23.3 Natural selection, genetic drift, and gene flow can alter allele frequencies in a population

Question 1

You are studying three populations of birds. Population A has ten birds, of which one is brown (a recessive trait) and nine are red. Population B has 100 birds, of which ten are brown. Population C has 30 birds, and three of them are brown.

40) In which population would it be least likely that an accident would significantly alter the frequency of the brown allele?
A) Population A.
B) Population B.
C) Population C.
D) They are all the same.
E) It is impossible to tell from the information given.

Answer 1

B) Population B.

Question 2

38) If four of the original colonists died before they produced offspring, the ratios of genotypes could be quite different in the subsequent generations. This would be an example of
A) diploidy.
B) gene flow.
C) genetic drift.
D) disruptive selection.
E) stabilizing selection.

Answer 2

C) genetic drift.

Question 3

You are studying three populations of birds. Population A has ten birds, of which one is brown (a recessive trait) and nine are red. Population B has 100 birds, of which ten are brown. Population C has 30 birds, and three of them are brown.

41) Which population is most likely to be subject to the bottleneck effect?

A) Population A.
B) Population B.
C) Population C.
D) They are all the same.
E) It is impossible to tell from the information given.

Answer 3

A) Population A.

Question 4

42) 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) cross your flies with flies from another lab.
B) reduce the number of flies that you transfer at each generation.
C) transfer only the largest flies.
D) change the temperature at which you rear the flies.
E) shock the flies with a brief treatment of heat or cold to make them more hardy.

Answer 4

A) cross your flies with flies from another lab.

Question 5

44) If the original finches that had been blown over to the Galapagos from South America had already been genetically different from the parental population of South American finches, even before adapting to the Galapagos, this would have been an example of
A) genetic drift.
B) bottleneck effect.
C) founderʹs effect.
D) all three of these
E) both A and C

Answer 5

E) both A and C

Question 5

43) If the frequency of a particular allele that is present in a small, isolated population of alpine plants decreases due to a landslide that leaves an even smaller remnant of surviving plants bearing this allele, then what has occurred?
A) a bottleneck
B) genetic drift
C) microevolution
D) A and B only
E) A, B, and C

Answer 5

E) A, B, and C

Question 6

45) Over time, the movement of people on Earth has steadily increased. This has altered the course of human evolution by increasing
A) non-random mating.
B) geographic isolation.
C) genetic drift.
D) mutations.
E) gene flow.

Answer 6

E) gene flow.

Question 7

46) Gene flow is a concept best used to describe an exchange between
A) species.
B) males and females.
C) populations.
D) individuals.
E) chromosomes.

Answer 7

C) populations.