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Biology Midterm Study Notes
Definitions
105
Biology
Undergraduate 1
02/08/2012

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Term
Evolution
Definition

The process of change that has transformed life on Earth from its earliest beginnings to the diversity of organisms living today

Descent with modification

The change in the genetic composition of a population from generation to generation

Term
Biology
Definition
Scientific study of life
Term
Properties of Life
Definition

Order

Evolutionary adaptation

Response to environment

Reproduction

Regulation

Energy processing

Growth and development

Term
Emergent Properties
Definition
New properties that arise with each step upward in the hierarchy of life, owing to the arrangement and interactions of parts as complexity increases
Term
Systems Biology
Definition
An approach to studying biology that aims to model the dynamic behavior of whole biological systems based on a study of the interactions among the system's parts
Term
Biosphere
Definition
The entire portion of Earth inhabited by life; the sum of all the planet's ecosystems
Term
Ecosystems
Definition
consists of all the living things in a particular area, along with all the nonliving components of the environment with which life interacts
Term
Communities
Definition
The entire array of organisms inhabiting a particular ecosystem is called a biological community
Term
Populations
Definition
Consists of all the individuals of a species living within the bounds of a specified area
Term
Organisms
Definition
Individual living things
Term
Organ and Organ Systems
Definition
A body part that carries out a particular function in the body
Term
Tissues
Definition
Each tissue is made up of a group of cells that work together, performing a specialized function.
Term
Cells
Definition
Life's fundamental unit of structure and function
Term
Organelles
Definition
The various functional components present in cells
Term
Molecules
Definition
Is a chemical structure consisting of two or more small chemical units, called atoms
Term
Three Levels of Biodiversity
Definition

1. Genetic diversity

2. Species diversity

3. Ecosystem diversity

Term
Genetic Diversity
Definition
Comprises not only the individual genetic variation within a population, but also the genetic variation between populations that is often associated with adaptations to local conditions
Term
Species Diversity
Definition
The variety of species in an ecosystem or across the biosphere.  As more species are lost to extinction, species diversity decreases
Term
Global Extinction
Definition
Species is lost from all ecosystems in which it lived, leaving them permanetly impoverished
Term
Ecosystem Services
Definition
Encompass all the processes through which natural ecosystems help sustain human life
Term
Examples of Threats to Biodiversity
Definition
Habitat loss, introduced species, overharvesting, and global change
Term
Introduced Species
Definition
Are those that humans move intentially or accidentally from the species native locations to new geographic regions
Term
Aristotle
Definition
Viewed species as fixed, recognized certain affinities among organisms
Term
Linaeus
Definition
Developed the two-part, or binomial, format for naming species
Term
Cuvier
Definition
Developed the idea of catastrophism
Term
Catastrophism
Definition

The principle that events in the past occured suddenly and were caused by mechanisms different from those operating in the present

Each boundary between strata represented a catastrophe

Term
Hutton
Definition
Proposed that Earth's geologic features could be explained by gradual mechanisms still operating today
Term
Lyell
Definition
Developed the idea of uniformitarianism-stated that mechanisms of change are constant over time
Term
Lamarck
Definition

Use and disuse-the idea that parts of the body that are used extensively become larger and stronger, while those that aren't used deteriorate

Inheritance of acquired characteristics-stated that an organism could pass these modifications to its offspring

Term
Darwin
Definition

Adaptations-inherited characteristics of organisms that enhance their survival and reproduction in specific environments

Natural selection-a process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits

Term
Artificial Selection
Definition
Humans have modified other species over time and many generations by selecting and breeding individuals that process desired traits
Term
Natural Selection
Definition

is a process in which individuals that have certain heritable traits survive and reproduce at a higher rate than other individuals because of those traits

-Over time, natural selection can increase the match between organisms and their environment

-If an environment changes, or if individuals move to a new environments, natural selection may result in adaptation to these new conditions, sometimes giving rise to new species

-Occurs through interactions between individual organisms and their environment, individual don't evolve, rather the population evolves over time

-Can amplify or diminish only those heritable traits that differ among the individuals in a population

Term
Microevolution
Definition
Small scale evolution, small changes in allele frequencies in a population over generations
Term
Three Mechanisms causing allele frequency change
Definition

1. Natural selection

2. Genetic Drift

3. Gene Flow

Term
Genetic Variation
Definition

Differences among individuals in the composition of their genes or other DNA segments

Without genetic variation, evolution cannot occur

Term
Discrete Characters
Definition
Can be classified on either-or basis
Term
Quantitative Characters
Definition
Vary along a continuum within a population
Term
Average heterozygosity
Definition
The average percentage of local that are heterozygous
Term
Geographic Variation
Definition
Differences in the genetic composition of spearate populations
Term
Cline
Definition
A graded change in a character along a geographic axis
Term
Point Mutation
Definition
A change as little as one base in a gene
Term
Speciation
Definition

The process by which one species splits into two or more species

When one species plits into two, the species that result share many characteristics because they are descended from this common ancestral species

Term
Macroevolution
Definition
The broad pattern of evolution above the species level
Term
Species
Definition
Is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring
Term
Reproductive Isolation
Definition
The existence of biological factors that impede members of two species from interbreeding and producing viable, fertile offspring
Term
Prezygotic Barriers
Definition

Block fertilization from occuring

 

