Consider the experiment described below. Fill in the blanks for
the experimental design. Biology students want to grow cucumber
plants and water them with different concentrations of diluted
laundry detergent: 5%, 10%, 15%, 20%. The plants will be grown in a
greenhouse for 24 days. The students plan to measure the weight of
the dried plant material (roots, stems and leaves) in grams to
determine if increasing the concentration of the laundry detergent
in the watering solution will slow plant growth.
a) Independent variable and the treatments (increments) used in
the experiment:
b) Dependent variable and the units in which it was
measured:
c) At least two controlled variables
d) Hypothesis
e) What would you suggest as a control treatment for the
experiment?