Biology: Evolution and Ecology Flashcards

Comprehensive vocabulary flashcards covering key ecology, evolution, and molecular genetics concepts.

Abiotic factor

A nonliving physical or chemical part of the environment, such as temperature, sunlight, water, wind, or soil chemistry.

Biotic factor

A living or once-living part of the environment, such as organisms and their interactions.

Biogeochemical cycle

The movement of an element or compound (water, carbon, nitrogen, phosphorus) between abiotic reservoirs and living organisms.

Reservoir

A place where an element is stored for a long time, such as the ocean, atmosphere, rocks, sediments, or fossil fuels.

Water cycle

Water moves among the ocean, atmosphere, land, and groundwater by evaporation, transpiration, condensation, precipitation, and runoff. Powered by solar energy.

Transpiration

Evaporation of water from plant leaves through stomata.

Groundwater

Water held in soil and in the spaces of porous rock; an aquifer is a rock layer that holds groundwater.

Watershed

An area of land from which all precipitation drains into a particular stream, river, or lake.

Carbon cycle

Carbon moves between the atmosphere ($CO_2$), producers (photosynthesis), consumers and decomposers (aerobic respiration), the oceans, and rocks/fossil fuels.

Main carbon reservoirs

Sedimentary rock, fossil fuels, and ocean water hold far more carbon than the atmosphere does.

Fossil fuel

Coal, oil, or natural gas formed from the remains of ancient organisms; burning it releases stored carbon as $CO_2$.

Greenhouse gas

A gas ($CO_2$, methane, water vapor, nitrous oxide, CFCs) that absorbs and re-radiates heat, warming the lower atmosphere.

Greenhouse effect

The natural warming of Earth's lower atmosphere by greenhouse gases; without it Earth would be far too cold.

Global warming

A long-term rise in Earth's average temperature, driven mainly by human release of $CO_2$ (fossil fuel burning, deforestation) and other greenhouse gases.

Weather vs. climate

Weather is short-term atmospheric conditions at a place; climate is the average weather pattern over many years.

Nitrogen cycle

Nitrogen moves between the atmosphere ($N_2$, the main reservoir), soil, and organisms through fixation, ammonification, nitrification, assimilation, and denitrification.

Nitrogen fixation

Bacteria (e.g., Rhizobium in legume root nodules, cyanobacteria) convert $N_2$ gas into ammonia/ammonium that plants can use.

Ammonification

Decomposers break down organic nitrogen in wastes and remains and release ammonium.

Nitrification

Soil bacteria convert ammonium to nitrite and then to nitrate, the form most plants take up.

Denitrification

Bacteria in oxygen-poor soil or sediment convert nitrate to $N_2$ gas, returning nitrogen to the atmosphere.

Phosphorus cycle

Phosphorus moves from rock (weathering) to soil and water to producers to consumers and back by decomposition; it has no gas phase and the atmosphere is not a reservoir.

Eutrophication

Nutrient (nitrogen and phosphorus) enrichment of a water body that causes algal blooms, then oxygen depletion when the algae die and decompose.

Dead zone

Area of water with too little oxygen to support most life, often caused by nutrient runoff and eutrophication.

Ozone layer

Layer of ozone ($O_3$) in the stratosphere that absorbs most UV radiation; thinned by chlorine compounds such as CFCs.

Troposphere vs. stratosphere

Troposphere is the lowest atmospheric layer, where weather happens; the stratosphere above it contains the ozone layer.

Uneven heating of Earth

Sunlight hits the equator more directly than the poles, so tropics receive more heat per unit area; this difference drives air circulation.

Seasons

Caused by the tilt (about $23.5^\circ$) of Earth's axis as it orbits the sun, not by distance from the sun.

Air circulation pattern

Warm air rises at the equator, cools and drops its moisture as rain, moves toward the poles, and sinks near $30^\circ$ latitude as dry air (deserts); similar rising and sinking occurs near $60^\circ$.

