G. Bio. Labs
aheise at ORCHARD.WASHTENAW.CC.MI.US
Sat Feb 1 09:48:33 EST 1997
Here's a cheap, simple lab.
What is the trade-off if a plant could either make a few well-endowed
more smaller ones? Students grow bean seeds with both cotyledons, one
cotyledon, or practically no cotyledons. You soak bean seeds overnight
so the seed coat can be slipped off. A whole cotyledon is easily
removed, or students might cut off half of each cotyledon w/ a knife.
For the no-cotyledon treatment, you carefully remove (w/ a knife) as much
of both cotyledons as you can. Plant, monitor. Allow maybe 6 weeks for
the plants to grow. I ask
students to decide what variables they will measure, so they can decide
for themselves how the plants are affected. (e.g, germination time, #
leaves, color of leaves, time to flower, etc.)
Since the seeds w/o as much stored energy usually do from worse to much
worse, you can use the results to talk about r and K strategies. It's
also fairly clean in terms of controls, and it's also intuitive.
Washtenaw Community College
Ann Arbor MI
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