Which of the following is a changeable element in an experiment?

________ variables can be manipulated by the researcher and are thought to directly affect the _______ variable.

An experiment was carried out to test the effects of radiation on mice using three groups of mice of the same age, gender, and physical features. The mice in the first two groups were exposed to radiation at two different distances, while the mice in the third group did not receive any radiation. It was observed that the frequency of mutations was higher in mice that were close to the radiation than in mice that were far away. Which of the statements about this experiment is true?

The group that is tested alongside the experimental group but does not receive any treatment is known as the _________ group.

A controlled experiment is simply one in which all factors except the ____________ are held constant.

In an experiment, scientists are testing the effectiveness of echinacea tea on the common cold. What will be a true statement regarding the control and experimental groups?

Which one of the following is incorrectly matched regarding the control and experimental group in an experiment: