Biotic and Abiotic components of ecosystems 

• As matter and energy flow through different organizational levels of living systems, many important elements and compounds cycle through the living (biotic) and nonliving (abiotic) components of the environment.
  • This chain of events continuously repeats.
  • The cycling of matter ensures its availability for life processes.

• Biotic factors are all the living, or once living, things that directly or indirectly affect an organism and its environment.
  • Biotic factors also include the presence of organisms, their parts, and wastes.
  • In addition, parasites and diseases are classified as biotic factors.
• Abiotic factors are nonliving components that determine the types and numbers of organisms that exist in an environment.
  • Some examples include annual rainfall, the pH level in lakes and ponds, levels of minerals in the soil, and the amount of light at different depths of the ocean.

Carbon, Water, and Nitrogen Cycles move matter through the ecosystem

The carbon, nitrogen, and water cycles serve to transfer matter through all levels of the ecosystem to support life processes.

• The processes of the nitrogen cycle include nitrogen fixation, nitrification, assimilation, ammonification, and de-nitrification (You don't have to memorize these names).




• The main processes of the carbon cycle include photosynthesis, respiration, combustion, and decomposition.










• The main processes of the water cycle include precipitation, evaporation, condensation, and transpiration.

You should:
• understand key processes in the water, carbon, and nitrogen cycles and how they support life

Food Webs and Energy model Energy Flow

• Within natural and designed systems, it is possible to track the flow, cycles, and conservation of matter and energy.
• Food chains and webs illustrate how energy is transferred from producers to different levels of consumers in an ecosystem.
• The amount of energy available decreases from producer to first-order, second-order, and third-order consumers.
  • This concept can be modeled through an energy pyramid.
  • No energy conversion is perfectly efficient.
  • Each level of the energy pyramid has less energy to pass on to the next with roughly one-tenth of the energy in one level available for the next.
  • Energy is given off to the environment as thermal energy through metabolism.

You should:
• understand the relationship between a population's position in a food web and its size
• determine the relative amount of energy available at each trophic level of an energy pyramid
• create a model of a food web using organisms found in a local ecosystem and classify organisms as producers or first-, second-, or third-order consumers

Producers, Consumers, Decomposers

• The life processes of plants and animals are interdependent and contribute to the flow of energy and cycles of matter within an ecosystem.
  • Producers are consumed (eaten) by consumers.
  • When either producers or consumers die, they are broken down and consumed by decomposers.
    • Decomposers return nutrients to the environment where they can be used by producers.
• Human actions can positively and negatively affect the populations of producers, consumers, and decomposers in an ecosystem.

• recognize examples of common producers, consumers, and decomposers and explain the role of each in the flow of energy and cycling of matter through an ecosystem