Question

In an experiment to determine the effect of exercise on pulse rate, a student checks his pulse rate before

Answer 1

3. It serves as the control for the experiment. If he only checks his pulse rate after exercising th en there is no comparison to show whether th rate has increased, decreased, or remained unchanged.

Answer 2

Answer:

The correct answer is option 3.

Explanation:

In the mentioned experiment, the pulse rate prior to performing exercise functions as a control of the experiment. Before doing exercise, the pulse rate would be under normal conditions, that is, without changing any variable, and thus is considered as the control for the experiment.  

In order to find a change witnessed in the pulse rate post performing exercise, the pulse rate post-exercise would be compared with the control pulse rate.