Bio- C4.2 Transfers of Energy and Matter

Ecosystems as open systems…

in which both energy and mater can enter and exit

Sunlight as the principal source of…

energy that sustains most ecosystems

Flow of chemical energy…

through food chains

Construction of food chains and food webs

to represent feeding relationships in a community

Supply of energy to decomposers…

as carbon compounds in dead organic matter

Autotrophs as organisms that use external energgy sources to

synthesize carbon compounds from simple inorganic substances

Use of light as the external energy source in …. as the energy source in chemoautotrophs

photoautotrophs and oxidation reactions

Heterotrophs as organisms that use carbon compounds obtained from other organisms to

synthesize the carbon compounds that they require

Release of energy in both autotrophs and heterotrophs by

oxidation of carbon comppounds in cell respiration

Classification of organisms

into trophic levels

Reductions in energy availability at each successive stage in food chains due to

large energy losses between trophic levels

Heat loss to the environment in both autotrophs and heterotrophs due to

conversions of chemical energy to heat in cell respiration

Restrictions on the number of trophic levels in ecosystems due to

energy loss

Primary production as

accumulation of carbon compounds in biomass by autotrophs

Secondary production as

accumulation of carbon compounds in biomass by heterotrophs

Ecosystems as carbon … and carbon …

sinks and sources

Release of carbon dioxide into the atmosphere during combustion of

biomass, peat, coal, oil and natural gas

Dependence of aerobic respiration on … and of photosynthesis on …

atmospheric oxygen produced by photosynthesis… atmospheric carbon dioxide produced by respiration

Recycling of all … required by living organisms in ecosystems

chemical elements