Term
Postzygotic Barriers
Definition
May contribute to reproductive isolation after the hybrid zygote is formed
Term
Habitat Isolation
Definition
Two specties that occupy different habitats within the same area may encounter eachother rarely, if at all
Term
Temporal Isolation
Definition
Species that breed during different times cannot mix their gametes
Term
Behavioral Isolation
Definition
Courtship rituals that attract mates and other behaviors unique to a species are effective reproductive barriers
Term
Mechanical Isolation
Definition
Mating is attempted, but morphological differences prevent its successful completion
Term
Gamete Isolation
Definition
Sperm of one species may not be able to fertilize the eggs of another species
Term
Reduced Hybrid Viability
Definition
The genes of different parent species may interact in ways that impair the hybrids development or survival in its environments
Term
Reduced Hybrid Fertility
Definition
Even if hybrids are vigorous, they may be sterile
Term
Hybrid Breakdown
Definition
Some first-generation hybrids are viable and fertile, but when they mate with one another or with either parent species, offspring of the next generation are feeble or sterile. 
Term
Morphological Species Concept
Definition
Characterizes a species by body shape and other structural features
Term
Ecological Species Concept
Definition
Views a species in terms of its ecological niche, the sum of how members of the species interact with the nonliving and living parts of their environment
Term
Phylogenetic Species Concept
Definition
Defines a species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life
Term
Allopatric Speciation
Definition

Gene flow is interrupted when a population is divided into geographically isolated subpopulations

Once geographic separation has occured, the separated gene pools may diverge

Term
Sympatric Speciation
Definition
Speciation occurs in populations that live in the same geographic area
Term
Polyploidy
Definition
A species may origniate from an accident during cell division that results in extra sets of chromosomes
Term
Autopolyploid
Definition
Is an individual that has more than two chromosome sets that are all derived from a single species
Term
Allopolyploid
Definition

In subsequent generations, various mechnisms can change a sterile hybrid into a fertile polyploid

Are fertile when mating whith eachother but cannot interbreed with either parent species

Term
Hybrid Zone
Definition
A region in which members of different species meet and mate, producing at least some offspring of mixed ancestry
Term
Reinforcement
Definition
Strengthening of reproductive barriers, hybrids gradually cease to be formed
Term
Fusion
Definition
Weakening of reproductive barrier, the two species fuse
Term
Stability
Definition
Continued production of hybrid individuals
Term
Punctuated Equilibria
Definition
To describe these periods of apparent stasis punctuated by sudden change
Term
Homology
Definition

Related species can have characteristics that have an underlying similarity yet function differently

Similarity resulting from common ancestry

Term
Homologous Structures
Definition

The underlying skeletons of the arms, forelegs, flippers, and wings of different mamals are homologous structures that represent variations on a structural theme that was present in their common ancestor

Share common ancestry, but not similar function

Term
Vestigial Structures
Definition
Are remnants of features that served as a function in the organisms ancestors
Term
Evolutionary Tree
Definition
A diagram that feflects evolutionary relationships among groups of organisms
Term
Convergent Evolution
Definition
The independent evolution of similar features in different lineages
Term
Analogous
Definition

Species share features because of convergent evolution, resemblances is said to be analogous

Share similar function, but not common ancestry

Term
Biogeography
Definition
The geographic distribution of species
Term
Endemic
Definition
Found nowhere else in the world
Term
Phylogeny
Definition
The evolutionary history of a species or group of species
Term
Systematics
Definition
A discipline focused on classifying organisms and determining their evolutionary relationships
Term
Taxonomy
Definition
How organisms are named and classified
Term
Binomial 
Definition
The two part format of the scientific name
Term
Domans and all the parts
Definition
Kingdom, phylum, class, order, family, genus, species
Term
Phylogenetic Tree
Definition
The evolutionary history of a group of organisms can be represented in a branching diagram
Term
PhyloCode
Definition
Only names groups that include a common ancestor and all of its descendants
Term
Branch Points
Definition
Relationships often are depicted as a series of dichotomies, or two-way branch points
Term
Sister Taxa
Definition
Groups of organisms that share an immediate common ancestor
Term
Rooted
Definition
Means that a branch point within the treee represents the most recent common ancestor of all taxa in the tree
Term
Basal Taxon
Definition
Refers to a lineage that diverges early in the history of a group
Term
Polytomy
Definition
A branch point from which more than two descendant groups emerge
Term
Analogy
Definition
Convergent evolution
Term
Homoplasies
Definition
Analogous structures that arose independently are also called homoplasies
Term
Molecular Systematics
Definition
The discipline that uses data from DNA and other molecules to determine evolutionary realtionships
Term
Cladistics
Definition
Attempts to place species into groups called clades
Term
Monophyletic
Definition
It consists of an ancestral species and all its descendants
Term
Paraphyletic
Definition
Consists of an ancestral species and some, but not all of, its descendants
Term
Polyphyletic
Definition
Group which includes taxa with different ancestors
Term
Shared ancestral character
Definition
A character that originated in an ancestor of the taxon
Term
Shared Derived Character
Definition
An evolutionary novelty unique to a clade
Term
Outgroup
Definition
A species or group of species from an evolutionary lineage that is known to have diverged before the lineage that includes the species we are studying (the ingroup)
Term
Maximum Parsimony
Definition
Investigate the simplest explanation that is consistent with the facts
Term
Maximum Likelihood
Definition
States that given certain probability rules about how DNA sequences change over time
Term
Orthologous Genes
Definition
Are those found in different species, and their divergence traces back to the speciation events that produced the species
Term
Paralogous Genes
Definition
The homology results from gene duplication, hence multiple copies of these genes have diverged from one another within a species
Term
Molecular Clock
Definition
A yardstick for measuring the absolute time of evolutionary change based on the observation that some genes and other regions of genomes appear to evolve at constant rates
Term
Neutral Theory
Definition
That much evolutionary change in genes and proteins has no effect on fitness and therefore is not influenced by natural selection
Term
Horizontal Gene Transfer
Definition
A process in which genes are transferred from one genome to another through mechanisms such as exchange of transposable elements and plasmids, viral infection, and perhaps fusions of organisms
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