Exam 21: The Evolution of Populations

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?

Which of the following describes a mechanism for generating more genes?

Evolution of a gene

Sexual dimorphism is most often a result of

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?

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

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

In peas,a gene controls flower color 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?

Phenylketonuria (PKU)is a birth defect that causes an amino acid called phenylalanine to build up in the body.The frequency of individuals born in a population with PKU is q².There is one PKU (q²)birth per 10,000 births.The frequency of the recessive allele for PKU in this population is q = 0.01.The frequency of the dominant allele in this population is p = 1 - q = 0.99.What is the frequency of carriers (2pq)in this population?

Use Figure 21.2 to answer the following question. Figure 21.2 Soon after the island of Hawaii rose above the sea surface (somewhat less than 1 million years ago),the evolution of life on this new island should have been most strongly influenced by

What is the founder effect?

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

What is a population in biology?

Please use the following information to answer the questions below. You are studying three populations of birds.Population A has 10 birds,of which 1 is brown (a recessive trait)and 9 are red.Population B has 100 birds,of which 10 are brown.Population C has 30 birds,and 3 of them are brown. -In which population would it be least likely that an accident would significantly alter the frequency of the brown allele?

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

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?

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?

Identify the statement that describes the imperfection of natural selection.

Which statement about variation is true?

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?