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171 Cards in this Set

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Ecology
The study of the natural environment and of the relations of organisms to each other and to their surroundings.
Organism
A living being; the most fundamental unit of ecology.
Ecosystem
All the interacting parts of the physical and biological worlds.
Population
The group of organisms of a particular species that inhabit a particular area.
Community
An association of interacting populations, usually defined by the nature of their interaction or the place in which they live.
Symbiosis
An intimate and often obligatory association of two species, usually involving coevolution. Symbiotic relationships can be parasitic or mutualistic.
Habitat
The place where an animal or plant normally lives, often characterized by a dominant plant form or physical characteristic (that is, a stream habitat, a forest habitat).
Niche
The ecological role of a species in the community; the ranges of many conditions and resource qualities within which the organism or species persists, often conceived as a multi-dimensional space.
Scale
The dimension in time or space over which variation is perceived.
Evolution
Change in the heritable traits of organisms through the replacement of genotypes within a population.
Adaptations
A genetically determined characteristic that enhances the ability of an individual to cope with its environment; the evolutionary process by which organisms become better suited to their environments.
Natural Selection
Change in the frequency of genetic traits in a population through differential survival and reproduction of individuals bearing those traits.
Hypotheses
A conjecture about or explanation for a pattern or relationship embracing a mechanism for its occurrence.
Prediction
A logical consequence of a hypothesis or outcome of a model describing some aspect of a system.
Experiments
A controlled manipulation of a system to determine the effect of a change in one or more factors.
Control
A treatment that reproduces all aspects of an experiment except the variable of interest.
Microcosm
A small, simplified system, often maintained in a laboratory, that contains the essential features of a larger natural system.
Acidity
The concentration of hydrogen ions in a solution, often written on the logarithmic scale of pH.
Oxidation
Removal of one or more electrons from an atom, ion, or molecule.
Reduction
Addition of one or more electrons to an atom, ion, or molecule.
Heterotrophs
An organism that uses organic materials as a source of energy and nutrients.
Assimilation
Incorporation of any material into the tissues, cells, and fluids of an organism.
Autotrophs
An organism that assimilates energy from either sunlight (green plants) or inorganic compounds (sulfur bacteria).
Photosynthesis
Use of the energy of light to combine carbon dioxide and water into simple sugars.
Respiration
Use of oxygen to break down organic compounds metabolically to release chemical oxygen.
Boundary layer
A layer of still or slow-moving water or air close to the surface of an object.
Anaerobic habitat
Without oxygen
Anoxic habitat
Lacking oxygen; anaerobic
Ultraviolet
Electromagnetic radiation having a wavelength shorter than about 400 nm.
Greenhouse effect
The warming of the earth's climate because of the increased concentration of carbon dioxide and certain other pollutants in the atmosphere.
Euphotic zone
The surface layer of water to the depth of light penetration at which photosynthesis balances respiration.
Radiant flux
Light intensity,expressed in energy per unit of area per unit of time.
Solar constant
The intensity of solar radiation reaching the outer limit of the earth's atmosphere, approximately 1,400 W per meter squared.
Radiation
Energy emitted in the form of electromagnetic waves.
Conduction
The ability of heat to pass through a substance.
Convection
Transfer of heat by the movement of a fluid (for example, air or water).
Evaporation
The transformation of water from the liquid to the gaseous phase with the input of heat energy.
Transpiration
Evaporation of water from leaves and other parts of plants.
Heat budget
All the gains and losses of heat by an organism, including metabolism, evaporation, radiation, conduction, and convection.
Water potential
The force by which water is held in the soil by capillary and hygroscopic attraction.
Matric potential
Referring to the water potential generated by soil.
Field capacity
The amount of water that soil can hold against the pull of gravity.
Wilting coefficient/wilting point
The minimum water content of the soil at which plants can obtain water.
Osmosis
Diffusion of substances in aqueous solution across the membrane of a cell.
Osmotic potential
The attraction of water to an aqueous solution owing to its concentration of ions and other small molecules; usually expressed as a pressure.
Semipermeable
Referring to a membrane that blocks the passage of some molecules, usually large ones, but not other, smaller molecules.
Active transport
Movement of molecules or ions through a membrane against a diffusion gradient.
Transpiration
Evaporation of water from leaves and other parts of plants.
