Archive for August 2017

Programmed cell death, or __________, takes place particularly in parts of the body where the cells are likely to accumulate significant genetic damage over time and are therefore at high risk of becoming cancerous.

10:58

Programmed cell death, or __________, takes place particularly in parts of the body where the cells are likely to accumulate significant genetic damage over time and are therefore at high risk of becoming cancerous.




Answer: apoptosis

Using a light microscope, it is easiest to see chromosomes:

10:56

Using a light microscope, it is easiest to see chromosomes:



a) during mitosis and meiosis because the condensed chromosomes are thicker and therefore more prominent.

b) during asexual reproduction.

c) in the mitochondria because they are circular.

d) during interphase when they are concentrated in the nucleus.

e) during interphase because they are uncoiled and have a more linear structure.




Answer: A

There are 40 individuals in population 1, all with genotype A1A1, and there are 25 individuals in population 2, all with genotype A2A2. Assume that these populations are located far from each other and that their environmental conditions are very similar. Based on the information given here, the observed genetic variation is most likely an example of

10:38

There are 40 individuals in population 1, all with genotype A1A1, and there are 25 individuals in population 2, all with genotype A2A2. Assume that these populations are located far from each other and that their environmental conditions are very similar. Based on the information given here, the observed genetic variation is most likely an example of 



A) genetic drift.
B) gene flow.
C) disruptive selection.
D) discrete variation.
E) directional selection.







Answer: A

Swine are vulnerable to infection by bird flu virus and human flu virus, which can both be present in an individual pig at the same time. When this occurs, it is possible for genes from bird flu virus and human flu virus to be combined. If the human flu virus contributes a gene for Tamiflu resistance (Tamiflu is an antiviral drug) to the new virus, and if the new virus is introduced to an environment lacking Tamiflu, then what is most likely to occur?

10:38

Swine are vulnerable to infection by bird flu virus and human flu virus, which can both be present in an individual pig at the same time. When this occurs, it is possible for genes from bird flu virus and human flu virus to be combined. If the human flu virus contributes a gene for Tamiflu resistance (Tamiflu is an antiviral drug) to the new virus, and if the new virus is introduced to an environment lacking Tamiflu, then what is most likely to occur? 




A) The new virus will maintain its Tamiflu-resistance gene, ust in case of future exposure to Tamiflu.
B) The Tamiflu-resistance gene will undergo mutations that convert it into a gene that has a useful function in this environment.
C) If the Tamiflu-resistance gene involves a cost, it will experience directional selection leading to reduction in its frequency.
D) If the Tamiflu-resistance gene confers no benefit in the current environment, and has no cost, the virus will become dormant until Tamiflu is present.





Answer: C

The volcano is currently dormant, but in a hypothetical future scenario, satellite cones at the base of Mt. Kilimanjaro spew sulfurous gases and lava, destroying all life located between the base and 6,000 feet above sea level. As a result of this catastrophe, how should the frequency of the sickle-cell allele change in the remnant human population that survives above 6,000 feet, and which phenomenon accounts for this change in allele frequency?

10:38

The volcano is currently dormant, but in a hypothetical future scenario, satellite cones at the base of Mt. Kilimanjaro spew sulfurous gases and lava, destroying all life located between the base and 6,000 feet above sea level. As a result of this catastrophe, how should the frequency of the sickle-cell allele change in the remnant human population that survives above 6,000 feet, and which phenomenon accounts for this change in allele frequency? 




A) decreases; disruptive selection
B) increases; genetic drift
C) decreases; gene flow
D) increases; nonrandom mating
E) decreases; bottleneck effect






Answer: E

Which of these is closest to the allele frequency in the founding population?

10:37
In the year 2500, five male space colonists and five female space colonists (all unrelated to each other) settle on an uninhabited Earthlike planet in the Andromeda galaxy. The colonists and their offspring randomly mate for generations. All ten of the original colonists had free earlobes, and two were heterozygous for that trait. The allele for free earlobes is dominant to the allele for attached earlobes.




Which of these is closest to the allele frequency in the founding population? 




A) 0.1 a, 0.9 A
B) 0.2 a, 0.8 A
C) 0.5 a, 0.5 A
D) 0.8 a, 0.2 A
E) 0.4 a, 0.6 A






Answer: A

In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the ß hemoglobin alleles in the human gene pool.

10:25

In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the ß hemoglobin alleles in the human gene pool. 


 In the United States, the parasite that causes malaria is not present, but African-Americans whose ancestors were from equatorial Africa are present. What should be happening to the sickle-cell allele in the United States, and what should be happening to it in equatorial Africa?



A) stabilizing selection; disruptive selection
B) disruptive selection; stabilizing selection
C) disruptive selection; directional selection
D) directional selection; disruptive selection
E) directional selection; stabilizing selection





Answer: E

What proportion of the population is probably heterozygous (Aa) for this trait?

10:24
A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants.

What proportion of the population is probably heterozygous (Aa) for this trait? 




A) 0.05
B) 0.25
C) 0.50
D) 0.75






Answer: C

HIV's genome of RNA includes the code for reverse transcriptase (RT), an enzyme that acts early in infection to synthesize a DNA genome off of an RNA template. The HIV genome also codes for protease (PR), an enzyme that acts later in infection by cutting long viral polyproteins into smaller, functional proteins. Both RT and PR represent potential targets for antiretroviral drugs. Drugs called nucleoside analogs (NA) act against RT, whereas drugs called protease inhibitors (PI) act against PR.

10:23
HIV's genome of RNA includes the code for reverse transcriptase (RT), an enzyme that acts early in infection to synthesize a DNA genome off of an RNA template. The HIV genome also codes for protease (PR), an enzyme that acts later in infection by cutting long viral polyproteins into smaller, functional proteins. Both RT and PR represent potential targets for antiretroviral drugs. Drugs called nucleoside analogs (NA) act against RT, whereas drugs called protease inhibitors (PI) act against PR.


Which of the following represents the treatment option most likely to avoid the production of drug-resistant HIV (assuming no drug interactions or side effects)? 



A) using a series of NAs, one at a time, and changed about once a week
B) using a single PI, but slowly increasing the dosage over the course of a week
C) using high doses of NA and a PI at the same time for a period not to exceed one day
D) using moderate doses of NA and two different PIs at the same time for several months



Answer: D



Within the body of an HIV-infected individual who is being treated with a single NA, and whose HIV particles are currently vulnerable to this NA, which of these situations can increase the virus' relative fitness? 



