Energy Flows and Matter Cycles

Primary Producers – autotrophs capable of converting solar energy into chemical energy (plants, photosynthetic protists, cyanobacteria and chemosynthetic bacteria

Primary Consumers – herbivores that eat primary producers Secondary consumers – primary carnivores that eat primary consumers Tertiary consumers – secondary carnivores eat the secondary consumers

Detritivores – consumers that obtain their energy by consuming dead plants and animals (detritus); the smallest are called decomposers and include fungi and bacteria; others include nematodes, earthworms insects and scavengers such as crabs, vultures, and jackals

Ecological Pyramids – used to show the relationship between the tropic levels; Horizontal bars or tiers are used to represent the relative size of the tropic levels, each represented in terms of energy (productivity), biomass or numbers of organisms; tiers are stacked upon one another in the order in which energy is transferred

Ecological Efficiency – describes the proportion of energy represented at one trophic level that is transferred to the next level; only about 10% of the productivity (energy) of one trophic levels is transferred to the next level; 90% of the energy is consumed by the individual metabolic activities of the organism

Food Chain – linear flow chart of who eats whom; shows energy flow Food Web – expanded, more complete version of food chain; Arrows connect all organisms that are eaten to the animals that eat them in the direction of the energy flow

Biogeochemical Cycles – describe the flow of essential elements from the environment to living things and back to the environment Why do we need these elements to be recycled? What purpose do they serve?

Hydrological cycle Reservoirs – oceans, air (as water vapor), groundwater, glaciers, (evaporation, wind and percipitation move water from oceans to lands Assimilation – plants absorb water from the soil animals drink water or eat other organisms (which are mostly water) Release – plants transpire; animals and plants decompose

Carbon Cycle Reservoirs – atmosphere (as CO2), fossil fuels (coal and oil), peat, durable organic material (i.e. cellulose) Assimilation – plants use CO2 in photosynthesis; animals consume plants or other animals Release – plants and animals release CO2 through respiration and decomposition; CO2 is released when organic material is burned

Nitrogen Cycle Reservoirs – atmosphere (N2); soil (NH4 ammonium, NH3 ammonia, NO2 nitrite, or NO3 nitrate) Assimilation – plants absorb nitrogen either as nitrate or ammonium; animals obtain nitrogen by eating plants or other animals

Nitrogen Assimilation Nitrogen Fixation – Nitrogen gas and ammonium are fixed by nitrogen-fixing prokaryotes (in soil or root nodules); nitrogen gas is converted to ammonia by lightening and UV radiation

Nitrogen Assimilation Nitrification – ammonium converted to nitrite and nitrite converted to nitrate by various nitrifying bacteria; ammonium or nitrate converted to organic compounds by plant metabolism

Nitrogen Cycle Release – denitrifying bacteria convert nitrate back to nitrogen gas (denitrification); detrivorous bacteria convert organic compounds back to ammonium (ammonification); animals excrete ammonium or ammonia, urea or uric acid

Phosphorus Cycle Reservoirs – rocks and ocean sediments Assimilation – plants absorb inorganic phosphate from soils; animals obtain organic phosphorous when then eat plants or other animals Release – plants and animals release phosphorous when they decompose; animals excrete phosphorous in their waste products