21. A loss of 90% of the population in the Pingelap atoll from a typhoon in 1775

Question

21. A loss of 90% of the population in the Pingelap atoll from a typhoon in 1775 resulted in a high percentage of the current population being affected by achromatopsia. As a result, all of these affected individuals _____.

a. have normal vision

b. are descendants of one of the 20 original survivors

c. receive genetic testing and genetic counseling

d. have exceptional hearing

e. are descendants of the 20 original survivors

22. The Hardy-Weinberg law is used to calculate allele and genotype frequencies ____.

a. in small populations

b. when mating is random

c. in migrating populations

d. when some alleles confer an evolutionary advantage over other alleles

e. the population descends from a single ancestor

23. A population that is in genetic equilibrium is said to ____.

a. have an equal number of homozygotes as heterozygotes for a given trait

b. deviate from the Hardy-Weinberg law

c. require genetic testing for estimation of allele frequencies

d. lose genetic variation with each generation but gains an equal amount

e. have an allele or alleles whose frequencies remain constant generation to generation

24. Albinism is a recessive trait controlled by a single gene. If the frequency of albinos in a population is 0.25, what is the expected frequency of heterozygotes for this trait?

a. 0.25    b. 0.50    c. 0.75    d. 0.90    e. 1.00

Explanation / Answer

21) the answer is (b) affected individual were descendent of one of 20 individual.They were colourblind due to the absence of cone cells.20 survivor were there.one of them was Nanmwarki Mwaneished was believed to be the carrier of the disease and when inbreeding took place affected indivuals were born as it was autosomal recessive disease.

22) The answer is (b) when random mating takes place.Hardy weinberg equation is p+q=1.The assumption for Hardy weinberg law were randome mating, no evolutionary force acting on it ( no migration, no immigration,no mutation) ,large population.

23) The anwer will be (e).In genetic equillibrium allel frequency doesnt change after generation to generation.

24) albinism occurs in recssive state and the frequency of albino is 0.25 means

    q2 = o.25

q= 0.5

According to Hardy Weinberg equation:

p+q= 1 or (p+q)2 = 1 or p2 + 2pq+ q2 =1

p=1-q

p=0.5

frequency of heterozygote wil be: 2pq= 2(0.5) (0.5) = 0.5

so the answer is 0.5

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