In the same science fair, tina asks the question "does caffeine increase the heart rate of an
earthworm? " in test 1, she measures the heart rate by looking at the earthworm under a
microscopes the earthworm has a heart rate of 50 bpm (beats per minute). in test 2, she
places a few drops of caffeine on the earthworm's skin and measures the rate again. in this test,
the heart rate is 68 bpm.
6) what is the manipulated variable in this experiment?
7) what is the responding variable in this experiment?
8) tina's experiment should have included a hypothesis. in a complete sentence, suggest a
hypothesis for tina's experiment.