Question 1

In populations that have a high degree of genetic diversity,the fundamental cause of evolutionary change is

Accepted Answer

In populations with high genetic diversity, there is a greater likelihood of genetic variation that can be acted upon by natural selection. Therefore, natural selection is the most likely fundamental cause of evolutionary change in such populations.

Question 2

Genetic variation is based on

Accepted Answer

Genetic variation is based on differences in DNA sequences between individuals in a population. This variation can arise through mechanisms such as mutation, genetic recombination during meiosis, and gene flow between populations. The inheritance of alleles that are accumulated during an individual's lifetime (choice A) does not contribute to genetic variation as these changes are not passed on to offspring. Mutations in somatic cells (choice C) also do not contribute to genetic variation as they are not passed on to offspring. The formation of new combinations of alleles during asexual reproduction (choice D) does not apply to sexual reproduction, which is the main source of genetic variation in most multicellular organisms.

Question 3

Four mechanisms can change the composition of a population's gene pool,but only ________ does so by creating new alleles.

Accepted Answer

Mutation is the only mechanism that introduces new alleles into a population's gene pool. Genetic drift, natural selection, and gene flow can all alter the frequency of existing alleles but do not create new ones.

Question 4

For a population to evolve,there must be genetic differences between organisms in that population.These differences come from

Accepted Answer

Genetic differences in a population come primarily from mutations, which are random changes in an organism's DNA sequence. These mutations can result in new traits that may be beneficial, detrimental, or neutral in terms of survival and reproduction, and can ultimately lead to evolutionary changes in the population through natural selection. Changes in an organism's behavior may be a response to environmental pressures, but do not alter its genetic makeup and therefore do not contribute to evolution. Common descent refers to the idea that all living organisms share a common ancestry, but does not explain how populations evolve over time.

Question 5

Before the industrial revolution,scholars believed that Earth was only 6,000 years old.What evidence first suggested that this belief might NOT be correct?

Accepted Answer

Geological studies indicating the slow transformation of Earth's surface by natural forces suggested a much older planet than previously believed, challenging the 6,000-year-old Earth theory.

Question 6

One of the reasons why scientists have had so much difficulty finding a cure for HIV (human immunodeficiency virus)and AIDS is that the virus is quick to evolve resistance to the drugs that are used to treat it.What is the most likely mechanism for this type of evolution?

Accepted Answer

A) This choice correctly describes the process of natural selection, where the HIV virus variants that are less susceptible to the drugs survive and reproduce, passing on their drug-resistant traits to their offspring. This evolutionary mechanism is a key reason why HIV is difficult to treat.

Question 7

Biological evolution can be defined as

Accepted Answer

Biological evolution is the process of change in the inherited characteristics of a population over successive generations. It is driven by the change in allele frequencies in a population's gene pool over time. Option A is incorrect as biological evolution is not a process that can be directly observed, but rather inferred from observations and evidence. Option B is partially correct as adaptations do occur as a result of the changes in allele frequencies, but it is not a complete definition of biological evolution. Option C is incorrect as biological evolution involves a constant change in life on Earth, rather than an unchanging nature.

Question 8

Species like the African cheetah,northern elephant seal,and Florida panther have all experienced a genetic bottleneck;what is the primary outcome of this experience?

Accepted Answer

A genetic bottleneck occurs when a population is drastically reduced in size, resulting in a decrease in genetic diversity. This means that the gene pool of the surviving individuals is limited, leading to a higher risk of inbreeding and genetic drift. As a result, genetic variation is greatly reduced, making the population more vulnerable to environmental changes, disease, and other challenges. Therefore, the primary outcome of a genetic bottleneck is a reduction in genetic diversity.

Question 9

Peppered moths in England evolved into a dark-colored form when soot darkened the bark of the trees they lived on and exposed the light-colored form to predation.However,air pollution control eventually restored the moths' habitat to its original condition.What would probably have happened to the peppered moth population if the light-colored alleles had been entirely lost from its gene pool during the period when dark-colored moths were selectively favored?

Accepted Answer

If the light-colored alleles were entirely lost from the gene pool, then the population would be unable to produce any light-colored moths even if their habitat returned to its original state. This would put the population at a selective disadvantage, as they would be more easily seen and preyed upon than the dark-colored moths. Over time, this could lead to a decline in the size of the population and possibly even extinction. Without the ability to produce the light-colored allele, the population would be unable to adapt to changes in their environment.

