bio chapter 19 and parts of 22

Emerging viruses arise by

) all of the above

Which of these naturalists synthesized a concept of natural selection independently of Darwin?

Alfred Wallace

Based on the above table, which virus meets the requirements for a bacteriophage?

Dnase Genome as mRNA- Polymerase -

What is the function of reverse transcriptase in retroviruses?

It uses viral RNA as a template for DNA synthesis.

Which pair would probably have agreed with the process that is depicted by this tree?

Lamarck and Wallace

In the mid-1900s, the Soviet geneticist Lysenko believed that his winter wheat plants, exposed to ever-colder temperatures, would eventually give rise to ever more cold-tolerant winter wheat. Lysenkoʹs attempts in this regard were most in agreement with the ideas of

Lamarck.

Which pair would have been likely to agree that strata such as those depicted here were deposited gradually over long periods of time by subtle mechanisms that are still at work?

Hutton and Lyell

Why do RNA viruses appear to have higher rates of mutation?

Replication of their genomes does not involve the proofreading steps of DNA replication

Which of Darwinʹs ideas had the strongest connection to Darwin having read Malthusʹs essay on human population growth?

Struggle for existence

Which of the following statements is an inferenceof natural selection?

Subsequent generations of a population should have greater proportions of individuals that possess traits better suited for success in unchanging environments.

A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have

T4 protein and T4 DNA.

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV). The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. Which of the following would be expected to occur?

The plants would develop the typical symptoms of TMV infection.

Which of the following represents a difference between viruses and viroids?

Viruses have capsids composed of protein, whereas viroids have no capsids.

Which of the five common ancestors, labeled V—Z, has been least successful in terms of the percent of its derived species that are extant?

W

Which statement about natural selection is mostcorrect?

Well-adapted individuals leave more offspring, and thus contribute more to the next generationʹs gene pool, than do poorly adapted individuals

Which of the five common ancestors, labeled V—Z, has given rise to the greatest number of species, both extant and extinct?

X

Which of the following describes plant virus infections?

They are spread throughout a plant by passing through the plasmodesmata.

Why are viruses referred to as obligate parasites

They cannot reproduce outside of a host cell

If you already knew that the infectious agent was either bacterial or viral, which treatment would allow you to distinguish between these two possibilities?

culturing the substance by itself on nutritive medium, away from any plant cells

Charles Darwin was the first person to propose

a mechanism for evolution that was supported by evidenc

In many ways, the regulation of the genes of a particular group of viruses will be similar to the regulation of the host genes. Therefore, which of the following would you expect of the genes of the bacteriophage?

control of more than one gene in an operon

Viral envelopes can best be analyzed with which of the following techniques?

antibodies against specific proteins not found in the host membranes

RNA viruses require their own supply of certain enzymes because

host cells lack enzymes that can replicate the viral genome.

Which of the following characteristics, structures, or processes is common to both bacteria and viruses?

genetic material composed of nucleic acid

Which of the following can be effective in preventing viral infection in humans?

getting vaccinated

Which of the following molecules make up the viral envelope

glycoproteins

Natural selection is based on all of the following except

individuals adapt to their environments and, thereby, evolve

Which of the following terms describes bacteriophage DNA that has become integrated into the host cell chromosome

prophages

Given Baltimoreʹs scheme, a positive sense single-stranded RNA virus such as the polio virus would be most closely related to which of the following?

retroviruses that require a DNA intermediate

What characteristics of electron microscopes make them most useful for studying viruses?

shorter wavelengths providing higher resolution

Viral genomes vary greatly in size and may include from four genes to several hundred genes. Which of the following viral features is most apt to correlate with the size of the genome?

size and shape of the capsid

The host range of a virus is determined by

the proteins on its surface and that of the host.

Which treatment would you use to determine if the agent is a prion

treating the sample with proteases that digest all proteins and then determining whether it is still infectious

Which treatment could definitively determine whether or not the component is a viroid?

treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectious

How many separate species, both extant and extinct, are depicted in this tree?

6

According to this tree, what percent of the species seem to be extant (i.e., not extinct)?

66%

Which of the following is characteristic of the lytic cycle?

A large number of phages is released at a time.

To observe natural selectionʹs effects on a population, which of these must be true? A) One must observe more than one generation of the population.

A and B only

Given a population that contains genetic variation, what is the correct sequence of the following events, under the influence of natural selection?

