In an Experiment Investigating Phototropism, Pieces of Shoot Apices Were

Multiple Choice

In an experiment investigating phototropism, pieces of shoot apices were applied to small blocks of agar with light shining from one side only. The apices were either partly or completely divided in two with a barrier that also divided the blocks. The figure summarizes the results of the experiment. Numbers indicate the percent of auxin moving from the apex into the agar segment below it. Which of the following hypotheses is best supported by the data?

A) light destroys auxin
B) auxin diffuses through the plant apoplast
C) auxin is synthesized on the shaded side of the apex
D) auxin can move away from light