Question 10

Many weeds have become resistant to the herbicides that were once used to control them.Which of the following statements best explains this observation?

Accepted Answer

Natural selection has acted on the genetic variability in the weeds' genomes,enabling plants that have herbicide resistance to reproduce more successfully. Over time, this results in a population of weeds that are largely resistant to the original herbicide.

Question 11

Jean-Baptiste Lamarck proposed that changes in the characteristics of a population are a result of traits acquired during an organism's lifetime being inherited by that organism's offspring.What is wrong with this proposal?

Accepted Answer

Lamarck's proposal is known as the theory of inheritance of acquired characteristics, which suggests that an organism can acquire traits during its lifetime and pass them on to its offspring. However, modern genetics has shown that the DNA sequence of an organism is what is inherited, and traits that are acquired throughout life do not alter DNA. Therefore, Lamarck's proposal is scientifically inaccurate.

Question 12

One frequently observed example of evolution is

Accepted Answer

Bacteria developing increased resistance to an antibiotic that is used to kill them is a clear example of evolution in action. As antibiotics kill the susceptible bacteria population, the resistant bacteria survive and reproduce, passing on their resistance traits to their offspring. Over time, the proportion of resistant bacteria in the population increases, leading to the evolution of antibiotic resistance.

Question 13

In genetic drift,the events that affect the survival and reproduction of individuals in a population occur

Accepted Answer

Genetic drift is defined as the random fluctuation of allele frequencies in a population. The events that affect survival and reproduction of individuals can occur by chance, and this chance element is the driving force behind genetic drift.

Question 14

A hurricane could cause genetic drift by

Accepted Answer

A hurricane could randomly kill more individuals of one genotype than another in a population, causing a change in allele frequencies due to genetic drift. This is known as the founder effect. However, hurricanes do not increase the mutation rate of a population, and there is no indication that hurricanes will randomly kill more males than females. Relocating a population to a different habitat is a form of natural selection, not genetic drift.

Question 15

Peppered moths are generally light in color and blend into the trunks of the trees they live on.Populations of peppered moths that are found in areas where soot has blackened the tree trunks are dark in color.This example demonstrates

Accepted Answer

This is an example of natural selection, where the moths that are better adapted to their environment (i.e. the darker-colored moths in the soot-covered trees) have a greater chance of surviving and passing on their advantageous traits to their offspring.

Question 16

Which of the following things is an example of gene flow?

Accepted Answer

Gene flow refers to the transfer of genetic material from one population to another. Pollen grains are a mechanism by which gametes can be transported from one population to another, thus leading to gene flow. The other choices do not involve the transfer of genetic material between populations.

Question 17

Natural selection tends to

Accepted Answer

Natural selection favors traits that improve survival and reproduction, leading to an increase in the commonality of these advantageous characteristics within a population. Option B is incorrect as natural selection does not necessarily decrease the population size, but rather favors individuals with traits that allow them to survive and reproduce in their environment. Option C is inaccurate as genetic drift is a random process that can lead to changes in the frequency of certain traits within a population, but it is not directly affected by natural selection. Option D is incorrect as natural selection actually increases the likelihood of adaptation by selecting for traits that improve survival and reproduction in a given environment.

Question 18

The main conclusion Darwin reached after his return from the expedition aboard the HMS Beagle was that

Accepted Answer

Darwin's main conclusion after his return from the expedition was that plant and animal populations slowly change over time as beneficial characteristics become more widespread, which eventually leads to the formation of new species. This idea became the foundation for his theory of evolution by natural selection.

Question 19

Which of the following statements best describes what happens in gene flow?

Accepted Answer

Gene flow involves the movement of individuals, and the alleles they carry, from one population to another. When new individuals join a population, they contribute their alleles to the gene pool, increasing genetic diversity. This can also counteract the effects of genetic drift and reduce differences between populations.

Question 20

Which of the following statements about natural selection is true?

Accepted Answer

Natural selection is the principal cause of evolutionary change as it is the process by which certain inherited traits become more or less common in a population, based on their ability to aid in survival and reproduction. It is not the principal cause of extinctions (although it may contribute to them), it occurs in all cells (not just gametes), and it can occur both with and without genetic drift.

Quiz 14: How Evolution Works