What is the total mass, in kilograms, of the grasshoppers needed to feed all of the chickens required to feed a human for one year? How many kilograms of soybeans are needed to feed all of the grasshoppers for one year? Now let’s assume we decide to eat grasshoppers instead of chickens. How many people could the grasshoppers feed for a year compared to the one human that the chickens fed for a year?
Background
A trophic level, or feeding level, is made up of all the organisms whose energy source is the same number of consumption steps from the sun in a given ecosystem. The trophic level of plants or producers is 1, while that of herbivores is 2 and that of animals that eat herbivores 3. Higher trophic levels can exist for animals even higher on the food chain. In this exercise, you will compute numerical values for human energy needs based on diets at different trophic levels.
In this case study the owner of a farm raises soybeans and chickens. Grasshoppers feed on the farmers soybeans, and are in turn eaten by the chickens. Humans can, though rarely do, eat grasshoppers for sustenance. Humans can also eat soybeans. For the purpose of this exercise, make the following assumptions:
- A human requires 1 chicken/day
- There are 365 days/year
- 1 chicken eats 25 grasshoppers/day
- 1 grasshopper requires about 30 g of soybeans/year
- 1,000 grasshoppers have a mass of 1 kg
- 1 human requires about 600 grasshoppers/day
- Dry soybeans have about 3.3 cal/g
- There are 1,000g/kg
- A typical human requires 3,000 cal/day
- What is the total mass, in kilograms, of the grasshoppers needed to feed all of the chickens required to feed a human for one year?
- How many kilograms of soybeans are needed to feed all of the grasshoppers for one year?
- Now let’s assume we decide to eat grasshoppers instead of chickens. How many people could the grasshoppers feed for a year compared to the one human that the chickens fed for a year?
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