Identify the dependent and independent variable in each of the examples below: 1. White mice are fed a treat every time they manage to ring a bell. The time required for the mice to learn the task is measured. 2. The diversity of fish in a stock pond is measured before and after the introduction of nitrogen fertilizers (such as would occur when excessive fertilizer is used on crops). 3. Batches of radish seeds are subjected to radiation in a microwave oven for 15 sec, 30 sec, 45 sec, and 60 sec. The seeds are then allowed to germinate and the percentage of successful germination is recorded.

1. IV: Time the Bell is rang DV: Time it takes to learn the task

2. IV: Nitrogen fertilizers DV: Diversity of fish

3. IV: Time of radiation DV: Percentage of successful germination

Explanation:

The independent variable of an experiment refers to the variable that the experimenter manipulates or changes in order to effect a measurable response in the dependent variable while the dependent variable is the variable that responds to the changes made to the independent variable.

1. In scenario 1, the TIME THE BELL RINGS is the independent variable because that is what the experimenter controls or has power to change. On the other hand, the dependent variable is the TIME IT TAKES TO LEARN THE TASK because it is the measured variable that responds to the independent variable.

2. In scenario 2, the USE OF NITROGEN FERTILIZER is the independent variable while the DIVERSITY OF FISH is the dependent variable.

3. In case 3, the TIME OF RADIATION is the independent variable while the PERCENTAGE OF SUCCESSFUL GERMINATION is the dependent variable.

digestion

it excretes wastes