Final answer:
The control group is a baseline group in an experiment that does not receive the experimental treatment, allowing for a comparison to evaluate the effect of a variable. It must be identical to the test group except for the one variable being tested to ensure valid comparisons.
Step-by-step explanation:
The control group in an experiment is the group of test subjects that are as similar as possible to the experimental group, but do not receive the experimental treatment or manipulation observed in the experiment. The control group serves as a standard or baseline for comparing results.
In the context of experiments aiming to determine the nutrients in a sample of food, the control group would be a sample that is known and not manipulated, thereby providing a benchmark against which the 'mystery' food sample can be analyzed for nutrients.
A critical aspect of a control group is that it must be identical to the test group except for the one variable being tested, which ensures that any differences in outcomes between the test and control groups can be attributed to the variable under consideration.
For instance, let's consider an experiment testing if a specific fertilizer promotes corn growth. The control group would be corn plants grown without the fertilizer, while the test group would be corn plants grown with the fertilizer. To maintain validity, all other conditions such as water supply, light, and soil type must be consistent across both groups.