A) 2 → 4 → 1 → 3

A biologist studied a population of squirrels for 15 years. During that time, the population was never fewer than 30 squirrels and never more than 45. Her data showed that over half of the squirrels born did not survive to reproduce, because of competition for food and predation. In a single generation, 90% of the squirrels that were born lived to reproduce, and the population increased to 80. Which inference(s) about this population might be true

A, B, and C

Which of these conditions should completely prevent the occurrence of natural selection in a population over time?

All variation between individuals is due only to environmental factors

Which of the following series best reflects what we know about how the flu virus moves between species

An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates and is passed to a new species such as a bird, the virus mutates and can be transmitted to humans.

Which group is composed entirely of individuals who maintained that species are fixed (i.e., unchanging)

Aristotle, Linnaeus, and Cuvier

Cutting the same 8 kb piece with both enzymes together results in bands at 4.0, 2.5, 1.0, and 0.5. Of the possible arrangements of the sites given below, which one is most likely?

B

If ʺxʺ indicates the location of fossils of two closely related species, then fossils of their most-recent common ancestor are most likely to occur in which stratum

C

During a study session about evolution, one of your fellow students remarks, ʺThe giraffe stretched its neck while reaching for higher leaves; its offspring inherited longer necks as a result.ʺ Which statement is most likely to be helpful in correcting this studentʹs misconception?

Characteristics acquired during an organismʹs life are generally not passed on through genes.

Darwinʹs mechanism of natural selection required long time spans in order to modify species. From whom did Darwin get the concept of Earthʹs ancient age?

Charles Lyell

Who would have proposed that the boundaries between each stratum mark the occurrence of different localized floods

Cuvier

Which stratum should contain the greatest proportion of extinct organisms?

D

Based on the above table, which virus meets the Baltimore requirements for a retrovirus?

D RNASE- GENOME as mRNA - Polymerase +

What was the prevailing notion prior to the time of Lyell and Darwin?

Earth is a few thousand years old, and populations are unchanging.

Which of the following mustexist in a population before natural selection can act upon that population?

Genetic variation among individuals

During drought years on the Galapagos, small, easily eaten seeds become rare, leaving mostly large, hard-cased seeds that only birds with large beaks can eat. If a drought persists for several years, what should one expect to result from natural selection?

More small-beaked birds dying than larger-beaked birds. The offspring produced in subsequent generations have a higher percentage of birds with large beaks.

Which of the following represents an idea that Darwin learned from the writings of Thomas Malthus

Populations tend to increase at a faster rate than their food supply normally allows.

Which of the following is the most probable fate of a newly emerging virus that causes high mortality in its host?

The newly emerging virus will die out rather quickly or will mutate to be far less lethal

Which of the following statements describes the lysogenic cycle of lambda (λ) phage?

The phage genome replicates along with the host genome.

Which of the events described below agrees with the idea of catastrophism?

The sudden demise of the dinosaurs, and various other groups, by the impact of a large extraterrestrial body with Earth

Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observations supports this theory?

Viral genomes are usually more similar to the genome of the host cell than to the genomes of viruses that infect other cell types

Which of the five common ancestors, labeled V—Z, has been most successful in terms of the percent of its derived species that are extant?

Z

If the HMS Beagle had completely bypassed the Galapagos Islands, Darwin would have had a much poorer understanding of the

ability of populations to undergo modification as they adapt to a particular environment.

Which of the following is the best predictor of how much damage a virus causes

ability of the infected cell to undergo normal cell division

To cause a human pandemic, the H5N1 avian flu virus would have to

become capable of human-to-human transmission

As a young biologist, Charles Darwin had expected the living plants of temperate South America would resemble those of temperate Europe, but he was surprised to find that they more closely resembled the plants of tropical South America. The biological explanation for this observation is most properly associated with the field of

biogeography

Which of the following accounts for someone who has had a herpesvirus-mediated cold sore or genital sore getting flare-ups for the rest of life?

copies of the herpesvirus genome permanently maintained in host nuclei

Antiviral drugs that have become useful are usually associated with which of the following properties?

interference with the viral reproduction

What are prions?

misfolded versions of normal brain protein

In Darwinʹs thinking, the more closely related two different organisms are, the

more recently they shared a common ancestor

) Most human-infecting viruses are maintained in the human population only. However, a zoonosis is a disease that is transmitted from other vertebrates to humans, at least sporadically, without requiring viral mutation. Which of the following is the best example of a zoonosis?

rabies

What is the name given to viruses that are single-stranded RNA that acts as a template for DNA synthesis

retroviruses

Catastrophism, meaning the regular occurrence of geological or meteorological disturbances (catastrophes), was Cuvierʹs attempt to explain the existence of

the fossil record

The difference between vertical and horizontaltransmission of plant viruses is that

vertical transmission is transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant.