AP Bio Unit 2 OAs

Why is it that once you have been exposed to a vaccine or disease you are unlikely to catch the same disease again?

"your immune system has a ""memory"" of what the pathogen looks like and can respond more quickly to destroy it"

If the genes of yeast are 50% orthologous to those of humans, and if the genes of mice are 99% orthologous to those of humans, then what percentage of the genes of fish might one validly predict to be orthologous to the genes of humans?

80%

Which statement represents the best explanation for the observation that the nuclear DNA of wolves and domestic dogs has a very high degree of homology?

Dogs and wolves shared a common ancestor very recently

What is the function of reverse transcriptase in retroviruses?

It uses viral RNA as a template for DNA synthesis.

Which of the following is not true of all horizontally oriented phylogenetic trees, where time advances to the right?

Each branch point represents a point in absolute time.

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.

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.

Why are viruses referred to as obligate parasites?

They cannot reproduce outside of a host cell.

Which of the following pairs are the best examples of homologous structures?

bat wing and human hand

In angiosperm plants, flower morphology can be very intricate. If a tree, such as a New Mexico locust, has flowers that share many morphological intricacies with flowers of the sweet pea vine, then the most likely explanation for these floral similarities is the same general explanation for the similarities between the

cranial bones of humans and those of chimpanzees

Pathogens such as bacteria and viruses can spread from one person to another by

all of the choices

If a bacterium regenerates from an endospore that did not possess any of the plasmids that were contained in its original parent cell, the regenerated bacterium will probably

lack antibiotic-resistant genes

A virus integrates its DNA into the DNA of the host cell but remains inactive for a while in the

lysogenic phase

A virus uses the host cells machinery to make copies of itself while in the

lytic phase

Which of the following diseases is thought to be caused by prions?

mad cow disease

Which of the following diseases is transmitted by a mosquito bite?

malaria

The following questions refer to structures found in a gram-positive prokaryotic cell. Not present in all bacteria, this structure enables those that possess it to germinate after exposure to harsh conditions, such as boiling:

endospore

The following questions refer to structures found in a gram-positive prokaryotic cell. Which of the following requires ATP to function, and permits some species to respond to taxes (plural of taxis)?

flagellum

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

genetic material composed of nucleic acid

The common housefly belongs to all of the following taxa. Assuming you had access to textbooks or other scientific literature, knowing which of the following should provide you with the most specific information about the common housefly?

genus Musca

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

The reason that paralogous genes can diverge from each other within the same gene pool, whereas orthologous genes diverge only after gene pools are isolated from each other, is that

having an extra copy of a gene permits modifications to the copy without loss of the original gene product.

RNA viruses require their own supply of certain enzymes because

host cells lack enzymes that can replicate the viral genome

Which of the following are responsible for many human diseases?

parasitic chemoheterotrophs

Which of the following use light energy to synthesize organic compounds from CO2?

photoautotrophs

Which of the following use light energy to generate ATP, but do not release oxygen?

photoheterotrophs

If the eukaryotic condition arose, independently, several different times during evolutionary history, and if ancestors of these different lineages are extant and are classified in the domain Eukarya, then the domain Eukarya would be

polyphyletic

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

The immune system once exposed to a pathogen will most likely upon exposure to the same pathogen a second time will

react quicker than the original immune response

A process that slows the growth of bacteria is known as

refrigeration

When using a cladistic approach to systematics, which of the following is considered most important for classification?

shared derived characters

"Viruses, such as the influenza virus or the common cold, are difficult to treat year after year because"

they mutate so quickly that are immune systems are unable to recognize them

Which of the following is characteristic of the lytic cycle?

A large number of phages is released at a time.

In a bacterium that possesses antibiotic resistance and the potential to persist through very adverse conditions, such as freezing, drying, or high temperatures, DNA should be located within, or be part of, which structures? 1. nucleoid region 2. flagellum 3. endospore 4. fimbriae 5. plasmids

1, 3, and 5

The thermoacidophile, Sulfolobus acidocaldarius lacks peptidoglycan. What is likely to be true of this species? 1. It is a bacterium. 2. It is an archaean. 3. The optimal pH of its enzymes will lie above pH 7. 4. The optimal pH of its enzymes will lie below pH 7. 5. It could inhabit certain hydrothermal springs. 6. It could inhabit alkaline hot springs.

