KEY CONCEPT Life in an ecosystem requires a source of energy.

All organisms must have a source of energy in order to survive All organisms must have a source of energy in order to survive. However, not all organisms obtain their energy by eating other organisms.

Producers provide energy for other organisms in an ecosystem. Producers get their energy from non-living resources and are also called autotrophs because they make their own food. Auto= self

Almost all producers obtain energy from sunlight. Most producers use sunlight (photosynthesis) as their energy source. Chemosynthesis in prokaryote producers use chemicals as an energy source instead of sunlight. carbon dioxide + water + hydrogen sulfide + oxygen sugar + sulfuric acid Chemosynthetic bacteria thrive in many of Yellowstone National Park’s hydrothermal pools

Consumers are organisms that get their energy by eating other living or once-living resources. They are also called heterotrophs because they feed off of different things. Hetero=different

ASSESSMENT If a spider is a keystone species in an ecosystem, what would happen if we removed all of the spiders? How does the stability of an ecosystem depend on its producers? 4. Could producers survive without consumers?

1. If a spider is a keystone species in an ecosystem, what would happen if we removed all of the spiders? Flys or other insects would take over. They might eat all of the plants, which would, in turn, leave no food for the herbavores that eat those plants. When those animals die, their will be no food for the carnivores. The whole ecosystem would collapse. 2. How does the stability of an ecosystem depend on its producers? Producers bring energy into an ecosystem. 3. Could producers survive without consumers? Producers do not require consumers to survive. Consumers on the other hand, cannot live without producers.