ISS Literature Review (Dylan)

Geotropism (also called gravitropism) is the directional growth of an organism in response to gravity. Roots display positive geotropism when they grow downward, while shoots display negative geotropism when they grow upward. 

Perception is the sensing of environmental stimuli. Perception allows organisms to gain information about properties and elements of the environment that are critical to their survival. 

Gravity sensing cells at the end of the roots called statocytes let the plant know the direction of gravity. The process is known as Gravitropism. Roots show a positive response to gravity as they grow downward, whereas the stems show the opposite response. 

• If a plant shoot display negative gravitropism and when it is placed on its side, a plant shoot will grow up
• If a plan root display positive gravitropism, they will grow down.

Gravity plays a role in the concentration of Auxin, a plant growth hormones, in the root celsl. Changes in the auxin concentration allow throughout the root allow its cells to divide and bend with gravity.

Bibligraphy
Maria (d.u.) How do roots grown when direction of gravity changes? Retrieved July 10 from http://www.indiastudychannel.com/projects/250-How-Do-Roots-Grow-When-Direction-Gravity-Changes.aspx

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/Auxin.html