1. Energy Flow in Ecosystems
Biology EOCT Review

2. Materials and Energy in Ecosystems
All organisms need materials and energy to stay alive.
These materials and energy are transferred between and among the organisms in an ecosystem.
Materials are recycled, but a continuous energy supply is needed. The sun is the main source of this energy.

3. Materials and Energy in Ecosystems
An ecosystem is the sum of all the living and nonliving things in an area and the interactions among them.
Producers aka autotrophs, such as plants, some kinds of bacteria, and algae, are organisms that capture energy and store it in the chemical bonds of glucose.
Almost all producers are photosynthetic organisms. Some are chemosynthetic and use chemicals such as hydrogen sulfide to obtain energy.

4. Materials and Energy in Ecosystems
Consumers aka heterotrophs are organisms that obtain their energy by eating other organisms.
Primary consumers, such as rabbits and deer, are consumers that eat producers.
Secondary consumers, such as river otters and hawks, eat primary consumers. Tertiary consumers eat secondary consumers.
Decomposers get energy from organic wastes such as fallen leaves or dead organisms. Mushrooms are decomposers. They break down the food outside their bodies and then absorb the nutrients.

5. Materials and Energy in Ecosystems
A food chain is the path of food and energy from producer to consumer to decomposer.
Food webs are food chains that interconnect through multiple feeding relationships.
No ecosystem can survive without producers and decomposers.

6. Trophic Levels Each feeding level in an ecosystem is a trophic level.
Consumers, such as cows, that eat only plants are called herbivores.
Secondary consumers, such as foxes, that eat only other consumers are called carnivores.
Consumers, such as bears, that eat both plants and animals are omnivores.

7. Trophic Levels
Energy pyramids show the energy loss between trophic levels.
Only about 10 % of the energy from any trophic level is passed to the next level.
Consumers at the top levels would have to eat enormous amounts to get the energy they need and therefore limits the number of organisms at the top trophic levels.
All the living matter in a habitat, trophic level, or ecosystem is its biomass.