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9th chap 8.1 ENV


POPULATION A _______________ is a group of organisms of the same species that live in a specific geographical area and interbreed.
BREED A population is a reproductive group because organisms usually________with members of their own population.
SIZE The word population refers to the group in general and also to the ______ of the population, or the number of individuals it contains.
DENSITY _________________ is the number of individuals of the same species in that live in a given unit of area.
DISPERSION ___________is the pattern of distribution of organisms in a population. A population’s dispersion may be even, clumped, or random.
PREDICT Size, density, dispersion, and other properties can be used to describe populations and to __________changes within them.
BIRTH DEATH A population gains individuals with each new offspring or _____ and loses them with each ______.
CHANGE The resulting population _______ over time can be represented by the equation below.
GROWTH RATE ______ _______ is an expression of the increase in the size of an organism or population over a given period of time. It is the birth rate minus the death rate.
EQUAL For the growth rate to be zero, the average number of births must ______ the average number of deaths.
TWO A population would remain the same size if each pair of adults produced exactly ____ offspring, and each of those offspring survived to reproduce.
NEGATIVE If the adults in a population are not replaced by new births, the growth rate will be ______ and the population will shrink
FACTORS Populations usually stay about the same size from year to year because various _______ kill many individuals before they can reproduce.
CARRYING CAPACITY ___________ _________ is the largest population that an environment can support at any given time.
BEYOND A population may increase_____________ this number but it cannot stay at this increased size.
CRASH Because ecosystems change, carrying capacity is difficult to predict or calculate exactly. However it may be estimated by looking at average population sizes or by observing a population___________ after a certain size has been exceeded.
SAME RATE A species reaches its carrying capacity when it consumes a particular natural resource at the ______ ________ at which the ecosystem produces the resource.
LIMITING RESOURCE That natural resource is then called a __________ ______________.
SUPPLY The ______________ of the most severely limited resources determines the carrying capacity of an environment for a particular species at a particular time.Competition Within a Population
COMPETE The members of a population use the same resources in the same ways, so they will eventually _______ with one another as the population approaches its carrying capacity.
TERRITORY instead of competing for a limiting resource, members of a species may compete indirectly for social dominance or for a ____________.
COMPETITION _______________within a population is part of the pressure of natural selection.
TERRITORY A_______________is an area defended by one or more individuals against other individuals.
VALUE The territory is of________not only for the space but for the shelter, food, or breeding sites it contains.
ENERGY Many organisms expend a large amount of time and ______ competing with members of the same species for mates, food, or homes for their families.
DENSELY Population size can be limited in ways that may or may not depend on the ______________________of the population.
DEATH Causes of _________in a population may be density dependent or density independent.
INDEPENDENT When a cause of death in a population is density ____________, deaths occur more quickly in a crowded population than in a sparse population.
DENSILY This type of regulation happens when individuals of a population are __________ packed together.
HIGHER Limited resources, predation and disease result in ________________ rates of death in dense populations than in sparse populations.
INDEPENDENT When a cause of death is density __________, a certain proportion of a population may die regardless of the population’s density.
ALL This type of regulation affects _____populations in a general or uniform way.
WEATHER Severe ________and natural disasters are often density independent causes of death
EVOLVES In the long run, the factors also determine how the population __________.
BIOTIC A species’ _____________potential is the fastest rate at which its populations can grow. This rate is limited by reproductive potential.
REPRODUCTIVE POTENTIAL A species’ biotic potential is the fastest rate at which its populations can grow. This rate is limited by ______________- _____________.
HIGHER Some species have much __________ reproductive potentials than others.
MORE Reproductive potential increases when individuals produce ______ offspring at a time, reproduce often, and reproduce earlier in life.
EARLIER Reproducing _____in life has the greatest effect on reproductive potential.
GENERATION Reproducing early shortens the _________ time, or the average time it takes a member of the population to reach the age when it reproduces.
GROW QUICKLY Small organisms, such as bacteria and insects, have short generation times and can reproduce when they are only a few hours or a few days old. As a result, their populations can ____________ _________.
EXPONENTIAL GROWTH __________ _________ is logarithmic growth or growth in which numbers increase by a certain factor in each successive time period.
ONLY Exponential growth occurs in nature _______ when populations have plenty of food and space, and have no competition or predators.
LARGE In exponential growth, a __________number of individuals is added to the population in each succeeding time period.
CANNOT Because natural conditions are neither ideal nor constant, populations ________ grow forever.
USED UP Eventually, resources are ________ __ or the environment changes, and deaths increase or births decrease.
Created by: asimien907