In an experiment testing a fertilizer's effect on plant growth, which group serves as the control?

In an experiment testing a fertilizer's effect on plant growth, which group serves as the control?

• A. Plants that receive the fertilizer
• B. All plants in the field
• C. Plants that receive no fertilizer
• D. Plants given double fertilizer

Answer: (C)

A control group provides a baseline by keeping all conditions the same except for the treatment being tested. In a fertilizer experiment, the variable is the presence and amount of fertilizer. The group of plants that receive no fertilizer serves as that baseline, so you can compare their growth to the plants given fertilizer and attribute any differences to the fertilizer itself. The plants that receive fertilizer are the experimental group, showing the effect of the treatment. Having all plants in the field under mixed conditions wouldn’t isolate the effect of fertilizer, and giving double fertilizer would be another treatment level rather than a baseline for comparison.

A control group provides a baseline by keeping all conditions the same except for the treatment being tested. In a fertilizer experiment, the variable is the presence and amount of fertilizer. The group of plants that receive no fertilizer serves as that baseline, so you can compare their growth to the plants given fertilizer and attribute any differences to the fertilizer itself. The plants that receive fertilizer are the experimental group, showing the effect of the treatment. Having all plants in the field under mixed conditions wouldn’t isolate the effect of fertilizer, and giving double fertilizer would be another treatment level rather than a baseline for comparison.