Genes Within Populations Clicker Questions - Chapter 20 Exam 1 Mosley BIO1082

Coloration in the peppered moth (Biston betularia) is determined by a single gene with two alleles showing complete dominance. Dark moths are homozygous dominant or heterozygous for the gene, light moths are homozygous recessive. In a sample of 100 moths, you determine that 64 of the moths are dark. According to the Hardy-Weinberg rule, the expected frequency of the dominant allele is ____. A. 0.4 B. 0.36 C. 0.6 D. 0.64 Level 4

A. 0.4 100-64= 36 q2= .36 q= 0.6 p= 1-0.6= 0.4

The California populations of the Northern elephant seal are descendants from a very small population of seals that was over-hunted in the 1890s. Heterozygosity in this population would be expected to be ________ due to _______________. A. slight; a bottleneck effect B. slight; the founder effect C. great; disruptive selection D. great; a bottleneck effect E. great; assortive mating Level 2

A. slight; a bottleneck effect

If a population with two alleles is at Hardy-Weinberg equilibrium and the frequency of one allele is 0.7, what is the heterozygote frequency? A. 0.7 B. 0.42 C. 0.3 D. 0.21 E. 0.49 Level 2

B. 0.42 q= 0.7 1-0.7= 0.3(p) 2pq 2 (0.7)(0.3) 2(.21) 0.42

Suppose you have a population of flour beetles with 1,000 individuals. Normally the beetles are red; however, this population is polymorphic for a mutant autosomal body color, black, designated by b/b. Red is dominant to black, so B/B and B/b genotypes are red. Assume the population is in Hardy-Weinberg equilibrium, with equal frequencies of the two alleles A. 0.5 red; 0.5 black B. 0.75 red; 0.25 black C. 0.25 red; 0.75 black D. 0 E. Insufficient information is given to answer the question Level 3

B. 0.75 red; 0.25 black

Both ancestral birds and ancestral mammals shared a common ancestor that was terrestrial. Today, penguins (which are birds) and seals (which are mammals) have forelimbs adapted for swimming. What term best describes the relationship of the bones in the forelimbs of penguins and seals, and what term best describes the flippers of penguins and seals? A. homologous; homologous B. analogous; homologous C. homologous; analogous D. analogous; analogous Level 2

C. homologous; analogous

Which of the following sets of allele frequencies would produce the greatest proportion of heterozygotes? A. p = 0.9 q = 0.1 B. p = 0.7 q = 0.3 C. p = 0.5 q = 0.5 D. p = 0.2 q = 0.8 E. p = 0.05 q = 0.95 Level 2

C. p = 0.5 q = 0.5 2pq the midpoint:

Suppose 64% of a remote mountain village can taste phenylthiocarbamide (PTC) and must therefore have at least one copy of the dominant PTC taster allele. If this population conforms to Hardy-Weinberg expectations for this gene, what percentage of the population must be heterozygous for this trait? A. 16% B. 32% C. 40% D. 48% E. 60% Level 3

D. 48% 100-64= 36 √.36= 0.6 q= 0.6 1-0.6= 0.4 p= 0.4 2pq 2(0.4)(0.6) 2(0.24) 0.48= 48%

Based on the lecture up to this point, the ultimate origin of genetic variation is A. Genetic drift B. Natural selection C. Sexual selection D. Mutations E. Nonrandom mating Level 2

D. Mutations

The presence of the disease sickle cell anemia illustrates that natural selection does not always eliminate _________ alleles. A. polymorphic B. dominant C. neutral D. recessive Level 2

D. recessive

If 81% of a population is homozygous recessive for a given trait, what is the predicted frequency for those who are homozygous dominant? A. 0.9 B. 0.36 C. 0.18 D. 0.1 E. 0.01 Level 2

E. 0.01 q2= 0.81 q= 0.9 p=1-0.9= 0.1 p2= 0.1 x 0.1= 0.01

In a population at Hardy-Weinberg equilibrium, the frequency of the a allele (homozygous recessive) is 0.60. What is the frequency of individuals heterozygous for the gene? A. 0.16 B. 0.24 C. 0.36 D. 0.40 E. 0.48 Level 2

E. 0.48 q=1-0.6= 0.4 (p) 2pq=0.4 x 0.6= 0.24 2(0.24)= 0.48

The gene pool includes all of the A. fitness within a population. B. individuals within a population. C. mutations within a population. D. adaptations within a population. E. alleles of genes within a population. Level 1

E. alleles of genes within a population.

A restriction in genetic variability caused by a drastic reduction in population size is called a A. Hardy-Weinberg effect. B. founder effect. C. polymorphic effect. D. adaptive effect. E. bottleneck effect. Level 1

E. bottleneck effect.