Class Activities
The Great Potato Chip Flame Out
Many people eat very fatty food without really making the connection to energy. Set up a pair of ringstands with clamps extended horizontally, a box of stick matches, and have several types of fatty and low fat snack foods (regular potato chips are especially useful here). Write a chemical equation for cellular respiration for either a monosaccharide or a fatty acid on the board. In addition to the usual ATP output at the end of the general formula, write the output in kilocalories. Next, place one regular potato chip in one clamp and one low-fat snack piece (optimally a low-fat potato chip) in the other. Ignite both and compare the height, brightness, and duration of the flame in the two foods. Regular potato chips burn like bandits (rapid, high, light-colored flame). In contrast, the low fat snack either burn with less intensity (although longer sometimes) or do not burn at all. The lesson about the relationship between fat as a tremendous source of chemical energy should be self-evident.
You can use this idea to create lessons about how to do experiments. Just have a weaker design (e.g. low-fat cheese curl vs. a regular potato chip) and elicit suggestions on how to improve it. It would not hurt to sneak in a word about dietary moderation either!
Have the students keep a diet diary for a few days. The diary might include entries such as approximate numbers of kilocalories, percentages of prominent nutrients consumed, and amount of dietary fiber. They should consult a standard reference (see below) to get the nutritional data.
References: Cnattingius, S., R. Bergstrom, L. Lipworth, and M.S. Kramer. 1998. Pregnancy Weight and the Risk of Adverse Pregnancy Outcomes. New Engl. J. Med. 338: 147-152.
Lehninger, A.L., D.L. Nelson, M.M. Cox. 1993. Principles of Biochemistry, 2nd ed. New York: Worth Publishers.
Here's the "inside view" of several digestive organs
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