Uploaded by Jeroen Spitael


Chapter 18 - Evolution of Populations
The combined genetic information of all members of a particular population forms a
a. gene pool
b. niche
c. phenotype
d. population
Mutations that improve an individual’s ability to survive and reproduce are
a. harmful
b. neutral
c. beneficial
d. chronological
Traits, such as human height, that are controlled by more than on gene are known as
a. single-gene traits
b. polygenic traits
c. recessive traits
d. dominant traits
Due to hunting, the population of Northern elephant seals was reduced to 20 individuals
at the end of the 19th century. Since then, their population has since rebounded to over
30,000. What is the most likely long-term effect of hunting on the elephant seal
a. individuals are genetically similar to each other
b. the population has allele frequencies similar to those in the original population
c. the population is more likely to survive disease
d. the population contains high allelic diversity
Page 1
A small group of squirrels gets separated from the rest of the population due to a large
flood. These squirrels, now confined to this new island, begin to start a new population.
This is an example of which of the following?
a. genetic drift
b. bottleneck effect
c. sympatric speciation
d. founder effect
A population of birds live on an island where seeds are their primary food source. Birds
with smaller beaks can eat small seeds more easily and birds with larger beaks can eat
large seeds more easily. A fungus destroys the plants that make large seeds, leaving only
the small seeds as food. Which type of natural selection will most likely occur?
a. directional stabilization
b. stabilizing selection
c. disruptive selection
d. artificial selection
In humans, babies that are born too small often lack the reserves to thrive, and babies
that are too large are prone to difficult births. Since babies at the extremes are less likely
to survive, evolutionary pressures favor moderately-sized babies. What type of selection is
this an example of?
a. stabilizing selection
b. disruptive selection
c. artificial selection
d. directional selection
What mechanism of evolution occurs when allele frequencies change over generations
due to random chance?
a. gene flow
b. natural selection
c. mutation
d. genetic drift
Page 2
In corn, purple kernels are dominant to yellow. A random sample of 100 kernels is taken
from a population in Hardy-Weinberg equilibrium. It is found that 9 kernels are yellow and
91 kernels are purple. What is the frequency of the yellow allele in this population?
a. 0.09
b. 0.3
c. 0.49
d. 0.7
What is true of populations that are in Hardy-Weinberg equilibrium?
a. natural selection is occurring
b. the populations must be very small
c. mating is random
d. organisms are constantly migrating
Temporal isolation occurs when two different populations
a. develop different mating behaviors
b. become geographically separated
c. reproduce at different times
d. interbreed
When two populations no longer interbreed, what is the result?
a. genetic equilibrium
b. reproductive isolation
c. stabilizing selection
d. artificial selection
A group of regulatory genes that determine which parts of an embryo develop into arms,
legs, or wings are known as
a. polygenic genes
b. molecular clocks
c. neutral genes
d. Hox genes
Page 3
Each “tick” of molecular clock is an occurrence of
a. genetic drift
b. crossing-over
c. DNA mutation
d. mitosis
Natural selection acts directly on
a. alleles
b. genes
c. phenotypes
d. mutations
In a fox population, the allele frequency of a gene for red fur changes from20 to 30
percent. What can you say about that population of foxes?
a. the population is expanding
b. the population is evolving
c. the population is decreasing
d. the population is not evolving
A change in the genetic material of a cell is called a
a. recombination
b. polygenic trait
c. single gene trait
d. mutation
In organisms that reproduce sexually, most variation that can be inherited is due to
a. mutations during gamete formation
b. polygenic traits
c. gene recombination during sexual reproduction
d. the effects of radiation
Page 4
A single gene trait that has two alleles and that show as a simple dominant-recessive
pattern will result in
a. one phenotype
b. two phenotypes
c. four phenotypes
d. millions of phenotypes
The frequency of phenotypes for a typical polygenic trait is most often illustrated as a
a. scatter plot
b. bell-shaped curve
c. pie chart
d. histogram
21. Label the three types of selection illustrated by the graphs below
If a mutation introduces new skin color in a lizard population, which factor might
determine whether the frequency of the new allele will increase>
a. how many other alleles are present
b. whether the mutation makes some lizards more fit for their environment than
other lizards
c. how many phenotypes the population has
d. whether the mutation was caused by nature or by human intervention
Page 5
Which of the following events do biologists consider a random change?
a. directional selection
b. speciation
c. disruptive selection
d. genetic drift
The type of genetic drift that follows the colonization of a new habitat by a small group
of individuals is called
a. the Hardy-Weinberg principle
b. the founder effect
c. directional selection
d. stabilizing selection
The situation in which allele frequencies in the gene pool of a population remain
constant is called
a. evolution
b. genetic drift
c. genetic equilibrium
d. natural selection
The separation of populations by barriers such as rivers, mountains or bodies of water is
a. temporal isolation
b. geographic isolation
c. behavioral isolation
d. genetic equilibrium
The definition of a species is:
a. similar types of animals from similar types of environments
b. similar types of animals that can interbreed
c. animals with similar genes and DNA
d. animals that can interbreed and produce fertile offspring
Page 6
Which of the following statements defines the members of a species?
a. they are temporarily isolated from each other
b. they are geographically isolated from each other
c. they mate and produce offspring
d. the have identical genes
The geographic isolation of two populations of a species tends to increase differences
between their gene pools because it
a. prevents interbreeding between the populations
b. prevents interbreeding within each population
c. causes temporal isolation of the two populations
d. increase differences in courtship behavior
Although they often live in the same habitat, the American toad breeds earlier in the
spring than the Fowler’s toad does. What can be inferred from this information?
a. the two species do not interbreed because of geographic isolation
b. the two species do not interbreed because of temporal isolation
c. the two species interbreed throughout the spring season
d. the American toad will cause the extinction of the Fowler’s toad
Species Y and Z have very similar proteins, genes and genetic sequences. What is most
likely true about these two species?
a. species Y is older than species Z
b. species Y is younger than species Z
c. species Y evolved for a long tie separately from species Z
d. species Y shares a relatively recent common ancestor with species Z
A large number of manatees is killed off due to a major hurricane event in the state of
Florida. What type of effect may occur within the population relating to its gene pool?
a. a founder effect
b. a speciation effect
c. a genetic equilibrium effect
d. a bottleneck effect
Page 7
Random flashcards
Arab people

15 Cards


39 Cards


30 Cards

Create flashcards