Honors Biology Exam

Concepts 1-7

Natural selection

Organisms with the "best" traits (adaptations) will live longer and reproduce more than others, causing changes in the population over time by acting on traits that are heritable.

Overproduction of Offspring

Lots of offspring and limited resources causes competition for those resources.

Variation

Differences in the physical traits of organisms.

Sources of Variation

Random mutations, genetic recombination during meiosis (crossing over), migration (gene flow).

Adaptation

A change in gene frequency over time leading to populations with new phenotypes adapted to new situations.

Descent with modification

A change in gene frequency over time; traits come from ancestors.

Fitness

Diversity within a species has resulted in an increase in fitness; the better-suited organisms will reproduce and increase the fitness of their offspring.

Individuals don't evolve, populations do

One individual cannot evolve on its own because its genes cannot be changed; it takes a population for the gene pool to change and species within the population to evolve.

Directional Selection

Increases the expression of an extreme version of a trait in a population.

Disruptive Selection

A process that splits a population into two groups; removes individuals with average traits and favors the two extremes.

Stabilizing Selection

Eliminates extreme expressions of a trait when the average expression leads to higher fitness.

Mutation

Any change in a DNA sequence; creates new genotypes and thus new phenotypes.

Genetic Drift

A mechanism of microevolution that has a bigger impact on smaller populations than larger ones.

Gene Flow

The transfer of alleles or genes from one population to another.

Sexual Selection

A mode of natural selection where certain traits increase mating success.

Genetic Equilibrium

A state in which allele frequencies in a population remain constant over time.

Conditions for no evolution

Population is large, must be random mating, no migration, no mutations, no natural selection.

Allele frequency

The number of times the allele appears in a population; shows how frequently the allele appears in the gene pool.

P

Frequency of the dominant allele

Q

Frequency of the recessive allele

p + q = 1

Equation representing the relationship between the frequency of dominant and recessive alleles in a population.

p² + 2pq + q² = 1

Equation used to calculate the frequency of genotypes in a population in Hardy-Weinberg Equilibrium.

P²

Genotypic frequency of homozygous dominant individuals.

2pq

Genotypic frequency of heterozygous individuals.

Q²

Genotype frequency of homozygous recessive individuals.

Evolution

The process of biological change in populations over time that makes descendants genetically different from their ancestors.

Microevolution

Evolution on a small scale affecting a single population.

Macroevolution

Evolution on a large scale affecting changes in species across populations.

Natural Selection

Organisms with the 'best' traits (adaptations) will live longer and reproduce more than others, causing changes in the population over time.

Fitness

A measure of how well you can survive in your environment.

Adaptation

A feature that allows an organism to better survive in its environment.

Gene Pool

The combined alleles of all individuals in a population.

Genetic Drift

Random change in the frequency of alleles in a population over time.

Founder Effect

Loss of genetic diversity when a very small group of colonizers leave a population to found a new one.

Population Bottleneck

An environmental event results in the loss of the majority of the population, with only a few individuals surviving.

Gene Flow

Movement of genes into/out of a population, occurring during migration.

Sexual Selection

The selection of traits that aren't necessarily good for survival fitness, but are necessary for reproduction.

Genetic Equilibrium

When there are NO changes in the allele frequencies in a population over time.

Speciation

Forming of a new species by evolution from a pre-existing species, requiring some sort of isolation.

Extinction

Elimination of a species.

Gradual Extinction

Occurs at a slow rate due to changes in climate or natural disasters.

Mass Extinction

Occurs when a catastrophic event changes the environment suddenly.

Gradualism

A model of evolution in which gradual change occurs over time.

Punctuated Equilibrium

A model of evolution in which long periods of stability are interrupted by brief periods of rapid change.

Gradualism

Slow, constant changes over a long period of time

Example of Gradualism

Gradual evolution of peppered moths becoming darker over time after the Industrial Revolution

Punctuated Equilibrium

Bursts of change followed by periods of stability

Example of Punctuated Equilibrium

Changes to the mammal population during the Mesozoic and Paleozoic eras

Divergent Evolution

A number of different species arise from one common ancestor. New environments caused differences to evolve in populations.

