354 ■ CHAPTER 19 Growth of Populations
(^2) A population that is growing exponentially increases
(a) by the same number of individuals in each generation.
(b) by a constant proportion in each generation.
(c) in some years and decreases in other years.
(d) none of the above
(^3) In a population with an S-shaped (logistic) growth curve, after
an initial period of rapid increase the number of individuals
(a) continues to increase exponentially.
(b) drops rapidly.
(c) remains near the carrying capacity.
(d) cycles regularly.
(^4) The growth of populations can be limited by
(a) natural disturbances.
(b) weather.
(c) food shortages.
(d) all of the above
(^5) The maximum number of individuals in a population that can be
supported indefinitely by the population’s environment is called the
(a) carrying capacity.
(b) J-shaped curve.
(c) sustainable size.
(d) exponential size.
(^6) Select the correct terms:
(Density-independent / Density-dependent) factors limit the
growth of populations more strongly at high densities than at
low densities. One example of a (density-independent / density-
dependent) factor is a natural disaster.
Challenge Yourself
(^7) A population of plants has a density of 12 plants per square
meter and covers an area of 100 square meters. What is the
population size?
(a) 120
(b) 1,200
(c) 12
(d) 0.12
(e) none of the above
(^8) Which of the following would not cause the carrying capacity
of a mosquito population to change?
(a) lower availability of standing water in which to lay eggs
(b) fewer animals for female mosquitoes to feed on
(c) warmer weather that increases overwintering survivorship
(d) All of the above would change carrying capacity.
(e) None of the above would change carrying capacity.
● (^) A population is a group of
individuals of a single species
located within a particular
area.
● (^) Population size is the total
number of individuals in
a population. Population
density is the population size
divided by the area covered
by that population.
● (^) Environmental factors such as
lack of space, food shortages,
predators, disease, and
habitat deterioration limit
populations. These factors
affect the carrying capacity,
the number of individuals that
can live in an environment
indefinitely.
● (^) In logistic growth,
a population grows
exponentially at first but
then stabilizes after reaching
the carrying capacity. It is
associated with an S-shaped
growth curve when graphed.
● (^) In exponential growth, a
population increases by a
constant proportion from
one generation to the next
generation. It is associated
with a J-shaped growth curve
when graphed.
● (^) Density-dependent
population change occurs
when birth and death rates
are affected by population
density, which is the case
when many individuals
occupy the same space
and therefore compete for
resources.
● (^) Density-independent
population change occurs
when population size is
affected by factors that have
nothing to do with the density
of the population.
● (^) Populations may rise and fall
over time, exhibiting irregular
fluctuations or cyclical
fluctuations.
REVIEWING THE SCIENCE
THE QUESTIONS
The Basics
(^1) A group of interacting individuals of a single species located
within a particular area is called
(a) a biosphere.
(b) an ecosystem.
(c) a community.
(d) a population.