BSCI160 Final Exam Key Terms

Evolution

Change in allele frequencies in a population over generations

Natural selection

Individuals with traits that improve survival or reproduction leave more offspring

Mutation

A random change in DNA that creates new alleles

Recombination

Rearrangement of genetic material during sexual reproduction that creates new allele combinations

Gene flow

Movement of genes between populations through migration and mating

Genetic drift

Random changes in allele frequencies due to chance, strongest in small populations

Genetic variation

Differences in genetic makeup among individuals in a population

Allele

An alternative form of a gene

Genotype

The genetic makeup of an organism

Phenotype

Observable traits produced by genes and the environment

Mendelian inheritance

Trait inheritance based on dominant and recessive alleles

Polygenic inheritance

A trait controlled by multiple genes, producing continuous variation

Independent assortment

Different genes are inherited independently during gamete formation

Epigenetic modification

Changes in gene expression without altering DNA sequence

Adaptation

A heritable trait that increases fitness in a specific environment

Fitness

An organism’s reproductive success

Speciation

Formation of new species due to genetic divergence

Reproductive isolation

When populations can no longer interbreed successfully

Niche

How a species uses resources and interacts with its environment

Population

Individuals of the same species living in the same area

Community

All interacting species in an ecosystem

Carrying capacity

Maximum population size an environment can support

Density dependence

When population growth is affected by population size

Dispersion

Pattern of spacing among individuals in a population

Habitat fragmentation

Breaking habitats into smaller, isolated patches

Competition

Organisms competing for limited resources

Predation

One organism consumes another

Mutualism

Interaction where both species benefit

Island biogeography theory

Species richness depends on colonization and extinction rates

Colonization rate

Rate at which new species arrive in an area

Extinction rate

Rate at which species disappear from an area

Equilibrium number of species

Stable species number when colonization equals extinction

Habitat patch

Isolated area of suitable habitat

Ecosystem

Organism interacting with their physical environment

Producer

Organism that makes its own food (photosynthesis)

Consumer

Organism that eats other organisms for energy

Trophic level

Feeding position in a food chain

Energy flow

Transfer of energy through trophic levels

Productivity

Rate at which energy becomes biomass

GPP (Gross primary productivity)

Total energy captured by photosynthesis

NPP (Net primary productivity)

Energy available to consumers after respiration

Reservoir

Location where a nutrient is stored

Flux

Movement of nutrients between reservoirs

Runoff

Water flowing over land into water bodies

Infiltration

Water soaking into soil

Groundwater

Water stored underground

Carbon sink

Reservoir that absorbs more carbon than it releases

Carbon source

Reservoir that releases more carbon than it absorbs

Photosynthesis

Conversion of CO2 into organic molecules using sunlight

Cellular respiration

Breakdown of organic molecules releasing energy and CO2

Decomposition

Breakdown of dead matter returning nutrients to the environment

Sedimentation

Long-term carbon storage in ocean sediments

Greenhouse gas

Gas that traps heat in the atmosphere

Greenhouse gas effect

Warming caused by trapped heat in Earth’s atmosphere

Nitrogen fixation

Conversion of N2 into usable forms by bacteria

Nitrification

Conversion of ammonia into nitrates

Denitrification

Conversion of nitrates into nitrogen gas

Weathering

Breakdown of rocks releasing phosphorus

Eutrophication

Nutrient pollution causing algal blooms and oxygen loss

Climate change

Long-term shifts in climate patterns

Global warming

Increase in Earth’s average temperature

Greenhouse gases

Heat-trapping gases like CO2 and methane

Positive feedback loop

A process that amplifies an initial change

Permafrost

Permanently frozen ground storing carbon

Fossil fuels

Coal, oil, and gas formed from ancient organisms

Biodiversity

Variety of life at genetic, species, and ecosystem levels

Biodiversity decline

Reduction in species and ecosystem diversity

Extinction

Permanent loss of a species

Mass extinction

Rapid global loss of many species

Ecosystem services

Benefits humans receive from ecosystems

Conservation

Protection of species and ecosystems

Restoration ecology

Repairing damaged ecosystems

Sustainability

Meeting present needs without harming future generations

Proactive action

Preventing environmental damage before it occurs

Reactive action

Responding after damage has occurred

Environmental justice

Fair distribution of environmental benefits and burdens

Anthropogenic change

Environmental change caused by humans