Biology- Chapter 13

If color is an inherited trait in beetles, and birds are more likely to eat brown beetles than green beetles,

the frequency of the green allele will increase

Genetic drift is a process based on _____.

the role of chance

Suppose that, with regard to a particular gene with two alleles, A and a, we know that 60% of the alleles in the gene pool of a particular large population are A. We observe this population for five generations, during which we know that no mutation, selection, or migration has occurred. After this period, the frequency of the a allele is expected to be _____.

0.4

Imagine that four people are infected with HIV from a common source (an infected blood sample). Initially, the patients' HIV populations are genetically identical. By the time they develop full-blown AIDS, how would the viral populations of the fourpatients compare?

Each patient's viral population would be unique, specifically adapted to deal with—and overcome—his or her unique immune system responses.

Color is an inherited trait in beetles. If brown beetles move into a population from a nearby island, which of the following statements is correct?

Gene flow causes the frequency of the brown allele to increase

Remember that color is an inherited trait in beetles. Which of the following is an example of natural selection?

Green beetles leave more offspring than brown beetles because they are better at finding food

How did Dr. Allison test his hypothesis that sickle cell disease was connected to malaria?

He expanded his study area beyond Kenya to the rest of East Africa to see if malaria and sickle disease were connected. He evaluated blood samples for malaria parasites and the presence of sickle cells.

In 1949, Dr. Tony Allison observed a high frequency of Kenyans carrying the sickle cell allele in coastal areas and near Lake Victoria, but a lower frequency in the highlands. What did he hypothesize?

He hypothesized that there was a connection between malaria and sickle cell disease.

As proposed by Darwin, what sorts of traits are favored by natural selection?

Heritable traits that help individuals survive and reproduce more successfully than others in the same population

Which of the following is a misconception regarding natural selection?

Natural selection progressively refines organisms' adaptations, eventually leading to perfection.

Compare sickle cell disease and malaria.

Sickle cell disease and malaria are both potentially lethal diseases.

Small lizards have difficulty defending their territory, but large lizards are more likely to be preyed upon by owls. Which type of selection would act on body size in these lizards under these conditions?

Stabilizing selection

The human immune system cannot effectively suppress the HIV virus on its own. What key feature of HIV makes it so hard to beat?

The HIV virus has an extremely high rate of mutation.

Sickle-cell disease is a debilitating disease that results from being homozygous recessive for the "sickle-cell allele" of a hemoglobin gene. Why is the allele present and even common in many human populations?

The sickle-cell allele confers malaria resistance to heterozygotes. In some regions where malaria is common, heterozygotes have an advantage over both homozygotes, and their reproductive success maintains the recessive allele at a high frequency in the population.

What was significant to Darwin about the fauna and flora of the Galápagos Islands?

The species were similar to South American species, indicating common descent, but they had been extensively modified and were well-adapted to island life

Why do dark-colored rock pocket mice on dark lava flows have white bellies?

There is no selection for dark bellies by visual predators.

Why did dark-colored rock pocket mice first appear in a population of light-colored rock pocket mice?

They have a genetic mutation that affects their fur color.

How did the Grants test their hypothesis that differences in birds' songs can keep different species of finches from breeding with one another?

They played the songs of medium ground finches and cactus finches through a loudspeaker to see which species responded to each song.

This unequal reproduction in a population leads to the gradual accumulation of __________ to the environment.

adaptations

HIV has become an important source of mortality for humans. If AIDS persists as a major factor for humans for many generations in the future, natural selection theory predicts that _____.

any heritable traits that help humans survive and reproduce in the presence of AIDS should become more frequent over time

In natural selection, _____ determine which phenotypes are successful

current conditions in the local environment

_________ favors phenotypes at one end of a range and is common in periods of environmental change.

directional selection

A large population of mice is isolated on an island. There are two varieties of the mice, brown and gray. Their fur colors closely match the gray rock outcrops and brown soils of the island. Hawks are their main predators. This situation most likely reflects the outcome of __________.

disruptive natural selection

_______ favors phenotypes at both ends of a range over intermediate phenotypes. This type of selection may occur when the habitat is varied

disruptive selection

The ____________ of life arises from the adaptation of species to different habitats over long spans of time.

diversity

The ease with which humans travel across the globe is likely to increase _____.

gene flow

All the genes in a population are that population's _____.

gene pool

Modern travel along with migration reduces the probability of _____ having an effect on the evolution of humans.

genetic drift

The evolution of populations due to chance is

genetic drift

In a population with brown and green alleles for color, genetic drift

has more effect on the evolution of a small population.

Which of these individuals is a homozygous genotype?

AA

In a species of snail, dark-shelled individuals are better hidden from bird predators in the shady forest, while light-shelled individuals are better hidden in well-lit brushy edge areas. If there were no areas of intermediate brightness in this habitat, which type of selection would act on shell color in these snails?

Disruptive selection

Natural selection and evolution are two terms that are sometimes confused, even by first year biology students. What is the relation between natural selection and evolution?

Natural selection is one of several mechanisms of evolution.

A population of small fish lives in a lake with a sandy bottom. The major predator of these fish is a wading bird that hunts by sight. Most of the fish are light sandy brown, but about 10% are mottled. The color pattern is heritable. A construction company dumps a load of gravel in the bottom of the lake, giving it a mottled appearance. Which of these statements presents the most accurate prediction?

