Question 1

What evidence supports the hypothesis that humans originated in Africa?
A)H.spaiens genomes contain some Neaderthal DNA sequences.
B)A Y chromosomal mutation is common in 1 in 1,000 males in Asia.
C)Mt sequence variation is least in African populations.
D)Mt sequence variation is highest in African populations.

Accepted Answer

Mt sequence variation is highest in African populations, which suggests a longer time for evolution and genetic diversity to accumulate within the population. This supports the hypothesis that humans originated in Africa and then migrated to other parts of the world.

Question 2

The Hardy-Weinberg equation is best at predicting short term genotypic frequencies since
A)the equation does not take into consdieration epistatic effects.
B)it is based on inhertiance based on Mendel's second law.
C)the equation is based on Mendelian principles of single gene inheritance.
D)over the long term some of the assumptions of the equation will not be true.

Accepted Answer

The Hardy-Weinberg equation makes several assumptions that may not hold true over the long term, such as the absence of migration, mutation, genetic drift, natural selection and non-random mating. Therefore, it is best at predicting short term genotypic frequencies when these assumptions may still hold true, but over the long term, they may not be accurate.

Question 3

Many human recessive genetic diseases are maintained despite continuing selection against them because
A)heterozygotes have a higher fitness than either homozygote.
B)the recessive alleles mutate to dominant type.
C)there is no inheritance for the recessive allele.
D)the dominant allele frequency remains the same over generations.

Accepted Answer

Heterozygotes for recessive genetic diseases often have a higher fitness than either homozygote. This is known as heterozygote advantage or the "carrier advantage." In this way, the recessive allele can persist in a population despite the selection against the associated disease.

Question 4

The proportion of individuals in a population that are of a particular phenotype is the
A)phenotype frequency.
B)genotype frequency.
C)allele frequency.
D)None of the choices is correct.

Accepted Answer

The definition given matches the term "phenotype frequency." Genotype frequency refers to the proportion of individuals with a specific genotype, while allele frequency refers to the proportion of a specific allele within a population.

Question 5

Why do the alleles that confer insecticide resistance in mosquitoes become less frequent in the population when insecticide application is disconintued?
A)The mosquiotes experienced a bottle neck effect
B)The alleles were linked to a color variation that allowed for the mosquitoes that were resistant to have a higher rate of predation.
C)The population experienced genetic drift
D)The alleles for resistance had a negative fitness cost.

Accepted Answer

The most likely reason for the decline in frequency of insecticide resistance alleles in mosquitoes after discontinuing insecticide application is because these alleles often come with a negative fitness cost in the absence of insecticide. This means that individuals with resistance alleles may be less fit than those without resistance alleles when insecticide is not present. Therefore, over time, natural selection favors individuals without the resistance alleles, causing them to become less frequent in the population.

Question 6

The proportion of individuals in a population that are of a particular genotype is the
A)phenotype frequency.
B)genotype frequency.
C)allele frequency.
D)None of the choices is correct.

Accepted Answer

Genotype frequency refers to the proportion of individuals in a population that have a particular genotype. Phenotype frequency refers to the proportion of individuals that express a particular trait or phenotype. Allele frequency refers to the proportion of a specific allele in a population. Therefore, genotype frequency is the most appropriate choice for this question.

Question 7

Biological ancestry describes the
A)the possibility of inheriting mitochondria from the mother.
B)memebers of different generations interact.
C)shared genes but not parentage.
D)parentage and not shared genes.

Accepted Answer

The answer of Biological ancestry describes the
A)the possibility of inheriting...

Question 8

The frequency of the Hemoglobin A allele is 0.9.The heterozygote with the recessive allele, s, shows resistance to the malarial parasite.What is the frequency of the heterozygote for the pair As?
A)0.81
B)0.1
C)0.01
D)0.18
E)0.09

Accepted Answer

The frequency of the A allele is given as 0.9, which means that the frequency of the recessive s allele would be (1-0.9) = 0.1.

The heterozygote for the pair As would be Aa (where A represents the dominant allele for normal hemoglobin, and a represents the recessive allele for sickle cell anemia).

We know that the heterozygote Aa shows resistance to the malarial parasite.

So, to find the frequency of the Aa heterozygote, we can use the Hardy-Weinberg equation:

p^2 + 2pq + q^2 = 1

where p is the frequency of the A allele, q is the frequency of the a allele, and pq is the frequency of the heterozygote.

Substituting the values, we get:

0.9^2 + 2(0.9)(0.1) + 0.1^2 = 0.81

Therefore, the frequency of the heterozygote for the pair As is 0.81, which is option D.

Question 9

The sum total of all alleles carried in all members of a population is called its
A)gene pool.
B)genome.
C)ploidy.
D)polygenic sum.
E)polymorphism.

Accepted Answer

The term "gene pool" refers to the collection of all the alleles in a population. It includes all the variations present in a population's genes.

Question 10

The loss of allelic variation due to an event that decreases the size of the entire population is called
A)gene flow.
B)genetic drift.
C)founder effect.
D)population bottleneck.
E)selection.

