Exam 23: The Evolution of Populations

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?

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

Use the following information to answer the questions below. In those parts of equatorial Africa where the malaria parasite is most common,the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool. -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?

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

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

The three main mechanisms that alter allele frequencies and change the genetic composition of populations are

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

Use this information below to answer the following questions. A large population of laboratory animals has been allowed to breed randomly for a number of generations.After several generations,25% of the animals display a recessive trait (aa),the same percentage as at the beginning of the breeding program.The rest of the animals show the dominant phenotype,with heterozygotes indistinguishable from the homozygous dominants. -What is the estimated frequency of allele A in the gene pool?

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

Which of the following statements about sexual selection is not true?

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 flu virus and human flu virus to be combined,thereby producing a genetically distinctive virus,which can subsequently cause widespread disease.The production of new types of flu virus in the manner described above is most similar to the phenomenon of

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

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?

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?

In modern terminology,diversity is understood to be a result of genetic variation.Which of the following is a recognized source of variation for 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

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?

Which of the following is most likely to produce an African butterfly species in the wild whose members have one of two strikingly different colour patterns?

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 flies carry both A1 and A2?

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?