Unit 2 Part 2 - Energy and Nutrient Cycling in Ecosystems

Cellular Respiration

The chemical process that occurs in all living cells whereby organic compounds are broken down to release energy required for life processes. For respiration, higher plants and animals require oxygen, and release carbon dioxide and water as waste products, but certain microorganisms do not require oxygen.

Chemical Energy

The potential energy that is contained in certain chemicals; most importantly, the energy that is contained in organic compounds such as food and fuels and that may be released through respiration or burning.

Compound

Any substance (gas, liquid, or solid) that is made up of two or more different kinds of atoms bonded together.

Consumer

In an ecosystem, those organisms that derive their energy from feeding on other organisms or their products.

Detritivores

Organisms (fungi, soil, insects, bacteria) that feed on dead or decaying organic matter, important in completing the breakdown of organic matter to inorganic constituents.

Detritus

The dead organic matter, such as fallen leaves, twigs, and other plant and animal wastes, that exists in any ecosystem.

Inorganic

In classifying chemical pollutants, some are inorganic, such as the heavy metals (lead, mercury and so forth) and salts.

Law of Conservation on of Matter

The law stating that, in chemical reactions, atoms are neither created nor changed nor destroyed; they are only rearranged.

Molecule

Two or more atoms held together by covalent bonds.

Natural Organic Compounds

The organic compounds that make up living organisms, to be distinguished from synthetic organic compounds, like plastics.

Organic

Any compound that contains carbon-carbon or carbon hydrogen bonds.

Photosynthesis

The chemical process carried on by green plants through which light energy is used to produce glucose from carbon dioxide and water. Oxygen is released as a by product.

Producers

In an ecosystem, those organisms (mostly green plants) that use light energy to construct their organic constituents from inorganic compounds.

Bioaccumulation

The gaining of toxic chemicals in the body during the lifetime of an organism.

Biomagnification

The accumulation of toxic chemicals in the body of organisms as you move up the food chain.

Nitrogen Fixation

Converts N2 from the atmosphere. Biotic processes convert N2 to Ammonia (NH3), whereas abiotic processes convert N2 to Nitrate (NO3).

Nitrogen Assimilation

Producers take up either ammonium NH4 or nitrate NO3. Consumers assimilate nitrogen by eating producers.

Ammonification

Decomposers in soil and water break down biological nitrogen compounds into ammonium (NH4).

Nitrification

Nitrifying bacteria convert ammonium (NH4) into nitrite (NO2) and then into nitrate (NO3).

Denitrification

In a series of steps, denitrifying bacteria in oxygen-poor soil and stagnant water convert nitrate (NO3) into nitrous oxide (N2O) and eventually Nitrogen gas (N2).