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148 Cards in this Set

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Dalton's Law of Partial Pressures a nuclide produced by the radioactive decay of another nuclide
Dalton's Law of Partial Pressures
dam a structure that is built across a river to control a river's flow
dam
Data any pieces of information acquired through observation or experimentation
Data
daughter nuclide a nuclide produced by the radioactive decay of another nuclide
daughter nuclide
day the time required for Earth to rotate once on its axis
day
Day light savings time time usually one hour ahead of standard time
Day light savings time
death rate the number of deaths occurring in a period of time
death rate
decapod a crustacean that has five pairs of legs; examples include shrimp, crabs, and lobsters
decapod
decay series a series of radioactive nuclides produced by successive radioactive decay until a stable nuclide is reached
decay series
decibel a dimensionless unit that describes the ratio of two intensities; the threshold of hearing is commonly used as the reference intensity
decibel
deciduous describes trees that lose their leaves at the end of the growing season
deciduous
Decision -making model a conceptual model that provides a systematic process for making decisions
Decision -making model
Declination the angle between true north and magnetic north
Declination
decomposer an organism that feeds by breaking down organic matter from dead organisms; examples include bacteria and fungi
decomposer
decomposition the breakdown of substances into simpler molecular substances; may result from effects of biological activity
decomposition
decomposition reaction a reaction in which a single compound breaks down to form two or more simpler substances
decomposition reaction
deep current a stream like movement of ocean water far below the surface
deep current
deep-ocean basin the part of the ocean floor that is under deep water beyond the continental margin and that is composed of oceanic crust and a thin layer of sediment
deep-ocean basin
deep-water zone the zone of a lake or pond below the open-water zone, where no light reaches
deep-water zone
deep-well injection deep-well disposal of hazardous waste
deep-well injection
deflation a form of wind erosion in which fine, dry soil particles are blown away
deflation
deflation hollow a shallow depression left after the wind has eroded a layer of exposed soil
deflation hollow
deforestation the process of clearing forests
deforestation
deformation the bending, tilting, and breaking of Earth's crust; the change in the shape of rock in response to stress
deformation
dehydration a condition resulting from excessive water loss
dehydration
deletion the loss of a part of DNA from a chromosome
deletion
delta a fan-shaped mass of rock material deposited at the mouth of a stream; for example, deltas form where streams flow into the ocean at the edge of a continent
delta
demographic transition the general pattern of demographic change from high birth and death rates to low birth and death rates, as observed in the history of more-developed countries
demographic transition
Demograph the study of the characteristics of populations, especially human populations
Demograph
denature to change irreversibly the structure or shape—and thus the solubility and other properties—of a protein by heating, shaking, or treating the protein with acid, alkali, or other species
denature
dendrite a cytoplasmic extension of a neuron that receives stimuli
dendrite
Denitrification the liberation of nitrogen from nitrogen-containing compounds by bacteria in the soil
Denitrification
density-dependent factor a variable affected by the number of organisms present in a given area
density-dependent factor
density-independent factor a variable that affects a population regardless of the population density, such as climate
density-independent factor
dental formula the number, kind, and placement of teeth that are specific to a particular kind of mammal
dental formula
denticle a small, sharp tooth like structure of some fish
denticle
deoxyribose a five-carbon sugar that is a component of DNA nucleotides
deoxyribose
dependent variable in an experiment, the factor that changes as a result of manipulation of one or more other factors (the independent variables)
dependent variable
deposition the process in which material is laid down
deposition
depressant a drug that reduces functional activity and produces muscular relaxation
depressant
depression contours a contour line that has marks on the downslope side and that indicates a depression
depression contours
derived trait a unique characteristic of a particular group of organisms
derived trait
derived units a unit of measure that is a combination of other measurements
derived units
dermal tissue the outer covering of a plant
dermal tissue
dermis the layer of skin below the epidermis
dermis
desalination a process of removing salt from ocean water
desalination
desertification the process by which human activities or climatic changes make arid or semiarid areas more desertlike
desertification
desert pavement a continuous cover of stones created as wind erodes fine sediment, leaving larger rocks behind
desert pavement a
destructive interference a superposition of two or more waves whose intensity is less than the sum of the intensities of the individual waves
destructive interference
detergent a water-soluble cleaner that can emulsify dirt and oil
