evolution ap bio exam

In seederacker finches from Cameroon, small- and large-billed birds specialize in cracking soft and hard seeds, respectively. It long-term climatic change resulted in all seeds becoming hard, what type of selection would then operate on the finch population?

B) directional selection

If the nucleotide variability of a locus equals 0%, what is the gene variability and number of alleles at that locus?

B) gene variability = 0%; number of alleles = 1

Heterozygote advantage should be most closely linked to which of the following?

B) stabilizing selection

In which population would it be least likely that an accident would significantly alter the frequency of the brown allele?

B. Population B

What proportion of the population is probably heterozygous (a) for this trait?

C) 0.50

Swine are vulnerable to infection by bird flu virus and human flu virus. which can both be present in an individual pig at the same time. When this occurs. it is possible for genes from bird fu virus and human flu virus to be combined. If the human flu virus contributes a gene for Tamiflu resistance (Tamillu is an antiviral drug) to the new virus. and it the new virus is introduced to an environment lacking Tamiflu, then what is most likely to occur?

C) If the Tamiflu-resistance gene involves a cost, it will experience directional selection leading to reduction in its frequency.

Soon after the island of Hawaii rose above the sea surface (somewhat less than I million years ago), the evolution of lite on this new island should have been most strongly intluenced by

D) founder effect.

Sexual dimorphism is most often a result of

D) intersexual selection.

1) Which of the following represents the treatment option most likely to avoid the production of drug-resistant HIV (assuming no drug interactions or side effects)?

D) using moderate doses of NA and two different Pls at the same time for several months

Natural selection changes allele frequencies because some..........more successfully than others survive and reproduce

D. individuals

Sparrows with average-sized wings survive severe storms better than those with longer or shorter wings, illustrating

D. stabilizing selection

A fruit fly population has a gene with two alleles, A1 and A2. Tests show that 70% of the gametes produced in the population contain the A1 allele. If the population is in Hardy-Weinberg equilibrium, what proportion of the llies carry both Al and A2?

c. 0.42

In evolution, which driving factor most consistently requires a small population as a precondition for its occurrence?

c. genetic drift

What is the result of adaptive evolution?

c. increase in frequency of alleles that provide reproductive advantage

Examining the figure, which type of selection eliminates extreme frequency of individuals' phenotype?

c. stabilizing selection

Most Swiss starlings produce four to five eggs in each clutch. Starlings producing fewer, or more, than this have reduced fitness. Which of the following terms best describes this situation?

c. stabilizing selection

Which of the following is most likely to produce an African butterfly species in the wild whose members have one pattern?

c. stabilizing selection

What is the founder effect?

c. when a few individuals become isolated from a larger population and their gene pool differs from that source population

Which of the following statements best summarizes evolution as it is viewed today?

d. It is the differential survival and reproduction of the most fit phenotypes.

Every HIV particle contains two RNA molecules. If two genes from one RNA molecule become detached and then, as a unit, get attached to one end of the other RNA molecule within a single HIV particle, which of these is true?

d. One of the RNA molecules has experienced gene duplication as the result of translocation.

If you assume that Hardy-Weinberg equilibrium applies to the population of colonists on this planet. about how many people will have attached earlobes when the planet's population reaches 10,000

A. 100

Which population is most likely to be subject to the bottleneck effect?

A. Population A

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?

d. directional selection; disruptive selection

Over time, the movement of people on Earth has steadily increased. This has altered the course of human evolution by increasing

d. gene flow

If the original finches that flew over to the Galapagos Islands from South America had already been genetically different from the parental population of South American finches, even before adapting to the Galapagos. this would have been an example of

d. genetic drift and the founder effect

Which one of the genetic drift effects would limit natural selection?

d. alter frequencies in small population

What is the estimated frequency of allele A in the gene pool?

b. 0.50

Examining the figure, which type of selection has two peaks of frequency of individuals?

b. disruptive selection

Considering the overall human population of the U.S. mainland at the time when the slave trade brought large numbers of people from equatorial Alrica, what was primarily acting to change the frequency of the sickle-cell allele in the overall U.S. population?

b. gene flow

Imagine you predict a particular frequency for a genotype, based upon detailed knowledge of that genotype frequency in population "X" of a species. Then, using the Hardy-Weinberg model, you find that the observed genotype frequency in a different population, named Y of the same species, is not significantly different from what you predicted/expected based on population "X." Which of the following should you conclude?

A) The particular gene of interest is not undergoing any mechanisms of evolution.

The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA Is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, this in turn selects for bacteria whose genomes are not methylated and whose restriction enzymes instead degrade methylated DNA. The outcome of the conflict between bacteria and bacteriophage at any point in time results from

A) frequency-dependent selection.

Which of these is closest to the allele frequency in the founding population?

