Question

What type of experiment did the student in the passage perform? controlled varying not controlled how do you know this? the experiment had multiple variables. the experiment had one variable. the experiment had no changing variables.

Answer 1

The student conducted a controlled experiment to test the effects of phosphate on algae growth, with phosphate being the independent variable, algae growth as the dependent variable, and water volume as a control variable.

Step-by-step explanation:

The student in the passage performed a controlled experiment. This can be determined by identifying the various characteristics of the experiment described. In a controlled experiment, researchers manipulate one variable, known as the independent variable, to see how it affects another variable, called the dependent variable. Meanwhile, control variables are kept constant to ensure that any observed effects are due to the manipulation of the independent variable only.

In the provided example, the student is testing the hypothesis that the presence of phosphate promotes the growth of algae in freshwater ponds. Here, the presence of phosphate is the independent variable, while the growth of algae is the dependent variable. The control variable could be the volume of water in each tank, and the control group is the set of tanks treated with a non-nutritional mineral instead of phosphate.