Question

To test the hypothesis that plants grow faster in green light, a student set up 3 of the same type of plants. She placed the first plant under a green light, the second plant under a regular light bulb, and the third plant under a red light. What is the dependent variable in this experiment?

Answer 1

The dependent variable is the speed of plant growth, and the-plant's general health and welfare.

The hypothesis is defective.  It should talk about whether the plant is
DEPRIVED of any green light.  The way the experiment is described,
the results won't be clear.  The "regular" light bulb has a lot of green
wavelengths in it, along with a lot of other stuff that the plant may or
may not be interested in.  So the plant's response to the green light
AND the 'regular' light may be very similar.