detergent
determinate cleavage a type of cleavage in which the resulting cells are predetermined to form specific parts of the embryo
determinate cleavage
detritivore a consumer that feeds on dead plants and animals
detritivore
deuterostome an animal whose mouth does not derive from the blastopore and whose embryo has indeterminate cleavage
deuterostome
development the process by which an organism grows
development
dew the water that forms when vapor cools and condenses on a surface whose temperature is above freezing but colder than the dew point of the air
dew
dew point at constant pressure and water vapor content, the temperature at which the rate of condensation equals the rate of evaporation
dew point
diabetes mellitus a serious disorder in which cells are unable to obtain glucose from the blood; caused by a deficiency of insulin or lack of response to insulin
diabetes mellitus
diamond a colorless, crystalline, solid form of carbon
diamond
diaphragm a dome-shaped muscle that is attached to the lower ribs and that functions as the main muscle in respiration
diaphragm
diastole the dilatation of the heart during which the atrial and ventricular muscle fibers enlarge and the chambers are filled with blood
diastole
diastolic pressure the blood pressure taken during the relaxation phase of the heartbeat cycle
diastolic pressure the
diatom a unicellular alga that has a double shell that contains silica
diatom
diatomaceous earth a soft, fine, porous deposit that is composed mainly of the skeletons of diatoms
diatomaceous earth
diatomic consisting of two atoms
diatomic
diatomic molecule a molecule that contains only two atoms
diatomic molecule
dichotomous key an aid that is used to identify unknown organisms and that consists of the answers to a series of questions, of which each involves alternate choices
dichotomous key
dicot a dicotyledonous plant; an angiosperm that has two cotyledons, net venation, and flower parts in groups of four or five
dicot
diencephalons the back part of the brain that contains the thalamus and the hypothalamus
diencephalon
diet the type and amount of food that a person eats
diencephalon
differential weathering the process by which softer, less weather resistant rocks wear away at a faster rate than harder, more weather resistant rocks do
differential weathering
differentiation the process in which the structure and function of the parts of an organism change to enable specialization of those parts
differentiation
diffraction a change in the direction of a wave when the wave finds an obstacle or an edge, such as an opening
diffraction
diffusion the movement of particles from regions of higher density to regions of lower density
diffusion
digestion the breaking down of food into chemical substances that can be used for energy
digestion
digestive gland any gland that secretes a substance to help transform food into substances that the body can use
digestive gland
digestive system the organs that break down food so that it can be used by the body
digestive system
digital signal a signal that can be represented as a sequence of discrete values
digital signal
dihybrid cross a cross between individuals that have different alleles for the same gene
dihybrid cross
dikaryotic describes a cell that has two haploid nuclei
dikaryotic
dike an igneous intrusion that cuts across rock layers
dike
dimensional analysis mathematical technique for studying dimensions of physical quantities
dimensional analysis
Dinosaur one of the great variety of extinct reptiles that lived 245 million to 65 million years ago
Dinosaur
diode an electronic device that allows electric charge to move more easily in one direction than in the other
diode
dipeptide two amino acids bonded by means of a condensation reaction
dipeptide
diploid a cell that contains two haploid sets of chromosomes
diploid
dipole a molecule or a part of a molecule that contains both positively and negatively charged regions
dipole
dipole-dipole forces interactions between polar molecules
dipole-dipole forces
diprotic acid an acid that has two ionizable hydrogen atoms in each molecule, such as sulfuric acid
diprotic acid
directional selection a natural selection process in which one genetic variation is selected and that causes a change in the overall genetic composition of the population
directional selection
direct proportion the relationship between two variables whose ratio is a constant value
direct proportion
disaccharide a sugar formed from two monosaccharides
disaccharide
discharge the volume of water that flows within a given time
discharge
disconformity a gap between rock layers that indicates that the rocks were not deposited continuously
disconformity
disinfectant a chemical substance that kills harmful bacteria or viruses
disinfectant
dispersion n ecology, the pattern of distribution of organisms in a population
dispersion
dispersion in optics, the process of separating a wave (such as white light) of different frequencies into its individual component waves (the different colors)
dispersion
displacement the change in position of an object
displacement
disruptive selection a type of natural selection in which two extreme forms of a trait are selected
disruptive selection
dissociation the separating of a molecule into simpler molecules, atoms, radicals, or ions
dissociation
distillation a process of separation in which a liquid is evaporated and then the vapor is condensed into a liquid
