Question

Josey wants to find out if environmental factors can affect how tall a pea plant will grow. She has designed two possible experiments to try to answer her question.

Experiment 1 Experiment 2
1. Place two similar pea plants indoors by a window. 1. Place two pea plants of different varieties outside in a sunny garden.
2. Give both plants water every day, and give one of the plants fertilizer twice a week. 2. Give both of the pea plants water every day and fertilizer twice a week.
3. Continue step 2 for one month. 3. Continue step 2 for one month.
4. Measure the growth of each plant to determine which grew more. 4. Measure the growth of each plant to determine which grew more.


Which statement best describes these experiments?
A.
Experiment 2 will answer Josey's question better than experiment 1.
B.
Both experiments can answer Josey's question.
C.
Neither experiment can help Josey answer her question.
D.
Experiment 1 will answer Josey's question better than experiment 2.

Answer 1

D.

Experiment 1 manipulates an environmental factor (fertilizer) while keeping the plants otherwise similar, so it can show whether that environmental change affects height. Experiment 2 compares different plant varieties while keeping the environment the same, so any height difference could be due to genetics, not environment.