1. mutations resulting in RTs with decreased rates of nucleotide mismatch
2. mutations resulting in RTs with increased rates of nucleotide mismatch
3. mutations resulting in RTs that have proofreading capability


A) 1 only
B) 2 only
C) 3 only
D) 1 and 3
E) 2 and 3


Answer: B 

There are those who claim that the theory of evolution cannot be true because the apes, which are supposed to be closely related to humans, do not likewise share the same large brains, capacity for complicated speech, and tool-making capability. They reason that if these features are generally beneficial, then the apes should have evolved them as well. Which of these provides the best argument against this misconception?

10:22

There are those who claim that the theory of evolution cannot be true because the apes, which are supposed to be closely related to humans, do not likewise share the same large brains, capacity for complicated speech, and tool-making capability. They reason that if these features are generally beneficial, then the apes should have evolved them as well. Which of these provides the best argument against this misconception? 



A) Advantageous alleles do not arise on demand.
B) A population's evolution is limited by historical constraints.
C) Adaptations are often compromises.
D) Evolution can be influenced by environmental change.






Answer: A

A proficient engineer can easily design skeletal structures that are more functional than those currently found in the forelimbs of such diverse mammals as horses, whales, and bats. The actual forelimbs of these mammals do not seem to be optimally arranged because

10:22

A proficient engineer can easily design skeletal structures that are more functional than those currently found in the forelimbs of such diverse mammals as horses, whales, and bats. The actual forelimbs of these mammals do not seem to be optimally arranged because 




A) natural selection has not had sufficient time to create the optimal design in each case, but will do so given enough time.
B) in many cases, phenotype is not merely determined by genotype, but by the environment as well.
C) though we may not consider the fit between the current skeletal arrangements and their functions excellent, we should not doubt that natural selection ultimately produces the best design.
D) natural selection is generally limited to modifying structures that were present in previous generations and in previous species.





Answer: D

The same gene that causes various coat patterns in wild and domesticated cats also causes the cross-eyed condition in these cats, the cross-eyed condition being slightly maladaptive. In a hypothetical environment, the coat pattern that is associated with crossed eyes is highly adaptive, with the result that both the coat pattern and the cross-eyed condition increase in a feline population over time. Which statement is supported by these observations?

10:21

The same gene that causes various coat patterns in wild and domesticated cats also causes the cross-eyed condition in these cats, the cross-eyed condition being slightly maladaptive. In a hypothetical environment, the coat pattern that is associated with crossed eyes is highly adaptive, with the result that both the coat pattern and the cross-eyed condition increase in a feline population over time. Which statement is supported by these observations? 



A) Evolution is progressive and tends toward a more perfect population.
B) Phenotype is often the result of compromise.
C) Natural selection reduces the frequency of maladaptive genes in populations over the course of time.
D) Polygenic inheritance is generally maladaptive, and should become less common in future generations.
E) In all environments, coat pattern is a more important survival factor than is eye-muscle tone.






Answer: B

When imbalances occur in the sex ratio of sexual species that have two sexes (i.e., other than a 50:50 ratio), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. This is most clearly an example of

10:21

When imbalances occur in the sex ratio of sexual species that have two sexes (i.e., other than a 50:50 ratio), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. This is most clearly an example of 



A) sexual selection.
B) disruptive selection.
C) balancing selection.
D) stabilizing selection.
E) frequency-dependent selection.






Answer: E

In seedcracker finches from Cameroon, small- and large-billed birds specialize in cracking soft and hard seeds, respectively. If long-term climatic change resulted in all seeds becoming hard, what type of selection would then operate on the finch population?

10:21

In seedcracker finches from Cameroon, small- and large-billed birds specialize in cracking soft and hard seeds, respectively. If long-term climatic change resulted in all seeds becoming hard, what type of selection would then operate on the finch population? 





A) disruptive selection
B) directional selection
C) stabilizing selection
D) No selection would operate because the population is in Hardy-Weinberg equilibrium.






Answer: B

The recessive allele that causes phenylketonuria (PKU) is harmful, except when an infant's diet lacks the amino acid phenylalanine. What maintains the presence of this harmful allele in a population's gene pool?

10:20

The recessive allele that causes phenylketonuria (PKU) is harmful, except when an infant's diet lacks the amino acid phenylalanine. What maintains the presence of this harmful allele in a population's gene pool? 




A) heterozygote advantage
B) stabilizing selection
C) diploidy
D) balancing selection




Answer: C

Most Swiss starlings produce four to five eggs in each clutch. Starlings producing fewer, or more, than this have reduced fitness. Which of the following terms best describes this situation?

10:19

Most Swiss starlings produce four to five eggs in each clutch. Starlings producing fewer, or more, than this have reduced fitness. Which of the following terms best describes this situation? 



A) artificial selection
B) directional selection
C) stabilizing selection
D) disruptive selection
E) sexual selection






Answer: C

Which of the following statements best summarizes evolution as it is viewed today?

10:19

Which of the following statements best summarizes evolution as it is viewed today? 




A) It represents the result of selection for acquired characteristics.
B) It is synonymous with the process of gene flow.
C) It is the descent of humans from the present-day great apes.
D) It is the differential survival and reproduction of the most-fit phenotypes.




Answer: D

Adult male humans generally have deeper voices than do adult female humans, which is the direct result of higher levels of testosterone causing growth of the larynx. If one excludes the involvement of gender in the situation, then the pattern that is apparent in the fossil record is most similar to one that should be expected from

10:19

Adult male humans generally have deeper voices than do adult female humans, which is the direct result of higher levels of testosterone causing growth of the larynx. If one excludes the involvement of gender in the situation, then the pattern that is apparent in the fossil record is most similar to one that should be expected from 



A) pansexual selection.
B) directional selection.
C) disruptive selection.
D) stabilizing selection.
E) asexual selection.







Answer: C

Adult male humans generally have deeper voices than do adult female humans, which is the direct result of higher levels of testosterone causing growth of the larynx. If the fossil records of apes and humans alike show a trend toward decreasing larynx size in adult females and increasing larynx size in adult males, then

10:18

Adult male humans generally have deeper voices than do adult female humans, which is the direct result of higher levels of testosterone causing growth of the larynx. If the fossil records of apes and humans alike show a trend toward decreasing larynx size in adult females and increasing larynx size in adult males, then 




A) sexual dimorphism was developing over time in these species.
B) intrasexual selection seems to have occurred.
C) stabilizing selection was occurring in these species concerning larynx size.
D) selection was acting more directly upon genotype than upon phenotype.






