Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne How plants grow toward light
Name: schwobtj
Location: N/A
Country: N/A
Date: N/A 


Question:
When a seed is planted below the surface of the ground, how does it "know" to grow toward the light?



Replies:
Plants don't know where the light is, they do respond to gravity. Since light is usually up, a plant seed grows up and finds light enough to keep things going.

Psych


One way that plants below ground can tell which way is up is with the use of STATOLITHS. Statoliths are dense pieces of material that settle to the bottom of a STATOCYST. In plants, pieces of starch or another material denser than water will settle to the bottom of the cell. Somehow the plant cell determines on what side the statolith has fallen, and then somehow relays a message (probably a chemical) that tells the bottom cells to grow faster than the top cells, therefore causing upward growth. There is still quite a lot of mystery in there to be discovered. I got this explanation from BIOLOGY by Neil Campbell. This is similar to the way in which plants use chemical signals to help them grow towards light.

Jim Murray "booga"



Click here to return to the Biology Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory