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Biology Final Study Guide
Chapters 26-28 & 17
93
Biology
Undergraduate 1
12/12/2011

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Term
Ecology
Definition
study of interactions among organisms and their environments
Term
Population
Definition
a group of organisms of the same species who live in a specific location and breed with one another more often than they breed with members of other populations
Term
Population Size
Definition
total number of individuals in a population
Term
Age Structure
Definition
of a population, the number of individuals in each of several age categories
Term
Reproductive Base
Definition
of a population, the number of individuals who are of reproductive age or younger
Term
Population Density
Definition
number of individuals per unit area
Term
Habitat
Definition
type of environment in which a species typically lives
Term
Population Distribution
Definition
where individuals are clumped, uniformly dispersed, or randomly dispersed in an area
Term
Emigration
Definition
movement of individuals out of a population
Term
Immigration
Definition
movement of individuals into a population
Term
Zero Population Growth
Definition
interval in which births equal deaths
Term
Exponential Growth
Definition
A population grows by a fixed percentage in successive time intervals; the size of each increase is determined by the current population size
Term
Biotic Potential
Definition
Maximum possible population growth rate under optimal conditions
Term
Limiting Factor
Definition
a necessary resource, the depletion of which halts population growth
Term
Carrying Capacity
Definition
Maximum number of individuals of a species that an environment can maintain
Term
Logistic Growth
Definition
A population grows slowly, then increases rapidly until it reaches carrying capacity and levels off
Term
Density-Independent Factor
Definition
Factor that limits population growth and arises regardless of population density
Term
Density-Dependent Factor
Definition
Factor that limits population growth and has a greater effect in dense populations than in less dense ones
Term
Life History Patterns
Definition
A set of traits related to growth, survival, and reproduction such as age-specific mortality, life span, age at first reproduction and number of breeding events
Term
Survivorship Curve
Definition
Graph showing the decline in numbers of a cohort over time
(Cohort: a group of individuals born during the same time interval)
Term
Type I Population Curve
Definition
A type I curve indicates survivorship is high until late in life.
Term
Type II Population Curve
Definition
A type II curve indicates that death rates do not vary much with age.
Term
Type III Population Curve
Definition
A type III curve indicates that the death rate for a population peaks early in life.
Term
J-Shaped Curve
Definition
A curve on a graph that records the situation in which, in a new environment, the population density of an organism increases rapidly in an exponential or logarithmic form, but then stops abruptly as environmental resistance (e.g. seasonality) or some other factor (e.g. the end of the breeding phase) suddenly becomes effective. The actual rate of population change depends on the biotic potential and the population size.
Term
S-Shaped Curve
Definition
A pattern of growth in which, in a new environment, the population density of an organism increases slowly initially, in a positive acceleration phase; then increases rapidly approaching an exponential growth rate as in the J-shaped curve; but then declines in a negative acceleration phase until at zero growth rate the population stabilizes. This slowing of the rate of growth reflects increasing environmental resistance which becomes proportionately more important at higher population densities. This type of population growth is termed ‘densitydependent’ since growth rate depends on the numbers present in the population.
Term
Community
Definition
All populations of all species that live in a particular region
Term
Producers
Definition
Organism that makes its own food using energy and simple raw materials from the environment; an autotroph
Term
Consumers
Definition
Organism that gets energy and nutrients by feeding on tissues, wastes or remains of other organisms; a heterotroph
Term
Niche
Definition
All of a species' requirements and roles in an ecosystem
Term
Commensalism
Definition
Species interaction that benefits one species and neither helps nor harms the other
Term
Mutualism
Definition
Species interaction that benefits both species involved
Term
Predation
Definition
one species captures, kills and eats another
Term
Parasitism
Definition
Relationship in which one species withdraws nutrients from another species without immediately killing it
Term
Symbiosis
Definition
One species lives in or on another in a commensal, mutualistic, or parasitic relationship
Term
Intraspecific Competition
Definition
Competition between the members of the same species
Term
Interspecific Competition
Definition
Competition between two species
Term
Competitive Exclusion
Definition
Process whereby two species compete for a limiting resource, and one drives the other to local extinction
Term
Resource Partitioning
Definition
Species become adapted in different ways to access different portions of a limited resource; allows species with similar needs to coexist
Term
Predator
Definition
An animal that naturally preys on others
Term
Prey
Definition
An animal hunted and killed by another for food
Term
Parasite
Definition
An organism that lives in or on another organism (its host) and benefits by deriving nutrients at the host's expense
Term
Host
Definition
An organism that is infected with or is fed upon by a parasitic or pathogenic organism
Term
Ecological Succession
Definition
the gradual and orderly process of change in an ecosystem brought about by the progressive replacement of one community by another until a stable climax is established
Term
Pioneer Species
Definition
Species that can colonize a new habitat
Term
Climax Community
Definition
a biological community of plants and animals which, through the process of ecological succession — the development of vegetation in an area over time — has reached a steady state. This equilibrium occurs because the climax community is composed of species best adapted to average conditions in that area
Term
Primary Succession
Definition
A new community becomes established in an area where there was no soil
Term
Secondary Succession
Definition
A new community develops in a site where the soil supported an old community remains
Term
Autotrophs
Definition
Organism that makes its own food using carbon from inorganic molecules such as CO2 and energy from the environment; a producer
Term
Primary Producers
Definition
In an ecosystem, an organism that captures energy from an inorganic source and stores it as biomass; first trophic level
Term
Heterotrophs
Definition
Organism that obtains energy and carbon from organic compounds assembled by other organisms; a consumer
Term
Trophic Levels
Definition
Position of an organism in a food chain
Term
Food Chain
Definition
Description of who eats whom in one path of energy in an ecosystem
Term
Food Web
Definition
Set of cross-connecting food chains
Term
Primary Productivity
Definition
the production of organic compounds from atmospheric or aquatic carbon dioxide, principally through the process of photosynthesis, with chemosynthesis being much less important. Almost all life on earth is directly or indirectly reliant on primary production. The organisms responsible for primary production are known as primary producers or autotrophs, and form the base of the food chain
Term
Grazing Food Chain
Definition
Food chain in which energy is transferred from producers to grazers (herbivores)
Term
Herbivores
Definition
An animal that feeds on plants
Term
Carnivores
Definition
an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging.
