Evolution is one of the unifying themes of biology. Evolution involves change in the frequencies of alleles in a population. For a particular genetic locus in a population, the frequency of the recessive allele (a) is 0.4 and the frequency of the dominant allele (A) is 0.6. (a) What is the frequency of each genotype (AA,Aa,aa) in this population? What is the frequency of the dominant phenotype?

Evolution is one of the unifying themes of biology. Evolution involves change in the frequencies of alleles in a population. For a particular genetic locus in a population, the frequency of the recessive allele (a) is 0.4 and the frequency of the dominant allele (A) is 0.6. (b) How can the Hardy-Weinberg principle of genetic equilibrium be used to determine whether this population is evolving?

The condition in which there are barriers to successful interbreeding between individuals of different species in the same community is referred to as
a) latent variations
b) sterility
c) structural differences
d) geographic isolation
e) reproductive isolation

A survey reveals that 25 percent of a population of 1,000 individuals have attached earlobes (are homozygous recessive for the trait). Unlike most natural populations, this population is best characterized in which of the following ways?
a) there is a genetic equilibrium
b) there is gene flow
c) there is genetic drift
d) mutations occur
e) mating is nonrandom

Female European corn borer moths (Ostrinia nubilalis) produce the sex pheromone 11−tetradecenyl acetate (11−TDA), which attracts males of their species. 11−TDA can be produced in two forms, E and Z, each with a different three-dimensional shape. Researchers have discovered two different strains of the European corn borer moth living in the same area. Females of the E strain produce primarily the E form of 11−TDA and females of the Z strain produce primarily the Z form of 11−TDA. Males of both strains are more attracted to the form of 11−TDA produced by the females of the same strain. Which of the following best predicts a long-term effect of the differences between the E and Z strains?
a) the difference between the forms of the sex pheromone 11-TDA produced by E and Z strains will act as a prezygotic reproductive barrier leading to sympatric speciation
b) The difference between the forms of the sex pheromone 11−TDA produced by E and Z strains will act as a postzygotic reproductive barrier, leading to allopatric speciation.
c) Since the E and Z strains are both part of the same species, they will produce fertile offspring, leading to a single strain that produces both forms of 11−TDA.
d) Since the E and Z strains are found in the same geographic area, they will hybridize, leading to a single strain that produces the dominant form of 11−TDA

Which of the following statements best expresses the concept of punctuated equilibrium?
a) Small variations gradually accumulate in evolving lineages over periods of millions of years.
b) Random mating ensures that the proportions of genotypes in a population remain unchanged from generation to generation.
c) Stability is achieved when selection favors the heterozygote, while both types of homozygotes are at a relative disadvantage.
d) Evolutionary changes consist of rapid bursts of speciation alternating with long periods in which species remain essentially unmodified.
e) Under competition for identical resources, one of the two competing species will be eliminated or excluded.

Evolution is one of the unifying themes of biology. Evolution involves change in the frequencies of alleles in a population. For a particular genetic locus in a population, the frequency of the recessive allele (a) is 0.4 and the frequency of the dominant allele (A) is 0.6. (c) Identify a particular environmental change and describe how it might alter allelic frequencies in this population. Explain which condition of the Hardy-Weinberg principle would not be met.

On a large volcanic island, researchers are studying a population of annual herbaceous plants. Which of the following observations best supports the prediction that speciation will occur within the existing plant population?
a) Individuals of the species sometimes reproduce asexually by producing runners.
b) Lava has separated the population into two areas: an upland forest and a lowland marsh.
c) Multiple groups of birds depend on the fruit produced by the plants as a source of food.
d) The plants produce more seeds during warm summers than they do during cool summers.

A scientist is studying a population of lizards with three different color phenotypes. The color phenotype is controlled by a single gene with two alleles: an incompletely dominant allele A and a recessive allele a. The scientist collected data on the color of 100 lizards. The data are shown in the table. RED AA 75
PURPLE Aa 15
BLUE aa 10 To test the hypothesis that the population is at Hardy-Weinberg equilibrium, the scientist performed a chi-square test. Which of the following values is closest to the chi-square value the scientist calculated?
a) 0.1
b) 1.9
c) 18.3
d) 23.1

Goats and sheep belong to the same family but different genera. While they often live together in the same pastures, the hybrid offspring that are occasionally produced between the two species rarely survive. When such a hybrid does survive, it is usually sterile. Which of the following best explains the mechanism that maintains reproductive isolation between goats and sheep?
a) Gene flow is prevented because the two species belong to different trophic levels and therefore do not share a food source.
b) Habitat isolation creates a prezygotic barrier between the two species.
c) The males of one species and the females of the other species are fertile at different times.
d) The two species have a different number of chromosomes, resulting in a postzygotic barrier.