1. Ecosystems are characterized by their biotic and abiotic factors
REVIEW:
Ecosystems are characterized by their biotic and abiotic factors
Biotic factors are the living and abiotic factors are the non-living
Food chain is a linear system of the ecological roles in an ecosystem
A food web represents the interaction of organisms in an ecosystem
An organism represents any living thing

2. The source of all energy is the SUN
Only a very small amount of the suns radiant energy is used by plants
Photosynthesis is chemical energy represented by the reaction:
CO2 + H2O  sugar + O2
To make stored energy the plant performs the complementary reaction called CELLULAR RESPIRATION
sugar + O2  CO2 + H2O + ENERGY
All organisms undergo cellular respiration

3. Higher trophic levels always have less energy
Ecological pyramids can be used to display energy, number and biomass relationships
Biomass is the mass of living organisms in a given area
Higher trophic levels always have less energy
Check your understanding by looking at the following questions:
Pg 35 #1-4. Pg 41 #1,5,8,9. Pg 47 #1-4, 7,8