Question 1

Which process below is NOT an agent of microevolutionary change?

Accepted Answer

Random mating does not change the frequency of alleles in a population and therefore does not cause microevolutionary change.

Question 2

What is the production of random evolutionary changes in small breeding populations known as?

Accepted Answer

The production of random evolutionary changes in small breeding populations is known as genetic drift. This occurs when chance events cause certain alleles to become more or less common in a population over time, independent of any selective pressure. The effects of genetic drift are most pronounced in small populations, where chance events can have a larger impact on the gene pool.

Question 3

What does "2pq" represents in the Hardy-Weinberg equation?

Accepted Answer

"2pq" represents the frequency of heterozygous genotypes in the population according to the Hardy-Weinberg equation.

Question 4

In a colony of 100 guinea pigs, 16 show the recessive trait of bristly hair. What is the frequency of the recessive allele in the population?

Accepted Answer

The frequency of the recessive allele can be calculated using the Hardy-Weinberg principle. If 16 out of 100 guinea pigs show the recessive trait, it means that 16% or 0.16 of the population is homozygous recessive (qq). The frequency of the recessive allele (q) can be found by taking the square root of 0.16, which gives 0.4. Therefore, the frequency of the recessive allele in the population is 0.4 or 40%.

Question 5

Because of fluctuations in the environment, such as depletion of food supply or an outbreak of disease, a population may periodically experience a rapid and marked decrease in the number of individuals, leading to a form of genetic drift. What is this form of genetic drift called?

Accepted Answer

A rapid and marked decrease in the number of individuals can lead to a genetic bottleneck, which is a form of genetic drift. The bottleneck reduces the genetic diversity of the population, as only a small subset of the original genetic variation is passed on to future generations.

Question 6

Which of the following is the source of new alleles in a population?

Accepted Answer

New alleles arise in a population through mutations, which can be caused by errors in DNA replication, exposure to radiation or chemicals, or other environmental factors.

Question 7

Which of the following is NOT an agent of microevolutionary change?

Accepted Answer

Random mating is not an agent of microevolutionary change because it does not cause any changes in allele frequencies or genetic variation. It is simply a way of describing the mating patterns within a population. In contrast, mutation, gene flow, and genetic drift can all lead to changes in the genetic makeup of a population over time.

Question 8

In a colony of 100 guinea pigs, 16 show the recessive trait of bristly hair. What is the percentage of heterozygotes in the population?

Accepted Answer

First, we need to use the Hardy-Weinberg equation to find the frequency of the recessive allele:

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

where:
p = frequency of dominant allele
q = frequency of recessive allele
p^2 = frequency of homozygous dominant individuals
q^2 = frequency of homozygous recessive individuals
2pq = frequency of heterozygous individuals

We know that:
- q^2 = 16/100 = 0.16
- p^2 + 2pq + q^2 = 1

We can solve for p^2 by rearranging the equation:
p^2 = 1 - 2pq - q^2
p^2 = 1 - 2(0.48)(0.16) - 0.16
p^2 = 0.7056
p = 0.84

Therefore, the frequency of the dominant allele is 0.84 and the frequency of the recessive allele is 0.16.

To find the percentage of heterozygotes, we use the 2pq part of the Hardy-Weinberg equation:
2pq = 2(0.84)(0.16) = 0.2688

The percentage of heterozygotes is:
0.2688 x 100% = 26.88%

However, the question is asking for the percentage of heterozygotes in the population, not just the frequency. Since we know there are 100 guinea pigs in the population, we can calculate the actual number of heterozygotes:
Number of heterozygotes = 2pq x total population size
Number of heterozygotes = 0.2688 x 100 = 26.88

The percentage of heterozygotes in the population is:
26.88/100 x 100% = 26.88%

Therefore, the best choice is C, 48%.

Question 9

According to the modern synthetic theory of evolution, what does the accumulation of mutations over time result in?

Accepted Answer

The answer of According to the modern synthetic theory of...

Question 10

Which process below is NOT a component of natural selection?

Accepted Answer

Genetic drift is a mechanism of evolution that takes place due to chance events rather than natural selection. It involves the random fluctuation of allele frequencies in a population. The other three processes listed (overproduction of offspring, limitations in vital resources, and genetic variation) are all components of natural selection.

Question 11

What does a sudden reduction in population size generally result in?

