What The Peanuts Say: Catabolism and Calories
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Clovis O. Price Jr. Lucy Flower High School
3545 W. Fulton
Chicago IL 60624
The objective of this lesson plan activity is to demonstrate the
relationship between heat, specific foods, and calories. The students will
learn how to calculate the temperature and mass of the foods and determine how
much heat is given off under specific conditions. The students will also learn
how to use laboratory equipment to develop this specific experiment.
One of each of the following apparatuses will be needed per group.
crucible and cover
Erlenmeyer flask-125 ml.
piece of soft string, 2.5 centimeters
samples: one walnut, one peanut, and peanut oil
200 mL of water
box of matches
The students will be told that when any fuel is burned, inside or outside
of our bodies, it consumes oxygen and liberates heat. Food fuels being burned
in our cells go through the same process. From our previous study we know that
energy can neither be created nor destroyed. It can only be converted from one
kind of energy to another. In the process of metabolism, bond energy is
released as foods are catabolized. This bond energy must be precisely balanced
by the body's total energy output. Therefore a very significant equilibrium
exists between the body's energy intake and its energy output. Energy intake
equals total output (heat + work + energy storage). The students will be
divided into four groups. The students will work together in groups of four.
Sample #1 Procedure
The students will obtain two different solid food samples. One peanut with
the shell and brown covering removed, and one-fourth of a shelled walnut. Each
should be the equivalent of one gram. The student(s) will turn the crucible
cover upside down on a crucible. A mounting pin and one of the samples should
be laid on the cover. All three items, the crucible cover, pin, and sample
should be weighed. The results should be recorded under the mass in Data Chart
I. The students should cool 200 mL of water including ice 10c below room
temperature. Using a graduated cylinder student(s) should pour 50 mL of water
in the 125 mL flask. The apparatus should have been assembled previous to this
experiment. Nevertheless it is important that the instructor model for the
students the process of loosening the clamp and turning the Erlenmeyer flask
around on the ring stand. The water temperature in the flask should be measured
after cooling. The students will make sure that the Erlenmeyer flask is 5
centimeters above the crucible. After this has been done, the student should
turn the Erlenmeyer flash opposite the crucible. This is done by loosening the
clamp on the ring stand.
Sample #2 Procedure
The longer side of the sample should be impaled on a pin. The sample
should be secured on the pin with just as little as possible of the sample
resting on the crucible cover. Ignite the sample and position the Erlenmeyer
flask as quickly as possible over the burning sample. Allow it to burn at least
2 minutes. Extinguish the flame and turn the Erlenmeyer flask opposite the
crucible and cover once again. Observe the water temperature. Record it at its
highest point. The temperature reading should be recorded in the Data Chart.
After burning the sample, weigh the crucible, pin, and cover along with the
sample and record the measurements in the Data Chart.
This process should be repeated for the samples of the other nut.
Sample #3 Procedure
The student should take an oil sample by placing 10 drops oil drops on the
crucible cover. About 2.5 centimeters of soft string should be placed in the
oil. Repeat the above procedure. The students should be able to answer the
following questions and finish the following calculations.
1) Food Calories produced= (mass of water x temp. change x 1cal/gCo)/(1000cal/Cal)
Food Calories/gram sample= Food Calories Produced/gram sample burned
2) Why was it necessary to find the amount of Calories produced per gram?
3) Why couldn't we just calculate the number of Calories by themselves? (Why
did we have to weigh the crucible, pin and cover?)
4) Which of the burned samples produced the most energy? Why? The students
will record all further findings in the data charts.
At the consumation of this experiment the student should understand that there
is a chemical correlation between the amount of heat given off by particular
foods burned and their Calorie content as evidenced through the calculations.
The student should be able to generalize this approach to other foods upon which
the scientist may wish to conduct similar experiments. There is a uniform
correlation between the metabolic processes in the human body and the burning of
The students are expected to fill out a Data Chart with at least 90-95%
accuracy. The students are expected to know the difference between a chemical
calorie and a food Calorie. Students should be able to duplicate all the
procedures in the experiment with at least 90-95% accuracy. After having become
proficient in this experiment, the students should be able to use various types
of nuts (Pistachios, pecans) and use this test as a valid measurement for
Calories and Caloric content. During food oxidation energy intake is equal to
Bolton, Ruth P., Lamphere, Elizabeth V., Menesini, Mario: Laboratory
Experiments Action Chemistry (New York: Holt,Rinehart, and Winston,1973).
Marieb, Elaine, Human Anatomy and Physiology (New York: Benjamin/Cummings
Publishing Company, Inc., 1992).