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
You are correct.
What was the question that the scientist started with
What' was his hypothesis
Correct! In this experiment, the independent variable is the motor oil. The scientist introduced motor oil into one tank while keeping the other tank free of oil. This variable is manipulated by the scientist and is expected to have an effect on the dependent variable.
The dependent variable, on the other hand, is the growth of seaweed. The scientist measures the growth of seaweed in both tanks and compares the results. This variable is the response or outcome that is being measured and is expected to be influenced by the independent variable.
Lastly, the experimental controls are the factors that the scientist kept constant throughout the experiment to ensure that any observed differences in seaweed growth can be attributed to the presence or absence of motor oil. In this case, the controls include the tanks (which are of equal size), the dissolved oxygen levels, and the temperature in each tank. By keeping these variables constant, the scientist can establish a baseline and accurately evaluate the impact of the motor oil on seaweed growth.