Question

1. Did the direction the seed was facing change how the roots and stems grew? Include in your answer how the growth looked for each of the four seeds.
2. Plants do not have any sensory organs so how do the stems of a plant know to grow up toward the light and the roots of a plant to grow down toward the water?
3. Describe how the roots looked in comparison to the stems; include color and any other characteristics you could see.
4. Plants may not be motile but they are capable of movement. Research phototropism and geotropism, how are they different and how are they the same?

Answer 1

2.

The plant hormone auxin is the driving force behind the plant's growth towards the sunlight to be able to generate energy by photosynthesis. Highly sensitive light-sensing proteins help seedlings find the shortest route (to sunlight) by elongating the cells of the stem on the side that is farthest from the sunlight.

The roots are made up of cells that are dense with ball-like structures called statoliths that respond to  gravity pulling it down. It enables the plant to grow perpendicular to the sky.

4. 

Tropism is the plant's response to stimulus. When the plants move toward the stimulus, it is called a  positive tropism. Negative tropism is the plants' movement away from the stimulus. Both Phototropism and Geotropism are both tropisms.

Phototropism is the mechanism that enables the plant to respond to light. Stems and leaves exhibit this process.

Geotropism or Gravitropism the mechanism that enables the plant to respond to gravity. It allows the plant to orient themselves for growth. Plant roots exhibit this process.