Answer: A

During breeding season, one should expect female house finches to prefer to mate with males with the brightest red feathers. Which of the following terms are appropriately applied to this situation?

10:18

During breeding season, one should expect female house finches to prefer to mate with males with the brightest red feathers. Which of the following terms are appropriately applied to this situation? 



A) sexual selection
B) mate choice
C) intersexual selection
D) Three of the responses are correct.
E) Two of the responses are correct.





Answer: D

In the wild, male house finches (Carpodus mexicanus) vary considerably in the amount of red pigmentation in their head and throat feathers, with colors ranging from pale yellow to bright red. These colors come from carotenoid pigments that are found in the birds' diets; no vertebrates are known to synthesize carotenoid pigments. Thus, the brighter red the male's feathers are, the more successful he has been at acquiring the red carotenoid pigment by his food-gathering efforts (all other factors being equal). During breeding season, one should expect female house finches to prefer to mate with males with the brightest red feathers. Which of the following is true of this situation?

10:18

In the wild, male house finches (Carpodus mexicanus) vary considerably in the amount of red pigmentation in their head and throat feathers, with colors ranging from pale yellow to bright red. These colors come from carotenoid pigments that are found in the birds' diets; no vertebrates are known to synthesize carotenoid pigments. Thus, the brighter red the male's feathers are, the more successful he has been at acquiring the red carotenoid pigment by his food-gathering efforts (all other factors being equal). During breeding season, one should expect female house finches to prefer to mate with males with the brightest red feathers. Which of the following is true of this situation? 



A) Alleles that promote more efficient acquisition of carotenoid-containing foods by males should increase over the course of generations.
B) Alleles that promote more effective deposition of carotenoid pigments in the feathers of males should increase over the course of generations.
C) There should be directional selection for bright red feathers in males.
D) Three of the statements are correct.
E) Two of the statements are correct.







Answer: D

Sexual dimorphism is most often a result of

10:17

Sexual dimorphism is most often a result of 



A) pansexual selection.
B) stabilizing selection.
C) intrasexual selection.
D) intersexual selection.
E) artificial selection.





Answer: D

The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, this in turn selects for bacteria whose genomes are not methylated and whose restriction enzymes instead degrade methylated DNA. Over the course of evolutionary time, what should occur?

10:17

The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, this in turn selects for bacteria whose genomes are not methylated and whose restriction enzymes instead degrade methylated DNA. Over the course of evolutionary time, what should occur? 




A) Methylated DNA should become fixed in the gene pools of bacterial species.
B) Nonmethylated DNA should become fixed in the gene pools of bacteriophages.
C) Methylated DNA should become fixed in the gene pools of bacteriophages.
D) Methylated and nonmethylated strains should be maintained among both bacteria and bacteriophages, with ratios that vary over time.
E) Both the first and second responses are correct.





Answer: D

The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, this in turn selects for bacteria whose genomes are not methylated and whose restriction enzymes instead degrade methylated DNA. The outcome of the conflict between bacteria and bacteriophage at any point in time results from

10:16

The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, this in turn selects for bacteria whose genomes are not methylated and whose restriction enzymes instead degrade methylated DNA. The outcome of the conflict between bacteria and bacteriophage at any point in time results from 




A) frequency-dependent selection.
B) evolutionary imbalance.
C) heterozygote advantage.
D) neutral variation.
E) genetic variation being preserved by diploidy.



Answer: A

What is true of natural selection?

10:14

What is true of natural selection? 





A) Natural selection is a random process.
B) Natural selection creates beneficial mutations.
C) The only way to eliminate harmful mutations is through natural selection.
D) Mutations occur at random; natural selection can preserve and distribute beneficial mutations.
E) Mutations occur when directed by the good of the species; natural selection edits out harmful mutations and causes populations to adapt to the beneficial mutations.





Answer: D

If the original finches that had been blown over to the Galápagos from South America had already been genetically different from the parental population of South American finches, even before adapting to the Galápagos, this would have been an example of

10:14

If the original finches that had been blown over to the Galápagos from South America had already been genetically different from the parental population of South American finches, even before adapting to the Galápagos, this would have been an example of 



A) genetic drift.
B) bottleneck effect.
C) founder effect.
D) all three of these.
E) both the first and third of these.







Answer: E

The production of new types of flu virus in the manner described above is most similar to the phenomenon of

10:14
Swine are vulnerable to infection by bird flu virus and human flu virus, which can both be present in an individual pig at the same time. When this occurs, it is possible for genes from bird flu virus and human flu virus to be combined, thereby producing a genetically distinctive virus, which can subsequently cause widespread disease.

The production of new types of flu virus in the manner described above is most similar to the phenomenon of 



A) bottleneck effect.
B) founder effect.
C) natural selection.
D) gene flow.
E) sexual selection.






Answer: D

Evolution

10:13

Evolution 





A) must happen, due to organisms' innate desire to survive.
B) must happen whenever a population is not well-adapted to its environment.
C) can happen whenever any of the conditions for Hardy-Weinberg equilibrium are not met.
D) requires the operation of natural selection.
E) requires that populations become better suited to their environments.





Answer: C

In peas, a gene controls flower color such that R = purple and r = white. In an isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population?

10:13

In peas, a gene controls flower color such that R = purple and r = white. In an isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population? 




A) 0.36
B) 0.64
C) 0.75
D) 0.80







Answer: D

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.1. What is the frequency of individuals with AA genotype?

10:13

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.1. What is the frequency of individuals with AA genotype? 




A) 0.20
B) 0.32
C) 0.42
D) 0.81
E) Genotype frequency cannot be determined from the information provided.





Answer: D

Hardy-Weinberg equilibrium must occur in populations wherein

10:12

Hardy-Weinberg equilibrium must occur in populations wherein 




A) an allele remains fixed.
B) no genetic variation exists.
C) natural selection is not operating.
D) All three of the responses above are correct.
E) Only two of the responses above are correct.




Answer: E

Whenever diploid populations are in Hardy-Weinberg equilibrium at a particular locus

10:11

Whenever diploid populations are in Hardy-Weinberg equilibrium at a particular locus 




A) the allele's frequency should not change from one generation to the next, but its representation in homozygous and heterozygous genotypes may change.
B) natural selection, gene flow, and genetic drift are acting equally to change an allele's frequency.
C) this means that, at this locus, two alleles are present in equal proportions.
D) the population itself is not evolving, but individuals within the population may be evolving.






