Activity: From Land to Mouth
Purpose
Is it more efficient for humans to consume autotrophs or heterotrophs?
Background Information
A field of corn contains a certain amount of food energy. If cattle eat the corn, they will gain some of the
food energy. How does the amount of energy in the corn compare with the amount of energy in the
cattle? Is it more efficient to feed on corn or beef? In this activity, you will compare the energy content of
some familiar human foods.
Energy Information:
The table below lists the average amount of energy (in kilojoules per square metre of land per
year) in different organisms that people use for food.
Organism
Wheat cereal
Oranges and grapefruits
Peanuts
Rice
Potatoes
Carrots
Apples
Peaches
Beet sugar
Cane sugar
Corn
Milk (cow)
Eggs (chicken)
Chicken
Pork (pig)
Beef (cow)
Fish
Energy
(KJ/m2/year)
3,400
4,200
3,850
5,200
6,700
3,400
6,300
3,800
8,300
14,650
6,700
1,800
840
800
800
550
8
Create a Bar Graph:
Make a bar graph to compare the relative amounts energy in each organism:
a. Include a LEGEND:
 Use one color for autotrophs and another colour for heterotrophs.
b. Label the x-axis with the names of each organism.
c. Label the y-axis with the energy content of each organism.
*Reference your “Notes: How to Graph” before creating the graph*
Analysis Questions: Answer the following questions in complete sentences onto your science notebook.
1. What are the autotrophs in this data?
2. Calculate the AVERAGE energy of all the autotrophs.
3. What are the heterotrophs in this data?
4. Calculate the AVERAGE energy of all the heterotrophs.
5. Which organisms (autotrophs or heterotrophs) can offer more energy (on average)? Be sure to
mention the average energy for both producers and consumers in your response.
Conclusion:
Write a paragraph (4-6 complete sentences) that answers the following question:
Is it more efficient for people to eat plant products (autotrophs) or animal products
(heterotrophs)? Why?
Explain and justify your answer. Make sure to address the fact on what happens to energy as you go up
trophic levels. Include what you have learned during our in-class discussion on energy flow.