Question 1

A dominant allele is found in a population with a frequency of 0.8.As the environment begins to change,the dominant allele is not favored.Scientists find that the frequency of the dominant allele decreases by half each generation.What are the allele,genotype,and phenotype frequencies before and one generation after the population begins to change? Is Hardy-Weinberg equilibrium maintained?

Accepted Answer

The answer of A dominant allele is found in a...

Question 2

Define and give an example of assortative mating.Will this affect genotype frequencies?

Accepted Answer

The answer of Define and give an example of assortative...

Question 3

Scientists have studied,in detail,the evolution of the peppered moth,Biston betularia,over the last two hundred years.The peppered moths rest on tree trunks and are a tempting treat for birds in the area.In the mid-1800s the trees in their England habitat were covered with lichens,which are a light,grayish-green color.Although color variations occurred,the vast majority of the moths were light-colored.Because their light coloration effectively camouflaged them against the lichens-covered trees,they were not as easily seen by birds as darker colored moths.The light-colored moths flourished.
The environment changed,as the Industrial Revolution progressed.By 1900,the lichens had died and trees were coated with soot due to industrial pollution.The lighter colored moths were no longer "hidden" in their environment,and in fact,were easily seen by their predators.Their numbers dwindled.At the same time,the darker-colored moths flourished because of their ability to hide on the soot-covered trees.
a.What type of selection is this?
b.What is the agent of selection?
c.What alleles were favored in the clean environment? The polluted environment?

Accepted Answer

The answer of Scientists have studied,in detail,the evolution of the...

Question 4

Social research indicates that a person is most likely to marry someone from the same village or city,or a high school or college classmate.Therefore,the Hardy-Weinberg equilibrium does not apply well to human populations because

Accepted Answer

Individuals are not pairing up by chance across the whole population, which violates the random mating condition of the Hardy-Weinberg equilibrium.

Question 5

What is the relative biological fitness of an individual who is heterozygous for sickle-cell disease who lives in central Illinois vs.an individual who is heterozygous and lives in South Africa?

Accepted Answer

The answer of What is the relative biological fitness of...

Question 6

The northern elephant seal was hunted almost to extinction during the 18th and 19th centuries.Less than 100 seals were left to contribute to the gene pool of their future generations.Since the early 20th century,the elephant seals have been protected by law in both the U.S.and Mexico.Over 100,000 seals now inhabit the western shores of North America,all related to the small population that survived the slaughter of hunters. Scientists fear the elephant seals may be more susceptible to disease and pollution due to

Accepted Answer

The bottleneck effect occurs when a population's size is significantly reduced for at least one generation, leading to a loss of genetic diversity. The northern elephant seal population was reduced to less than 100 individuals, which is a classic example of a bottleneck effect. This makes them more susceptible to disease and pollution due to reduced genetic variation.

Question 7

You have been studying a newly discovered species of lemur.You have established that sexual selection has been a powerful force in the evolution of this species and it is clear that female choice plays an important role in determining which males procure mates.After many hours of observation and data collection,you find that females prefer males that are more proficient at collecting sap and fruit.You should conclude that your data strongly supports the good genes hypothesis.

Accepted Answer

The good genes hypothesis suggests that females choose mates with traits that indicate genetic superiority, which can be passed on to offspring. Proficiency in collecting sap and fruit may indicate better survival skills and overall fitness, supporting this hypothesis.

Question 8

Which of the following is required for natural selection to occur in a population?

Accepted Answer

Natural selection requires heritable variation, differential reproduction, and the accumulation of adaptive traits in a population.

Question 9

Scientists have studied,in detail,the evolution of the peppered moth,Biston betularia,over the last two hundred years.The peppered moths rest on tree trunks and are a tempting treat for birds in the area.In the mid-1800s the trees in their England habitat were covered with lichens,which are a light,grayish-green color.Although color variations occurred,the vast majority of the moths were light-colored.Because their light coloration effectively camouflaged them against the lichens-covered trees,they were not as easily seen by birds as darker colored moths.The light-colored moths flourished.
The environment changed,as the Industrial Revolution progressed.By 1900,the lichens had died and trees were coated with soot due to the industrial pollution.The lighter colored moths were no longer 'hidden' in their environment,and in fact,were easily seen by their predators.Their numbers dwindled.At the same time,the darker-colored moths flourished because of their ability to hide on the darkened trees.
Describe what the initial normal population curve would look like before pollution.Describe what the population curve would look like after the Industrial Revolution and indicate what phenotype was favored.

Accepted Answer

The answer of Scientists have studied,in detail,the evolution of the...

