When watering the yard, a student made on observation about the height and position of blades of grass in the areas that get different amounts of sunlight. When conducting an experiment to answer their question of "Why do the grass blades grow away from the side in the shade?" the student gathered the following data: (picture)

The only difference between the control group and the experimental group was light conditions. The control group was provided full light, while the experimental group was shaded on one side. The diagrams show the average heights and positions of blades of grass in the experiment.

Explain, with detail, why the grass tips of the experimental group bent toward the light. Include the following terms in your explanation: phototropism, hormone, and shoot system.