Question

more experimental design practice

bacteria are grown in a petri dish. one side of the dish is sprayed with an antibiotic. after a week, the number of bacteria colonies are counted on each side.

the independent variable is

the dependent variable is

Explanation:

The independent variable is the factor manipulated in an experiment. Here, the presence/absence of antibiotic (sprayed vs. unsprayed side) is controlled. The dependent variable is the measured outcome affected by the independent variable, which is the number of bacteria colonies counted.

Answer:

Independent variable: Presence of antibiotic
Dependent variable: Number of bacteria colonies