Ecosystems & Biomes

Chapter 28

I. Chemicals needed for life:

a. Water cycle:

b. Carbon cycle

a. photosynthesis fixes about 10% of the carbon dioxide in the atmosphere, which makes up about .03% of the atmospheric gases.

c. Nitrogen cycle

a. bacteria fix nigtrogen for use by other organisims.

b. N2 + 3H2è 2NH3

a. Triple bond stability

d. Phosphorus cycle

II. Trophic levels: who eats whom (composed of food chains)

a. Autotrophs

b. Heterotrophs

c. Primary producers

d. Consumers

i. Ditritivores:

1. scavengers

2. decomposers

III. Energy flow:

a. Primary productivity

b. Gross productivity total produced (even that used by phototrophs)

c. Net productivity avail for heterotrophs

d. Biomass total mass of all living organisms

e. Secondary productivity