Term
Detrital Food Chain
Definition
Food chain in which energy is transferred directly from producers to detritivores
Term
Detritivore
Definition
Consumer that feeds on small bits of organic material
Term
Ecological Pyramids
(Trophic Pyramid or Energy Pyramid)
Definition
A graphical representation designed to show the biomass or biomass productivity at each trophic level in a given ecosystem.
Term
Pyramid of Biomass
Definition
Biomass pyramids show how much biomass is present in the organisms at each trophic level
Term
Biogeochemical Cycles
Definition
Movement of a chemical pollutant becomes increasingly concentrated as it moves up through food chains
Term
Omnivores
Definition
Species that eat both plant and animals
Term
Phosphorous Cycle
Definition
Movement of phosphorous among Earth's rocks and waters, and into and out of food webs
Term
Carbon Cycle
Definition
Movement of carbon, mainly between the oceans, atmospheres, and living organisms
Term
Greenhouse Effect
Definition
Warming of Earth's lower atmosphere and surface as a result of heat trapped by greenhouse gases
Term
Global Warming
Definition
A gradual increase in the overall temperature of the earth's atmosphere generally attributed to the greenhouse effect caused by increased levels of carbon dioxide, CFCs, and other pollutants
Term
Nitrogen Cycle
Definition
Movement of nitrogen among the atmosphere, soil, and water and into and out of food webs
Term
Ecosystem
Definition
A community interacting within in its environment
Term
Decomposition
Definition
the process by which organic material is broken down into simpler forms of matter.
Term
Speciation
Definition
One of several processes by which new species arise
Term
Species
Definition
A type of organism. Designated by genus name together with specific epithet
Term
Gene Flow
Definition
The movement of alleles into and out of a population
Term
Genetic Divergence
Definition
the process in which two or more populations of an ancestral species accumulate independent genetic changes (mutations) through time, often after the populations have become reproductively isolated for some period of time
Term
Reproductive Isolating Mechanisms
Definition
Refers to the end of gene flow between populations. It is part of the process by which reproducing species attain and maintain their separate identities. By preventing successful interbreeding, reproductive isolation reinforces differences
Term
Pre-Zygotic Isolation
Definition
If pollination or mating cannot occur or if zygotes cannot form
Term
Behavorial Isolation
Definition
Behavorial differences can stop gene flow between related species.
Term
Temporal Isolation
Definition
Some populations cannot interbreed because the timing of their reproduction differs.
Term
Mechanical Isolation
Definition
In some cases, the size or shape of an individual's reproductive parts prevent it from mating with members of another population.
Term
Ecological Isolation
Definition
Populations adapted to different microenvironments in the same region may be ecologically isolated.
Term
Gametic Isolation
Definition
Even if gametes of different species do meet up, they often have molecular incompatibilities that prevent them from fusing.
Term
Post-Zygotic Isolation
Definition
If hybrids form but are unfit or infertile.
Term
Allopatric Speciation
Definition
Speciation pattern in which a physical barrier that separates members of a population ends gene flow between them
Term
Geographic Isolation
Definition
A physical barrier separates two populations and ends gene flow between them
Term
Sympatric Speciation
Definition
Pattern in which speciation occurs in the absence of a physical barrier
Term
Parapetric Speciation
Definition
Speciation model in which different selection pressures lead to divergences within a single population
Term
Cladogenesis
Definition
an evolutionary splitting event in a species in which each branch and its smaller branches forms a "clade", an evolutionary mechanism and a process of adaptive evolution that leads to the development of a greater variety of sister species
Term
Anagenesis
Definition
the evolution of species involving an entire population rather than a branching event
Term
Evolutionary Trees
Definition
Type of diagram that summarizes evolutionary relationships among clades
Term
Adaptive Radiation
Definition
A burst of genetic divergences from a lineage gives rise to many new species
Term
Extinction
Definition
refers to a species that has been permanently lost
Term
Mass Extinctions
Definition
simultaneous loss of many lineages from Earth
Term
Biology Species Concept
Definition
Species are groups of interbreeding natural populations that are reproductively isolated from other such groups.
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