Principles of Ecology & Molecular Genetics

Flashcards covering key concepts from ecology, community dynamics, and genetics, focusing on definitions, processes, and the scientists involved.

Ecology

The scientific discipline in which the relationships among living organisms and the interaction the organisms have with their environments are studied.

Biosphere

The portion of Earth that supports life. It extends several kilometers above Earth's surface into the atmosphere and several kilometers below the ocean's surface to the deep-ocean vents. It includes landmasses, bodies of freshwater and saltwater, and all locations below Earth's surface that support life.

Biotic Factor

The living factors in an organism's environment, such as other fish, algae, frogs, and microscopic organisms.

Abiotic Factor

The nonliving factors in an organism's environment, such as temperature, air or water currents, sunlight, soil type, rainfall, or available nutrients.

Population

Individual organisms of a single species that share the same geographic location at the same time.

Biological Community

A group of interacting populations that occupy the same geographic area at the same time.

Ecosystem

A biological community and all of the abiotic factors that affect it.

Biome

A large group of ecosystems that share the same climate and have similar types of communities.

Habitat

An area where an organism lives.

Niche

The role or position that an organism has in its environment, including how it meets its needs for food, shelter, and reproduction.

Predation

The act of one organism pursuing and consuming another organism for food.

Symbiosis

The close relationship that exists when two or more species live together.

Mutualism

The relationship between two or more organisms that live closely together and benefit from each other.

Commensalism

A relationship in which one organism benefits and the other organism is neither helped nor harmed.

Parasitism

A symbiotic relationship in which one organism benefits at the expense of another organism.

Autotroph

An organism that collects energy from sunlight or inorganic substances to produce food; also known as a primary producer.

Heterotroph

An organism that gets its energy requirements by consuming other organisms; also called a consumer.

Herbivore

A heterotroph that eats only plants.

Carnivore

A heterotroph that preys on other heterotrophs.

Omnivore

An organism that eats both plants and animals.

Detritivore

An organism that eats fragments of dead matter in an ecosystem, returning nutrients to the soil, air, and water.

Trophic Level

Each step in a food chain or food web.

Food Chain

A simple model that shows how energy flows through an ecosystem.

Food Web

A model representing the many interconnected food chains and pathways in which energy flows through a group of organisms.

Biomass

The total mass of living matter at each trophic level.

Matter

Anything that takes up space and has mass.

Nutrient

A chemical substance that an organism must obtain from its environment to sustain life and to undergo life processes.

Biogeochemical Cycle

The exchange of matter through the biosphere; involves living organisms (bio), geological processes (geo), and chemical processes (chemical).

Nitrogen Fixation

The process of capture and conversion of nitrogen into a form that is usable by plants.

Denitrification

A process in which some soil bacteria convert fixed nitrogen compounds back into nitrogen gas, which returns it to the atmosphere.

Population Density

The number of organisms per unit area.

Dispersion

The pattern of spacing of a population within an area.

Density-Independent Factor

Any factor in the environment that does not depend on the number of members in a population per unit area.

Density-Dependent Factor

Any factor in the environment that depends on the number of members in a population per unit area.

Population Growth Rate

Explains how fast a given population grows.

Emigration

The number of individuals moving away from a population.

Immigration

The number of individuals moving into a population.

Carrying Capacity

The maximum number of individuals in a species that an environment can support for the long term.

Demography

The study of human population size, density, distribution, movement, and birth and death rates.

Demographic Transition

The change in a population from high birth and death rates to low birth and death rates.

Zero Population Growth (ZPG)

Occurs when births plus immigration equals deaths plus emigration.

Age Structure

A population's age structure is the number of males and females in each of three age groups: pre-reproductive stage, reproductive stage, and post-reproductive stage.

Community

A group of interacting populations that occupy the same area at the same time.

Limiting Factor

Any abiotic factor or biotic factor that restricts the numbers, reproduction, or distribution of organisms.

Tolerance

The ability of any organism to survive when subjected to abiotic factors or biotic factors.

Ecological Succession

The change in an ecosystem that happens when one community replaces another as a result of changing abiotic and biotic factors.

Primary Succession

The establishment of a community in an area of exposed rock that does not have any topsoil.

Climax Community

The stable, mature community that results when there is little change in the composition of species.

Secondary Succession

The orderly and predictable change that takes place after a community of organisms has been removed but the soil has remained intact.

Weather

The condition of the atmosphere at a specific place and time.