Accepted Answer

A population bottleneck is an event that causes a significant decrease in the size of the entire population, resulting in the loss of allelic variation. This can occur due to natural disasters, disease outbreaks, or human activities. Genetic drift can also occur in smaller populations, but the loss of variation is specific to events that decrease the size of the entire population. Gene flow refers to the movement of genes between populations, while founder effect refers to the establishment of a new population by a small number of individuals, which can also lead to a loss of variation. Selection can lead to a decrease in the frequency of certain alleles, but it does not necessarily result in a loss of variation.

Question 11

Which of the following is not one of the assumptions of the Hardy-Weinberg law?
A)The population is very large.
B)Non-random mating occurs within the population.
C)Mutations in the alleles do not occur.
D)No migration occurs into or out of the population.
E)The ability of all genotypes for survival and reproduction is the same.

Accepted Answer

The Hardy-Weinberg law assumes random mating within the population, not non-random mating.

Question 12

New mutations that arise within a population are typically lost primarily do to
A)most mutations occur in individuals that are exposed to environmental mutagens and they therefore experience mutations in many different genes which means that they do not survive to reproduce.
B)most mutations are lethal.
C)new mutations all result in a lower reproductive fitness.
D)populations are of a finite size and new mutations are frequently lost by genetic drift.

Accepted Answer

Populations are of a finite size, and new mutations are frequently lost by genetic drift. In small populations, genetic drift can have a significant impact on the frequency of alleles, and new mutations may not be passed on to future generations simply because they were not present in the individuals who happened to reproduce. Thus, while some mutations may be lethal or result in lower reproductive fitness, the primary reason for the loss of new mutations is due to genetic drift in small populations.

Question 13

In humans, brachydactyly is a dominant condition; 6,400 people in a population of 10,000 show the disease (1,600 are BB, 4,800 are Bb) and 3,600 are normal phenotypes (bb).The frequency of the b allele is
A)0.6.
B)0.4.
C)0.36.
D)0.48.
E)0.16.

Accepted Answer

The frequency of the b allele can be calculated using the formula: frequency of b = (2 * number of bb + number of Bb) / (2 * total population). Here, it is (2*3600 + 4800) / (2*10000) = 0.6.

Question 14

How has DNA sequencing clarified the relationship between modern humans and other lineages?
A)It has demonstrated that humans are the direct descendants of a linage that was started by Denisovian and Neadtheral interbreeding.
B)It has demonstrated that modern humans did not interbreed extensively with other lineages.
C)It has demonstrated that modern humans interbred extensively with other lineages.
D)It has demonstrated that modern humans are the direct descendants of Neaderthals.

Accepted Answer

DNA sequencing has shown that modern humans interbred extensively with other lineages such as Neanderthals and Denisovans. This is evident from the presence of fragments of Neanderthal and Denisovan DNA in the genomes of modern humans. This has helped to clarify the relationship between modern humans and other lineages and to better understand the evolutionary history of our species.

Question 15

In forensics analysis 13 loci are types and the probability of finding an individual in a population with that specific combination of SSR types calculated based on
A)determining whihc allele is the rarest for each loci and then determining of the individual sample contains those loci.
B)calculating the total number of alleles for all loci ion the population.
C)the Hardy-Weinberg Law
D)multiplying the total number of alleles in the population by 2.

Accepted Answer

The Hardy-Weinberg Law is a mathematical equation used to calculate the frequency of alleles in a population. It considers the frequency of homozygous dominant, homozygous recessive, and heterozygous individuals and assumes that the population is in equilibrium. This makes it a reliable method for determining the probability of finding an individual with a specific combination of SSR types in a population. Choice A is incorrect because the rareness of an allele does not necessarily determine the probability of finding an individual with a specific combination of SSR types. Choice B and D are also incorrect because they do not take into account the frequencies of different genotypes or the equilibrium of the population.

Quiz 20: Variation and Selection in Populations

What evidence supports the hypothesis that humans originated in Africa?

The Hardy-Weinberg equation is best at predicting short term genotypic frequencies since

Many human recessive genetic diseases are maintained despite continuing selection against them because

The proportion of individuals in a population that are of a particular phenotype is the

Why do the alleles that confer insecticide resistance in mosquitoes become less frequent in the population when insecticide application is disconintued?

The proportion of individuals in a population that are of a particular genotype is the

Biological ancestry describes the

The frequency of the Hemoglobin A allele is 0.9.The heterozygote with the recessive allele, s, shows resistance to the malarial parasite.What is the frequency of the heterozygote for the pair As?

The sum total of all alleles carried in all members of a population is called its

The loss of allelic variation due to an event that decreases the size of the entire population is called

Which of the following is not one of the assumptions of the Hardy-Weinberg law?

New mutations that arise within a population are typically lost primarily do to

In humans, brachydactyly is a dominant condition; 6,400 people in a population of 10,000 show the disease (1,600 are BB, 4,800 are Bb) and 3,600 are normal phenotypes (bb) .The frequency of the b allele is

How has DNA sequencing clarified the relationship between modern humans and other lineages?

In forensics analysis 13 loci are types and the probability of finding an individual in a population with that specific combination of SSR types calculated based on