Tension-cohesion theory
The idea that the force required to draw water from the soil and roots is generated by the evaporation of water from the leaves of plants.
Stomate
The opening in a leaf surface through which gas exchange with the atmosphere takes place.
Compensation point
The depth of water or level of light at which respiration and photosynthesis balance each other; the lower limit of the euphotic zone.
C3 photosynthesis
Photosynthetic pathway in which carbon dioxide is initially assimilated into a three-carbon compound, phosphoglyceraldehyde (PGA), in the Calvin cycle.
C4 photosynthesis
Photosynthetic pathway in which carbon dioxide is initially assimilated into a four-carbon compound, such as oxaloacetic acid (OAA) or malate.
Crassulacean acid metabolism, CAM.
Photosynthetic pathway in which the initial assimilation of carbon dioxide into a four-carbon compound occurs at night; found in some succulent plants in arid habitats.
Hyperosmotic
Having an osmotic potential (generally, salt concentration) greater than that of the surrounding medium.
Hypo-osmotic
Having an osmotic potential (generally, salt concentration) less than that of the surrounding medium.
Homeostasis
The maintenance of constant internal conditions in the face of a varying external environment.
Negative feedback
The tendency of a system to counteract externally imposed change and return to a stable state.
Homeothermy
The ability to maintain a constant body temperature in the face of a fluctuating environmental temperature; warm-bloodedness.
Poikilothermic
Inability to regulate body temperature: cold-bloodedness (opp of homeothermy).
Ectothermy
The capacity to maintain body temperature by gaining heat from the environment, either by conduction or by absorbing radiation.
Endothermy
The capacity to maintain body temperature by the metabolic generation of heat.
Torpor
Loss of the power of motion and feeling, usually accompanied by a greatly reduced rate of respiration.
Countercurrent circulation
Movement of fluids in opposite directions on either side of a separating barrier through which heat or dissolved substances can pass.
Optimum
The narrow range of environmental conditions to which an organism is best suited.
Solar equator
The parallel of latitude that lies directly under the sun at any given season.
Hadley cell
Vertical and latitudinal circulation of air within the atmosphere driven by the warming effect of the sun.
Intertropical convergence
The region within which surface currents of air meet near the equator and begin to rise under the warming influence of the sun.
Subtropical high pressure belts
Regions of high atmospheric pressure and dry air centered approximately 30 degrees north and south of the equator.
Rain shadows
A dry area on the leeward side of a mountain range.
Upwelling
Vertical movement of water, usually near coasts and driven by offshore winds, that brings nutrients from the depths of the ocean to surface layers.
Mediterranean climate
A pattern of climate found in middle latitudes, characterized by cool, wet winters and warm, dry summers.
Temperature profile
The relationship of temperature to depth below the surface of the water or soil, or height above the ground.
Spring overturn
The vertical mixing of water layers in temperate lakes in spring as surface ice disappears.
Thermocline
The zone of water depth within which temperature changes rapidly between the upper warm water layer (epilimnion) and lower cold water layer (hypolimnion).
Stratification
The establishment of distinct layers of temperature or salinity in bodies of water based on the different densities of warm and cold water or saline and fresh water.
Epilimnion
The warm, oxygen-rich surface layers of a lake or other body of water. (comp. with hypolimnion)
Hyoplimnion
The cold, oxygen depleted part of a lake or other body of water that lies below the zone of rapid change in water temperature (thermocline). (comp with epilimnion).
Fall overturn
The vertical mixing of water layers in temperate lakes in autumn following breakdown of thermal stratification.
Fall (autumn) bloom
The rapid growth of algae in temperate lakes following the autumnal breakdown of thermal stratification.
Riparian
Along the bank of a river or lake.
Xeric
Referring to habitats in which plant production is limited by the availability of water.
Mesic
Referring to habitats with plentiful rainfall and well-drained soils.
Adiabatic cooling
The decrease in temperature with increasing elevation caused by the expansion of air the the lower atmospheric pressure.
Life zones
A more or less distinct belt of vegetation occurring within and characteristic of a particular latitude or range of elevation.
Soil
The solid substrate of terrestrial communities, resulting from the interaction of weather and biological activities with the underlying geologic formation.
Horizons
A layer of soil distinguished by its physical and chemical properties.
Weathering
Physical and chemical breakdown of rock and its component of minerals at the base of the soil.