Answer: A

How many of these statements regarding populations are true?

10:11

How many of these statements regarding populations are true?




1. Mature males and females of a population can interbreed with each other.
2. Populations are sometimes geographically isolated from other populations.
3. Biological species are made up of populations.
4. Members of a population tend to be genetically more similar to each other than to members of other populations.
5. Populations have genomes, but not gene pools.




A) Only one of these statements is true.
B) Two of these statements are true.
C) Three of these statements are true.
D) Four of these statements are true.
E) All five of these statements are true.








Answer: D

Which of the following is a true statement concerning genetic variation?

10:11

Which of the following is a true statement concerning genetic variation? 




A) It is created by the direct action of natural selection.
B) It arises in response to changes in the environment.
C) It must be present in a population before natural selection can act upon the population.
D) It tends to be reduced by the processes involved when diploid organisms produce gametes.
E) A population that has a higher average heterozygosity has less genetic variation than one with a lower average heterozygosity.






Answer: C

Most invertebrates have a cluster of ten similar Hox genes, all located on the same chromosome. Most vertebrates have four such clusters of Hox genes, located on four nonhomologous chromosomes. The process that could have potentially contributed to the cluster's presence on more than one chromosome was ________.

10:10

Most invertebrates have a cluster of ten similar Hox genes, all located on the same chromosome. Most vertebrates have four such clusters of Hox genes, located on four nonhomologous chromosomes. The process that could have potentially contributed to the cluster's presence on more than one chromosome was ________. 




A) binary fission
B) translation
C) gene duplication
D) nondisjunction
E) transcription






Answer: D

Rank the following one-base point mutations (from most likely to least likely) with respect to their likelihood of affecting the structure of the corresponding polypeptide:

10:10

Rank the following one-base point mutations (from most likely to least likely) with respect to their likelihood of affecting the structure of the corresponding polypeptide: 




1. insertion mutation deep within an intron
2. substitution mutation at the third position of an exonic codon
3. substitution mutation at the second position of an exonic codon
4. deletion mutation within the first exon of the gene



A) 1, 2, 3, 4
B) 4, 3, 2, 1
C) 2, 1, 4, 3
D) 3, 1, 4, 2
E) 2, 3, 1, 4





Answer: B

Which statement about variation is true?

10:10

Which statement about variation is true? 




A) All phenotypic variation is the result of genotypic variation.
B) All genetic variation produces phenotypic variation.
C) All nucleotide variability results in neutral variation.
D) All new alleles are the result of nucleotide variability.
E) All geographic variation results from the existence of clines.






Answer: D

In modern terminology, diversity is understood to be a result of genetic variation. Which of the following is a recognized source of variation for evolution?

10:09

In modern terminology, diversity is understood to be a result of genetic variation. Which of the following is a recognized source of variation for evolution? 



A) mistakes in translation of structural genes
B) mistakes in protein folding
C) rampant changes to the dictionary of the genetic code
D) binary fission
E) recombination by crossing over in meiosis





Answer: E

Although each of the following has a better chance of influencing gene frequencies in small populations than in large populations, which one most consistently requires a small population as a precondition for its occurrence?

10:09

Although each of the following has a better chance of influencing gene frequencies in small populations than in large populations, which one most consistently requires a small population as a precondition for its occurrence? 





A) mutation
B) nonrandom mating
C) genetic drift
D) natural selection
E) gene flow




Answer: C

Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is true?

10:08

Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is true? 





A) Each bird evolved a deeper, stronger beak as the drought persisted.
B) Each bird's survival was strongly influenced by the depth and strength of its beak as the drought persisted.
C) Each bird that survived the drought produced only offspring with deeper, stronger beaks than seen in the previous generation.
D) The frequency of the strong-beak alleles increased in each bird as the drought persisted.



Answer: B

Which of these variables is likely to undergo the largest change in value as the result of a mutation that introduces a brand-new allele into a population's gene pool at a locus that had formerly been fixed?

10:08

Which of these variables is likely to undergo the largest change in value as the result of a mutation that introduces a brand-new allele into a population's gene pool at a locus that had formerly been fixed? 




A) average heterozygosity
B) nucleotide variability
C) geographic variability
D) average number of loci




Answer: A

Within six months of effectively using methicillin to treat S. aureus infections in a community, all new infections were caused by MRSA. How can this result best be explained?

23:24

Within six months of effectively using methicillin to treat S. aureus infections in a community, all new infections were caused by MRSA. How can this result best be explained? 




A) S. aureus can resist vaccines.
B) A patient must have become infected with MRSA from another community.
C) In response to the drug, S. aureus began making drug-resistant versions of the protein targeted by the drug.
D) Some drug-resistant bacteria were present at the start of treatment, and natural selection increased their frequency.
E) The drug caused the S. aureus DNA to change.







Answer: D

Which of the following is not an observation or inference on which natural selection is based?

23:24

Which of the following is not an observation or inference on which natural selection is based? 





A) There is heritable variation among individuals.
B) Poorly adapted individuals never produce offspring.
C) Species produce more offspring than the environment can support.
D) Individuals whose characteristics are best suited to the environment generally leave more offspring than those whose characteristics are less well suited.
E) Only a fraction of an individual's offspring may survive.





Answer: B

If the six ground finch species have evolved most recently, then which of these is the most logical prediction?

23:24

If the six ground finch species have evolved most recently, then which of these is the most logical prediction? 





A) They should be limited to the six islands that most recently emerged from the sea.
B) Their genomes should be more similar to each other than are the genomes of the five tree finch species.
C) They should share fewer anatomical homologies with each other than they share with the tree finches.
D) The chances of hybridization between two ground finch species should be less than the chances of hybridization between two tree finch species.






Answer: B

A high degree of endemism is most likely in environments that are

23:24

A high degree of endemism is most likely in environments that are 




A) easily reached and heterogeneous.
B) isolated and heterogeneous.
C) isolated and homogeneous.
D) isolated and extremely cold.
E) easily reached and homogeneous.




Answer: B

If one wanted to find the largest number of endemic species, one should visit which of the following geological features (assuming each has existed for several millions of years)?

23:23

If one wanted to find the largest number of endemic species, one should visit which of the following geological features (assuming each has existed for several millions of years)? 




A) an isolated ocean island in the tropics
B) an extensive mountain range
C) a midcontinental grassland with extreme climatic conditions
D) a shallow estuary on a warm-water coast





Answer: A

It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that

23:23

It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that 



A) island forms and mainland forms descended from common ancestors.
B) common environments are inhabited by the same organisms.
C) the islands were originally part of the continent.
D) the island forms and mainland forms are converging.
E) island forms and mainland forms have identical gene pools.






