to the pesticide rather than other factors. This is the definition and purpose of a control group.
Why the other options are wrong
- A. The independent variable is the pesticide dosage, which is manipulated by the experimenter, not a plot itself.
- C. Experimental error refers to inaccuracies or uncertainties in measurements or procedures, not a specific experimental plot.
- D. Plots A and B are the variable (or experimental) groups, as they receive different levels of the manipulated variable.
Control Group
In an experiment, the group that does not receive the treatment or manipulation, serving as a baseline for comparison.
- All conditions except the independent variable are kept the same as the experimental groups.
- Helps isolate the effect of the independent variable.
- Essential for establishing cause-and-effect relationships.
Memory trick: Controls check changes, variables vary.