Chapter 48 - Ecosystems and Human Interference
48.1 The Nature of Ecosystems
Biosphere - the part of the earth that can support life
Ecosystem - all the organisms in an environment (community) plus the nonliving factors (temperature, humidity..)
Autotrophs - producers, usually plants, that create organic nutrients using an outside energy source (photosynthesis)
Heterotrophs - consumers, gain their energy by feeding on other organisms
Carnivores - eat other animals
Omnivores - eat both plants and animals
Herbivores - eat plants
Detritivores - eat dead or decaying organisms
48.2 Energy Flow
- energy flows through an ecosystem starting from the sun, then to the producers and then to the consumers. At each level, some of the energy is lost as heat
Law of Thermodynamics
First Law of Thermodynamics: Energy can be changed from one form to another, but it cannot be created or destroyed. The total amount of energy and matter in the Universe remains constant, merely changing from one form to another. Energy is always conserved, it cannot be created or destroyed. (This is often called the Law of Conservation of Energy)
Second Law of Thermodynamics: in all energy exchanges, if no energy enters or leaves the system, the potential energy of an end state will be less than its starting state. This is called ENTROPY. Living things must add energy to their systems to maintain order and life.Food Webs and Food Chains
Food webs illustrate how energy is transferred in an ecosystem.
Ecological Pyramids also illustrate relationships
Pyramids also illustrate the relative numbers of species.
In any system, there will be more individuals lower on a food chain. An ecosystem can only support a small number of top predators.
46.3 Biogeochemical Cycles
Energy flows through an ecosystem, but most chemicals are recycled.
Carbon Cycle | Phosophorous Cycle | Water Cycle | Nitrogen Cycle
Environmental Issues
Habitat Destruction | Pollution | Biological Magnification | Climate Change