Answer: A

What is true of pseudogenes?

23:23

What is true of pseudogenes? 




A) They are composed of RNA, rather than DNA.
B) They are the same things as introns.
C) They are unrelated genes that code for the same gene product.
D) They are vestigial genes.





Answer: D

What must be true of any organ that is described as vestigial?

23:23

What must be true of any organ that is described as vestigial? 



A) It must be analogous to some feature in an ancestor.
B) It must be homologous to some feature in an ancestor.
C) It must be both homologous and analogous to some feature in an ancestor.
D) It need be neither homologous nor analogous to some feature in an ancestor.







Answer: B

Both ancestral birds and ancestral mammals shared a common ancestor that was terrestrial. Today, penguins (which are birds) and seals (which are mammals) have forelimbs adapted for swimming. What term best describes the relationship of the bones in the forelimbs of penguins and seals, and what term best describes the flippers of penguins and seals?

23:22

Both ancestral birds and ancestral mammals shared a common ancestor that was terrestrial. Today, penguins (which are birds) and seals (which are mammals) have forelimbs adapted for swimming. What term best describes the relationship of the bones in the forelimbs of penguins and seals, and what term best describes the flippers of penguins and seals? 




A) homologous; homologous
B) analogous; homologous
C) homologous; analogous
D) analogous; analogous





Answer: C

Ichthyosaurs were aquatic dinosaurs. Fossils show us that they had dorsal fins and tails, as do fish, even though their closest relatives were terrestrial reptiles that had neither dorsal fins nor aquatic tails. The dorsal fins and tails of ichthyosaurs and fish are

23:22

Ichthyosaurs were aquatic dinosaurs. Fossils show us that they had dorsal fins and tails, as do fish, even though their closest relatives were terrestrial reptiles that had neither dorsal fins nor aquatic tails. The dorsal fins and tails of ichthyosaurs and fish are 




A) homologous.
B) examples of convergent evolution.
C) adaptations to a common environment.
D) Three of the responses above are correct.
E) Two of the responses above are correct.




Answer: E

Members of two different species possess a similar-looking structure that they use in a similar fashion to perform the same function. Which information would best help distinguish between an explanation based on homology versus one based on convergent evolution?

23:22

Members of two different species possess a similar-looking structure that they use in a similar fashion to perform the same function. Which information would best help distinguish between an explanation based on homology versus one based on convergent evolution? 




A) The two species live at great distance from each other.
B) The two species share many proteins in common, and the nucleotide sequences that code for these proteins are almost identical.
C) The sizes of the structures in adult members of both species are similar in size.
D) Both species are well adapted to their particular environments.





Answer: B

Which of the following statements most detracts from the claim that the human appendix is a completely vestigial organ?

23:21

Which of the following statements most detracts from the claim that the human appendix is a completely vestigial organ? 




A) The appendix can be surgically removed with no immediate ill effects.
B) The appendix might have been larger in fossil hominids.
C) The appendix has a substantial amount of defensive lymphatic tissue.
D) Individuals with a larger-than-average appendix leave fewer offspring than those with a below-average-sized appendix.
E) In a million years, the human species might completely lack an appendix.






Answer: C

Logically, which of these should cast the most doubt on the relationships depicted by an evolutionary tree?

23:21

Logically, which of these should cast the most doubt on the relationships depicted by an evolutionary tree? 




A) None of the organisms depicted by the tree ate the same foods.
B) Some of the organisms depicted by the tree had lived in different habitats.
C) The skeletal remains of the organisms depicted by the tree were incomplete (in other words, some bones were missing).
D) Transitional fossils had not been found.
E) Relationships between DNA sequences among the species did not match relationships between skeletal patterns.





Answer: E

Over evolutionary time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses?

23:21

Over evolutionary time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses? 




A) Natural selection cannot account for losses, only for innovations.
B) Natural selection accounts for these losses by the principle of use and disuse.
C) Under particular circumstances that persisted for long periods, each of these structures presented greater costs than benefits.
D) The ancestors of these organisms experienced harmful mutations that forced them to find new habitats that these species had not previously used.






Answer: C

Structures as different as human arms, bat wings, and dolphin flippers contain many of the same bones, these bones having developed from very similar embryonic tissues. How do biologists interpret these similarities?

23:21

Structures as different as human arms, bat wings, and dolphin flippers contain many of the same bones, these bones having developed from very similar embryonic tissues. How do biologists interpret these similarities? 




A) by identifying the bones as being homologous structures
B) by the principle of convergent evolution
C) by proposing that humans, bats, and dolphins share a common ancestor
D) Three of the statements above are correct.
E) Two of the statements above are correct.







Answer: E

If two modern organisms are distantly related in an evolutionary sense, then one should expect that

23:20

If two modern organisms are distantly related in an evolutionary sense, then one should expect that 



A) they live in very different habitats.
B) they should share fewer homologous structures than two more closely related organisms.
C) their chromosomes should be very similar.
D) they shared a common ancestor relatively recently.
E) they should be members of the same genus.






Answer: B

If the bacterium Staphylococcus aureus experiences a cost for maintaining one or more antibiotic-resistance genes, then what should happen in environments from which antibiotics are missing?

23:20

If the bacterium Staphylococcus aureus experiences a cost for maintaining one or more antibiotic-resistance genes, then what should happen in environments from which antibiotics are missing? 




A) These genes should continue to be maintained in case the antibiotics ever appear.
B) These bacteria should be outcompeted and replaced by bacteria that have lost these genes.
C) The bacteria should try to make the cost worthwhile by locating, and migrating to, microenvironments where traces of antibiotics are present.
D) The bacteria should start making and secreting their own antibiotics.





Answer: B

DDT was once considered a "silver bullet" that would permanently eradicate insect pests. Today, instead, DDT is largely useless against many insects. Which of these would have been required for this pest eradication effort to be successful in the long run?

23:19

DDT was once considered a "silver bullet" that would permanently eradicate insect pests. Today, instead, DDT is largely useless against many insects. Which of these would have been required for this pest eradication effort to be successful in the long run? 




A) Larger doses of DDT should have been applied.
B) All habitats should have received applications of DDT at about the same time.
C) The frequency of DDT application should have been higher.
D) None of the individual insects should have possessed genomes that made them resistant to DDT.
E) DDT application should have been continual.





