Use this information to answer the following questions: You are studying three p

Question

Use this information to answer the following questions: 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. 37.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. 38. Which populati be subject to the botleneck effect? A) population A B) population B C) population C D) They are all equally likely. E) It is impossible to tell from the information giver Use the following information to answer the following questions: In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the ß hemoglobin alleles in the human gene pool. 39. What should be the proportion of heterozygous individuals in populations that live here? A) 0.04 B) 0.16 C) 0.20 D) 0.32 E) 0.80 e sickle-cell allele is recessive, what proportion of the population should be susceptible to sickle- cell anemia under typical conditions? A) 0.04 B) 0.16 C) 0.20 D) 0.32 E) 0.80 41.In the United States, the parasite that causes malaria is not present, but African-Americans whose ancestors were from equatorial Africa are present. What should be happening to the sickle-cell allele in the United States, and what should be happening to it in equatorial Africa? A) stabilizing selection; disruptive selection B) directional selection; disruptive selection C) disruptive selection; stabilizing selection D) directional selection; stabilizing selection E) disruptive selection; directional selection

Explanation / Answer

37. (A) population A. Since accidental event or genetic drift largely depend on population size, population with least number of individuals is more likely to be affected, irrespective of same allelic frequencies of various populations. In this case, population A has only 10 birds and out of that only one is showing recessive trait. If accident results in death of bird with recessive trait, it will take hard time to recover the loss of allelic frequency.

38. (B) population B. In bottleneck effect, population size drastically reduced to a few individuals. So larger the population size will be, greater will the chance of bottleneck effect.

39. (D) 0.32

According to Hardy Weinberg principle, p+q = 1, where p and q are dominant sand recessive allele frequencies. Given that q = 20% or 0.20, so p = 1-q = 0.80. Thus,

Homozygous dominant genotype frequency = p2 = (0.80)2 = 0.64

Heterozygous genotype frequency = 2pq = 2(0.80)(0.20) = 0.32

Homozygous recessive frequency = q2 = (0.20)2 = 0.04

40. (A) 0.04

Individuals with homozygous recessive genotype only will be susceptible to sickle cell anemia. (see answer 39 for calculations)

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