2, 4, and 5

If this figure is an accurate depiction of relatedness, then which taxon is unacceptable, based on cladistics?

3

In this 8-year experiment, 12 populations of E. coli, each begun from a single cell, were grown in low-glucose conditions for 20,000 generations. Each culture was introduced to fresh growth medium every 24 hours. Occasionally, samples were removed from the populations, and their fitness in low-glucose conditions was tested against that of members sampled from the ancestral (common ancestor) E. coli population. Among the six statements below, which two best account for the results obtained by the researchers? 1. Low-glucose conditions caused mutations that made individual E. coli cells better suited to these conditions. 2. Daughter cells acquired the ability to tolerate low-glucose conditions as they received the enzymes and membrane components that had been modified by their mother cell. 3. The initial E. coli population may have included some cells whose genes favored their survival in low-glucose conditions-OR-such genetic variants arose by chance early in the experiment. 4. The first few generations of E. coli in low-glucose conditions responded to the challenge by increasing the use of certain enzymes and ion pumps, while decreasing the use of others. This behavior was recorded in their gene sequences, which were later transmitted to daughter cells. 5. From generation to generation, there was an increase in the proportion of the experimental populations adapted to low-glucose conditions, because such bacteria produced relatively more offspring than did ancestral bacteria under low-glucose conditions. 6. During each generation, individual cells evolved to increase their survival in low-glucose conditions.

3 and 5

Match the numbered terms to the descriptions that follow. For each item, choose all appropriate terms, but only appropriate terms. 1. autotroph 2. heterotroph 3. phototroph 4. chemotroph an organism that relies on photons to excite electrons within its membranes

3 only

A common ancestor for both species C and E could be at position number

4

The tree's horizontal axis is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V—Z) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species. How many separate species, both extant and extinct, are depicted in this tree?

6

A researcher compared the nucleotide sequences of a homologous gene from five different species of mammals with the homologous human gene. The sequence homology between each species' version of the gene and the human gene is presented as a percentage of similarityWhat conclusion can be drawn validly from these data?

Among the organisms listed, humans shared a common ancestor most recently with chimpanzees

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.

When sufficient heat is applied, double-stranded DNA denatures into two single-stranded molecules as the heat breaks all of the hydrogen bonds. In an experiment, molecules of single-stranded DNA from species X are separately hybridized with putatively homologous single-stranded DNA molecules from five species (A-E). The hybridized DNAs are then heated, and the temperature at which complete denaturation occurs is recorded. Based on the data below, which species is probably most closely related to species X?

B

Typically, mutations that modify the active site of an enzyme are more likely to be harmful than mutations that affect other parts of the enzyme. A hypothetical enzyme consists of four domains (A—D), and the amino acid sequences of these four domains have been determined in five related species. Given the proportion of amino acid homologies among the five species at each of the four domains, which domain probably contains the active site?

C

Which statement about bacterial cell walls is false?

Cell walls prevent cells from dying in hypertonic conditions

If organisms A, B, and C belong to the same class but to different orders and if organisms D, E, and F belong to the same order but to different families, which of the following pairs of organisms would be expected to show the greatest degree of structural homology?

D and F

Refer to the treatments listed below to answer the following questions. You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent. I. treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectious II. filtering the substance to remove all elements smaller than what can be easily seen under a light microscope III. culturing the substance by itself on nutritive medium, away from any plant cells IV. treating the sample with proteases that digest all proteins and then determining whether it is still infectious Which treatment would you use to determine if the agent is a prion?

IV

What is true of gene duplication (NOTE: gene duplication is a process that is distinct from DNA replication)?

It can increase the size of a genome over evolutionary time

Regarding prokaryotic reproduction, which statement is correct?

Mutation is a primary source of variation in prokaryote populations

Which statement about the domain Archaea is false?

The genomes of archaeans are unique, containing no genes that originated within bacteria

Morphologically, Species A is very similar to four other species, B—E. Yet the nucleotide sequence deep within an intron in a gene shared by all five of these eukaryotic species is quite different in Species A compared to that of the other four species when one studies the nucleotides present at each position. If the sequence of Species A differs from that of the other four species due to simple misalignment, then what should the computer software find when it compares the sequence of Species A to those of the other four species?

