Question

the one thing that they forgot to mention was to include a control group. a control group is a group or sample that receives no independent variable and acts as a baseline for comparison. if they were to include a control group, how would they do it?

have a third plant that receives more sunlight than the other two.

have a third plant that is entirely the same except receives absolutely no water over spring break.

have a third plant that receives more water than the other two.

Explanation:

Identify the experimental goal

The question asks how to design a control group for an experiment involving plants. Based on the context, the independent variable being tested is likely the amount of water given to the plants (or a specific watering schedule over spring break). A control group serves as a baseline for comparison and receives no treatment (no independent variable).

Analyze the definition of a control group

Using the Scientific Controls and Experimental Design knowledge points, a control group is defined as a group or sample that receives no independent variable and acts as a baseline for comparison. If the experiment is testing the effects of watering treatments on plants, the control group should represent the baseline condition where the treatment (water) is withheld or kept at a zero/natural baseline level to see what happens without it.

Evaluate the given options

• Option 1: "Have a third plant that receives more sunlight than the other two." This introduces a confounding variable (sunlight) rather than establishing a baseline for the watering treatment.
• Option 2: "Have a third plant that is entirely the same except receives absolutely no water over spring break." This removes the independent variable (watering treatment) entirely, serving as a perfect baseline to compare against the watered plants.
• Option 3: "Have a third plant that receives more water than the other two." This is another experimental treatment group, not a control group.

Select the correct option

The second option correctly removes the independent variable (water) to act as a baseline for comparison.

Answer:

• Have a third plant that receives more sunlight than the other two.
• Have a third plant that is entirely the same except receives absolutely no water over spring break. (Correct answer)
• Have a third plant that receives more water than the other two.