chapters 5-8

biogeochemical cycle
the complete path a chemical takes through the four major components of Earth’s system
four major components of Earth’s system





limiting factor
the single requirement for growth available in the least supply in comparison to the need of an organism
ecological communities
all the species found in an area, whether or not they interact
an ecological community and its local nonbiological community; minimum system that includes and sustains life
keystone species

a species that has a large effect on its community or ecosystem


ex: wolf, alligator

biological diversity
refers to the variety of life forms in an area
Charles Darwin

biological evolution


-change in inherited characteristics of a population from generation to generation

when cells divide; leads to evolution
natural selection
leads to evolution; a process by which organisms whose biological characteristics better fit them to the environment are represented by more descendants in future generations than those whose characteristics are less fit for the environment
describes a relationship between two organisms
the large scale geographic pattern in the distribution of species, and the causes and history of this distribution
island biogeography

-small islands tend to have fewer habitat types

-farther away, fewer species


chemical elements required in very small amounts by at least some forms of life






elements required in large amounts by living things; “the big 6”


-carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur

drainage basin
the area that contributes surgace water to a particular stream network
trophic levels
consists of all those organisms in a food web that are the same number of feeding levels away from the original source of energy
how much energy is transferred from each trophic level?

-organisms who make their own food and inorganic chemicals and a source of energy

-ex: green plants, algae

trophic levels




fourth level (carnivores eat carnivores)



feed on waste and dead organisms of all trophic levels
food chain

the linkage of who feeds on whom


food web

a network of who feeds on whom or a diagram showing who feeds on whom



oceanic food chain

-more trophic levels


-1st: planktonic algae, bacteria

-2nd: zoo plankton

-3rd: fish, intervertabraes

-4th: killer whales

terrestrial food chain

ex: north american temperate woodland


1st: grass, trees

2nd: mice, deer

3rd: foxes, wolves

4th: humans

community level interactions

-indirect and more complicated community. wide influences species have on one another


ex: sea otters

how many elements are required for life?
what happens to rocks during physical weathering?

-happens when rocks freeze and then thaw

-produces sediment such as gravel, sand and silt

the rock cycle

-consists of numerous processes that produce rocks and soils

-depends on the tectonic cycle for energy ad hydrologic cycle for water

-igneous, metamorphic, sedimentary

chemical weathering
occurs when weak acids in water dissolve chemicals from rocks
species dominance
most abundant species

how many of which species on earth?


-1.5 million have been named

-insects, plants, few mammals

why is the carbon cycle so important?


carbon is the element that anchors all organic substances
limiting factor to lake washington example
migration and geographic isolation
two populations become geographically isolated for a long time
genetic drift
occurs when change in the frequency of a gene in a population are due not to mutation rejection or migration but simply to chance
mosquitoes and malaria
mutate and resistant to pesticides

missing carbon sink


millions of tons of carbon are burned each year and end up somewhere unknown to science
why is understanding biogeochemical cycles so important?
they are the major way in which elements important to earth processes and life are moved through the atmosphere, hydrosphere, lithosphere, and biosphere
competitive exclusion principle

two species that have exactly the same requirements cannot exist in exactly the same habitat


ex: brush red squirrel

american grey squirrel


-series of chemical reactions

-living green plants and sunlight energy source create carbon dioxide and water

-it makes the carbon dioxide into sugar and oxygen

tectonic cycle
involves creation and destruction of the solid outer layer of earth (lithosphere)

nitrogen fixing bacteria


-process of converting atmospheric nitrogen to nitrate or ammonium.

-almost all organisms depends on these

-some have formed sympiotic relationships in the roots of plants or stomach on animals

why is tectonic cycle important?

-change the location and size of continents

-altering climate 

-create islands


-give off oxygen

-reverse of photosynthesis

ecological niche
explains how so many species can coexist
big source of energy
plate tectonics

-plates float on denser material and more

-driven by forces originating deep within earth

genetic diversity
total number of genetic characteristics of a specific species, sub species, or group of species
habitat diversity
the different kinds of habitat in a given unit area
genetic engineering

-info contained in DNA is enourmous

-we now have ability to manipulate inherited characteristics

-new possibilities pose novel problems

species richness
total number of species
a group of individuals capable of breeding
anthropocene extinction
E.O. wilson and others say that the influence of people are causing extinction currently
biotic province

-organisms classified into taxa

-based on who is related to whom


-similar environments provide similar opportunities and similar constraints

-based on niches and habitat

convergent evolution
the process by which species evolve in different places or different times and develop similar external forms and structures because of adaption to similar environments
divergent evolution
organisms with the same genetic heritage migrate to different habitats and evolve into species with different external forms and structures, but set to same habitats
permanantly frozen ground
relationship between climate and vegetation

climate: average or expected conditions over long periods of time


vegetation depends on climate

ecological island
an area that is biologically isolated so that a species occurring within the area cannot mix with any other population of the same species
biome we live in
temperate deciduous 

-driest regions where rainfall is less than 50 cm/year

-soil has low organic matter, high nutrients

taiga or boreal forest

-fire, storms, insects

-largest remaining wilderness area

temperate woodlands

-somewhat dry and warm

-dominant vegetation (small trees)

-fire disturbance