Ecology The study of interactions between organisms and

Ecology The study of interactions between organisms and their environment.

In the biosphere…. . • Abiotic and biotic factors depend on each other – Ex. Reptiles depend on temperature to regulate body heat • Organisms have relationships among each other such as competition, mutualism, etc. • Organisms find their “niche” to survive • There are levels that organize our living world

Levels of Organization • • • Cells Tissues Organ systems Organism • • Population Community Ecosystem Biosphere

Food Chain • The sun is the ultimate source of energy • An autotroph (producer) is always at the bottom of the food chain. • A heterotroph (consumer) always complete the food chain. • Each level of the food chain is called a trophic level.

10 % Law • Energy is lost in the form of heat and used to fuel the body • Only about 10% of the energy consumed is available

Food Web • Shows all possible feeding relationships at each trophic level in a community.

Food Web

Life in a community • Any factor that affects an organisms ability to survive is called a limiting factor – Ex. water, increase in predators • A density-dependent factor increases as a population increases – Ex. disease, competition, predation

• A density- independent factor affects populations regardless of size – Ex. drought, storms, volcanoes

Succession- any natural change in a community • Primary – A disaster that wipes out all life and soil such as a volcano, or glacier break-off • Secondary – A disturbance that affects life but doesn’t completely wipe it out, such as a fire or storm.

Importance of the Biogeochemical Cycles • Water is recycled in our atmosphere through precipitation, evaporation, and transpiration. • Carbon, Nitrogen, and phosphorous are all important in the production of DNA and proteins

• Carbon is emitted into the atmosphere via cars, factories, respiration, etc. • Phosphorous enters our atmosphere through rock erosion, decaying plants/animals, and waste • Nitrogen is found mostly in our atmosphere and is converted into usable forms by nitrogen fixing bacteria.