ECO Notes

Vocabulary Habitat-place where a particular population of a species lives Community-many different species that live together in a habitat

Ecosystem- a community and all the physical aspects of its habitat (i.e. soil, water, etc.) Abiotic factors- non-living parts of a habitat Biotic factors- living organisms in a habitat

Energy Flow in Ecosystems Everything that organisms do in an ecosystem requires energy. Life on Earth depends on energy from the sun. The rate at which organic material is produced by photosynthetic organisms is called primary productivity

Producers-organisms that can make their own food from inorganic material (plants, some bacteria, algae) Consumers-organisms that consume plants or other organisms to obtain energy and build molecules

1st trophic level are producers 2nd level are herbivores, animals that eat plants or other primary producers (ex: cows, horses) 3rd level are carnivores, animals that eat meat (generally herbivores) (ex: tigers, wolves, snakes

There is a 4th trophic level in many ecosystems made up of carnivores that eat other carnivores (hawk that eats a snake, or killer whale that eats a seal)

In most ecosystems, energy does not flow in a simple chain because individuals often eat at various trophic levels. This creates a food web, many interconnected food chains.

Energy is lost at it travels through an ecosystem. Most as heat. The general rule is only about 10% of the energy in an organism ends up at the next trophic level. 90% of the energy is lost as heat or in making molecules for that organism

To determine the amount of energy present in trophic levels, ecologists measure biomass. Biomass is the dry weight of tissue and other organic matter found in specific ecosystems. Each level contains only 10% of the previous levels biomass.

Ecosystems Cycle Materials Although energy cannot be cycled through an ecosystem (it only travels one direction), matter can be cycled.

Biogeochemical Cycle-a pathway formed when a substance enters a living organism, stays for a while, and then returns to the non-living environment..