Exam Two

What is the limiting factor for the Lake Washington Example?
The sewage was being disposed of into the lake which caused the abundance of phosphorus in the lake. This phosphorus caused a lot of algea, and fish to die. Therefore the phosphorus is the limiting factor.
Why is understanding biogeochemical cycles important?
They are the major way in which elements important to Earth processes and life are moved through the atmosphere, hydrosphere, lithosphere, and biosphere
What is a biogechemical cylce?
A series of reservoirs, or storage compartments, and pathways or fluxes, between reservoirs
Chemical Reaction
A process in which new chemicals are formed from elements and compounds that undergo a chemical change

– series of chemical reactions

– Living green plants + sunlight as energy source create carbon dioxide and water.

– Then it makes the carbon dioxide into sugar and oxygen


The Tectonic Cycle:


creation and destruction of the lithosphere


Lithosphere = outer layer of Earth.


The movement of these plates are called plate tectonics

Tectonic Cycle
Involves creation and destruction of the solid outer layer of earth (lithosphere)
Plate Tectonics

– Plates float on denser material and more

– driven by forces originating deep within the Earth


Why is tectonic cycle important

– change the location and size of continents

-altering atmospheric and ocean circulation

– therefore altering climate

– can create islands

– When the islands are formed evolution must take place because some species are moved from habitat.

The rock cycle

– consists of numerous processes that produce rocks and soils

– depends of the tectonic cycle for energy and hydrologic cycle for water

– Rocks classified as:

– igneous, sedimentary, metamorphic

Nitrogen Fixing bacteria

– Process of converting atmospheric N to NO3– or NH4+


– almost all organisms depend on these


– some have formed symbiotic relationships in the roots of plants or stomach on animals

required either in small/moderate amounts

required in large amounts








Drainage basin

* at reginal & local level, the funadmental hydrologic unit of the landscape is this*


-the area that contributes surface runoff to a particular streatm or river


-usually used to evaluate the hydrology of an area

Why is the carbon cycle so important
– carbon is the element that anchors all organic substances
Missing Carbon Sink

-millions of tons of carbon are burned each year and end up somwhere unknown to science


– Marine or land photosynthesis, or both must provide the additional flux

What happends to rocks during physical weathering?

– Happends when the rocks freeze and then thaw


– produces sediment such as gravel, sand and silt

What happens to rocks during chemical weathering?
– Occurs when weak acids in water dissolve chemicals from rocks
Basic Characteristics of Ecosystems

1. Structure

– made up of living and nonliving

2. Process

– cycling of chemical elements and flow of energy

3. Change

– undergo development through succession

Ecological Communities

– A set of interacting species found in the same place and functioning together to maintain life


– Operational definition = all the species found in an area, whether or not they interact

First Trophic Level

– Use energy from the sun and carbon dioxide from the air to photosynthesize


– green plants, algae and certain bacteria


– called autotrophs

* grasses, herbs and trees

Second Trophic Level

– Organisms that feed on autotrophs


– called herbivores


* mice, pine borer and deer

Third Trophic Level

– feed directly on herbivores


– called carnivores


* foxes, wolves, hawks

Forth Trophic Level


– Carnivores that feed on third level carnivores


* Humans


– Feed on waste and dead organisms of all trohpic levels


– bacteria and fungi


– would be considered on the fourth trophic level

Keystone Species

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

* wolf, alligator


– its removal or a change in its role within the ecosystem changes the basic nature of the community

Terrestrial Food Chain

Example: North American Temperate Woodland


1st- grasses, herbs and trees

2nd- mice pine borer and deer

3rd- foxes wolves hawks

4th- humans

Oceanic Food Chain



* Involve more species and have more trohpic levels


Community level interactions

– Sea otters have community level effect

– where more kelp is present more habitat for many species


When one species effects nonliving and living communities

Biological Diversity

– refers to the variety of life forms in an area


* expressed as number of species in an area

* or number of genetic types in an area

Charles Darwin

– Explanation of diversity known as biological evolution


– refers to the change in inherited characteristics of a population from generation to generation


– When cells divide

– DNA is reproduced

– each cell gets a copy

– if an error occurs in teh reproduction of DNA it gets passed to new cells


DNA Change = Mutation

Natural Selection

– some individuals may be better suited to the env. than others

– those better able to survive and reproduce leave more offspring

– their descendants form a larger proportion of the next generation

Migration and Geographic Isolation

– two populations become geographically isolated for a long time

– enough change accumulates so that they no longer reproduce

– two new species have formed

– migration important evolutionary process ( hawaii honey creeper and Darwin’s finches)

Genetic Drift

– occurs when changes in the frequency of a gene in a pop are due not to mutation, selection, or migration, but simply to chance.


-Happns through the founder effect

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
Species richness
total number of species
species evenness
the relative abundance of species
species dominance
the most abundant species

How many of which species on Earth?


– 1.5 have been named


– most are insect or plants


– many species of fungi and protists


– relatively few mammals

Competitive Exclusion Principle

– Two species that have exactly the same requirements cannot coexist in exactly the same habitat


* British red squirrel and American Grey squirrel

Ecological Niche
Explains how so many species can coexist
Benefits both participants
Genetic Engineering

– Information contained in DNA is enormous


– we now have the ability to manipulate inherited characteristics


– new possibilities pose novel problems