One experiment in phototropism involved cutting off the tips of grass seedlings before exposing them to light from one side. The decapitated seedlings did not bend toward the light. A valid conclusion from this experiment would be that
A) plants cannot engage in photosynthesis without the tip of the plant.
B) light is perceived by the tip of grass plants.
C) a foil cover over the tip of the seedlings would cause them to bend.
D) hormones are produced in all parts of the plant.

Question

Quizplus · Accepted Answer

The fact that the decapitated seedlings did not bend towards the light indicates that the tip of grass plants is responsible for perceiving the light and initiating phototropism. This conclusion is supported by other studies that have demonstrated that the tip of the plant (specifically the cells in the tip) are the site of auxin production, which is responsible for the bending response. The other answer choices are not supported or suggested by the experiment.

One Experiment in Phototropism Involved Cutting Off the Tips of Grass