Hadley cell

The large circulation loop between the equator and about $30^\circ$ latitude: air rises at the equator and sinks around $30^\circ$.

Intertropical convergence zone (ITCZ)

Belt near the equator where trade winds meet and warm moist air rises, producing heavy rainfall.

Coriolis effect

Earth's rotation deflects moving air and water to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

Prevailing winds

Trade winds blow from east to west near the equator ($0$-$30^\circ$); westerlies blow from west to east at mid-latitudes ($30$-$60^\circ$); polar easterlies blow near the poles.

Ecosystem

A community of organisms interacting with one another and with their physical environment, with energy flowing through and nutrients cycling.

Producer (autotroph)

Organism that makes its own food from inorganic sources, usually by photosynthesis (plants, algae, some bacteria).

Consumer (heterotroph)

Organism that gets energy and carbon by eating other organisms or their remains.

Herbivore / carnivore / omnivore

Eats plants / eats animals / eats both plants and animals.

Decomposer

Organism (bacteria, fungi) that breaks down wastes and remains and releases nutrients back to the environment.

Detritivore

Consumer that feeds on small bits of organic debris (e.g., earthworms, millipedes).

Trophic level

An organism's position in a food chain, counted by number of steps from the primary producer.

Primary / secondary / tertiary consumer

A consumer on the 2nd / 3rd / 4th trophic level (eats producers / eats primary consumers / eats secondary consumers).

Food chain vs. food web

A food chain is one linear path of who eats whom; a food web is the many interconnected food chains in an ecosystem.

Energy flow vs. nutrient cycling

Energy flows one way through an ecosystem (sun to producers to consumers, lost as heat); nutrients are recycled.

Ten percent rule

Only about $10\%$ of the energy at one trophic level is stored in the next level; the rest is lost as metabolic heat or never eaten.

Energy pyramid

Diagram showing energy at each trophic level; it always narrows toward the top because energy is lost at each transfer.

Biomass

Total dry weight of organisms (or of a trophic level) in an area.

Primary production

Rate at which producers capture and store energy as organic compounds (gross primary production minus respiration = net primary production).

Biological magnification

A fat-soluble or nonbreakable chemical (e.g., DDT, mercury) becomes more concentrated in the tissues of organisms at higher trophic levels.

Biosphere

All regions of Earth's crust, waters, and atmosphere in which organisms live.

Biome

A large region defined by its climate and dominant vegetation (e.g., desert, tundra, tropical rain forest).

Ocean currents

Large streams of moving seawater driven by winds, Earth's rotation (Coriolis), and temperature/salinity differences; they redistribute heat and affect coastal climate.

Upwelling

Nutrient-rich cold water rises from the deep to the surface, supporting high productivity and large fisheries.

El Nino

Periodic warming of the eastern Pacific that weakens trade winds and upwelling and shifts weather patterns worldwide.

Rain shadow

Dry area on the leeward side of a mountain range, because air loses its moisture as rain on the windward side.

Monsoon

Seasonal shift in wind direction that brings a wet season and a dry season to a region.

Desert

Biome with less than about $25\,\text{cm}$ of rain a year, often near $30^\circ$ latitude or in a rain shadow; plants and animals conserve water (e.g., cacti, nocturnal animals).

Grassland

Biome dominated by grasses with too little rain for forests; includes temperate grassland (prairie) and tropical savanna.

Savanna

Tropical grassland with scattered trees and distinct wet and dry seasons.

Shrubland (chaparral)

Biome of dense, drought-adapted shrubs with mild wet winters and hot dry summers; fire-prone.

Temperate deciduous forest

Forest of broadleaf trees that drop leaves in fall; moderate rainfall and distinct seasons.

Tropical rain forest

Biome near the equator with high rainfall, warm temperatures year-round, and the highest species diversity; nutrients are mostly in the biomass, not the thin soil.

Boreal forest (taiga)

Cold biome of coniferous trees (spruce, fir, pine) with long winters and short summers; the largest land biome.