Answer: D

In a hypothetical environment, fishes called pike-cichlids are visual predators of algae-eating fish (in other words, they locate their prey by sight). If a population of algae-eaters experiences predation pressure from pike-cichlids, which of the following is least likely to be observed in the algae-eater population over the course of many generations?

23:19

In a hypothetical environment, fishes called pike-cichlids are visual predators of algae-eating fish (in other words, they locate their prey by sight). If a population of algae-eaters experiences predation pressure from pike-cichlids, which of the following is least likely to be observed in the algae-eater population over the course of many generations? 




A) selection for drab coloration of the algae-eaters
B) selection for nocturnal algae-eaters (active only at night)
C) selection for larger female algae-eaters, bearing broods composed of more, and larger, young
D) selection for algae-eaters that become sexually mature at smaller overall body sizes
E) selection for algae-eaters that are faster swimmers





Answer: C

The rise of methicillin-resistant Staphylococcus aureus (MRSA) can be considered to be an example of artificial selection because

23:19

The rise of methicillin-resistant Staphylococcus aureus (MRSA) can be considered to be an example of artificial selection because 




A) humans purposefully raise MRSA in large fermenters in an attempt to make the bacteria ever-more resistant.
B) S. aureus is cultivated by humans to replenish the soil with nutrients.
C) humans synthesize methicillin and create environments in which bacteria frequently come into contact with methicillin.
D) Humans are becoming resistant to bacteria by taking methicillin.






Answer: C

Currently, two extant elephant species (X and Y) are placed in the genus Loxodonta, and a third species (Z) is placed in the genus Elephas. Thus, which statement should be true?

23:19

Currently, two extant elephant species (X and Y) are placed in the genus Loxodonta, and a third species (Z) is placed in the genus Elephas. Thus, which statement should be true? 




A) Species X and Y are not related to species Z.
B) Species X and Y share a greater number of homologies with each other than either does with species Z.
C) Species X and Y share a common ancestor that is still extant (in other words, not yet extinct).
D) Species X and Y are the result of artificial selection from an ancestral species Z.
E) Species X, Y, and Z share a common ancestor, but nothing more can be claimed than this.






Answer: B

The role that humans play in artificial selection is to

23:18

The role that humans play in artificial selection is to 




A) determine who lives and who dies.
B) create the genetic variants, which nature then selects.
C) choose which organisms breed, and which do not.
D) train organisms to breed more successfully.
E) perform artificial insemination.





Answer: C

If Darwin had been aware of genes, and of their typical mode of transmission to subsequent generations, with which statement would he most likely have been in agreement?

23:18

If Darwin had been aware of genes, and of their typical mode of transmission to subsequent generations, with which statement would he most likely have been in agreement? 




A) If natural selection can change one gene's frequency in a population over the course of generations then, given enough time and enough genes, natural selection can cause sufficient genetic change to produce new species from old ones.
B) If an individual's somatic cell genes change during its lifetime, making it more fit, then it will be able to pass these genes on to its offspring.
C) If an individual acquires new genes by engulfing, or being infected by, another organism, then a new genetic species will be the result.
D) A single mutation in a single gene in a single gamete will, if perpetuated, produce a new species within just two generations.






Answer: A

Which of Darwin's ideas had the strongest connection to Darwin having read Malthus's essay on human population growth?

23:18

Which of Darwin's ideas had the strongest connection to Darwin having read Malthus's essay on human population growth?




A) descent with modification
B) variation among individuals in a population
C) struggle for existence
D) the ability of related species to be conceptualized in "tree thinking"
E) that the ancestors of the Galápagos finches had come from the South American mainland







Answer: C

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 both 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?

23:18

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 both 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) The amount of available food may have increased.
B) The parental generation of squirrels developed better eyesight due to improved diet; the subsequent squirrel generation inherited better eyesight.
C) The squirrels of subsequent generations should show greater levels of genetic variation than previous generations, because squirrels that would not have survived in the past will now survive.
D) Three of the statements above are correct.
E) Two of the statements above are correct.






Answer: E

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

23:17

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




1. Well-adapted individuals leave more offspring than do poorly adapted individuals.
2. A change occurs in the environment.
3. Genetic frequencies within the population change.
4. Poorly adapted individuals have decreased survivorship.



A) 2 ? 4 ? 1 ? 3
B) 4 ? 2 ? 1 ? 3
C) 4 ? 1 ? 2 ? 3
D) 4 ? 2 ? 3 ? 1
E) 2 ? 4 ? 3 ? 1







Answer: A

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

23:17

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



A) Technological innovation in agricultural practices will permit exponential growth of the human population into the foreseeable future.
B) Populations tend to increase at a faster rate than their food supply normally allows.
C) Earth changed over the years through a series of catastrophic upheavals.
D) The environment is responsible for natural selection.
E) Earth is more than 10,000 years old.






Answer: B

Natural selection is based on all of the following except

23:17

Natural selection is based on all of the following except 



A) genetic variation exists within populations.
B) the best-adapted individuals tend to leave the most offspring.
C) individuals who survive longer tend to leave more offspring than those who die young.
D) populations tend to produce more individuals than the environment can support.
E) individuals adapt to their environments and, thereby, evolve.







Answer: E

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

23:16

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




A) All variation between individuals is due only to environmental factors.
B) The environment is changing at a relatively slow rate.
C) The population size is large.
D) The population lives in a habitat where there are no competing species present.






Answer: A

Charles Darwin was the first person to propose

23:16

Charles Darwin was the first person to propose 



A) that evolution occurs.
B) a mechanism for how evolution occurs.
C) that Earth is older than a few thousand years.
D) a mechanism for evolution that was supported by evidence.
E) that population growth can outpace the growth of food resources.






Answer: D

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. Lysenko's attempts in this regard were most in agreement with the ideas of

23:16

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. Lysenko's attempts in this regard were most in agreement with the ideas of 




A) Cuvier.
B) Hutton.
C) Lamarck.
D) Darwin.
E) Lyell.





Answer: C

Which of the following is the most accurate summary of Cuvier's consideration of fossils found in the vicinity of Paris?

23:15

Which of the following is the most accurate summary of Cuvier's consideration of fossils found in the vicinity of Paris? 




