2. III. Ecosystem
Def. - the combination of biotic and abiotic components through which energy flows and materials cycle (usually a self-contained unit, such as a pond, swamp, meadow, or woods)
A. Energy Flow
1. Ultimate source - SUN
- 50% of suns energy reaches surface of earth
- 0.1 % of that ends up in living organisms

5. Trophic levels (food chain or web)
a. Producers - first trophic level , primarily plants on the land and algae in the water
(99% of all organic matter is at this level)
b. Primary consumer (herbivores)
c. Secondary consumer (carnivores), eat herbivores
d. Tertiary consumer (carnivores) eat carnivores
[There a three levels of consumer in most food chains]

10. The Price of Butter Depends on the Number of Old Maids
“The price of butter depends on the number of old maids in the area, because
old maids keep cats, cats eat mice, mice eradicate bees, bees pollinate clover,
cows eat clover, the more clover there is, the less it costs the farmer to produce milk, butter is made from milk, therefore…”
- adapted from Charles Darwin ORIGIN of SPECIES: Chapter 3 – Struggles for Existence
Using the statement above, answer the following questions:
1. This sentence is a good illustration of what science?
2. Which of the above organisms is a good example of an omnivore?
3. Which is a producer?
4. Which is a primary consumer?
5. Which organism is the gamete transporter?
6. Which substance is the lipid?
7. Which organism is the autotroph?
8. Which organism is the carnivore?
9. Which is an insectivore?
10. List the above organisms which produce carbon dioxide?
11. Which of the above organisms use food?
12. Which of the above organisms is at the top of the food chain?
13. Which organism is a good example of a secondary consumer?
14. Which of the above is a good example of an herbivore?
15. Construct a trophic pyramid using the organisms above.

13. d. Detritovores - live on the refuse of the. ecosystem, i. e
d. Detritovores - live on the refuse of the ecosystem, i.e. dead leaves, branches, carcasses, feces, etc.
i. Scavengers - consumers of dead prey
- vultures, jackals, crabs, earthworms
ii. Decomposers - specialized organisms that get at the trapped chemical energy
- fungi, bacteria

14. 3. Efficiency of energy transfer
a. In Cayuga Lake in New York
1000 calories of light yields
150 calories of algae, which yields
30 calories of smelt, which yields
6 calories of trout, which yields
1.2 calories of human

15. b. Energy flow pyramid (“10% rule”)

16. How many beef quarter pounders can be grown on 1 acre of land?
Let's say we have 20,000 kcal of corn. Assume that we feed it to cattle. The cow will produce about 2,000 kcal of useable energy from that 20,000 kcal of corn. That 2,000 kcal of beef would support one person for a day, assuming a 2000 kcal per day diet, which is common in the US.
If instead people ate the 20,000 kcal of corn directly, instead of passing it through the cow, we would be able to support more people for that given unit of land being farmed; Beef cattle produce about 19 kg of protein per acre per yr while soybeans produce 200 kg/ac/yr. So, 1kg = 2.2lb ~8 quarter pounders
How many beef quarter pounders can be grown on 1 acre of land?
How many soy quarter pounders can be grown on 1 acre of land?
Oregon State University. (2009) Trophic Issues. Retrieved January 30, 2009, from

17. Bioaccumulation the buildup of chemicals in an organisms body
Bioaccumulation the buildup of chemicals in an organisms body. The longer it lives, the more it absorbs.
Biological magnification  increase in the concentration of toxins as those toxins move through the food chain (DDT, PCB’s)

19. What’s the Ecology?

20. What’s the Ecology?

21. What’s the Ecology?