Tundra

Cold, treeless biome with very short growing season; arctic tundra has permafrost (permanently frozen soil layer).

Permafrost

Permanently frozen layer of soil in tundra regions.

Aquatic biome types

Freshwater (lakes, ponds, streams, rivers, wetlands) and marine (open ocean, coastal waters, estuaries, intertidal, coral reefs).

Photic vs. aphotic zone

Photic zone is the upper water layer with enough light for photosynthesis; aphotic zone is below that and dark.

Lake zones

Littoral zone is shallow water near shore; limnetic zone is open water with light; profundal zone is deep water below the reach of light.

Oligotrophic vs. eutrophic lake

Oligotrophic lakes are nutrient-poor, clear, and low in production; eutrophic lakes are nutrient-rich, cloudy, and highly productive.

Wetland

Land that is covered with water for at least part of the year (marsh, swamp, bog); filters water and buffers floods.

Estuary

Partially enclosed coastal area where fresh water from rivers mixes with seawater; highly productive nursery habitat.

Intertidal zone

Shoreline area exposed to air at low tide and covered by water at high tide.

Coral reef

Marine ecosystem built by coral animals living in warm, shallow, clear water; very high species diversity.

Pelagic vs. benthic zone

Pelagic zone is the open water; benthic zone is the ocean or lake bottom.

Hydrothermal vent

Deep-sea opening that releases hot, mineral-rich water; supports communities based on chemosynthetic bacteria.

Ecology

The study of how organisms interact with one another and with their physical environment.

Levels of ecological organization

Individual, population, community, ecosystem, biosphere.

Population

A group of individuals of the same species living in a given area.

Community

All populations of all species living in a given area.

Habitat

The type of place where a species typically lives, defined by its physical and biological features.

Niche

The full range of physical and biological conditions a species can tolerate and the resources it uses and role it plays in its ecosystem.

Fundamental vs. realized niche

Fundamental niche is the full range a species could use; realized niche is the narrower range it actually uses because of competition and other interactions.

Species richness

The number of different species in a community.

Symbiosis

A close, long-term interaction between two species in which at least one benefits.

Mutualism

Interaction that benefits both species (+/+), such as pollinators and flowering plants or mycorrhizae and plant roots.

Commensalism

Interaction that benefits one species and neither helps nor harms the other (+/0).

Parasitism

Interaction in which a parasite lives on or in a host and feeds on it, harming the host (+/-) but usually not killing it quickly.

Parasitoid

An insect (such as a certain wasp) whose larvae develop inside a host and eventually kill it.

Predation

Interaction in which a predator captures, kills, and eats prey (+/-).

Competition

Interaction in which two or more individuals use the same limited resource, harming both (-/-).

Intraspecific vs. interspecific competition

Competition between members of the same species vs. between members of different species.

Interference vs. exploitation competition

Interference: individuals directly prevent others from using a resource. Exploitation: individuals use up the resource, leaving less for others.

Competitive exclusion

Two species with identical niche requirements cannot coexist indefinitely; one will eliminate the other.

Resource partitioning

Species with similar needs avoid competition by using different resources or the same resources in different ways, places, or times.

Coevolution

Reciprocal evolutionary change in two interacting species over time (flowers and pollinators, predator and prey).

Camouflage

Prey defense in which an organism blends in with its background.

Warning coloration (aposematism)

Bright colors that advertise that an organism is toxic or dangerous.

Batesian mimicry

A harmless species resembles a harmful or unpalatable one.

Mullerian mimicry

Two or more harmful species resemble one another, reinforcing the predator's learning.

Keystone species

A species that has a disproportionately large effect on community structure compared with its abundance (e.g., sea star Pisaster).

Invasive (exotic) species

A nonnative species that spreads in a new habitat, often outcompeting native species.

Ecological succession

The gradual, orderly change in a community's species composition after a disturbance or on new habitat.