Exam 23: The Evolution of Populations

Anopheles mosquitoes, which carry the malaria parasite, cannot live above elevations of 1800 metres. 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 793 metres above sea level and its peak is 5895 metres 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?

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

Which of these variables is likely to undergo the largest change in value as the result of a mutation that introduces a brand-new allele into a population's gene pool at a locus that had formerly been fixed?

The Hardy-Weinberg equilibrium theorem

The following questions refer to the following paragraph. HIV's genome of RNA includes the code for reverse transcriptase (RT), an enzyme that acts early in infection to synthesize a DNA genome from an RNA template. The HIV genome also codes for protease (PR), an enzyme that acts later in infection by cutting long viral polyproteins into smaller, functional proteins. Both RT and PR represent potential targets for antiretroviral drugs. Drugs called nucleoside analogues (NA) act against RT, whereas drugs called protease inhibitors (PI) act against PR. -HIV has nine genes in its RNA genome. Every HIV particle contains two RNA molecules, and each molecule contains all nine genes. If, for some reason, the two RNA molecules within a single HIV particle do not have identical sequences, then which of these terms can be applied due to the existence of the nonidentical regions?

Use the following figure to answer the questions below. In a very large population, a quantitative trait has the following distribution pattern: -What would be the most probable cause for a population depicted in the figure above to shift both to the left and to the right?

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?

A trend toward the decrease in the size of plants on the slopes of mountains as altitudes increase is an example of

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.1. What is the frequency of individuals with AA genotype?

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

Use the following information to answer the questions below. In the year 2500, five male space colonists and five female space colonists (all unrelated to each other) settle on an uninhabited Earthlike planet in the Andromeda galaxy. The colonists and their offspring randomly mate for generations. All ten of the original colonists had free earlobes, and two were heterozygous for that trait. The allele for free earlobes is dominant to the allele for attached earlobes. -Which of these is closest to the allele frequency in the founding population?

In peas, a gene controls flower colour such that R = purple and r = white. In an isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population?

Use this information to answer the following questions. You are studying three populations of birds. Population A has ten birds, of which one is brown (a recessive trait) and nine are red. Population B has 100 birds, of which ten are brown. Population C has 30 birds, and three of them are brown. -Which population is most likely to be subject to the bottleneck effect?

Blue light is that portion of the visible spectrum that penetrates the deepest 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 1000 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 following graphs 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?

During an individual organism's lifetime, which of these is most likely to help the organism respond properly to changes in its environment?

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

Use the following information to answer the questions below. In the year 2500, five male space colonists and five female space colonists (all unrelated to each other) settle on an uninhabited Earthlike planet in the Andromeda galaxy. The colonists and their offspring randomly mate for generations. All ten of the original colonists had free earlobes, and two were heterozygous for that trait. The allele for free earlobes is dominant to the allele for attached earlobes. -If one assumes 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 10000?

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 one excludes the involvement of gender in the situation, then the pattern that is apparent in the fossil record is most similar to one that should be expected from

Use this information to answer the following questions Many species once roamed across large areas of continents, and for millions of years these species were "shaped" by their environment. Today, numerous species, especially large carnivores, are found in national parks and nature reserves that are isolated by hundreds or thousands of kilometres of land now occupied by humans. The cheetah is one example of a species that has shown several dramatic decreases in numbers over time, and now occupies a small fraction of its historic range. -Captive breeding programs have the potential to save species from extinction. Which factor(s)do biologists working with captive cheetahs have to pay particular attention to and why?

Use the following figure to answer the questions below. In a very large population, a quantitative trait has the following distribution pattern: -If the curve in the above figure 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? 1. immigration or emigration 2. directional selection 3. adaptation 4. genetic drift 5. disruptive selection