Consider a polymorphic gene with three alleles: A, B, and C.
A. If the frequencies of the alleles A and B are 0.2 and 0.3, the frequency of allele C is closest to ___.
a. 0.25
b. 0.5
c. 0.2
d. 0.3
Consider a gene with only two alleles: dominant A and recessive a. In a population of 1,000 organisms, the fraction expressing the homozygous recessive phenotype is 0.37.
B. The calculated allele frequencies p and q have values that are closest to ___.
a. 0.69 and 0.31
b. 0.31 and 0.69
c. 0.37 and 0.63
d. 0.63 and 0.37
C. The calculated number of individuals in this population that are heterozygotes is closest to ___.
a. 240
b. 230
c. 430
d. 476
Mountain pine beetles (Dendroctonus ponderosae) were collected from a one-acre tract of lodge pole pine trees (Pinus contorta) in a region of British Columbia where the forests are under temperature stress. The beetles were crushed, and a cellulase enzyme was extracted. Three polymorphs of the enzyme were observed when separated by gel electrophoresis. The three proteins observed correspond to alleles labeled C1, C2, and C3. The numbers of beetles with each allele are shown in the following table.
D. The calculated allelic frequencies pC1, pC2, and pC3 are closest to ___.
a. $\quad \mathrm{P_{Cl}}=0.57 \mathrm{P_{C2}}=0.57 \mathrm{P_{C3}}=0.59$
b. $\quad \mathrm{P_{Cl}}=0.29 \mathrm{P_{C2}}=0.29 \mathrm{P_{C3}}=0.42$
c. $\quad \mathrm{P_{Cl}}=0.61 \mathrm{P_{C2}}=0.80 \mathrm{P_{C3}}=0.59$
d. $\quad \mathrm{P_{Cl}}=0.31 \mathrm{P_{C2}}=0.40 \mathrm{P_{C3}}=0.29$
E. In order to investigate the presence of selection at the cellulase locus due to changing temperature, a biologist should:
a. calculate the values of the sums $\mathrm{P_{Cl}}+\mathrm{P_{C2}}+\mathrm{P_{C3}}+$ and $(\mathrm{P_{Cl}}+\mathrm{P_{C2}}+\mathrm{P_{C3}}+)^{2}$.If these numbers are not equal to 1, the gene is not in Hardy-Weinberg equilibrium, and the gene is evolving.
b. return next year and repeat this examination of the enzyme, calculating frequencies of each allele each year. Then calculate the values of the sums $\mathrm{P_{Cl}}+\mathrm{P_{C2}}+\mathrm{P_{C3}}+$ and $(\mathrm{P_{Cl}}+\mathrm{P_{C2}}+\mathrm{P_{C3}}+)^{2}$ . If these numbers are not the same each year, the gene is not in Hardy-Weinberg equilibrium, and the gene is evolving.
c. return each year for several years and repeat this examination of the enzyme, calculating
frequencies of each allele each year. If the allele frequencies are changing, the gene is not in Hardy-Weinberg equilibrium, and temperature is exerting a selection pressure.
d. return each year for several years and repeat this examination of the enzyme, calculating
frequencies of each allele each year. If the allele frequencies are changing, the gene is not in Hardy-Weinberg equilibrium. Analysis of the dependence of allele frequencies on temperature could indicate selection.