Glossary Quantitative Skills

Glossary acceleration the rate of change of velocity with time accuracy describes how close a measurement is to a known or accepted value age-structure diagram a graphical representation of the distribution of ages within a population alternative hypothesis one of several hypotheses that experimental observations are the result of some nonrandom cause angular acceleration the rate at which the angular velocity changes as a result of an applied torque angular momentum a measure of the rotation of an object; it is the product of the object’s angular velocity and its moment of inertia best-fit line also called a trend line; a straight line drawn on a scatter plot that indicates the pattern of the data; typically has approximately the same number of data points above and below the line buoyant force a force due to a fluid’s pressure difference acting on an object in contact with or completely submerged within a fluid capacitor an electrical device that stores both charge and energy carrying capacity the maximum population size that can be supported by a particular environment at a certain point in time without disruption to the habitat centripetal acceleration the acceleration of an object in a circular motion that is directed radially toward the center of the circle chemical equilibrium the dynamic state of a chemical reaction when the concentration of reactants and products is constant over time; the rates of the forward and backwards reactions are the same chi-square test a statistical method that is used to determine if there is a significant relationship between two groups of data coefficient of determination the r 2 value of a line of regression that indicates how well a proposed model fits the data confidence interval a range of values within which the true value of the population has a probability of being current the rate of charge moving past a given point in a conductor dependent variable also called the response or experimental variable; the response to the independent variable in an experiment; what is measured by the researcher dilution a less concentrated chemical or solution GLOSSARY dimensional analysis also called the factor-label method; a method of converting one unit of measure to another using conversion factors and rules of algebra dose-response curve a graphical illustration of the dose of a drug and its effect on the sample group dot product also called the scalar product; the product that takes two vectors and performs an operation where the product’s value is a scalar value electromagnetic radiation how energy travels through spaces as waves electromotive force also called emf; the electric current produced by a difference in electric potential electric field the vector field that surrounds a charged particle energy the ability for an object or system to do work or produce heat enthalpy the thermodynamic quantity that measures the heat of a system entropy the thermodynamic quantity that measures the disorder of a system experimental error an error that occurs while performing an experiment exponential function a function in the form A and b are arbitrary constants exponential growth occurs when populations grow at a constant rate; usually shown by a J-shaped growth curve factor-label method also called dimensional analysis; a method of converting one unit of measure to another using conversion factors and rules of algebra flux the magnitude of a vector field that permeates space through a particular defined area force the movement of an object (i.e., the push or pull) that results from its interaction with another object free energy the energy that is available to do work in a system frequency the number of waves that pass through a specific point in space per second fundamental units the basic units of length, mass, and time gross primary productivity (GPP) the rate at which plants convert solar energy into chemical energy (organic compounds) half-life the time it takes for 50% of the substance to decay Hardy–Weinberg theorem the allele frequencies of a gene (at a specific locus) in a population will stay the same from one generation to the next as long as the following requirements are met: (1) no mutations occur, (2) no movement into or out of the population occurs, (3) the population is large, (4) mating is random, and (5) no natural selection occurs , where GLOSSARY impulse a measure of the amount of force exerted on an object with time independent variable also called the explanatory or controlled variable; the variable that the researcher controls; it is not changed by other variable(s) measured in an experiment kinetic energy energy of movement kinetic friction when the two surfaces in contact are in relative motion to each other lethal dose the dose of a drug that causes death limiting reactant the reactant that is completely consumed at the end of a chemical reaction logistic growth occurs when populations grow steadily until the carrying capacity of the habitat is reached; usually shown be an S-shaped growth curve magnetic flux the magnitude of the magnetic field that permeates space through a particular defined area magnification an increase in the size of an image maximum the data point in a set of data with the highest numerical value mean the average of a set of data median the middle number in an ordered set of data; when there is an even number of data points, the median is the average of the two middle numbers minimum the data point in a set of data with the lowest numerical value momentum a measure of the amount of mass that is in motion net primary productivity (NPP) the energy in the organic compounds left over for consumers after the primary producers meet their own needs through cellular respiration normal distribution also known as a bell curve; in science, normal distributions apply to repeated measurements of a single value null hypothesis the hypothesis that there is no difference between two groups of data in an investigation and that the experimental observations are the result of chance photon a particle of light power the rate at which energy is transferred to a system or object or transformed within a system precision how close several measurements are to each other; the closer measured values are to each other, the higher their precision pressure a measure of the magnitude of normal force per unit area exerted by a fluid or a gas GLOSSARY pressure potential the component of water potential that is a result of the pressure of the cell wall on the water inside a cell; it generally has a positive effect on water potential and causes water potential to increase primary productivity the rate at which organic compounds are stored quadratic function a function in the form qualitative data data that is observed rather than measured; e.g., observations of appearance, behaviors, smell, taste, etc. quantitative data data that is measured and recorded in numerical form; e.g., absorbance, size, time, height, and mass quartile a value that divides a data set into quarters; one fourth of a data set random errors unpredictable errors that occur during an experiment refraction the bending of light as it moves from one optical medium to another regression analysis a curve-fitting procedure used to fit data to a mathematical model when the data do not follow a linear pattern resistance the obstruction to the flow of charge rotational inertia qualitatively defined as the measurement of inertia of an extended body (system) in response to a torque acting on the system; formally named the moment of inertia, represented by the symbol I rotational kinetic energy the energy of an object or extended body rotating about an axis rule of 70 a method of determining how long it takes for a population to double in size scientific notation an expression of a number that is too small or too large to be written as a decimal; the number is written as a coefficient multiplied by the base 10 raised to an exponent significant digits also called significant figures; the digits in a measurement or a calculation that are meaningful significant figures also called significant digits; the digits in a measurement or a calculation that are meaningful simple harmonic motion occurs when an object is subjected to a linear restoring force, such as a force exerted by a spring on an object solute potential the component of water potential that is a result of the concentration of solute in a cell; high solute potential generally has a negative effect on water potential and causes water potential to decrease survivorship curves graphs that show the relative survival rates of a cohort of organisms at different ages; three types of survivorship curves: type I, type II, and type III specific heat capacity the amount of heat required to change the temperature of 1 gram of the material by 1 K , where a, b, and c are constants GLOSSARY standard deviation a tool for measuring the spread, or variance, in a sample population; provides an estimate of the variation in the entire sample set; a large sample standard deviation indicates that the data have a lot of variability; a small sample standard deviation indicates that the data are clustered close to the sample mean and do not have much variability standard error a statistic that allows a researcher to make an inference about how well the sample mean of a data set matches up to the true mean of the population static friction occurs when the two surfaces in contact are not in relative motion to each other stock solution a concentrated solution that is diluted systematic errors experimental errors that occur every time a particular measurement is taken threshold level of toxicity the lowest concentration of a drug that elicits toxic effects torque the force that causes an object to rotate trend line also called a best-fit line; a straight line drawn on a scatter plot that indicates the pattern of the data; typically has approximately the same number of data points above and below the line vector mathematical representations that show the direction and magnitude of certain physical quantities velocity the rate of change of position with time water potential the tendency of water to move by osmosis from one area to another; influenced by pressure potential and solute potential wavelength the distance between two consecutive peaks (or troughs) of a wave work force that acts over a distance x-axis the horizontal axis of a graph; denotes the independent variable y-axis the vertical axis of a graph; denotes the dependent variable