Deck 15: Genetic Variation

Question 1

With regard to alleles that encode different forms of the phenylthiocarbamide taste receptor in humans, which options are genotypes?

A)taster
B)PAV/PAV
C)nontaster
D)PAV/AVI
E)aversion to broccoli

Answer 1

B, D

Question 2

Which of the following statements are TRUE of the 32 allele in the CCR5 gene?

A)It codes for a mutant protein that is completely inactive.
B)It is a deletion that maintains the reading frame.
C)It provides some protection against HIV progression to AIDS in both its heterozygous and homozygous forms.
D)It is an example of a beneficial mutation.
E)It affects the attachment of HIV to an animal cell by altering one of the viral proteins.

Answer 2

A, C, D

Question 3

An individual is heterozygous for a gene if:

A)his or her mother is heterozygous for the gene.
B)his or her father is heterozygous for the gene.
C)he or she developed from a sperm and egg that carried different alleles.
D)he or she developed from a sperm and egg that carried the same allele.
E)only one allele is present in the population.

Answer 3

C

Question 4

Which of the following types of mutations are thought to be the LEAST common?

A)somatic mutations
B)germ-line mutations
C)neutral mutations
D)harmful mutations
E)beneficial mutations

Question 5

Ultraviolet light is a mutagen, but humans need some exposure to it in order to synthesize vitamin D3. The amount of ultraviolet light that penetrates the skin depends on the skin's pigmentation: more melanin (skin pigment) means less penetration. Certain mutations result in decreased melanin production. Such mutations:

A)are harmful only if inherited from both parents.
B)are beneficial only if inherited from both parents.
C)are neutral only if inherited from one parent, not the other.
D)may be harmful in one environment and beneficial in another.

Question 6

Gene A exists in five forms in the human population. Each form, or allele, has a different number of tandem repeats. The alleles are amplified with PCR and then run on a polyacrylamide gel for analysis, yielding the following banding pattern. Which of the lanes in the gel above could represent the alleles found in one individual?

A)All 5 lanes are possible.
B)Lanes 2, 4, and 5 are possible.
C)Lanes 2, 3, 4, and 5 are possible.
D)Lanes 1, 2, 3, and 4 are possible.

Question 7

With regard to alleles that encode different forms of the phenylthiocarbamide taste receptor in humans, which options are phenotypes?

A)taster
B)PAV/PAV
C)nontaster
D)PAV/AVI
E)aversion to broccoli

Question 8

Approximately half of the small insertions or deletions that are found in coding regions of DNA have lengths that are an exact multiple of 3. If the lengths of insertions or deletions in coding regions were completely random, what proportion would be expected to be an exact multiple of 3?

A)1/6
B)1/3
C)2/3
D)1/2
E)None of the answer options is correct.

Question 9

For the majority of SNPs implicated in disease, how does carrying a copy affect a person's risk for acquiring that disease?

A)It increases it dramatically.
B)It increases it moderately.
C)It decreases it dramatically.
D)It decreases it moderately.
E)It decreases it minimally.

Question 10

Which statement about the PiZ allele is NOT true? Consult Figure 15.2 below.

A)The PiZ allele is common in populations of European descent.
B)The product of nonmutant alleles of the gene inhibits elastase in the lungs.
C)Individuals homozygous for the PiZ allele have normal lung elasticity.
D)Normal lung elasticity depends on elastase inhibition.
E)Smokers who are homozygous for the PiZ allele have a shortened life expectancy.

Question 11

The taster phenotype detects glycosinolates, which are antithyroid compounds that, when eaten in large quantities, can interfere with the thyroid's ability to use iodine to produce important thyroid hormones and can result in an enlarged thyroid. The taster phenotype has been associated with reduced risk of thyroid enlargement. Under what conditions might the nontaster phenotype be slightly harmful?

A)when iodine is readily available and incorporated into the diet
B)when glycosinolates are rarely ingested in large quantities
C)when iodine is scarce and dietary iodine is deficient
D)when thyroid enlargement is treatable

Question 12

A polymorphism is a nucleotide pair, gene, or region of the genome:

A)that has recently undergone mutation.
B)that has escaped DNA repair mechanisms sometime in the past.
C)for which every individual is homozygous.
D)that decreases the risk of a genetic disease.
E)that increases the risk of a genetic disease.

Question 13

The phenylthiocarbamide "taster" allele is denoted PAV and the "nontaster" allele AVI. Heterozygous genotypes are almost all tasters. The frequency of nontasters is low in West Africa but high in India. Based on this information, which allele is expected to be more common in India?

A)PAV allele
B)S allele
C)A allele
D)PiZ allele
E)AVI allele

Question 14

In a population of organisms with 3 alleles, how many homozygous genotypes are possible? How many heterozygous genotypes are possible?

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

Question 15

The term "genotype-by-environment interaction" applies to a situation in which:

A)the genotype has the same effect on a phenotype across all environments.
B)the environment has the same effect on a phenotype across all genotypes.
C)some genotypes have bigger effects on a phenotype than other genotypes.
D)some environments have bigger effects on a phenotype than other environments.
E)the effects of genotype and environment on a phenotype are interdependent.

Question 16

Figure 15.1 shows the three alleles for the beta-globin gene. Which of the following statements BEST describes the effect of having the S allele, which codes for sickle-cell anemia?

A)Having the allele is always harmful.
B)Having the allele is always beneficial.
C)The effect depends on whether the allele occurs in its homozygous or heterozygous form.
D)The effect depends on the environment (i.e., whether malaria is present).
E)The effect depends on whether the allele occurs in its homozygous or heterozygous form, and the environment (i.e., whether malaria is present).

