Question 1

Which of the following is an incorrect assumption of the Hardy-Weinberg law?

Accepted Answer

The Hardy-Weinberg law assumes an infinite population size. If the population is very small, genetic drift can occur and alter the allele frequencies, violating the assumptions of the law.

Question 2

Genomic studies of Neanderthals, modern humans, and chimpanzees confirms which of the following?

Accepted Answer

Genomic studies have confirmed that modern humans and Neanderthals interbred, meaning that they are closely related. However, humans did not evolve from Neanderthals - rather, both species share a common ancestor. Additionally, humans and Neanderthals did not evolve from chimpanzees; rather, humans and chimpanzees share a common ancestor, and all three species (humans, Neanderthals, and chimpanzees) have diverged over time.

Question 3

Which of the following species of Homo did NOT live contemporaneously with H. sapiens?

Accepted Answer

H. habilis lived approximately 2.8 to 1.5 million years ago, while H. sapiens did not appear until around 300,000 years ago, meaning that they did not coexist. However, H. neanderthalensis, H. floresiensis, and H. erectus all did overlap with H. sapiens at some point in human history.

Question 4

If natural selection is real, why do lethal recessive disorders still exist in populations?

Accepted Answer

Recessive alleles can persist in a population because they are hidden in carriers who do not express the disorder, and sometimes being heterozygous for a recessive allele can confer a selective advantage, such as in the case of sickle cell trait providing resistance to malaria.

Question 5

Albinism is a recessive trait controlled by a single gene. If the frequency of albinos in a population is 0.25, what is the expected frequency of heterozygotes for this trait? (Hint: use the Hardy-Weinberg formula)

Accepted Answer

According to the Hardy-Weinberg formula, the expected frequency of heterozygotes for a recessive trait can be calculated as 2pq, where p is the frequency of the dominant allele and q is the frequency of the recessive allele. Since albinism is a recessive trait, the frequency of the recessive allele q must be the square root of 0.25, which is 0.5. Therefore, the frequency of heterozygotes (2pq) is 2 x 0.5 x 0.5 = 0.50.

Question 6

The trend toward increased mobility of the world populations will probably lead to

Accepted Answer

As people move from one place to another, they bring their genes with them, resulting in increased gene flow and decreased genetic differences among populations. Therefore, option B is the best choice. Option A is incorrect because increased gene flow leads to decreased allele frequency differences rather than increased. Option C is incorrect as there is no evidence to suggest that increased mobility of world populations affects the mutation rate. Option D is incorrect as increased gene flow will lead to decreased allele frequency differences, regardless of selection pressure.

Question 7

It has been suggested that the allele for cystic fibrosis may confer some protection against

Accepted Answer

The answer of It has been suggested that the allele...

Question 8

Because of a population crash in 1775, the Pingalese have the highest incidence of ____________ in the world.

Accepted Answer

Achromatopsia, also known as monochromatism, is a rare genetic disorder that affects the cone cells in the retina, leading to total or partial color blindness. The Pingalese population experienced a genetic bottleneck in 1775, which significantly reduced the gene pool and increased the prevalence of certain genetic disorders, including achromatopsia.

Question 9

To be effective as a force changing genetic diversity, drift requires

Accepted Answer

Genetic drift is the random fluctuation of allele frequencies in small, isolated populations. Therefore, small, isolated populations are necessary for drift to have a noticeable effect on genetic diversity. A long period of time may increase the chance of drift occurring, but it is not a requirement. Selection and large-scale migrations are unrelated to genetic drift. Geographic stability may indirectly affect drift by promoting isolation of populations, but it is not a direct requirement for drift to occur.

Question 10

The phenotypic differences between chimps and humans is best explained by ______________.

Accepted Answer

The phenotypic differences between chimps and humans are best explained by patterns of gene expression and regulation. Both species share a similar set of genes, but they are often expressed differently in each species, leading to different physical and behavioral traits.

Question 11

Godfrey Hardy and Wilhelm Weinberg mathematically proved that as time goes by in a non-evolving population

Accepted Answer

Hardy-Weinberg equilibrium states that in a non-evolving population, the proportion of all genotypes will remain constant from generation to generation, given certain conditions (such as random mating, no mutation, no migration, etc.). Therefore, the answer is D.

Question 12

Of the following hominin species, which appears first in the fossil record?

Accepted Answer

Australopithecus anamensis appears first in the fossil record, with fossils dating back to about 4.2 to 3.9 million years ago.

Question 13

The relatively high percentage of individuals in West Africa who are heterozygous for the sickle cell trait is an example of _______________.

Accepted Answer

The high percentage of individuals in West Africa who are heterozygous for the sickle cell trait is an example of natural selection. This is because individuals with the sickle cell trait are more resistant to malaria, which is endemic in the region. As a result, they have a higher chance of survival and reproduction, passing on the sickle cell gene to their offspring. This leads to an increase in the frequency of the sickle cell trait in the population over time.

Question 14

According to Darwin, fitness is a measure of

Accepted Answer

According to Darwin, fitness is a measure of both survival and differential reproduction. Surviving is not enough to be considered fit, an organism must also reproduce and pass its genes on to the next generation. Differential reproduction means that some individuals are better suited to their environment and have a greater likelihood of producing more offspring. Thus, fitness is determined by both survival and reproduction.

Question 15

Mutation as a force in genetic diversity serves to

Accepted Answer

Mutation introduces new genetic variants, resulting in an increase in genetic diversity within a population. This increased diversity can provide the raw material for natural selection to act upon, leading to the evolution of new traits and adaptation to changing environments. Therefore, option A is the correct choice.

Question 16

A predictable effect of genetic drift in a small population is an increase in

Accepted Answer

Genetic drift in a small population reduces genetic variation due to the loss of alleles through random sampling. As a result, over time, homozygosity increases as fewer alleles are available to create heterozygotes.

Question 17

Genetic analysis indicates that North America was originally populated by three or four different waves of immigrants who

Accepted Answer

The answer of Genetic analysis indicates that North America was...

Question 18

Assume brown eyes is completely dominant to blue eyes and this trait is controlled by a single gene. If 400 people in a population of 10,000 have blue eyes, how many people would be expected to be heterozygous for this trait? (Hint: use the Hardy-Weinberg formula)

Accepted Answer

The answer of Assume brown eyes is completely dominant to...

Question 19

The taxonomic category that includes species of apes, humans, and their ancestors is the ___________.

Accepted Answer

The answer of The taxonomic category that includes species of...

Question 20

Why is it easy to measure allele frequencies in a codominant allele system?

Accepted Answer

In a codominant allele system, the heterozygote expresses both traits equally, so the phenotype can be directly used to determine the genotype. This makes it much easier to determine allele frequencies since genotypes can be directly counted without resorting to population genetics calculations.

Quiz 19: Population Genetics and Human Evolution