Living Things! Factors that affect living things are: Biotic factors – things that are alive or were alive (other organisms) Abiotic factors – things that are non-living (temperature, water etc.) The interaction of all biotic and abiotic factors creates an ecosystem.

Roles of Organisms Organisms can be either producers or consumers in terms of energy flow through an ecosystem. All living things need energy to survive and grow. The source of this energy is the sun. Plants are autotrophs and through photosynthesis (an endothermic process) create food (sugar), to store energy for later use. To release stored energy from the sugar the plants carry out respiration ( an exothermic process). Not all organisms can produce their own food, so some must depend on other organisms as a source of food (energy) and are heterotrophs.

Producers: These are autotrophs that can make organic molecules (glucose) by the process of photosynthesis by using inorganic molecules (carbon dioxide - CO 2 and water - H 2 O). Examples: Algae, grasses, trees, etc.

The Consumers: They are the heterotrophes, that depend on other living organisms for food. They cannot make their own food. Primary Consumers: Herbivores that each vegetation Ex. : Grasshoppers, rabbits, snails, etc. Secondary Consumers: Carnivores that eat the herbivores Ex. : cats, foxes, owls, etc. Tertiary Consumers: Top carnivores (may eat other consumers) Ex. : Lions, bears, wolves, etc.

The Decomposers: They decompose (break down) dead organic material and return essential nutrients to the soil which helps plants grow. Ex. : Bacteria and mushrooms

Trophic level Refers to the organism’s position in the food chain Autotrophs are at the base (first trophic level). Organisms that eat autotrophs are called herbivores or primary consumers (second trophic level). An organism that eats herbivores is a carnivore and a secondary consumer. (third trophic level) A carnivore that eats a carnivore that eats a herbivore is a tertiary consumer (forth trophic level). Omnivores eat both animals and plants.

Feeding Levels

Energy and Nutrient Flow Through the Ecosystem The movement of energy is shown by the dark arrows. The movement of the inorganic nutrients is shown by the open arrows. Inorganic nutrients are cycled, energy is not.

ENERGY At each level of the food chain, about 90% of the energy is lost in the form of heat. The total energy passed from one level to the next is only about one-tenth of the energy received from the previous organism. Therefore, as you move up the food chain, there is less energy available. Animals located at the top of the food chain need a lot more food to meet their energy needs.

Food Chains A food chain is the path of food from a given final consumer back to a producer. grass  grasshopper  mouse  snake  hawk

The real world is more complicated than a simple food chain. A more realistic depiction of who eats whom is called a food web that depicts interlocking food chains.

Example of a food chain (out of order) and the associated trophic (feeding) levels - complete OrganismsRavenGrasshopperLadybugGrassesMushrooms Bacteria Type Trophic Levels

Example of a food chain (our of order) and the associated trophic (feeding) levels OrganismsRavenGrasshopperLadybugGrassesMushrooms Bacteria Type Tertiary Consumer (top carnivore) Primary Consumer (herbivore) Secondary Consumer (carnivores) Producer (plants) Decomposer Trophic Levels FourthSecondThirdFirstFeed off all levels

G4nb3M (ecology song) G4nb3M