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.
Both experiments can answer Josey's question.
B.
Experiment 2 will answer Josey's question better than experiment 1.
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 will answer Josey's question better than experiment 2.

Explanation: Experiment 1 uses similar plants and changes only one environmental factor (fertilizer), so it isolates the effect of that environmental factor on height. Experiment 2 compares different varieties (a genetic difference) while keeping the environment the same, so any difference in growth could be due to genetics, not environment.