Question
Which of the following best explains the role of variation in natural selection?
(A) Variation is not necessary for evolution, but increases the speed at
which evolution occurs.
(B) Variation impedes natural selection but is an inevitable
consequence of sexual reproduction.
(C) Environmental pressures applied to a population of genetically
different individuals may result in divergent evolution.
(D) Variations result in new species, regardless of the selective
pressures present.
▶️Answer/Explanation
Ans: C
The three essential elements of natural selection are
reproduction, heritable variation, and selection. Without variation, there
are no options to select from (eliminating choices A and B). Choice D is
incorrect. Variations alone cannot result in a new species: It is necessary
(sine qua non), but not sufficient, for speciation.
Question.
All of the following statements concerning the theory of evolution by natural selection are true EXCEPT:
(A) Organisms produce far more offspring than are required for replacement.
(B) The individuals in a population show variation in survivability and in their ability to cope with environmental stress.
(C) The number of offspring that survive to reproduce varies among individuals.
(D) The bodies of organisms in a population change by use and disuse, and the changes are inherited by the next generation.
(E) Some of the variation in adaptation is the result of genetic differences that may be passed on to the next generation.
▶️Answer/Explanation
Ans:D
Question.
In evolutionary terms, which of the following organisms is the most successful?
(A) The one that lives the longest
(B) The one that grows the most rapidly
(C) The one that leaves the greatest number of offspring that survive to reproduce
(D) The one that has the best characteristics for the current environment
(E) The one that has the biggest territory
▶️Answer/Explanation
Ans:C
Question
Which of the following statements best describes the effect of a genetic drift on the gene frequencies of a population?
a. Genes enter a population through immigration, thus changing gene frequencies
b. Genes leave a population through emigration, thus changing gene frequencies
c. Chance alone can cause significant changes in gene frequencies of small populations
d. Mutations over time cause gene frequencies to change
e. Selection against one allele causes gene frequencies to change
▶️Answer/Explanation
Ans:C
Question
In a small group of people living in a remote area, there is a high incidence of “blue skin”, a condition that results from a variation in the structure of hemoglobin. All of the “blue-skinned” residents can trace their ancestry to one couple, who were among the original settlers of this region. The unusually high frequency of “blue skin” in the area is an example of
(A) mutation
(B) genetic drift
(C) natural selection
(D) sexual selection
(E) heterozygote advantage
▶️Answer/Explanation
Ans:B