The purpose of this experiment is to determine
the potential effect of three concentrations of antifreeze (ethylene glycol)
on fresh-water worms. There are five steps.
| CH2 |
CH2 |
| | |
| |
| OH |
OH |
|
ethylene glycol
|
Your teacher will provide you with:
-
Five
small, clean plastic cups
-
Live,
fresh-water black worms (hair worms)
-
Tape
and markers
-
Five
copies of a Student Worksheet
for recording your observations
-
Antifreeze
(ethylene glycol) solutions of 6 percent, 12 percent, 24 percent
-
Refrigerated
tap water.
| Step 1 |
Label one cup "low dose," the second cup "medium dose," the third
cup "high dose." Label the fourth cup "control pre-test" and the fifth
cup "control post-test." |
| Step 2 |
Add just enough cold tap water to barely cover the bottom of the
container marked "control pre-test," and place about 10 worms in the
water. (DO NOT SUBMERGE THE WORMS: THEY WILL DIE.) Observe
the worms for 4 minutes and watch for any changes in their behavior.
Record the results on the appropriate line of the Worksheet. Set the
"control pre-test" cup aside, but do not throw it away. |
| Step 3 |
After
recording the behavior of the "control pre-test" group, conduct
similar observations of different worms (about 10 per cup)
in order from "low dose" to "high dose" or from "high dose"
to "low dose" depending on your instructor's directions. Use
the appropriate antifreeze mixture prepared by your instructor
for each dose level. Use the Worksheet to record the behavior
of each group of worms at the end of 4 minutes.
|
| Step 4 |
After
you have observed the results from all 3 solutions, repeat
the control test by again adding barely enough cold water
to cover the bottom of the cup labeled "control post-test,"
and place about 10 worms in the water. Observe for 4 minutes
for any behavioral changes. Record the results on the Worksheet.
|
| Step 5 |
At the end of the experiment observe the total time and take one
last look at the worm behavior in all of the cups.. |
| Step 6 |
Answer the questions on the Worksheet. |
|
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