A) extinction of species yes; evolution of new species yes
B) extinction of species no; evolution of new species yes
C) extinction of species yes; evolution of new species no
D) extinction of species no; evolution of new species yes





Answer: C

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

23:15

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




A) Characteristics acquired during an organism's life are generally not passed on through genes.
B) Spontaneous mutations can result in the appearance of new traits.
C) Only favorable adaptations have survival value.
D) Disuse of an organ may lead to its eventual disappearance.
E) If the giraffes did not have to compete with each other, longer necks would not have been passed on to the next generation.





Answer: A

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

23:15

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




A) Earth is a few thousand years old, and populations are unchanging.
B) Earth is a few thousand years old, and populations gradually change.
C) Earth is millions of years old, and populations rapidly change.
D) Earth is millions of years old, and populations are unchanging.
E) Earth is millions of years old, and populations gradually change.






Answer: A

Which of the following statements best describes theories?

23:14

Which of the following statements best describes theories? 




A) They are nearly the same things as hypotheses.
B) They are supported by, and make sense of, many observations.
C) They cannot be tested because the described events occurred only once.
D) They are predictions of future events.



Answer: B

Estrogens do all of the following EXCEPT:

13:54

Estrogens do all of the following EXCEPT:



A) stimulate the development of secondary sex characteristics in females
B) stimulate growth of facial hair
C) stimulate menstruation
D) help maintain pregnancy
E) prepare the uterus to receive a fertilized egg






Answer: B

The pineal gland produces

13:53

The pineal gland produces



A) thymosin
B) melatonin
C) estrogen
D) insulin
E) cortisol





Answer: B

Insulin causes:

13:52

Insulin causes:



A) a decrease in the concentration of blood glucose
B) an increase in the concentration of blood glucose
C) an increase in blood pressure
D) an increase in the production of glucagon
E) a decrease in blood pressure





Answer: A

Insulin works as an antagonist to:

13:47

Insulin works as an antagonist to:



A) testosterone
B) oxytocin
C) thyroid hormone
D) glucagon
E) thymosin





Answer: D

Which one of the following is NOT an action of the catecholamines:

13:46

Which one of the following is NOT an action of the catecholamines:




A) stimulation of the sympathetic nervous system
B) dilation of the small passages of the lungs
C) increased heart rate
D) decreased blood pressure
E) increased blood glucose levels





Answer: D

Glucocorticoids do all of the following EXCEPT:

13:45

Glucocorticoids do all of the following EXCEPT:




A) help resist long-term stress
B) increase blood glucose levels
C) decrease edema
D) suppress inflammation
E) regulate salt content of the blood






Answer: E

The thyroid gland is located:

13:40

The thyroid gland is located:



A) above the kidneys
B) below the Adam's apple
C) within the mediastinum
D) within the pancreas
E) within the parathyroid glands





Answer: B

Alcohol inhibits the secretion of:

13:40

Alcohol inhibits the secretion of:



A) parathyroid hormone (PTH)
B) antidiuretic hormone (ADH)
C) glucagon
D) oxytocin
E) prolactin (PRL)




Answer: B

Which one of the following is NOT a function of oxytocin:

13:39

Which one of the following is NOT a function of oxytocin:



A) stimulation of uterine contractions
B) stimulation of breast milk ejection
C) stimulation of menstruation
D) postpartum bleeding control
E) labor induction




Answer: C

Growth hormone:

13:28

Growth hormone:



A) is secreted by the thymus gland
B) prevents urine production
C) promotes growth in long bones and skeletal muscles
D) is produced by the thyroid gland
E) results in Cushing's disease if produced in excess






Answer: C

Tropic hormones:

13:28

Tropic hormones:



A) stimulate the pineal gland to secrete hormones
B) stimulate the thymus gland to secrete hormones
C) stimulate other endocrine glands to secrete hormones
D) stimulate nervous tissue
E) stimulate prostaglandins





Answer: C

Negative feedback mechanisms regulate:

13:27

Negative feedback mechanisms regulate:




A) steroid hormones only
B) amino acid-based hormones only
C) prostaglandin hormones only
D) very few hormones
E) most hormones





Answer: E

Being lipid soluble, steroids can do all the following EXCEPT:

13:27

Being lipid soluble, steroids can do all the following EXCEPT:




A) diffuse through the plasma membranes of target cells
B) catalyze cyclic AMP
C) enter the nucleus
D) bind to receptor proteins within the nucleus
E) activate genes to transcribe mRNA for protein synthesis





Answer: B

Prostaglandins are:

13:27

Prostaglandins are:




A) amino acid-based hormones
B) steroid hormones
C) lipid hormones manufactured in cell plasma membranes
D) glycerol hormones
E) target organs





Answer: C

A group of six students has taken samples of their own cheek cells, purified the DNA, and used a restriction enzyme known to cut at zero, one, or two sites in a particular gene of interest.

13:25

A group of six students has taken samples of their own cheek cells, purified the DNA, and used a restriction enzyme known to cut at zero, one, or two sites in a particular gene of interest. 


Their next two steps, in order, should be



A) use of a fluorescent probe for the gene sequence, then electrophoresis.
B) electrophoresis of the fragments followed by autoradiography.
C) electrophoresis of the fragments, followed by the use of a probe.
D) use of a ligase that will anneal the pieces, followed by Southern blotting.
E) use of reverse transcriptase to make cDNA, followed by electrophoresis.





Answer: C

Bacteria that contain the plasmid, but not the eukaryotic gene, would grow

13:24

Bacteria that contain the plasmid, but not the eukaryotic gene, would grow 



A) in the nutrient broth plus ampicillin, but not in the broth containing tetracycline.
B) only in the broth containing both antibiotics.
C) in the broth containing tetracycline, but not in the broth containing ampicillin.
D) in all four types of broth.
E) in the nutrient broth without antibiotics only.





Answer: D

As genetic technology makes testing for a wide variety of genotypes possible, which of the following is likely to be an increasingly troublesome issue?

13:24

As genetic technology makes testing for a wide variety of genotypes possible, which of the following is likely to be an increasingly troublesome issue? 




A) use of genotype information to provide positive identification of criminals
B) using technology to identify genes that cause criminal behaviors
C) the need to legislate for the protection of the privacy of genetic information
D) discrimination against certain racial groups because of major genetic differences
E) alteration of human phenotypes to prevent early disease




Answer: C

Which of the following is one of the technical reasons why gene therapy is problematic?

13:23

Which of the following is one of the technical reasons why gene therapy is problematic? 




A) Most cells with an engineered gene do not produce gene product.
B) Most cells with engineered genes overwhelm other cells in a tissue.
C) Cells with transferred genes are unlikely to replicate.
D) Transferred genes may not have appropriately controlled activity.
E) mRNA from transferred genes cannot be translated.






