Science Test Flashcards

Front 1

ecology

Back 1

scientific study of interactions among organisms and between organisms and their environment

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biosphere

Back 2

part of Earth in which life exists including land, water, and air or atmosphere

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species

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group of similar organisms that can breed and produce fertile offspring

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population

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group of individuals of the same species that live in the same area

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community

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assemblage of different populations that live together in a defined area

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ecosystem

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collection of all the organisms that live in a particular place, together with their nonliving environment

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biome

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group of ecosystems that have the same climate and dominant communities

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autotroph

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organism that can capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds; also called a producer

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photosynthesis

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process by which plants and some other organisms use light energy to convert water and carbon dioxide into oxygen and high-energy carbohydrates such as sugars and starches

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chemosynthesis

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process by which some organisms, such as certain bacteria, use chemical energy to produce carbohydrates

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heterotroph

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organism that obtains energy from the foods it consumes; also called a consumer

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consumer

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organism that relies on other organisms for its energy and food supply; also called a heterotroph

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detrivore

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organism that feeds on plant and animal remains and other dead matter

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food chain

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series of steps in an ecosystem in which organisms transfer energy by eating and being eaten

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food web

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network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem

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trophic level

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step in a food chain or food web

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ecological system

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diagram that shows the relative amounts of energy or matter within each trophic level in a food chain or food web

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biomass

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total amount of living tissue within a given trophic level

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biogeochemical cycle

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process in which elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another

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transpiration

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loss of water from a plant through its leaves

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nutrient

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chemical substance that an organism requires to live

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nitrogen fixation

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process of converting nitrogen gas into ammonia

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denitrification

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conversion of nitrates into nitrogen gas

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primary productivity

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rate at which organic matter is created by producers in an ecosystem

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limiting nutrient

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single nutrient that either is scarce or cycles very slowly, limiting the growth of organisms in an ecosystem

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algal bloom

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an immediate increase in the amount of algae and other producers that results from a large input of a limiting nutrient

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greenhouse effect

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natural situation in which heat is retained in Earth's atmosphere by carbon dioxide, methane, water vapor, and other gases

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biotic factor

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biological influence on organisms within an ecosystem

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abiotic factor

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physical, or nonliving, factor that shapes an ecosystem

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resource

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any necessity of life, such as water, nutrients, light, food, or space

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competitive exclusion principle

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ecological rule that states that no two species can occupy the same exact niche in the same habitat at the same time

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symbiosis

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relationship in which two species live closely together

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ecological succession

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gradual change in living communities that follows a disturbance

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primary succession

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succession that occurs on surfaces where no soil exists

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pioneer species

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first species to populate an area during primary succession

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secondary succession

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succession following a disturbance that destroys a community without destroying the soil

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tolerance

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organism's capacity to grow or thrive when subjected to an unfavorable environmental factor

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microclimate

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climate within a small area that differs significantly from the climate of the surrounding area

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humus

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material formed from decaying leaves and other organic matter

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taiga

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biome in which the winters are cold but summers are mild enough to allow the ground to thaw

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permafrost

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layer of permanently frozen subsoil in the tundra

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phytoplankton

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population of algae and other small, photosynthetic organisms found near the surface of the ocean and forming part of plankton

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zooplankton

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tiny animals that form part of the plankton

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wetland

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ecosystem in which water either covers the soil or is present at or near the surface of the soil for at least part of the year

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tetritus

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particles of organic material that provide food for organisms at the base of an estuary's food web

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salt marsh

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temperate-zone estuary dominated by salt-tolerant grasses above the low-tide line and by seagrasses under water

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mangrove swamp

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coastal wetland dominated by mangroves, salt-tolerant woody plants

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photic zone

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well-lit upper layer of the oceans

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aphotic zone

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permanently dark layer of the oceans below the photic zone

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zonation

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prominent horizontal banding of organisms that live in a particular habitat

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coastal ocean

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marine zone that extends from the low-tide mark to the end of the continental shelf

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benthos

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organisms that live attached to or near the ocean floor

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population density

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number of individuals per unit of area

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immigration

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movement of individuals into an area occupied by an existing population

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emigration

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movement of individuals out of an area

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exponential growth

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growth pattern in which the individuals in a population reproduce at a constant rate

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logistic growth

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growth pattern in which a population's growth rate slows or stops following a period of exponential growth

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carrying capacity

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largest number of individuals of a population that a given environment can support

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limiting factor

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factor that causes the growth of a population to decrease

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density dependent limiting factor

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limiting factor that depends on population size

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predator prey relationship

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mechanism of population control in which a population is regulated by predation

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density independent limiting factor

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limiting factor that affects all populations in similar ways, regardless of population size

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demography

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scientific study of human populations

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demographic transition

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

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age structure diagram

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graph of the numbers of males and females within different age groups of a population

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monoculture

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farming strategy in which large fields are planted with a single crop, year after year

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green revolution

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the development of highly productive crop strains and the use of modern agricultural techniques to increase yields of food crops

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sustainable development

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using natural resources at a rate that does not deplete them

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soil erosion

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wearing away of surface soil by water and wind

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desertification

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in areas with dry climates, a process caused by a combination of poor farming practices, overgrazing, and drought that turns productive land into desert

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aquaculture

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the raising of aquatic organisms for human consumption

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acid culture

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rain containing nitric and sulfuric acids

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biodiversity

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biological diversity; the sum total of the variety of organisms in the biosphere

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ecosystem diversity

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variety of habitats, living communities, and ecological processes in the living world

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species diversity

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number of different species in the biosphere

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genetic diversity

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sum total of all the different forms of genetic information carried by all organisms living on Earth today

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habitat fragmentation

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splitting of ecosystems into small fragments

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biological magnification

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increasing concentration of a harmful substance in organisms at higher trophic levels in a food chain or food web

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invasive species

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plants and animals that have migrated to places where they are not native

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conservation

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wise management of natural resources, including the preservation of habitats and wildlife

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ozone layer

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atmospheric layer in which ozone gas is relatively concentrated

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global warming

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increase in the average temperatures on Earth