Question 1

Most types of organisms evolve at about the same rate.

Accepted Answer

The rate of evolution varies between different types of organisms. Some organisms, such as bacteria, can evolve very quickly while others, such as humans, have a slower rate of evolution. Factors such as generation time and reproductive output can influence the rate of evolution.

Question 2

________________ results from microevolutionary changes that increase the likelihood of survival and reproduction.

Accepted Answer

Adaptation results from microevolutionary changes that increase the likelihood of survival and reproduction. These changes can result from natural selection, genetic drift, or gene flow. Adaptations can be anatomical, physiological, or behavioral, and they allow organisms to better exploit their environment and avoid predation or competition.

Question 3

If two species of birds occur in the same area but occupy different habitats they do not mate.This is an example of:

Accepted Answer

Ecological isolation occurs when two species occur in the same area but occupy different habitats, and as a result, they do not mate. This is because they do not come into contact with each other frequently enough to mate, and even if they do, their behaviors and physiological mechanisms are adapted to their specific habitats. Therefore, ecological isolation is the best choice for this scenario. Behavioral isolation refers to differences in behaviors or mating rituals, mechanical isolation is physical incompatibility between reproductive organs, and temporal isolation is differences in timing of reproduction.

Question 4

Biochemical changes that occur in organisms through time can help us:

Accepted Answer

All of these options are correct. Biochemical changes can help us infer relatedness and construct molecular family trees, both of which allow us to understand how groups of organisms have changed through time.

Question 5

In human infants,there has long been evolution toward having the highest survival rate at a 6-7 pound birth weight.This is an example of:

Accepted Answer

Stabilizing or balancing selection is where natural selection favors the average or middle phenotype, resulting in reduced variation in the population. In the case of human infants, evolution has favored a birth weight around 6-7 pounds, which has the highest survival rate. This is a type of stabilizing selection.

Question 6

In small populations,gene frequencies can change drastically by chance alone.This phenomenon is called:

Accepted Answer

Genetic drift is the phenomenon where gene frequencies can change drastically by chance alone in small populations. Migration refers to the movement of individuals from one population to another, while density-independent and density-dependent effects are factors that affect population growth, but do not specifically refer to the change in gene frequencies.

Question 7

The notion that organisms that are more distantly related should have time to accumulate more biochemical differences than those more closely related can best be illustrated using:

Accepted Answer

The notion that organisms that are more distantly related should have time to accumulate more biochemical differences than those more closely related can be illustrated using a molecular clock. This utilizes the idea that DNA and protein sequences evolve at a relatively constant rate over time, allowing us to estimate how long ago two species diverged based on the number of differences in their sequences.

Question 8

In pools below waterfalls,where predation is _____,male guppies are _____,whereas in pools above waterfalls where predation is ______,male guppies are ______.

Accepted Answer

In environments with high predation, male guppies tend to be drab colored to avoid attracting predators, whereas in environments with low predation, they are more colorful to attract mates.

Question 9

The molecular evidence of how the cytochrome c gene changes with time suggests that this gene evolves:

Accepted Answer

The molecular evidence suggests that the cytochrome c gene evolves at a constant rate, meaning it changes at a steady and predictable pace over time. This is supported by the fact that the amino acid sequences of cytochrome c in different species differ by a fairly consistent amount, indicating a steady accumulation of mutations over time.

Question 10

Over time,the same bones in different vertebrates were put to different uses.This falls under the category of:

Accepted Answer

This concept is described by homologous structures, which are anatomical features in different species that have a similar form or function due to shared ancestry, but may be used differently across species.

Question 11

Two populations of flowers are separated by a mountain range and would not be capable of interbreeding.This is an example of:

Accepted Answer

Geographical isolation refers to a physical barrier, such as a mountain range, that separates populations and prevents gene flow, leading to divergence and potentially speciation. The other options, behavioral isolation, mechanical isolation, and ecological isolation, refer to different types of reproductive barriers that can also lead to speciation, but they do not involve a physical barrier like geographical isolation.