Answer: D

One successful form of gene therapy has involved delivery of an allele for the enzyme adenosine deaminase (ADA) to bone marrow cells of a child with SCID, and delivery of these engineered cells back to the bone marrow of the affected child. What is one major reason for the success of this procedure as opposed to many other efforts at gene therapy?

13:23

One successful form of gene therapy has involved delivery of an allele for the enzyme adenosine deaminase (ADA) to bone marrow cells of a child with SCID, and delivery of these engineered cells back to the bone marrow of the affected child. What is one major reason for the success of this procedure as opposed to many other efforts at gene therapy? 




A) The engineered bone marrow cells from this patient can be used for any other SCID patient.
B) The ADA-introduced allele causes all other ADA-negative cells to die.
C) The engineered cells, when reintroduced into the patient, find their way back to the bone marrow.
D) No vector is required to introduce the allele into ADA-negative cells.
E) The immune system fails to recognize cells with the variant gene.






Answer: C

Scientists developed a set of guidelines to address the safety of DNA technology. Which of the following is one of the adopted safety measures?

13:22

Scientists developed a set of guidelines to address the safety of DNA technology. Which of the following is one of the adopted safety measures? 



A) Microorganisms used in recombinant DNA experiments are genetically crippled to ensure that they cannot survive outside of the laboratory.
B) Genetically modified organisms are not allowed to be part of our food supply.
C) Transgenic plants are engineered so that the plant genes cannot hybridize.
D) Experiments involving HIV or other potentially dangerous viruses have been banned.
E) Recombinant plasmids cannot be replicated.






Answer: A

Genetically engineered plants

13:22

Genetically engineered plants 




A) are more difficult to engineer than animals.
B) include a transgenic rice plant that can help prevent vitamin A deficiency.
C) are being rapidly developed, but traditional plant breeding programs are still the only method used to develop new plants.
D) are able to fix nitrogen themselves.
E) are banned throughout the world.






Answer: B

Genetic engineering is being used by the pharmaceutical industry. Which of the following is not currently one of the uses?

13:22

Genetic engineering is being used by the pharmaceutical industry. Which of the following is not currently one of the uses? 



A) production of human insulin
B) production of human growth hormone
C) production of tissue plasminogen activator
D) genetic modification of plants to produce vaccines
E) creation of products that will remove poisons from the human body






Answer: E

Let us suppose that someone is successful at producing induced pluripotent stem cells (iPS) for replacement of pancreatic insulin-producing cells for people with type 1 diabetes. Which of the following could still be problems?

13:22

Let us suppose that someone is successful at producing induced pluripotent stem cells (iPS) for replacement of pancreatic insulin-producing cells for people with type 1 diabetes. Which of the following could still be problems? 




I. the possibility that, once introduced into the patient, the iPS cells produce non pancreatic cells
II. the failure of the iPS cells to take up residence in the pancreas
III. the inability of the iPS cells to respond to appropriate regulatory signals



A) I only
B) II only
C) III only
D) I and II
E) all of them




Answer: E

In recent times, it has been shown that adult cells can be induced to become pluripotent stem cells (iPS). In order to make this conversion, what has been done to the adult cells?

13:21

In recent times, it has been shown that adult cells can be induced to become pluripotent stem cells (iPS). In order to make this conversion, what has been done to the adult cells? 



A) A retrovirus is used to introduce four specific regulatory genes.
B) The adult stem cells must be fused with embryonic cells.
C) Cytoplasm from embryonic cells is injected into the adult cells.
D) An adenovirus vector is used to transfer embryonic gene products into adult cells.
E) The nucleus of an embryonic cell is used to replace the nucleus of an adult cell.




Answer: A

The first cloned cat, called Carbon Copy, was a calico, but she looked significantly different from her female parent. Why?

13:21

The first cloned cat, called Carbon Copy, was a calico, but she looked significantly different from her female parent. Why? 




A) The environment, as well as genetics, affects phenotypic variation.
B) Fur color genes in cats are influenced by differential acetylation patterns.
C) Cloned animals have been found to have a higher frequency of transposon activation
D) X inactivation in the embryo is random and produces different patterns.
E) The telomeres of the parent's chromosomes were shorter than those of an embryo.






Answer: D

In animals, what is the difference between reproductive cloning and therapeutic cloning?

13:21

In animals, what is the difference between reproductive cloning and therapeutic cloning? 



A) Reproductive cloning uses totipotent cells, whereas therapeutic cloning does not.
B) Reproductive cloning uses embryonic stem cells, whereas therapeutic cloning does not.
C) Therapeutic cloning uses nuclei of adult cells transplanted into enucleated unfertilized eggs.
D) Therapeutic cloning supplies cells for repair of diseased or injured organs.






Answer: D

A researcher is using adult stem cells and comparing them to other adult cells from the same tissue. Which of the following is a likely finding?

13:20

A researcher is using adult stem cells and comparing them to other adult cells from the same tissue. Which of the following is a likely finding? 




A) The cells from the two sources exhibit different patterns of DNA methylation.
B) Adult stem cells have more DNA nucleotides than their counterparts.
C) The two kinds of cells have virtually identical gene expression patterns in microarrays.
D) The non stem cells have fewer repressed genes.
E) The non stem cells have lost the promoters for more genes.




Answer: A

Which of the following is true of embryonic stem cells but not of adult stem cells?

13:20

Which of the following is true of embryonic stem cells but not of adult stem cells? 



A) They can differentiate into many cell types.
B) They make up the majority of cells of the tissue from which they are derived.
C) They can continue to replicate for an indefinite period.
D) They can provide enormous amounts of information about the process of gene regulation.
E) One aim of using them is to provide cells for repair of diseased tissue.





Answer: B

Reproductive cloning of human embryos is generally considered unethical. However, on the subject of therapeutic cloning there is a wider divergence of opinion. Which of the following is a likely explanation?

13:20

Reproductive cloning of human embryos is generally considered unethical. However, on the subject of therapeutic cloning there is a wider divergence of opinion. Which of the following is a likely explanation? 



A) Use of adult stem cells is likely to produce more cell types than use of embryonic stem cells.
B) Cloning to produce embryonic stem cells may lead to great medical benefits for many.
C) Cloning to produce stem cells relies on a different initial procedure than reproductive cloning.
D) A clone that lives until the blastocyst stage does not yet have human DNA.
E) No embryos would be destroyed in the process of therapeutic cloning.





Answer: B
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