How many drops of caffeine she drops on the worm is the manipulated variable.
In an experiment, the independent variable is a manipulated variable. Due to the fact that you may alter it, it is termed the "manipulated" one. In other words, you can choose in advance whether to raise it or lower it. Only one variable should be changed at a time throughout an experiment.
The Independent variable is Caffeine's impact. the production and use of nitrogen fertilizers, as well as the burning of fossil fuels in autos, power plants, and industries, are dependent variables that are local in scope. the heart rate of the worm is the responding variable in this experiment.
When an earthworm is given a stimulant like caffeine, its heart rate rises. Does coffee make an earthworm's heart beat faster? is the research topic upon which the experiment is based. The effect of coffee is the independent variable in this research question, and the response it causes is a change in heart rate (the dependent variable) This brings us to the following theory: "If an earthworm is given a stimulant like caffeine, then its heart rate accelerates."
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