Cycling of Matter and Energy Flow in an Ecosystem Bio 2.1.1 Analyze the flow of energy and cycling of matter (water, carbon, nitrogen, and oxygen) through ecosystems relating the significance of each to maintaining the health and stability of an ecosystem.

Water Cycle Key processes in the water cycle are evaporation, transpiration, and precipitation.

Carbon cycle Photosynthesis and cellular respiration are the two main steps in the carbon cycle.

Nitrogen cycle Nitrogen-fixing bacteria are important in the nitrogen cycle because they change nitrogen gas into a usable form of nitrogen for plants. This type of nitrogen is vital to make proteins, DNA, and RNA.

Phosphorus Cycle In the phosphorus cycle, phosphorus moves from phosphate deposited in rock, to the soil, to living organisms, and finally to the ocean. You have to have it for proteins, DNA, and RNA

Cycle imbalances Over use of water lowers river and lake levels. Since all water is headed to the ocean and it is inefficient to get the salt out of water when we over use fresh water we don’t have enough for everyone. We are releasing more carbon dioxide into the atmosphere than can currently be used by the existing photosynthesizes. That means CO2 builds up in the atmosphere and traps heat.

Cycle imbalances When nitrogen and phosphorus are used as part of fertilizers they end up in the water supply. The algae over grow when nitrogen and phosphorus are at high levels. The algae can release toxins that poison the local wildlife. When the algae die the bacteria doing decomposition use up the oxygen in the water. Eutrophication can result in a dead lake or a dead area in a larger body of water, like an ocean.

Organisms and Their Environments Species interact with both other species and their nonliving environment. Interdependence is a theme in ecology— one change can affect all species in an ecosystem. Ecologists recognize a hierarchy of organization in the environment: biosphere, ecosystem, community, population, and organism.

Levels of Organization The Biosphere The broadest, most inclusive level of organization is the biosphere, the volume of Earth and its atmosphere that supports life. Ecosystems An ecosystem includes all of the organisms and the nonliving environment found in a particular place.

Levels of Organization Communities, Populations, and Organisms A community is all the interacting organisms living in an area. Below the community level of organization is the population level, where the focus is on the individual organisms of a single species.

Biotic and Abiotic Factors Both biotic, or living, factors and abiotic, or nonliving, factors influence organisms. Acclimation Some organisms can adjust their tolerance to abiotic factors through the process of acclimation. Control of Internal Conditions Conformers are organisms that do not regulate their internal conditions; they change as their external environment changes. Regulators use energy to control some of their internal conditions. Escape from Unsuitable Conditions Some species survive unfavorable environmental conditions by becoming dormant or by migrating.

The Niche A niche is a way of life, or a role in an ecosystem.

Producers Most producers are photosynthetic and make carbohydrates by using energy from the sun. Gross primary productivity is the rate at which producers in an ecosystem capture the energy of sunlight by producing organic compounds. The rate at which biomass accumulates is called net primary productivity.

Consumers Consumers obtain energy by eating other organisms and include herbivores, omnivores, carnivores, detritivores, and decomposers.

Energy flow Food Chains and Food Webs A single pathway of energy transfer is a food chain. A network showing all paths of energy transfer is a food web.

Energy transfer Ecosystems contain only a few trophic levels because there is a low rate of energy transfer between each level.