Food Type = ? Calories / Square Meter

O. Truman Holtzclaw
1991 Woodrow Wilson Biology Institute

GOALS:

Students will gain an understanding:

of different food types and their relative efficiencies in producing calories for human consumption.
as to why eating plant products is more efficient than eating animal products.
as to how we can feed many more people on the same amount of land.
as to how much land is required to supply his or her food for a: day, year and/or a lifetime. (see previous exercise," may be too difficult for remedial classes").
of what food calories are ( Big Mac = 800 K-Calories) and how many are needed to maintain normal growth and activities.
of what unit of square area is.
of how to make and read a bar graph.

PROCEDURES:

Pass out "FOOD TYPE = ? CALORIES / SQUARE METER" DATA SHEET.
If possible, take students outside to a grassy area and mark off one square meter. If this is not practical, mark off one square meter on the floor in the classroom.
Discuss the general concepts of photosynthesis (ex. Sun produces energy and "green" plants have the ability to trap a little bit of that energy in the form of "food".).
Discuss the relationships between "producers" and "consumers". (ex. a.There is approximately a 90% energy loss when food is passed from one organism to another organism. b.There is always more producer biomass than consumer biomass.)
After your discussion, let the students start to make their guesses on their data sheets as to the number of useable food calories captured by the different organisms . Have the students make one guess at a time and then give them the correct answer. Also have the students first write down their guess, and then the correct answer after it has been given. Be sure that they write their guesses and answers in the correct columns. Note: If you can have examples of each (or some) of the organisms, it will make this exercise more meaningful. example: wheat cereal box, peanuts, potatoes, cane sugar, egg, milk carton, etc... You might also make some squares that represent "X" number of calories and have the students fill in the square meter with the appropriate number of squares (calories) for each organism.
After K-Calories have been filled in, ask students to look for discrepencies and discuss what might be the reason(s) for these discrepencies.
Next give the students the graphing sheet and have them make a bar graph showing the relative amounts of usable calories each organism captured. Have them start (left side)with the least efficient organism and progress in order to the most efficient organism (right side). You might suggest that they color their graphs to make them more attractive. Post some of the "better?" graphs; students do enjoy those perks.

"Food Type = ? Caloriees / Square Meters"
(Food, calories, per unit of surface area & graphing activity.)

DIRECTIONS:

For each food type listed below guess how many food "K calories" it is capable of producing (in a positive growing habitat) per "square meter". After you have made your guess, the teacher will tell you the correct answer for each food type. Record the correct answer for each food item. Only guess at one item at a time and wait for the correct answer before guessing at the next item. After you have recorded all the correct answers make a bar graph illustrating which organisms are the are the best (most efficient) at producing human food. Arrange the bar graph so that it goes from the least efficient to the most efficient.

Food Type (organism):	Your Guess	Answer (Kcal/m2)
(C3 Plants: Rice, Wheat, Vegetables, Fruits:)
1. Bread (example)
2. Wheat Cereal
3. Oranges & Grapefruit (Fresh)
4. Frozen Orange Juice
5. Coffee
6. Tea
7. Peanut Butter
8. Rice Or Rice Cereal
9. Potatoes
10. Carrots
11. Other Vegetables
12. Apples
13. Pears & Peaches
14. Vegetable Oil
15. Margarine
16. Beet Sugar
(C4 Plants: Corn & Sugar Cane)
17. Cane Sugar
18. Soft Drinks
19. Corn Cereal
20. Sweet Corn
(Animal Products)
21. Milk
22. Cheese
23. Eggs
24. Chicken
25. Pork
26. Beef (Feedlot)
27. Fish Fillets (Frozen)

Source: Brewer, Richard And M.T. Mccann, Laboratory And Field Manual Of Ecology, Saunders College Publishing, Philadelphia, (1982)

* Answer Key *

Food Type (organism):	Your Guess	Answer (Kcal/m2)
(C3 Plants: Rice, Wheat, Vegetables, Fruits:)
1. Bread (example)		650
2. Wheat Cereal		810
3. Oranges & Grapefruit (Fresh)		1000
4. Frozen Orange Juice		410
5. Coffee		4
6. Tea		40
7. Peanut Butter		920
8. Rice Or Rice Cereal		1250
9. Potatoes		1600
10. Carrots		810
11. Other Vegetables		200
12. Apples		1500
13. Pears & Peaches		900
14. Vegetable Oil		300
15. Margarine		300
16. Beet Sugar		1990
(C4 Plants: Corn & Sugar Cane)
17. Cane Sugar		3500
18. Soft Drinks		3500
19. Corn Cereal		1600
20. Sweet Corn		250
(Animal Products)
21. Milk		420
22. Cheese		40
23. Eggs		200
24. Chicken		190
25. Pork		190
26. Beef (Feedlot)		130
27. Fish Fillets (Frozen)		2

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