Marine biologist study the oceans and the creatures/bacteria living in it
Exotic species might endanger the natural ecosystem of the place where they would be introduced by changing the food chain, or over multiplying, or anything similar.
Answer:
It is a group designed to not be affected by any variables and to be used as a comparison to the other groups. It helps increase the reliability of your results, as it shows your independent variable is what made something happen in your experiment.
