Question 1

A variety of genotypes and phenotypes in a population is useful because it

Accepted Answer

A variety of genotypes and phenotypes in a population allows the species to survive if the environment changes. This is because there is a greater chance that some individuals will possess traits or adaptations that are favorable in the new environment, allowing those individuals to survive and reproduce, passing on those beneficial traits to their offspring.

Question 2

Social research indicates that a person is most likely to marry someone from the same village or city, or a high school or college classmate. Therefore, the Hardy-Weinberg equilibrium does not apply well to human populations because

Accepted Answer

The Hardy-Weinberg equilibrium assumes random mating, which is not the case in human populations where people are more likely to marry someone from the same village/city or a classmate. This results in nonrandom mating, disrupting the equilibrium.

Question 3

Which of the following contributes to evolution?

Accepted Answer

All of the answer choices describe agents of evolution. Mutations introduce new genetic variation, gene flow can introduce new alleles from different populations, genetic drift can cause random changes in allele frequencies, and natural selection acts on existing variation to favor certain traits. Therefore, all of these factors contribute to the process of evolution.

Question 4

If all the conditions of the Hardy-Weinberg equilibrium are met

Accepted Answer

If all the conditions of Hardy-Weinberg equilibrium are met, then there is no evolution because the allele frequencies remain the same. The conditions are no mutation, no selection, no migration, a large population size, and random mating. In other words, the genetic makeup of the population is not changing over time.

Question 5

If the frequency of the dominant gene is 0.7, what is the frequency of the recessive gene?

Accepted Answer

The frequency of the recessive gene is 1 minus the frequency of the dominant gene, so 1 - 0.7 = 0.3.

Question 6

When a natural disaster kills off a large proportion of the population, resulting in a severe reduction in the gene pool, it is called

Accepted Answer

The situation described in the question is the bottleneck effect, where a significant event such as a natural disaster significantly reduces the size of a population, resulting in a reduced gene pool. Natural selection, directional selection, and gene flow all impact the gene pool in different ways but are not specific to this scenario. The founder effect occurs when a small group of individuals establishes a new population, which is not the case in this scenario.

Question 7

A student proposes that left-handedness is a recessive trait. A survey of a class of 36 students finds that 27 (0.75) are right-handed and 9 (0.25) are left-handed. Using the Hardy-Weinberg formula, what would the expected genotype and allele frequencies be in this theoretical population?

Accepted Answer

The answer of A student proposes that left-handedness is a...

Question 8

Which of the following mechanisms can disrupt genetic equilibrium?

Accepted Answer

All of the listed mechanisms can disrupt genetic equilibrium. The founder effect occurs when a small group of individuals becomes isolated from the larger population, resulting in a loss of genetic diversity. Differential reproduction occurs when certain individuals have greater reproductive success than others, leading to a change in allele frequencies. Genetic drift is a random change in allele frequencies that can occur in small populations. Natural selection favors certain traits over others, resulting in changes in the genetic makeup of a population over time.

Question 9

The idea that population growth is kept in check because an environment can support only a limited number of people was formulated by

Accepted Answer

The concept of population growth being limited by available resources and food supply was first proposed by economist Thomas Malthus in his book, An Essay on the Principle of Population, published in 1798.

Question 10

Which of the following is the only source of new variation in a population?

Accepted Answer

Only mutation can create new genetic variation in a population. Gene flow is the movement of genes from one population to another and can introduce existing variation, but it cannot create new variation. Genetic drift and nonrandom reproduction can change the frequency of existing variation, but again, cannot create new variation. Natural selection acts on existing variation but does not create new genetic variation.

Question 11

The equation, p² + 2 pq + q² = 1.0, describes

Accepted Answer

The equation describes the Hardy-Weinberg equilibrium, which assumes a nonevolving population. The equation represents the expected genotypic frequencies of a population with two alleles (p and q) at a given locus.