Podsolization
Breakdown and removal of clay particles from the acidic soils of cold, moist regions.
Laterization
Leaching of silica from soil, usually in warm, moist regions with an alkaline soil reaction.
Biome
A major type of ecological community (e.g., the grassland biome).
Growth form
One of several categories of the physical structure of plants, such as tree, herbaceous perennial, or liana.
Forb
Herbaceous, broad-leaved begetation (e.e., other than grasses) consumed by grazers.
Ecological tolerances
The range of conditions within which a species can survive.
Edaphic
Pertaining to or influenced by the soil.
Specializations
An adaptation of form or function that suits an individual particularly well to a restricted range of habitats, resources, or environmental conditions; the evolutionary process of such restriction.
Specialists
A species that uses a restricted range of habitats or resources.
Generalists
A species with broad food or habitat preferences.
Climate zone
A region in Heinrich Walter's classification of the climates of the earth defined by temperature and precipitation.
Growing season
The period of the year during which conditions are suitable for plant growth; in temperate regions, generally between the first and last frosts.
Prairies
An extensive area of level or rolling, almost treeless grass-land in central North America.
Steppes
Usually treeless plains, especially in southeastern Europe and Asia in regions of extreme temperature range and sandy soil.
Rhizomes
An underground, usually horizontal stem of a plant that produces both roots and aboveground shoots and that may be modified to store carbohydrate nutrient reserves.
Sclerophyllous
Referring to the tough, hard, often small leaves of drought-adapted vegetation.
Taiga
A moist coniferous forest bordering the arctic zone, dominated by spruce and fir trees.
Permafrost
A layer of permanently frozen ground in very cold regions, especially the Arctic and Antarctic.
Canopy
The uppermost layer of vegetation in a forest.
Emergent trees
Trees that rise above the canopy to heights of 55 m.
Understory
A layer of vegetation under the canopy of a forest.
Lianas
A climbing plant of tropical rain forests, usually woody, that roots in the ground.
Epyphytes
A plant that grows on another plant and derives its moisture and nutrients from the air and rain.
Streams
Water running over the surface of the land.
Riffles
A shallow stretch of fast-moving, often rough water between quieter pools in a stream.
Pools
A stretch of slow-flowing, often deep water in a stream between riffles.
Allochthonous
Referring to materials transported into a system, particularly minerals and organic matter transported into streams and lakes. (comp with autochthonous).
Riparian zone
Along the bank of a river or lake.
Autochthonous
Referring to materials produced within a system, particularly organic matter produced and minerals cycled within streams and lakes. (comp with allochthonous).
River continuum
The idea that a river system encompasses a continuum of conditions from the headwaters to the mouth, characterized by increasing streambed size and water flow and interconnected by the movement of nutrients and organisms with downstream currents.
Lakes
A body of fresh water in any kind of depression.
Littoral zone
Pertaining to the shore of the sea, especially the intertidal zone, and often including waters to the depth limit of emergent vegetation.
Limnetic zone
Of or inhabiting the open water of a lake.
Benthic zone
On or within the bottom of a river, lake, or ocean.
Estuaries
A semi-enclosed coastal water body, often at the mouth of a river, having a high input of fresh water and great fluctuation in salinity.
Zonation
The distribution of organisms in bands or regions corresponding to changes in ecological conditions along a continuum, for example, intertidal zonation and elevational zonation.
Neritic zone
The region of shallow water adjoining a seacoast.
Oceanic zone
Region of the ocean beyond the continental shelves.
Benthic zone
On or within the bottom of a river, lake, or ocean.
Photic zone
Pertaining to surface waters to the depth of light penetration.
Aphotic zone
In lakes and oceans, the water layer below the depth to which light penetrates.
Coral reefs
In tropical oceans, a structure built of living corals in the shallow water, often surrounding an island or ringing a submerged island, in which case the reef is an atoll.
Food web
A representation of the various paths of energy flow through populations in the community, taking into account the fact that each population shares resources and consumers with other populations.
Ecosystem
All the interacting parts of the physical and biological worlds.
Thermodynamic principles
Relating to heat and motion.
Food chain
A representation of the passage of energy from a primary producer through a series of consumers at progressively higher tropic (feeding) levels.
Trophic level
Pertaining to food or nutrition.