Accepted Answer

A sudden reduction in population size will result in genetic drift. This is because the smaller the population, the greater the impact of chance events on the genetic makeup of the population. This can lead to the loss of alleles and a change in allele frequencies, potentially resulting in reduced genetic diversity and an increased risk of inbreeding. While extinction is a possible outcome of a population decline, it is not a guaranteed result. Mutation and speciation are not directly related to a reduction in population size.

Question 12

A baby is born with wrinkled, poorly-formed skin and blood vessels prone to rupturing. What can we say the baby has inherited?

Accepted Answer

The baby has likely inherited a deleterious mutation, which is causing the wrinkled, poorly-formed skin and the blood vessels prone to rupturing. Deleterious mutations result in negative effects on an organism's function or survival, and this is evident in the symptoms that the baby is displaying.

Question 13

In which of the following scenarios will genetic drift have a progressively larger impact on allele frequencies in a population?

Accepted Answer

Genetic drift has a greater impact on smaller populations because chance events can have a greater effect on the allele frequencies. In larger populations, the effects of genetic drift are diluted by the presence of more individuals. Therefore, as population size decreases, genetic drift will have a progressively larger impact on allele frequencies.

Question 14

If individuals move from one population to another, it may cause a shift in allele frequencies. What causes this shift?

Accepted Answer

Gene flow is the movement of individuals and their genes between populations. As individuals migrate from one population to another, they bring along their alleles, which can cause a shift in allele frequencies in the receiving population. Therefore, gene flow is the best choice to explain why the shift in allele frequencies occurs.

Question 15

Which of the following best characterize mutations that confer no apparent selective advantage or disadvantage in a particular environment?

Accepted Answer

Neutral mutations are changes in DNA sequence that do not affect the fitness of an organism in a particular environment. These mutations may occur randomly, without any selective advantage or disadvantage.

Question 16

Which of the following processes results in microevolution without any form of natural selection?

Accepted Answer

Genetic drift is the random fluctuations of allele frequencies in small populations, which can lead to microevolution without any form of natural selection. The other options (mutation, development of new characteristics during an individual's lifetime, and genetic variation) can also contribute to microevolution, but they are not necessarily without any form of natural selection.

Question 17

We are sending a small number of dogs to colonize a new planet. Through a random selection process, we end up only with dachshunds and Chihuahuas. The subsequent colony is all small dogs with short legs. What is this an example of?

Accepted Answer

This scenario exemplifies genetic drift, a mechanism of evolution that involves random changes in the gene pool, in this case, due to the random selection of only dachshunds and Chihuahuas for the colony, leading to a population of small dogs with short legs.

Question 18

Imagine that the only survivors of a colony on Venus are a man and a woman, who happen to be both originally from southern Ukraine. Which of the following will their descendants show?

Accepted Answer

Genetic drift is the random fluctuation of gene frequencies due to chance events, such as the bottleneck effect that could occur in a small surviving population on Venus. Because the surviving individuals are both from southern Ukraine, their descendants will likely have reduced genetic diversity due to the founder effect, which increases the impact of genetic drift. Therefore, their descendants are most likely to show genetic drift. Punctuated equilibrium, excessive mutation, and heterozygote advantage are not likely to be significant factors in this scenario.

Question 19

If the frequency of the recessive allele (q) for a particular two-allele gene in a population is 0.20, what percentage of the individuals in the population will be heterozygotes for that gene?

Accepted Answer

The frequency of the dominant allele (p) can be calculated by subtracting the frequency of the recessive allele (q) from 1: 
p = 1 - 0.20 = 0.80

The frequency of homozygous dominant individuals (p^2) can be calculated by squaring the frequency of the dominant allele: 
p^2 = (0.80)^2 = 0.64

The frequency of homozygous recessive individuals (q^2) can be calculated by squaring the frequency of the recessive allele: 
q^2 = (0.20)^2 = 0.04

The frequency of heterozygous individuals (2pq) can be calculated using the following formula: 
2pq = 2(0.80)(0.20) = 0.32

Therefore, 32% of the individuals in the population will be heterozygotes for that gene. The answer is C.

Question 20

There are two alleles for a gene in a population, and the frequency of the dominant allele (p) is 0.50. What is the frequency of the recessive allele (q) then?

Accepted Answer

The sum of the frequencies of the dominant allele (p) and the recessive allele (q) must equal 1. Therefore, q = 1 - p = 1 - 0.50 = 0.50.

Quiz 18: Microevolution: Changes Within Populations