5. Which of the following statements about a con- trolled experiment is true?
a. All the variables must be kept the same.
b. Only one variable is tested at a time.
c. Everything can be studied by setting up a con-
trolled experiment.
d. Controlled experiments cannot be performed
on living things.

Which type of respiration takes place when there is no oxygen present

What is the best conclusion based on this data? the hypothesis was not supported because the data indicated that fertilizing plants does not improve plant growth. the hypothesis was supported; to get the best growth, use 5 milliliters of fertilizer per plant. the hypothesis was not supported; the data indicated that too much fertilizer can inhibit plant growth. the hypothesis was supported; to get the best growth, use 15 milliliters of fertilizer per plant.

Describe the layers of the suns atmosphere?