Pyramid of energy
The concept that the energy flux through any given link in the food chain decreases with progressively higher trophic levels.
Primary production
Assimilation (gross primary production) or accumulation (net primary production) of energy and nutrients by green plants and other autotrophs.
Primary productivity
The rate at which primary production occurs within an ecosystem.
Primary producers
A green plant or other autotroph that assimilates the energy of light to synthesize organic compounds.
Gross primary production
The total energy assimilated by plants through photosynthesis.
Net primary production
Energy accumulated in the tissues of plants.
Photosynthetic efficiency
Percentage of light energy assimilated by plants, based either on net production (net photosynthetic efficiency) or on gross production (gross photosynthetic efficiency).
Transpiration efficiency
The ratio of net primary production to transpiration of water by a plant, usually expressed as grams per kilogram of water; water use efficiency.
Water use efficiency
same as transpiration efficiency: The ratio of net primary production to transpiration of water by a plant, usually expressed as grams per kilogram of water.
Assimilation efficiency
A percentage expressing the proportion of ingested energy that is absorbed into the bloodstream.
Net production efficiency
The percentage of assimilated food used for growth and reproduction by an organism.
Detritus
Freshly dead or partially decomposed organic matter.
Exploitation efficiency
The proportion of production on one trophic level that is consumed by organisms on the next higher level.
Residence time
The ratio of the size of a compartment to the flux through it, expressed in units of time; thus, the average time spent by energy or a substance in the compartment.
Biomass accumulation ratio
The ratio of weight to annual production.
Assimilatory
Referring to a biochemical transformation that results in the reduction of an element to an organic form and hence its gain by the biological compartment of the ecosystem.
Dissimilatory
Referring to a biochemical transformation that results in the oxidation of the organic form of an element and hence its loss from the biological compartment of the ecosystem.
Compartment models
A representation of a system in which the various parts are portrayed as units (compartments) that receive inputs from and provide outputs to other such units.
Nitrogen fixation
Biological assimilation of atmospheric nitrogen to form organic nitrogen-containing compounds.
Ammonification
Metabolic breakdown of proteins and amino acids with ammonia as an excreted by-product.
Nitrification
Breakdown of nitrogen-containing organic compounds by microoganisms, yielding nitrates and nitrites.
Denitrification
Biochemical reduction, primarily by microorganisms, of nitrogen from nitrate (NO3)- eventually to molecular nitrogen (N2).
Photoautotrophs
An organism that uses sunlight as its primary energy source for the synthesis of organic compounds.
Chemoautotrophs
An organism that oxidizes inorganic compounds (often hydrogen sulfide) to obtain energy for synthesis of organic compounds (e.g., sulfur bacteria).
Watershed
The drainage area of a stream or river.
Mycorrhiza
Close associations of fungi and tree roots in the soil that facilitate the uptake of minerals by trees.
Endomycorrhizae
Mutualistic associations of fungi with the roots of plants in which part of the fungus resides within the root tissues.
Ectomychorrhizae
Mutualistic associations of fungi with the roots of plants in which the fungus forms a sheath around the outside of the root.
Laterite
A hard substance rich in oxides of iron and aluminum, frequently formed when tropical soils weather under alkaline conditions.
Eutrophic
Rich in the mineral nutrients required by green plants; pertaining to an aquatic habitat or soil with high productivity.
Oligotrophic
Poor in the mineral nutrients required by green plants; pertaining to an aquatic habitat with low productivity.
Eutrophication
Enrichment of water by nutrients required for plant growth; often refers to overenrichment caused by sewage and runoff from fertilized agricultural lands and resulting in excessive bacterial growth and oxygen depletion.
Biological oxygen demand (BOD)
The amount of oxygen required to oxidize the organic material in a water sample; high values in aquatic habitats often indicate pollution by sewage and other sources of organic wastes, or the over-production of plant material resulting from overenrichment by mineral nutrients.
Acid mine drainage
Water runoff from surface mining, usually coal strip mining, containing sulfuric acid, which forms when organic sulfur is oxidized on contact with the atmosphere.
Bioremediation
Restoration of natural habitats or ecological conditions by use of biological agents (e.g., bacterial degradation of spilled oil or other pollutants).
Ozone holes
A region of severe ozone depletion in the upper atmosphere, usually at high latitude.