Bio: Evolution Online work

Natural selection: Camouflage

1. A drought causes a habitat to turn dry and brown 2. Green beetles are more visible to birds and brown beetles so birds eat more green beetles 3. Brownville survive to reproduce more than green beetles do. The brown allele increases and fluency

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

2-3

How are adaptations beneficial to organisms?

Adaptations help organisms survive and reproduce in a particular environment.

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.

Click on the diagram to start the animation. Which of these gametes contain one or more recombinant chromosomes?

B, C, F, and G

Click on the diagram to start the animation. What process is illustrated by this animation?

gene flow

In artificial selection, humans provide the selective pressure for species to change and shape the evolution of various breeds. What provides the selective pressure in natural selection?

the environment

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 events could NOT be caused by a population bottleneck?

Increased population size

Genetic drift is a process based on _____.

the role of chance

A mutation occurs when _____.

there is a change in the DNA sequence of a gene

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.

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.

Certain bacterial strains have traits that allow them to resist the effects of antibiotic drugs. How do the resistance traits arise in a bacterial population, and under what circumstances will the resistance traits be most common?

The resistance traits are produced by chance mutations and are present to varying degrees in most bacterial populations. Resistance traits will be most prevalent, however, in bacteria that are chronically exposed to antibiotic drugs.

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

Which option best describes the concept of an evolutionary tree diagram?

Evolutionary trees relate species to each other by ancestry. An ancestor common to all of the species is placed at the root of the tree. Branch points are defined by homologous features that are shared by the descendant species along a particular branch.

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.

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.

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

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

stabilizing selection

Sometimes critics charge that evolution is based on mere speculation because it cannot be directly observed or experimentally induced. Is this true of evolution by natural selection?

Natural selection changes the traits of some organisms quite quickly, in ways that are clearly adaptive. Scientists have documented such changes in thousands of studies.

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 and uncertain steps, and there will be aspects of the wing that reflect its history and are not perfectly suited for flight.

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

disruptive selection

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

genetic drift

________________ 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

Which statement reflects a possible weakness of the fossil record?

Many species probably did not die in the right place at the right time to be captured in fossils, and many fossils will never by found by paleontologists.

The forelimbs of humans, cats, and bats have a number of detailed similarities in their construction. What best explains these similarities?

The forelimbs are similar because all of these organisms inherited the basic forelimb design from a common ancestor.

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

nonsister chromatids of homologous chromosomes

The ____________ species concept defines species as the smallest group of individuals that share a common ancestor and form one branch on the tree of life.

phylogenetic

Many plant species have formed by ________________, in which accidents in cell division result in extra sets of chromosomes.

polyploid speciation

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

gene pool

Click on the diagram to start the animation. What process is illustrated by this animation?

natural selection

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.

Natural selection: Pesticides

1. Pesticide is applying to population of insects 2. Some insects have a gene that makes them resistant to the pesticide. These insects service. Insects without the gene die. 3. The surviving insects reproduce. The frequency of resistant insects in the population increases

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

directional selection

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.

When a horse and a donkey mate, they produce infertile hybrids called mules. According to the _____ species concept, horses and donkeys are _____.

biological ... different species

Microevolution is _____.

changes in the gene pool of a population from one generation to the next

Click on the diagram to start the animation. This animation illustrates _____ as it occurs during _____.

crossing over ... prophase I

In the ______ species concept, species are defined by their niche--the role they play in the environment.

ecological

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

flipper

The Illinois populations of the greater prairie chicken benefited when managers brought in prairie chickens from other populations. This restored genetic variation to the Illinois populations through the process of _____.

gene flow

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

gene flow

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

Genetic drift is _____.

more likely to have an impact on small populations

The _____ species concept is the most applicable to classifying species from the fossil record.

morphological

Alternatively, the _________ species concept identifies species based on physical traits or body form. This species concept can be applied to asexual and _______ species, and it is the way most of the 1.8 million named species have been identified.

morphological; asexual and extinct

Which choice contributes the most to genetic variation among individuals in most prokaryote species?

mutation

Both allopatric speciation and sympatric speciation depend on the establishment of ____________________, which prevent(s) gene flow between a new species and its parent species.

reproductive barriers

In ________________, a new species may arise as mating and gene flow are reduced between populations that share the same area.

sympatric speciation

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

the one that is the darkest brown

Which best describes how an organism's Darwinian fitness is measured?

the organism's reproductive success relative to other individuals in the same population

According to the _______ species concept, a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring. The separation between species is maintained by __________ isolation, which prevents gene flow between species. But in some cases, distinct species can occasionally interbreed, producing _____ offspring.

Biological; reproductive, hybrid

What broad set of ideas was established by the work of Lamarck, Lyell, and Darwin?

Earth and its life are ancient and ever-changing; fossils document the evolution of life-forms over time.

Which of these individuals is a homozygous genotype?

AA

In which of the following situations is adaptive radiation least likely to occur?

A species with inflexible morphological traits finds itself in a species-rich, highly competitive environment.

Why was Darwin's acceptance of an ancient, continuously changing Earth so important in his development of his ideas about evolution?

Darwin hypothesized that species changed gradually, over long spans of time, in response to diverse and changing habitats.

True or False. In the example described in the tutorial, the red amoebas survived the catastrophic event, and all future generations of amoebas were red because the red amoebas had a higher reproductive rate than the blue ones.

False

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.

Which of the following is true of homologous structures?

They are structurally similar due to inheritance from a common ancestor.

______________________ occur(s) when a species gives rise to many new species after colonizing a region with diverse habitats.

adaptive radiation

In _________________, a population isolated by a geographic barrier becomes a new species as it accumulates changes by natural selection or genetic drift.

allopatric speciation

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