Find the Toxic
Toxicology Enrichment Materials
Teacher's Notes
Introduction:
This laboratory exercise will help introduce
your biology, chemistry or physiology class to the science behind
many contemporary issues. Testing new drugs and determining cause
and effect relationships between the presence of chemicals in
the environment and detrimental effects on wildlife are examples
which draw on the basic principles of toxicology. This lab will
help students understand the concept of dose vs. response.
Features:
As we know from the famous quote from Paracelsus,
all chemicals are poisonous. The students will be allowed to choose
their own chemical to deduce its toxicity to a germinating seed.
The materials are readily available, the experiment takes a small
amount of space, and it takes a limited amount of time over the
course of a week. Mathematical principles are emphasized when
they use serial dilutions to establish a dose range. The experiment
can be adapted to emphasize botany, algebra, graphing or the relationship
between different chemicals (for example, comparing different
acids or bases).
Scientific
Writing:
The exercise is not written with "cookbook"
instructions. Instead, only guidelines are provided. To emphasize
scientific writing, have students write their results in the style
of a scientific paper.
Introduction:
- purpose of this type of experiment
- choice of chemical and dose range
- type of information hoped to gain
Materials
and methods:
- source of chemical
- treatments, dilutions
- seeds, containers, wicks, etc.
Results
- organized presentation of all observations
- tables, graphs, drawings
Discussion
- conclusions
- significance of results (relate back to introduction)
- proposal of further experiments
Materials:
Brassica rapa
seeds are available from Carolina Biological Supply (as are other
Wisconsin Fast Plants materials) or adapt the experiment to use
seeds from other plants. Seeds that are relatively large will
probably fall off the wicks as they are used in this experiment.
You will need to set up a horizontal, rather than vertical, wick
arrangement.
This laboratory exercise was adapted from materials written
by Wisconsin Fast Plants Program, College of Agriculture and Life Science,
University of Wisconsin-Madison. www.fastplants.org
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