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Links:
Biology II AP Curriculum Page
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Purpose:
To provide the students with a better understanding of toxicity and how toxic chemicals are studied. Students will learn that not all humans react the same way to the same chemical, and that thresholds of various substances vary widely. The effects of dose, route of exposure, intrinsic toxic potential, and duration and frequency of exposure are discussed. In addition, the reasons and need for animal testing and alternate forms of experimentation to test consumer product safety is introduced. In addition, students will learn to make a solution that represents a one part per million concentration, and identify their visual detection limit for the dissolved substance by observing the Tyndall effect.
These tasks will be accomplished by the students first doing the prelab reading on toxicity and answering questions over the material. Students then explore the differences between acute and chronic toxicity by estimating their total lifetime ingestion of toothpaste and contrasting this to the amount that might be ingested accidentally. Students then conduct an experiment in which dilute toothpaste solutions are used to determine the taste threshold for a certain type of toothpaste.
Objectives Links:
Process Skills Checklist
Materials:
For the class:
- milk
- distilled water
- class set of student reading and worksheets
- one 8.2 oz or large tube of toothpaste (Tartar Control Crest works well)
For lab groups of 2-4:
- towel sheets
- calculators
- Q-tip swabs
- metric ruler
- 1 plastic spoon
- paper sheets "2x4"
- felt tip marker
- 10 cm by 10 cm wax paper
- clean 100 mL graduated cylinder
- five 8 oz. plastic cups
- light and dark paper for background
- seven clear 8 oz plastic cups
- dark colored unsweetened drink mix (i.e. unsweetened Kool-Aid)
Safety Concerns:
no concerns
Revision Date:
Summer 2001
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