1. Ecosystem Structure
Pg 43-48

2. Food Chains and Trophic Levels
Energy flow from one organism to next
Shows only one possible sequence
Trophic Level
Position an organism occupies in a food chain

3. Food Web
Complex network of interrelated food chains

4. Food Web Kodiak Shrews Bulbs Wolves Bats Lemmings Caribou Insects
Arctic fox
Musk Ox
Small herbivores
Snowy Owl
Otters
Roots
Fish
Rhizomes

5. Describe and Explain the relationship between snowy owl nest numbers and lemming abundance

6. Ecological Pyramids
Graphical models of the quantitative differences between amounts of living material at each trophic level
Three types of ecological pyramid
Pyramid of numbers
Pyramid of biomass
Pyramid of productivity

7. A pyramid of numbers shows the numbers of individual organisms at each trophic level in an ecosystem.
tertiary
consumers
secondary
primary
producers 5
5000
500,000
5,000,000
A vast number of producers are required to support even a few top level consumers.

8. Other pyramid models illustrate an ecosystem’s biomass and distribution of organisms.
tertiary
consumers
secondary
primary
producers
75 g/m2
150g/m2
675g/m2
2000g/m2
Biomass is a measure of the total dry mass of organisms in a given area.
Summary of one given time period

9. An energy pyramid shows the flow of energy among trophic levels.
energy transferred
energy
lost
Energy pyramids compare energy used by producers and other organisms on trophic levels.
Only approx. 10 percent of the energy at each tier is transferred from one trophic level to the next.
Show flow over time

10. Text Book
Pg 48 – 55
Advantages and Disadvantages of diff pyramid models
Pg 52 TO DO questions 1-4
Test yourself questions 1-3