Question 12

Sickle-cell anemia in humans is an example of:

Accepted Answer

Sickle-cell anemia is an example of stabilizing or balancing selection because the heterozygous genotype confers a survival advantage in malaria-endemic areas, maintaining the allele in the population despite its harmful effects in homozygotes.

Question 13

The fossil record indicates that whales evolved from:

Accepted Answer

Fossil evidence shows that whales share several anatomical features with even-toed ungulates (Artiodactyla), such as hip bones, ankle bones, and elongated fingers in their flippers. Therefore, it is most likely that whales evolved from a group of hoofed land animals that took to the water over time.

Question 14

A population of frogs developing a slight difference in their mating calls is an example of:

Accepted Answer

The slight difference in mating calls is a small change in the population's gene pool, which is an example of microevolutionary change. Macroevolutionary change refers to the formation of new species or the divergence of large groups from a common ancestor, which is not the case in this scenario. Hardy-Weinberg equilibrium refers to a population in which allele frequencies remain constant over time, which is not relevant to the scenario given. Artificial selection refers to the selective breeding of organisms to produce desired traits, which is not relevant to the scenario given.

Question 15

When selection operates to eliminate intermediate phenotypes,it is referred to as:

Accepted Answer

Disruptive selection specifically targets and eliminates intermediate phenotypes, favoring the extremes at both ends of the spectrum. This process increases the variance in the population by promoting phenotypic diversity.

Question 16

Features that are similar in organisms that are not evolutionarily related are due to:

Accepted Answer

Similar selective pressures cause similar adaptations to evolve in unrelated organisms. This is referred to as convergent evolution.

Question 17

In a certain population,the frequency of a dominant allele is represented by p = 0.7,and the frequency of the recessive allele is represented by 0.3.What is the frequency of the heterozygous genotype?

Accepted Answer

The frequency of the homozygous dominant genotype (AA) can be calculated as p^2 = (0.7)^2 = 0.49. 
The frequency of the homozygous recessive genotype (aa) can be calculated as q^2 = (0.3)^2 = 0.09. 
The frequency of the heterozygous genotype (Aa) can be calculated as 2pq = 2(0.7)(0.3) = 0.42. Therefore, the answer is C) 0.42.

Question 18

Choose the phrase that best represents microevolutionary change.

Accepted Answer

Microevolutionary change refers to small-scale changes in allele frequencies within a population over time. Choice A refers to an individual response to environmental factors, while choice C refers to macroevolutionary change. Choice D refers to mass extinctions, which can have significant impacts on the course of evolution but are not themselves examples of microevolution.

Question 19

When only a very few individuals give rise to a new population in a new area of favorable habitat,they might differ in appearance from the other,larger population from which they separated.This effect is called the:

Accepted Answer

The scenario described in the question is the founder effect, where a small group of individuals give rise to a new population and show differences in appearance from other larger populations as a result of genetic drift. The mutation effect refers to a change in genetic material due to mutation, inbreeding effect refers to mating between close relatives leading to an increase in homozygosity and outbreeding effect refers to the introduction of new genetic material from unrelated individuals resulting in increased heterozygosity. None of these effects fully describe the scenario described in the question.

Question 20

The Hardy-Weinberg equilibrium is based on a number of assumptions.Which of the following is NOT one of those?

Accepted Answer

The Hardy-Weinberg equilibrium assumes that mating occurs randomly, with no preferences or biases towards certain individuals. This is important because nonrandom mating can disrupt the balance between allele frequencies, leading to evolutionary changes that deviate from the original equilibrium. The other assumptions of the equilibrium are that the population size is large (to avoid genetic drift), there is no migration (to avoid introduction of new alleles), and there are no mutations (to maintain the gene pool at a steady state).

Quiz 14: Evolution and Natural Selection