1. Energy Flow in an Ecosystem
Bio Analyze the flow of energy and cycling of matter (water, carbon, nitrogen, and oxygen) through ecosystems relating the significance of each to maintaining the health and stability of an ecosystem.

2. Organisms and Their Environments
Species interact with both other species and their nonliving environment.
Interdependence is a theme in ecology— one change can affect all species in an ecosystem.
Ecologists recognize a hierarchy of organization in the environment: biosphere, ecosystem, community, population, and organism.

3. Levels of Organization
The Biosphere
The broadest, most inclusive level of organization is the biosphere, the volume of Earth and its atmosphere that supports life.
Ecosystems
An ecosystem includes all of the organisms and the nonliving environment found in a particular place.

4. Levels of Organization
Communities, Populations, and Organisms
A community is all the interacting organisms living in an area.
Below the community level of organization is the population level, where the focus is on the individual organisms of a single species.

5. Biotic and Abiotic Factors
Both biotic, or living, factors and abiotic, or nonliving, factors influence organisms.
Acclimation
Some organisms can adjust their tolerance to abiotic factors through the process of acclimation.
Control of Internal Conditions
Conformers are organisms that do not regulate their internal conditions; they change as their external environment changes.
Regulators use energy to control some of their internal conditions.
Escape from Unsuitable Conditions
Some species survive unfavorable environmental conditions by becoming dormant or by migrating.

6. The Niche
A niche is a way of life, or a role in an ecosystem.

7. Producers
Most producers are photosynthetic and make carbohydrates by using energy from the sun.
Gross primary productivity is the rate at which producers in an ecosystem capture the energy of sunlight by producing organic compounds.
The rate at which biomass accumulates is called net primary productivity.

8. Consumers
Consumers obtain energy by eating other organisms and include herbivores, omnivores, carnivores, detritivores, and decomposers.

9. Energy flow Food Chains and Food Webs
A single pathway of energy transfer is a food chain.
A network showing all paths of energy transfer is a food web.

11. Energy transfer
Ecosystems contain only a few trophic levels because there is a low rate of energy transfer between each level.