Chapter 23 Test (1-10) Flashcards
In a very small population of birds, assume 5 out of 20 alleles are the type that code for blue feathers. What is the allele frequency of the “blue feather allele” in this population?
A) 0.40
B) 0.20
C) 5
D) 0.25
E) 0.50
D) 0.25
When imbalances occur in the sex ratio of sexual species that have two sexes (i.e., other than a 50:50 ratio), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. This is most clearly an example of
A) frequency-dependent selection.
B) sexual selection.
C) stabilizing selection.
D) balancing selection.
E) disruptive selection.
A) frequency-dependent selection.
Whenever diploid populations are in Hardy-Weinberg equilibrium at a particular locus
A) the population itself is not evolving, but individuals within the population may be evolving.
B) the allele’s frequency should not change from one generation to the next, but its representation in homozygous and heterozygous genotypes may change.
C) this means that, at this locus, two alleles are present in equal proportions.
D) natural selection, gene flow, and genetic drift are acting equally to change an allele’s frequency
What is true of natural selection?
A) The only way to eliminate harmful mutations is through natural selection.
B) Natural selection creates beneficial mutations.
C) Mutations occur at random; natural selection can preserve and distribute beneficial mutations.
D) Mutations occur when directed by the good of the species; natural selection edits out harmful mutations and causes populations to adapt to the beneficial mutations.
E) Natural selection is a random process.
A) The only way to eliminate harmful mutations is through natural selection.
Natural selection selects for or against certain:
A) phenotypes.
B) gene pools.
C) populations.
D) alleles.
E) genotypes.
A) phenotypes.
The extreme loss of genetic diversity that has occurred in cheetah populations due to overhunting is the result of:
A) natural selection.
B) a population bottleneck.
C) genetic drift.
D) coevolution.
E) the founder effect.
B) a population bottleneck.
In peas, a gene controls flower color such that R = purple and r = white. In an isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population?
A) 0.80
B) 0.64
C) 0.36
D) 0.75
A) 0.80
Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is true?
A) Each bird’s survival was strongly influenced by the depth and strength of its beak as the drought persisted.
B) Each bird that survived the drought produced only offspring with deeper, stronger beaks than seen in the previous generation.
C) The frequency of the strong-beak alleles increased in each bird as the drought persisted.
D) Each bird evolved a deeper, stronger beak as the drought persisted.
A) Each bird’s survival was strongly influenced by the depth and strength of its beak as the drought persisted.
You are maintaining a small population of fruit flies in the laboratory by transferring the flies to a new culture bottle after each generation. After several generations, you notice that the viability of the flies has decreased greatly. Recognizing that small population size is likely to be linked to decreased viability, the best way to reverse this trend is to
A) shock the flies with a brief treatment of heat or cold to make them more hardy.
B) change the temperature at which you rear the flies.
C) transfer only the largest flies.
D) cross your flies with flies from another lab.
E) reduce the number of flies that you transfer at each generation.
If two or more phenotypes in a population are both favored by selection, what is happening?
A) sexual selection
B) balanced polymorphism
C) gene flow
D) directional selection
E) stabilizing selection
B) balanced polymorphism
