Question

Which experimental procedure would provide the best evidence for the effect of light on plant growth?

1.Measure plants receiving different amounts of light in their natural environments.
2.Plant seeds in different soils and expose them to different amounts of light, then measure plant growth.
3.Plant seeds of the same variety in the same conditions and vary only the amount of light, then measure plant growth.
4.Measure plants of the same variety grown in environments that receive different amounts of light.

Answer 1

3. Plant seeds of the same variety in the same conditions and vary only the amount of light, then measure plant growth.

This experimental procedure would provide the best evidence for the effect of light on plant growth because it controls for all other possible variables that could influence plant growth. By keeping all other conditions the same and only varying the amount of light, any differences in plant growth can be attributed to the light levels.