A. 0.1 a, 0.9 A

You are maintaining a small population of fruit flies in the laboratory by transferring the flies to a new culture bottle after each generation. After several generations, you notice the viability of the flies has decreased greatly. Recognizing that small population size is likely to be linked to decreased viability, the best way to reverse this trend is to

A. cross your flies with flies from another lab

There are 25 individuals in population 1, all with genotype AA, and there are 40 individuals in population 2, all with genotype a. Assume these populations are located far from each other and that their environmental conditions are very similar. Based on the information given here, the observed genetic variation most likely resulted from

A. genetic drift

Blue light is a portion of the visible spectrum that penetrates deep into bodies of water. Ultraviolet (UV) light, though, can penetrate even deeper. A gene within a population of marine fish that inhabits depths from 500 m to 1,000 m has an allele for a photopigment that is sensitive to UV light and another allele for a photopigment that is sensitive to blue light. Which of the graphs in Figure 21.1 best depicts the predicted distribution of these alleles within a population if the fish that carry these alleles prefer to locate themselves where they can see best?

B) B (the graph looks like an X with UV in the bottom right corner)

The same gene that causes various coat patterns in wild and domesticated cats also causes a cross-eved condition in these cats. the cross-eved condition being slightly maladaptive. In a hypothetical environment, the coat pattern that is associated with crossed eyes as highly adaptive, with the result that both that coat pattern and the cross-eyed condition increase in a feline population over time. Which statement is supported by these observations?

B) Phenotype is often the result of compromise.

In a hypothetical population's gene pool, an autosomal gene, which had previously been fixed, undergoes a mutation that introduces a new allele, one inherited according to incomplete dominance. Natural selection then causes stabilizing selection at this locus. Consequently, what should happen over the course of many generations?

B) The proportion of the population that is heterozygous at this locus should remain constant

What is the most reasonable conclusion that can be drawn from the fact that the frequency of the recessive trait (ag) has not changed over lime?

B) The two phenotypes are about equally adaptive under laboratory conditions

Anopheles mosquitoes, which carry the malaria parasite, cannot live above elevations of 5,900 feet. In addition, oxygen availability decreases with higher altitude. Consider a hypothetical human population that is adapted to life on the slopes of Mt. Kilimanjaro in Tanzania, a country in equatorial Africa. Mt. Kilimanjaro's base is about 2,600 feet above sea level and its peak is 19,341 feet above sea level. If the incidence of the sickle-cell allele in the population is plotted against altitude (feet above sea level), which of the following distributions is most likely, assuming little migration of people up or down the mountain?

B. (B) (graph is a negative straight line)

With respect to the sickle-cell allele, what should be true of the B hemoglobin locus in U.S. populations of Alrican Americans whose ancestors were trom equatorial Africa!

B. 1 and 3

Evolution of a gene.....

C) can happen whenever any of the conditions for Hardy- Weinbere eguilibrium are not met for that particular gene.

No two people are genetically identical, except for identical twins. The main source of genetic variation among human individuals is

C) the reshuffling of alleles in sexual reproduction.

The sickle-cell allele is pleiotropic (i.e., it affects more than one phenotypic trait). Specifically, this allele affects oxygen delivery to tissues and affects an individual's susceptibility to malaria. Under conditions of low atmospheric oxygen availability, individuals heterozygous for this allele can experience life-threatening sickle-cell "crises." Such individuals remain less susceptible to malaria. Thus, plesotropic genes/alleles such as this can help explain why

C. adaptations are often compromises.

Identity the statement that describes the imperfection of natural selection.

D) Natural selection is generally limited to modifying structures that were present in previous populations and in previous species.

If four of the original colonists died before they produced offspring, the ratios of genotypes could be quite different in the subsequent generations. This would be an example of

C. genetic drift

Although selection is clearly present, if the ideal equilibrium of alleles existed, what should be the proportion of heterozygous individuals in populations who live here?

D) 0.32

What is true of natural selection?

D) Mutations occur at random; natural selection can preserve and distribute beneficial mutations.

Again, if this population were in equilibrium, and it the sickle-cell allele is recessive, what proportion of the population should be susceptible to sickle-cell disease under typical conditions?

a. 0.04

Adult male humans generally have deeper voices than do adult female humans, which is the direct result of higher levels of testosterone causing growth of the larynx. If the fossil records of apes and humans alike show a trend toward decreasing larynx size in adult females and increasing larynx size in adult males, then

a. sexual dimorphism was developing over time in these species.

Mountains also have an unmatched power to drive human evolution. Starting tens of thousands of years ago, people moved to high altitudes, and there they experienced natural selection that has reworked their biology. In Tibet, for example, people have broader arteries and capillaries. In the Andes, they can dissolve more oxygen into their blood. These different traits of people who live in high altitudes illustrate

c. adaptive evolution

How can gene flow improve adaptation of population?

c. beneficial alleles are transferred to a new population

In a very large population, a quantitative trait has the distribution pattern shown in Figure 21.3. If the curve in Figure 21.3 shifts to the left or to the right, there is no gene flow, and the population size consequently increases over successive generations. Which of the following is (are) probably occurring?

c. directional selection and adaptation