distillation
distribution the relative arrangement of the members of a statistical population; usually shown in a graph
distribution
diurnal describes animals that are active during the day and sleep at night
diurnal
divergent boundary the boundary between two tectonic plates that are moving away from each other
divergent boundary
divergent evolution the process by which two or more related but reproductively isolated populations become more and more dissimilar
divergent evolution
divide the boundary between drainage areas that have streams that flow in opposite directions
divide
division in taxonomy, a grouping of similar classes of plants
division in taxonomy,
DNA deoxyribonucleic acid, the material that contains the information that determines inherited characteristics
DNA
DNA fingerprint the pattern of bands that results when an individual's DNA sample is fragmented, replicated, and separated
DNA fingerprint
DNA helicase an enzyme that unwinds the DNA double helix during DNA replication
DNA helicase
DNA polymerase an enzyme that catalyzes the formation of the DNA molecule
DNA polymerase
DNA replication the process of making a copy of DNA
DNA replication
doldrums a narrow zone of low air pressure at the equator characterized by weak and variable winds
doldrums
domain n a taxonomic system based on rRNA analysis, one of the three broad groups that all living things fall into
domai
dome mountain a circular or elliptical, almost symmetrical elevation or structure in which the stratified rock slopes downward gently from the central point of folding
dome mountain
domesticated describes organisms that have been bred and managed for human use
dominance the tendency of certain (dominant) alleles to mask the expression of their corresponding (recessive) alleles
dominance
dominant describes the allele that is fully expressed when carried by only one of a pair of homologous chromosomes
dominant
dominant trait the trait observed when at least one dominant allele for a characteristic is inherited
dominant trait
dopamine a neurotransmitter in the central and peripheral nervous systems
dopamine
doping the addition of an impurity element to a semiconductor
doping
Doppler effect an observed change in the frequency of a wave when the source or observer is moving
Doppler effect
dormancy a state in which seeds, spores, bulbs, and other reproductive organs stop growth and development and reduce their metabolism, especially respiration
dormancy
dormant describes the inactive state of a seed and other plant reproductive organs
dormant
dorsal lying on or near the back
dorsal
dorsal fin the fin or finlike structure that develops in bony fishes and sharks
dorsal fin
dorsal nerve chorda neural tube dorsal to the notochord
dorsal nerve chorda
Dose the quantity of medicine that needs to be taken over a period of time; also the amount of a harmful substance to which a person is exposed
Dose
dose-response curve a graph that shows the relative effect of various doses of a drug or chemical on an organism or organisms
dose-response curve
double bond a covalent bond in which two atoms share two pairs of electrons
double bond
double-displacement reaction a reaction in which a gas, a solid precipitate, or a molecular compound forms from the apparent exchange of atoms or ions between two compounds
double-displacement reaction
double fertilization the process by which one of the two sperm nuclei fuses with the egg nucleus to produce a diploid zygote and the other fuses with the polar nuclei to produce a triploid endosperm
double fertilization
double helix the spiral-staircase structure characteristic of the DNA molecule
double helix
double refraction a property exhibited by transparent minerals that produce a double image of any object viewed through them
double refraction
down feather a soft feather that covers the body of young birds and provides insulation to adult birds
down feather
Down syndrome (trisomy-21) a disorder caused by an extra twenty-first chromosome and characterized by a number of physical and mental abnormalities
Down syndrome (trisomy-21)
Drag a force parallel to the velocity of the flow; it opposes the direction of an aircraft and, in combination with thrust, determines the speed of the aircraft
Drag
drainage basin a region that collects streams (surface runoff) that then become part of a body of water, such as a lake or a river
drainage basin
Drift the speed of an ocean current
Drift
drift velocity the net velocity of a charge carrier moving in an electric field
Drift velocity
drone a male bee that develops from an unfertilized egg and functions only to fertilize eggs from the queen
drone
drought a long period when rainfall is less than average
drought
drought resistance a characteristic of a plant that allows the plant to survive in areas of light rainfall or sporadic rainfall
drought resistance
Drug a chemical compound used to prevent, treat, or cure a disease or to alleviate pain; also a chemical substance that alters a person's mental state and can be addictive and whose use is restricted or illegal
ductility
drumlin a small, tear-shaped hill composed of glacial till
drumlin
ductility the ability of a substance to be hammered thin or drawn out into a wire
Drug
Dune a mound of wind-deposited sand that moves as a result of the action of wind
Dune
Duodenum the first section of the small intestine
Duodenum
dura mater the outermost of the three sacs that enclose the brain and spinal cord
dura mater