Question 12

Genetic drift

Accepted Answer

Genetic drift refers to the random fluctuations in allele frequencies that occur due to chance events. It is more likely to occur in small populations rather than large ones because chance events have a bigger impact on small populations. Genetic drift may lead to an allele becoming fixed (i.e., the allele is the only one present in the population) or lost in a population, which can have significant effects on the genetic diversity of the population. Therefore, choice B is correct. Choices A, C, D, and E are incorrect because they do not accurately describe the impacts of genetic drift.

Question 13

Which statement describes the bottleneck effect?

Accepted Answer

The bottleneck effect occurs when a population is subjected to near extinction, resulting in a drastic reduction in the population size and genetic diversity. This can lead to a loss of rare alleles and an increase in genetic drift, potentially reducing the population's adaptive potential.

Question 14

The random alteration in a sequence of DNA nucleotides that provides a new variant of a gene is

Accepted Answer

A random alteration in a sequence of DNA nucleotides that provides a new variant of a gene is known as a gene mutation. This may result in a change in the phenotype of an organism and can be the basis for evolution. Polymorphism refers to the coexistence of different forms of a particular trait within a population, whereas genetic drift is a random fluctuation in allele frequency in a population. Disruptive and stabilizing selection refer to the different types of natural selection that can act on a population.

Question 15

The Amish of Lancaster, Pennsylvania, have a higher frequency of an unusual form of dwarfism than the population at large. This is probably due to

Accepted Answer

The higher frequency of an unusual form of dwarfism among the Amish of Lancaster, Pennsylvania, is probably due to founder effect. This occurs when a small group breaks away from a larger population and establishes a new colony with limited genetic diversity. Any unique genes present in this smaller founder population will have a higher frequency in future generations due to genetic drift.

Question 16

What is the term used to describe the accumulation of small changes in the gene pool of a species over time?

Accepted Answer

Microevolution refers to the small changes that occur in the gene pool of a species over time, which can lead to the development of new traits or adaptations. Genetic drift and the founder effect are specific types of microevolutionary processes, while directional selection and mutation rate are factors that can influence microevolution.

Question 17

Changes in the allele frequencies of a gene pool due to the random meeting of gametes during fertilization is called

Accepted Answer

Genetic drift refers to the random fluctuations in allele frequencies that occur in small populations due to chance events, such as the random meeting of gametes during fertilization. This is in contrast to natural selection, which occurs as a result of differential survival and reproduction of individuals with certain alleles, and gene flow, which occurs when individuals migrate between populations and bring their alleles with them. Mutations and nonrandom mating can also influence allele frequencies, but they are not specifically related to the random meeting of gametes during fertilization.

Question 18

Lamarck's proposal of the inheritance of acquired characteristics included the idea that

Accepted Answer

Lamarck proposed that an organism can pass on traits that it acquired during its lifetime to its offspring. For example, he believed that giraffes developed longer necks because they continually stretched them to reach leaves, and this acquired characteristic was passed on to their offspring.

Question 19

In a population, freckles is inherited as a dominant trait. Individuals that are homozygous recessive lack freckles. If 1% of the population lacks freckles, and the population is in Hardy-Weinberg equilibrium at this locus, what percentage of the next generation will lack freckles?

Accepted Answer

In a population in Hardy-Weinberg equilibrium, the frequency of the recessive allele (in this case, for not having freckles) is represented by the square root of the frequency of homozygous recessive individuals. Since 1% of the population lacks freckles, the frequency of the homozygous recessive genotype is 0.01. Taking the square root of 0.01 gives a frequency of 0.1 for the recessive allele. Using the Hardy-Weinberg equation, the frequency of homozygous recessive individuals in the next generation would be 0.01 (or 1%), which corresponds to the individuals lacking freckles.

Question 20

The Hardy-Weinberg equilibrium requires

Accepted Answer

All of the choices listed (no new mutations, no migration of alleles, large population size, and random mating in a sexually reproducing population) are necessary for a population to be in Hardy-Weinberg equilibrium. If any of these conditions are violated, the gene frequencies in the population will change over time, indicating that evolution is occurring.

Quiz 27: Evolution of Life