The nucleotide sequence of Species A should have long sequences that are nearly identical to those of the other species, but offset in terms of position number

Morphologically, Species A is very similar to four other species, B—E. Yet the nucleotide sequence deep within an intron in a gene shared by all five of these eukaryotic species is quite different in Species A compared to that of the other four species when one studies the nucleotides present at each position. If the sequence of Species A differs from that of the other four species due to simple misalignment, then what should the computer software find when it compares the sequence of Species A to those of the other four species?

The nucleotide sequence of Species A should have long sequences that are nearly identical to those of the other species, but offset in terms of position number.

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

The phage genome replicates along with the host genome.

Why do people keep catching diseases like the common cold year after year even after they have already been exposed to the disease?

The virus that causes the disease mutates very quickly and looks different to the immune system

Which of these statements about prokaryotes is correct?

They divide by binary fission, without mitosis or meiosis

The tree's horizontal axis is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V—Z) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species. 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

Nucleic acid sequences that undergo few changes over the course of evolutionary time are said to be conserved. Conserved sequences of nucleic acids

are abundant in ribosomes

The following questions refer to structures found in a gram-positive prokaryotic cell. Which of the following is an important source of endotoxin in gram-negative species?

cell wall

The following questions refer to structures found in a gram-positive prokaryotic cell. Which of the following is composed almost entirely of peptidoglycan?

cell wall

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

Which characteristic distinguishes eubacteria from archaebacteria

eubacteria contain peptidoglycan in their cell walls

Modes of obtaining nutrients, used by at least some bacteria, include all of the following except

heteroautotrophy

Species that are not closely related and that do not share many anatomical similarities can still be placed together on the same phylogenetic tree by comparing their

homologous genes that are highly conserved

If, someday, an archaean cell is discovered whose SSU-rRNA sequence is more similar to that of humans than the sequence of mouse SSU-rRNA is to that of humans, the best explanation for this apparent discrepancy would be

homoplasy.

Evolutionary trees such as this are properly understood by scientists to be

hypotheses

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

interference with the viral reproduction

The correct sequence, from the most to the least comprehensive, of the taxonomic levels listed here is

kingdom, phylum, class, order, family, genus, and species

In this 8-year experiment, 12 populations of E. coli, each begun from a single cell, were grown in low-glucose conditions for 20,000 generations. Each culture was introduced to fresh growth medium every 24 hours. Occasionally, samples were removed from the populations, and their fitness in low-glucose conditions was tested against that of members sampled from the ancestral (common ancestor) E. coli population. Which term best describes what has occurred among the

microevolution

The lakes of northern Minnesota are home to many similar species of damselflies of the genus Enallagma that have apparently undergone speciation from ancestral stock since the last glacial retreat about 10,000 years ago. Sequencing which of the following would probably be most useful in sorting out evolutionary relationships among these closely related species?

mitochondrial DNA

The term that is most appropriately associated with clade is

monophyletic

Bacteria that convert atmospheric nitrogen into nitrogen containing compounds utilizable by other organisms are called

nitrogen fixers

Which of these items does not necessarily exist in a simple linear relationship with the number of gene-duplication events when placed as the label on the vertical axis of the graph below?

phenotypic complexity

Cyanobacteria are

photoautotrophs

Which of the following are responsible for high levels of O2 in Earth's atmosphere?

photoautotrophs

A researcher wants to determine the genetic relatedness of several breeds of dog (Canis familiaris). The researcher should compare homologous sequences of __________ that are known to be __________.

proteins or nucleic acids; poorly conserved

A process that destroys bacteria by subjecting them to great heat is known as

sterilization

Which kind of DNA should provide the best molecular clock for gauging the evolutionary relatedness of several species whose common ancestor became extinct billions of years ago?

that coding for ribosomal RNA

sexually transmited diseases are most often transmitted by

the exchange of bodily fluids

People die as a result of AIDS because

the virus destroys the bodys immune system thus allowing normally non lethal pathogens to overwhelm the body

Phylogenetic hypotheses (such as those represented by phylogenetic trees) are strongest when

they are supported by more than one kind of evidence, such as when fossil evidence corroborates molecular evidence

Which of the following statements about viruses is true?

viruses cannot reproduce unless they infect a living cell