Question

Why do plants grow against gravity and have you tried to answer that question yet by tests in outter space? Have any of those test failed?

On Earth, gravity plays a critical role in plant growth. The growth and movements of a plant in response to the directional stimulus of gravity is called gravitotropism. Plant roots grow in the direction of the gravity vector and away from sunlight, while shoots grow against gravity and toward sunlight. Planets use specialized hormones to sense gravity. Many experiments have been done involving the growth of plants in space, partly to distinguish their response to sunlight from their response to gravity. Some plants grow well in the absence of gravity, others do not. Changes have been documented in the cell structure and hormone levels as well as external properties of these plants. I am not sure what is meant by your question whether any of these tests have failed. As far as I know, they have all yielded useful information on this complex topic. For more information see [http://library.thinkquest.org/C003763/print.php?page=human03] or other sites that come up when you search the web for "gravitational biology". David Morrison
NAI Senior Scientist
February 3, 2006