10 pointsA seventh-grade student has designed an experiment to study phototropism in radish seedlings. Six radish seedlings will be planted
in Individual foam cups filled with soll. Three cups will be covered with
Box A and three cups will be covered with Box B as shown in the
diagram.
The only light source for each set of seedlings will be an overhead
fluorescent light that enters through the openings cut into the sides of
each box. The plants will receive 8 hours of light per day and will
remain inside the boxes for four days. At the end of the testing period,
the boxes will be removed and the direction of seedling growth will be
compared
opening
in box
opening
in bok
Box A
Box B
Which of the following modifications of the experimental design would
significantly increase the validity of the results? (7.13A/7.2A)
A.
using light bulbs designed for growing indoor plants
B.
doubling the number of seedlings grown in the experiment
C. including a set of three plants grown without a box
D.
planting all the seedlings for each box in one large container