Gen. Bio. 2 CH 13 HW

Which of these gametes contain one or more recombinant chromosomes?

B, C, F, and G

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.

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

The wing of a bat is homologous to the _____ of a whale.

flipper

Which of the following are causes of evolutionary change?

gene flow and genetic drift and mutation and natural selection

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

gene pool

Darwin proposed a mechanism for how evolution occurs, which he called________.

natural selection

is a group of individuals of the same species living in the same area that interact with each other.

population

What is the frequency of cats with long tails in the population? Long tails(TT)=180 Long tail(Tt)= 240 Short tail(tt)=80 Total=500

0.84

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

Drag the labels onto the flowchart to indicate the correct sequence. Selective pressure

Green beetles are more visible to birds than brown beetles, so birds eat more green beetles

Drag the labels onto the flowchart to indicate the correct sequence. Environmental change

a drought causes a habitat to turn dry and brown

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

Evolution that occurs by _______ results in a change in a population's gene pool due to the movement of individuals into and out of the population.

gene flow

Drag the labels onto the flowchart to place them in the correct sequence. Environmental change

pesticide is applied to a population of insects

Genetic drift is a process based on _____.

the role of chance

What is the frequency of cats with short tails in the population? Long tails(TT)=180 Long tail(Tt)= 240 Short tail(tt)=80 total=500

0.16

What is the frequency of cats that are homozygous dominant in the population? Long tails(TT)=180 Long tail(Tt)= 240 Short tail(tt)=80 total=500

0.36

What is the frequency of the t allele in the gene pool of this population? Long tails(TT)=180 Long tail(Tt)= 240 Short tail(tt)=80 total=500

0.40

What is the frequency of the T allele in the gene pool of this population? Long tails(TT)=180 Long tail(Tt)= 240 Short tail(tt)=80 total=500

0.60

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.

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

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.

Which of the following statements about the amoeba population described at the end of the tutorial is true?

It is more vulnerable to extinction due to lack of genetic variation.

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 1977, medium ground finches on Daphne Major experienced a severe drought. The figure shows the beak depths of the initial population before the drought (red bars) and of the drought survivors (black bars). What do the data show?

More than one-half of the initial population died during the drought. Finches with larger beaks had a survival advantage in the 1977 drought. The most common beak size of the initial population was 8.8 millimeters. A very small proportion (~5%) of the initial population with this beak size survived. Submit

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.

Why is natural selection considered to be the most important mechanism of microevolution?

Natural selection is the only mechanism that consistently leads to adaptive changes in populations.

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.

Drag the labels onto the flowchart to place them in the correct sequence. Change in population

The surviving insects reproduce. The frequency of the resistant insects in the population increases

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

There is no selection for dark bellies by visual predators. Submit

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.

Which of the following is(are) homologous to the bones of the whale in this image?

a cats foot

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

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

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

Consider a population of birds living on an island. Suppose several individuals of the same species from a different population migrate to the island. Due to the arrival of the new birds, the allele frequencies in the original population change.

gene flow

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

gene flow

The total collection of alleles in a population at a given time is the population's

gene pool

Evolution that occurs by ________ results in a change in a population's gene pool due to chance.

genetic drift

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 Europe at the time Darwin voyaged on HMS Beagle, the popularly accepted explanation of the origin of Earth's plants and animals held that the various species __________.

had been created rapidly by a divine creator a few thousand years before

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

has more effect on the evolution of a small population.

Under some conditions, heterozygotes have greater reproductive success than homozygotes. What is this called?

heterozygote advantage

5. 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

A change in allele frequencies in a population over a span of generations is

microevolution

Changes in allele frequencies in a population over time is

microevolution

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

Of the choices listed below, which contributes the most to genetic variation among individuals in most prokaryote species?

mutation

The original source of all genetic variation is __________.

mutation

is a change in the nucleotide sequence of DNA.

mutation

Evolution that occurs by _______ results in nonrandom reproductive success and adaptive change.

natural selection

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

nonsister chromatids of homologous chromosomes

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

offspring

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

Genetic variation in a population of animals or plants depends mainly on which of the following?

sexual reproduction

Organisms that possess homologous structures probably __________.

share a common ancestor that also had this structure

Which of the following structures would be the LEAST likely to fossilize?

skin

Drag the labels onto the flowchart to place them in the correct sequence. Selective pressure

some insects have a gene that makes them resistant to the pesticide. These insects survive. Insects without the gene die.

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

stabilizing selection

The first tetrapods (four-legged animals) were amphibians, which evolved from a specialized group of lobed-fin fish. An unusual fossilized animal (named Tiktaalik) was recently found; this animal possessed a mixture of fish and amphibian characteristics. What is the term used to describe such an intermediate organism?

transitional form

Which of these individuals is a homozygous genotype?

AA

is an alternative version of a gene.

allele

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.

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?

As the sand-colored fish are eaten, more will be produced to keep their frequency at 90%.

Which time point on the graph shows when the antibiotic was first added?

B

Which three statements may correctly explain why the population size increases after time point C?

Between time points C and D, drug-resistant bacteria were reproducing faster than non-drug resistant bacteria were dying. Bacteria that acquired a mutation that conferred drug- resistance had a growth advantage over non-resistant bacteria. The few drug-resistant bacteria in the population reproduced, quickly leading to a large drug- resistant population.

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

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

Drag the labels onto the flowchart to indicate the correct sequence. Change in population

Brown beetles survive to reproduce more than green beetles do. The brown allele increases in frequency

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.

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 four patients 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. Submit

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

He proposed natural selection as the mechanism of evolution.

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. Submit

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?

If q2 equals 1/2,500, then q equals 1/50, p equals 49/50, and 2pq equals approximately 1/25.

Which of the following events could NOT be caused by a population bottleneck?

Increased population size

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. Geographic isolation and different environments led to changes in traits that affected mating. Males only court females that have a similar beak and similar size.

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

In a certain group of African people, 4% are born with sickle-cell disease, an autosomal recessive disorder. Heterozygous individuals not only don't have sickle-cell disease, but also are resistant to malaria. If this group is in Hardy-Weinberg equilibrium, what percentage of the population is heterozygous and resistant to malaria?

The 4% born with sickle-cell disease are homozygous for the sickle hemoglobin allele, so q2 = 0.04 and q = 0.2. Because p = 1 - q, p = 0.8, and the heterozygotes would be equal to 2pq, or 0.32. 32%

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 replicates its genome with a great deal of precision (i.e., has a low mutation rate).

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. Submit

Which best describes the fossil record?

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

The top figure shows beak sizes of the 1976 finch population before the drought of 1977 (red bars) and after the drought (black bars). The lower figure shows the beak sizes of the offspring of the drought survivors in 1978. What do these figures tell us?

The overall beak depths of the 1978 offspring population are larger the original 1976 population.

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.