Question 10

The difference in temperature preference between two populations of Daphnia water fleas is due to a mutation.The original population prefers temperatures near 20°C,while the mutant population prefers temperatures between 25°C and 30°C.Predict how natural selection might affect the geographical distribution of these two populations.

Accepted Answer

The answer of The difference in temperature preference between two...

Question 11

A population was surveyed to determine the percentage of individuals with detached earlobes and attached earlobes.16% of the population was found to have attached earlobes,a trait coded for by a recessive allele.Calculate the allele,genotype and phenotype frequencies of the population,assuming Hardy-Weinberg equilibrium is maintained.

Accepted Answer

The answer of A population was surveyed to determine the...

Question 12

If the small groups of Viking explorers in Greenland and North America had survived and given rise to new populations,such a scenario would be an example of

Accepted Answer

The scenario describes the founder effect, where a small group of individuals establishes a new population, leading to reduced genetic variation and a gene pool that reflects the traits of the initial members.

Question 13

In a population,the allele frequency for red flower color remained at 0.7 and the allele frequency for white flower remained at 0.3 for six generations.This ________ an example of a Hardy-Weinberg equilibrium in that ________.

Accepted Answer

The allele frequencies remained constant over generations, indicating no evolution, which is a condition of Hardy-Weinberg equilibrium.

Question 14

Natural selection can maintain genetic variation by favoring heterozygous genotypes.In equatorial Africa,the best genotype to have for hemoglobin is heterozygous (HbA / HbS).In the United States,there is no advantage to the heterozygous genotype.HbA codes for normal hemoglobin,whereas HbS codes for abnormal hemoglobin that causes red blood cells to become distorted in shape (sickle cell).Explain why the heterozygous state is advantageous in Africa,but not in the United States.What has happened to the sickle-cell allele in Africa? What has happened to the sickle-cell allele in the United States?

Accepted Answer

The answer of Natural selection can maintain genetic variation by...

Question 15

The black bellied seed cracker,Pyrenestes,is a West African finch.Within the same geographic region,two subspecies of the finch are found.One subspecies has a large beak,which is efficient at cracking the hard seeds of the sedge,Scleria verrucosa.The other subspecies has a small beak,which is more efficient at eating the soft seeds of the sedge,Scleria goossensii.What type of selection occurred to produce this situation? Explain what a population distribution graph would look like that would depict this type of selection.

Accepted Answer

The answer of The black bellied seed cracker,Pyrenestes,is a West...

Question 16

Over the course of millions of years various environments have changed.As grasslands slowly took the place of forests the inhabitants were forced to adapt or they went extinct.During this time period the horse gradually evolved from a small cat sized creature to the size of the modern horses we see today.This is an example of which type of natural selection?

Accepted Answer

Directional selection occurs when one extreme of a trait is favored over others, leading to a shift in the population's traits over time, as seen in the evolution of horses from small to larger sizes.

Question 17

In the case of the peppered moths in England,when Kettlewell set up cameras to document that more white or black moths were eaten by birds on clean or sooty trees,he was verifying which factor involved in evolution by natural selection?

Accepted Answer

Kettlewell's experiment was designed to show that moths with coloration matching their environment were less likely to be eaten by predators, demonstrating that some individuals are better adapted to their environment, a key factor in natural selection.

Question 18

Amish populations in Lancaster County,Pennsylvania have high rates of a rare form of dwarfism.The recessive allele that codes for this disorder is found in 1 of 14 individuals in this Amish population,in contrast to 1 in 1,000 in the general population.In Ohio,an Amish population suffers with higher than normal rates of cystic fibrosis and a host of other genetic diseases so rare that some have not yet been named.What factors have caused such severe genetic problems in these two communities?

Accepted Answer

The answer of Amish populations in Lancaster County,Pennsylvania have high...

Question 19

Hospital data shows that human infants born with an intermediate birth weight have a better chance of survival than those that weigh much less or much more.Larger than normal babies may have a difficult delivery,while smaller than normal babies may not be fully developed.What type of selection is occurring? Is the variability in birth weight in human populations increasing or decreasing?

Accepted Answer

The answer of Hospital data shows that human infants born...

Question 20

If the mutation rate of individual genes is taken to be about one in 100,000 genes per cell cycle across many organisms,we might expect evolution to proceed at a consistent rate for various forms of life.Which factor could make the accumulation of gene mutations faster or slower among different organisms?

Accepted Answer

All the factors listed can influence the rate at which gene mutations accumulate in different organisms.

Quiz 16: How Populations Evolve