The proportion of mottled fish will increase over time

Mutations are always __________.

a change in an individual's DNA

Natural selection is best described as _____.

a filtering process that fine-tunes the traits of populations by sorting among existing, randomly produced variations

Generation-to-generation change in the allele frequencies in a population is _____.

microevolution

The phrase Darwin used to describe his broad theory of evolution is ''descent with

modification

The original source of all genetic variation is __________.

mutation

Which of the following are causes of evolutionary change?

mutation, natural selection, gene flow, genetic drift

Darwin proposed a mechanism for how evolution occurs, which he called ______________

natural selection

Crossing over, resulting in an increase in genetic variation, occurs between _____.

nonsister chromatids of homologous chromosomes

Darwin inferred that those organisms with traits best suited to the environment tend to leave more ___________ than other members of a population

offspring

A geneticist studied a large grass population growing in an area of erratic rainfall and found that plants with alleles for curled leaves reproduced better in dry years and plants with alleles for flat leaves reproduced better in wet years. This situation would __________.

preserve the variability in the grass population

In sexual selection, individuals with certain inherited characteristics are more likely to obtain mates than other individuals. This often results in __________ , differences between the sexes in size, appearance, and behavior.

sexual dimorphism

Predict what will happen to the frequency of the sickle cell allele in areas where malaria has been eradicated.

The sickle cell allele will decrease in frequency.

Which of the following is a true statement about Charles Darwin?

He proposed natural selection as the mechanism of evolution

What does Dr. Carroll mean when he says, "while mutation is random, natural selection is not"?

Natural selection favors some mutations. Mutations for advantageous traits are more likely to be passed on to the next generation. Natural selection acts on traits.

Approximately one out of every 2,500 Caucasians in the United States is born with the recessive genetic disorder cystic fibrosis. According to the Hardy-Weinberg equilibrium equation, approximately how many people are carriers?

1 in 25

Which of the following lists of assumptions was part of Charles Darwin's theory of natural selection?

1. Organisms vary in heritable ways. 2. Some traits improve the survival and reproduction of individuals who possess them. 3. Populations produce more offspring than their environment can support, so individual organisms must compete for limited resources. 4. Earth and its life are very old.

In human gamete production there is an average of _____ crossover events per chromosome pair.

2-3

Of the scenarios below, which represents the occurrence of evolution at its smallest scale?

A pesticide spray is heavily used on a particular farm. Initially it kills 98% of the grasshoppers on contact. Over several generations, the local grasshopper population becomes resistant to the pesticide through inheritance of resistance alleles. Other nearby grasshopper populations do not change in any noticeable way.

Suppose that every few years, all people over 6 feet tall do not have any children. How will this affect the human population?

Alleles that promote "tallness" will decrease in frequency

The Grants witnessed strong selection during droughts in 1977 and 1985. Compare the two droughts.

Both droughts events provided strong natural selection on medium ground finch populations. Both droughts resulted in changes to food sources that favored the survival of some medium ground finches over others.

Different finch species have beaks of different shapes and sizes. What do these beak differences tell us?

Different finch beak shapes are evidence that finch species adapted to different environments over many generations

How does Dr. Allison's work provide an example of natural selection in humans?

In areas without malaria, individuals with two sickle cell alleles reproduced at lower rates than those without sickle cell disease. In areas with malaria, individuals with one sickle cell allele reproduced at higher rates than those with no sickle cell alleles.

Which example below presents a misconception about how antibiotic resistance develops?

Individual bacteria and viruses become immune to antibiotics after they are exposed to them. Eventually the antibiotics are useless.

The film defines species as populations whose members don't interbreed. What keeps different Galápagos finch species from mating?

Individuals recognize and only respond to songs of their own species. Males only court females that have a similar beak and similar size. Geographic isolation and different environments led to changes in traits that affected mating.

In some populations, 1 in 500 people have sickle cell disease. What reason does the film give for why a potentially deadly, inherited disease is found at such high frequencies?

Individuals with one sickle cell allele are protected from malaria and do not have sickle cell disease, thus keeping the allele in the population.

Genetic evidence supports which of the following explanations for the presence of 13 different finch species on the Galápagos islands?

Many years ago, a small population of a single finch species migrated to the islands and evolved into the current 13 species

In the normal course of evolution and adaptation, what is the most likely way for wings to develop in a tetrapod (four-limbed organism)?

The forelimbs (or possibly hind limbs) will be used for the new purpose of flight. This new function will arise through many gradual steps, and there will be aspects of the wing that reflect its history and are not perfectly suited for flight.

Which best describes the fossil record?

The fossil record is the highly ordered sequence in which fossils are found in layers of sedimentary rock

If a person has two normal copies of the hemoglobin allele, which statements are true?

The person is susceptible to malaria. The person is homozygous at the hemoglobin locus.

Consider a hypothetical insect population of 100 individuals. Two equally represented alleles (A and a) exist for a particular gene. Which scenario is an example of microevolution in this population?

The population is exposed to a toxin that kills individuals with the A allele. After exposure to the toxin the population has 25 surviving individuals, and 95% of them have the aa genotype.

Two key observations underlying natural selection are that members of a population vary in their __________ and that all species can produce more offspring than the environment can support

inherited traits

________ is a type of sexual selection in which individuals of one sex (usually males) compete directly for mates. This may involve ritualized displays or physical combat

intrasexual selection

In a type of sexual selection often called _______, individuals of one sex (usually females) are choosy in selecting their mates. This choice is often based on the showy appearance or behavior of the male.

mate choice

Homologous pairs of chromosomes are lined up independently of other such pairs during _____.

metaphase I

Organisms that possess homologous structures probably __________.

share a common ancestor that also had this structure

__________ favors intermediate phenotypes, selecting against phenotypes at both ends of a range and reducing variation.

stabilizing selection

A mutation occurs when _____.

there is a change in the DNA sequence of a gene

All of life is related through common ancestry, accounting for the ________ of life.

unity