Latitude

The distance of any point on the surface of Earth north or south from the equator.

Climate

The average weather conditions in an area, including temperature and precipitation.

Tundra

A treeless biome with a layer of permanently frozen soil below the surface called permafrost.

Boreal Forest

Also called northern coniferous forest or taiga, a broad band of dense evergreen forest extending across North America, Europe, and Asia.

Temperate Forest

Composed mostly of broad-leaved, deciduous trees—trees that shed their leaves in autumn.

Woodland

Open woodlands and mixed shrub communities in areas with less annual rainfall than in temperate forests.

Grassland

A biome that is characterized by fertile soils that are able to support a thick cover of grasses.

Desert

An area in which the annual rate of evaporation exceeds the rate of precipitation.

Tropical Savanna

Characterized by grasses and scattered trees in climates that receive less precipitation than some other tropical areas.

Tropical Seasonal Forest

Also called tropical dry forests, grow in areas of Africa, Asia, Australia, and South and Central America.

Tropical Rain Forest

Warm temperatures and large amounts of rainfall throughout the year characterize this biome.

Sediment

Material that is deposited by water, wind, or glaciers.

Littoral Zone

The area closest to the shore of a lake or pond.

Limnetic Zone

The open water area of a lake or pond that is well lit and is dominated by plankton.

Plankton

Free-floating photosynthetic autotrophs that live in freshwater or marine ecosystems.

Profundal Zone

Minimal light is able to penetrate through the limnetic zone into the deepest areas of a large lake.

Wetlands

Areas of land such as marshes, swamps, and bogs that are saturated with water and that support aquatic plants.

Estuary

An ecosystem that is formed where freshwater from a river or stream merges with salt water from the ocean.

Intertidal Zone

A narrow band where the ocean meets land.

Photic Zone

The area of the pelagic zone to a depth of about 200 m; shallow enough that sunlight is able to penetrate.

Aphotic Zone

An area where sunlight is unable to penetrate.

Benthic Zone

The area along the ocean floor that consists of sand, silt, and dead organisms.

Abyssal Zone

The deepest region of the ocean.

Double Helix

The twisted ladder shape, formed by two strands of nucleotides twisted around each other, of DNA.

Nucleosome

A structure consisting of DNA tightly coiled around a group of beadlike proteins called histones.

Semiconservative Replication

Parental strands of DNA separate, serve as templates, and produce DNA molecules that have one strand of parental DNA and one strand of new DNA.

DNA Polymerase

The enzyme that catalyzes the addition of appropriate nucleotides to the new DNA strand.

Okazaki Fragment

Small segments synthesized discontinuously into on the lagging strand during DNA replication.

RNA

A nucleic acid that is similar to DNA, containing the sugar ribose, the base uracil in place of thymine, and is usually single stranded.

Messenger RNA (mRNA)

Long strands of RNA nucleotides that are formed complementary to one strand of DNA and travel from the nucleus to the ribosome to direct the synthesis of a specific protein.

Ribosomal RNA (rRNA)

The type of RNA that associates with proteins to form ribosomes in the cytoplasm.

Transfer RNA (tRNA)

Smaller segments of RNA nucleotides that transport amino acids to the ribosome.

Transcription

The synthesis of mRNA from DNA.

RNA Polymerase

The enzyme that regulates RNA synthesis.

Intron

Intervening sequences, segments that do not code for proteins

Exon

Coding sequences that remain in the final mRNA.

Codon

A three-base code in DNA or mRNA.

Translation

The process where the code is read and translated to make a protein.

Gene Regulation

The ability of an organism to control which genes are transcribed in response to the environment.

Operon

A section of DNA that contains the genes for the proteins needed for a specific metabolic pathway.

Mutation

A permanent change that occurs in a cell's DNA.

Mutagen

Substances which cause mutations.

Carrier

An individual who is heterozygous for a recessive disorder.

Pedigree

A diagram that traces the inheritance of a particular trait through several generations.

Incomplete Dominance

The heterozygous phenotype is an intermediate phenotype between the two homozygous phenotypes.

Codominance

Both alleles are expressed in the heterozygous condition.

Multiple Alleles

Some forms of inheritance are determined by more than one pair alleles.

Epistasis

One allele hiding the effects of another allele.

Sex Chromosome

One pair of chromosomes that determines an individual's gender.

Autosome

The other 22 pairs of chromosomes that, along with the sex chromosomes make up each cell in your body.