Example of Divergent Evolution

A common ancestor of mammals gave rise to bears, monkeys, elephants, and koalas.

Convergent Evolution

When unrelated species evolve similar characteristics because they live in similar environments.

Example of Convergent Evolution

Although birds, mammals, and reptiles fly, none are actually related ancestrally.

Coevolution

Occurs when two populations of organisms form a specialized relationship and thus change in response to each other.

Example of Coevolution

Flowers and the insects that pollinate them.

Species

Group of organisms that can successfully interbreed and produce viable, fertile offspring.

Adaptive Radiation

A type of divergent evolution occurring on a small scale over a shorter period of time.

Transitional Fossils

Link ancestral species to their development. Critical for piecing together evolutionary history.

Example of Transitional Fossils

Archaeopteryx, the transitional fossil between birds and dinosaurs.

Homologous Structures

Similar structures that suggest evidence of common ancestry. Similar structure, but different function due to being used in different environments. Result of divergent evolution.

Example of Homologous Structures

Similar bone structures in arms.

Vestigial Structures

Structures with little or no function to an organism. Could be leftover from an ancestor that had used the structure and thus could provide evidence of divergent evolution.

Example of Vestigial Structures

Ostrich wings.

Analogous Structures

Similar structures that evolved independently in different organisms due to serving similar purposes. Different structurally but same functionally due to living in similar environments. Result of convergent evolution.

Example of Analogous Structures

Wings on an insect vs. wings on an owl.

Evidence in Biogeography

The distribution of organisms lines up with what has been discovered about continental drift and Pangea. Species in nearby geographic areas often resemble each other, with variation for their specific environments.

Example of Evidence in Biogeography

Island species are more closely related to mainland species than they are to species on similar islands on the other side of the world.

Evidence in Embryology

Similarities in the embryos of vertebrates early in development suggests common ancestry among vertebrates.

Macromolecules in Evolution

Analyzing DNA and proteins from different species allows us to compare similarities to predict common ancestry.

Closely Related Species

Would have similar DNA sequences.

Microevolution

Evolution that occurs in populations with short life cycles that reproduce quickly.

Peppered moths

An example of microevolution observed in the last century.

Mosquitoes resistant to pesticides like DDT

An example of microevolution observed in the last century.

MRSA

A type of antibiotic resistant bacteria.

Paleontology

Study of prehistoric life through the fossil record.

Morphology

Study of the form of living things.

Biogeography

Study of the geographic distribution of plants and animals.

Embryology

Study of embryo development.

Biochemistry

Study of chemical processes in living things.

Fossils

Preserved remains of organisms (bones, footprints, feces, etc.).

Endemic species

Species that exist only in one geographic region.

Galapagos tortoises

An example of an endemic species.

Pseudogenes

Non-functional genes.

Vestigial structures

Structures in DNA that provide evidence of divergent evolution.

Phylogeny

Evolutionary history of a species.

Eubacteria

Prokaryotes; 'true' bacteria, like pathogens.

Archaebacteria

Prokaryotes in extreme environments.

Eukarya

Eukaryotes.

Taxonomy

Field of biology that classifies organisms by similar characteristics.

Binomial nomenclature

2-name naming system, Genus species.

Endosymbiotic theory

Suggests that over time, coevolution of two prokaryotes occurred and eventually led to speciation and the 1st eukaryotes.

Phylogenetic trees

Diagrams used to predict evolutionary relationships among groups of organisms.

Maximum parsimony

Use the simplest explanation for creating the tree.

Homologous features

Any heritable traits (DNA, proteins, anatomical structures, etc.) that are the result of divergent evolution.

Speciation

Branching of a family tree.

Extinction

Loss of one of the branches.

Water Cycle

The cycle of water movement through the environment, influenced by human activities such as deforestation, paving, and pollution.

Deforestation

Decreased transpiration due to the removal of trees.

Eutrophication

When a body of water becomes overly enriched with nutrients, causing excessive algae growth.

Carbon Cycle

The cycle that describes the movement of carbon among the atmosphere, land, and oceans, significantly impacted by combustion.

Combustion

The process of burning wood or fossil fuels, which releases a major increase of CO2 in the atmosphere.