A scientist was studying the effects of oil contamination on ocean seaweed. He thought that oil runoff from storm drains would keep seaweed from growing normally so he decided to do an experiment. He filled two tanks of equal size with water and monitored the dissolved oxygen and and temperature in each to be sure they were equal. He introduces some motor oil into one tank and then measured the growth of seaweed in the tank. In the tank with no oil, the average growth was 2.7cm. The average growth of the seaweed in the tank with the oil was 2.37cm. Based on this experiment:

Question

A scientist was studying the effects of oil contamination on ocean seaweed. He thought that oil runoff from storm drains would keep seaweed from growing normally so he decided to do an experiment. He filled two tanks of equal size with water and monitored the dissolved oxygen and and temperature in each to be sure they were equal. He introduces some motor oil into one tank and then measured the growth of seaweed in the tank. In the tank with no oil, the average growth was 2.7cm. The average growth of the seaweed in the tank with the oil was 2.37cm. Based on this experiment:

3. Identify the independent variable, the dependent variable, and the experimental controls

Answer: independent variable is motor oil
Dependent variable is growth of seaweed
Experimental controls:
Tanks, dissolved oxygen, and temperature

Answer 1

Control is amount of water in tanks. Otherwise correct.

Answer 2

Correct! The independent variable in this experiment is the motor oil because it is the factor being manipulated or changed by the scientist. The dependent variable is the growth of seaweed because it is the outcome or result that is being measured. The experimental controls in this case are the tanks, dissolved oxygen, and temperature. These are kept constant to ensure that any changes in seaweed growth can be attributed to the presence or absence of motor oil. By having the two tanks of equal size, monitoring the dissolved oxygen and temperature in each tank, and only introducing motor oil into one tank, the scientist is able to isolate the effects of oil contamination on seaweed growth.