Exam 23: The Evolution of Populations

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 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

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 that 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 the formula for determining a population's genotype frequencies,the pq in the term 2pq is necessary because

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?

The volcano is currently dormant,but in a hypothetical future scenario,satellite cones at the base of Mt.Kilimanjaro spew sulphurous gases and lava,destroying all life located between the base and 1830 metres above sea level.As a result of this catastrophe,how should the frequency of the sickle-cell allele change in the remnant human population that survives above 1830 metres,and which phenomenon accounts for this change in allele frequency?

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. -If the sickle-cell allele is recessive,what proportion of the population should be susceptible to sickle-cell anemia under typical conditions?

A proficient engineer can easily design skeletal structures that are more functional than those currently found in the forelimbs of such diverse mammals as horses,whales,and bats.The actual forelimbs of these mammals do not seem to be optimally arranged because

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.Over the course of evolutionary time,what should occur?

The recessive allele that causes phenylketonuria (PKU)is harmful,except when an infant's diet lacks the amino acid phenylalanine.What maintains the presence of this harmful allele in a population's gene pool?

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?

Evolution

Most invertebrates have a cluster of ten similar Hox genes,all located on the same chromosome.Most vertebrates have four such clusters of Hox genes,located on four nonhomologous chromosomes.The process that could have potentially contributed to the cluster's presence on more than one chromosome was