Alexis was in a hurry to get to school and accidentally knocked over a plant that was sitting on the ground. she figured that she could just pick it up when she got home from school. a week later, alexis remembers that she had knocked over the plant, and she had never gone back to pick it up! when she picks the plant up she notices that it has started to grow in an unusual way. even though the plant is lying horizontal to the ground, the stem of the plant has started to grow upward. which of the following best explains why the plant alexis knocked over is starting to grow upward? gravitropism phototropism photoperiodism thigmotropism