PLANT RESPONSES
Published on Nov 20, 2015
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PRESENTATION OUTLINE
PLANT TROPISMS
-THE WAY PLANT GROWS IN RESPONSE TO STIMULI IN THE ENVIRONMENT
Photo by Hammonton Photography
KEY POINTS
*positive gravitropism
---occurs when roots grow in soil because they grow in the direction of gravity
*negative gravitropism.
--occurs when shoots grow upward toward sunlight in the opposite direction of gravity
*amyloplasts- settle at the bottom of the cells of the shoots and roots in response to gravity, causing calcium signaling and the release of indole acetic acid
*indole acetic acid- inhibits cell elongation in the lower side of roots, but stimulates cell expansion in shoots, which causes shoots to grow upward
Photo by Matt Lavin
* gravitropism- a plant's ability to change its growth in response to gravity
*amyloplast- a non-pigmented organelle found in some plant cells thatbis responsible for the synthesis and storage of starch granules through the polymerization of glucose
*statolith- a specialized form of amyloplast involved in the graviperception by plant roots and most invertebrates
Photo by BlueRidgeKitties
Phototropism
- is growing shoots in response to blue light
- other responses are stimulated by different light responses
- positive phototropism is the growth towards the light source
Photo by herefordcat