Question 17

The phenotype of an individual results from an interaction between:

A)allele frequency and mutation rate.
B)allele frequency and genotype.
C)genotype and mutation rate.
D)genotype and the environment.
E)allele frequency and the environment.

Question 18

If 8 alleles exist in a population, what is the maximum number of copies a normal individual is expected to have?

A)8
B)5
C)4
D)3
E)2

Question 19

A male child is born with an XYY constitution of sex chromosomes. The parents are normal XX and XY individuals, so their child's genotype must be the result of nondisjunction in the formation of one of their gametes. When (and in whom) could the nondisjunction have taken place?

A)in the father in mitosis
B)in the father in meiosis I
C)in the father in meiosis II
D)in the zygote at the first mitotic division
E)in the mother in meiosis I

Question 20

In a population of organisms with 4 alleles, how many homozygous genotypes are possible? How many heterozygous genotypes are possible?

A)3; 4
B)4; 3
C)4; 4
D)4; 6
E)4; 10

Question 21

Figure 15.1 shows the three alleles of the beta-globin gene. Which one of the following genotypes is heterozygous?

A)AA
B)SS
C)CC
D)AS
E)None of the answer options is correct.

Question 22

Harmful mutations are often eliminated in a population because they:

A)are fatal to the individual.
B)are repaired.
C)decrease survival and/or reproduction of the individuals.
D)do not confer a benefit to the individual.

Question 23

Which one of the following BEST describes genotype-by-environment interactions?

A)Genetic and environmental factors combine to influence phenotype.
B)The genotype of an organism determines how that organism will behave in its environment.
C)The environment of an organism determines the genetic make-up of that organism.
D)Under certain circumstances, two organisms with identical genotypes have different phenotypes.
E)Under certain circumstances, two organisms with identical phenotypes have different genotypes.

Question 24

Beneficial mutations can:

A)protect from disease.
B)be repaired.
C)permit an organism to become adapted to its environment.
D)None of the other answer options is correct.

Question 25

"Any difference among individuals that is sufficiently common such that it would almost certainly be present in a group of 50 individuals chosen at random" is the definition of a(n):

A)allele.
B)genotype.
C)polymorphism.
D)restriction site.
E)phenotype.

Question 26

Ultraviolet light can penetrate the skin and damage DNA, and it can also destroy the B vitamin folate needed for bone-marrow maturation and the development of red blood cells. On the other hand, exposure to ultraviolet light is beneficial in the synthesis of vitamin D3, which is important for growth, calcium absorption, and bone development. The amount of ultraviolet light that penetrates the skin depends on the skin's pigmentation: more melanin (skin pigment) means less penetration. Which of the following do you think would BEST describe the pressure of natural selection on human skin pigmentation?

A)a constant pressure for skin to become more and more pigmented
B)a constant pressure for skin to become less and less pigmented
C)a pressure for darker or lighter skin, depending on the intensity of UV in a geographical region

Question 27

When the DNA sequence of the gene that codes for the peptide hormone insulin is compared in two mammals (e.g., humans and rats), most of the sequence differences are synonymous mutations. These far outnumber sequence differences that result in amino acid substitutions. Why might this be?

A)Mutations are random with respect to an organism's needs.
B)Amino acid substitutions often result in proteins that have lost or compromised function and, therefore, are selected against.
C)A DNA sequence is more likely to mutate if the change does not alter the amino acid sequence.
D)Most amino acid substitutions result in a beneficial phenotype that improves fitness and results in a greater number of offspring.
E)Synonymous mutations occur in noncoding DNA sequences.

Question 28

Phenotypic variation among individuals is not always visible and can include which of the following trait characteristics?

A)only developmental differences
B)only physiological differences
C)only behavioral differences
D)developmental and physiological differences
E)developmental, physiological, and behavioral differences

Question 29

An individual is homozygous for a gene if:

A)the mother is homozygous for the gene.
B)the father is homozygous for the gene.
C)they developed from a sperm and an egg that carried the same allele.
D)they developed from a sperm and an egg that carried different alleles.
E)None of the other answer options is correct.

Question 30

Cancer can be caused by mutations. Genetic analysis of a tumor found in a patient we shall call Anna shows that the cell proliferation was triggered by a somatic mutation in the MYC gene, causing this gene to be inappropriately activated. Anna is concerned about passing this cancer on to the children she plans to have in the future. Should she be concerned?

A)Yes, she should worry because tumor growth was triggered by a genetic change, and mutations are passed on through cell divisions.
B)No, this is not something to worry about because mutations in cancer cells cannot be passed on in cell division.
C)No, she should not worry about her children because this did not occur in a germ-line cell.

Question 31

Harmful mutations are always eliminated from the genome in one or a few generations, because they decrease the survival and reproduction rates of the individuals that carry them.

Question 32

The nonmutant allele of the BRCA1 gene helps to suppress tumor formation in women who are heterozygous for the mutation. Women homozygous for BRCA1 nevertheless have a 50% to 70% chance of developing breast cancer before age 70, and the usual reason is that the nonmutant allele is lost or inactivated in a lineage of cells. One possible mechanism for such "loss of heterozygosity" is:

A)germ cells in the affected individual develop a mutation in the nonmutant allele of BRCA1.
B)a somatic mutation in a breast cell inactivates the nonmutant BRCA1 allele.
C)a silent mutation occurs in the nonmutant BRCA1 allele.

Question 33

MOST genetic variation in a population is:

A)obvious.
B)beneficial.
C)harmful.
D)deleterious.
E)neutral.

Question 34

You perform PCR to amplify DNA from a specific small region of a person's genome to detect whether the individual's DNA contains a small deletion in a gene. You separate the PCR products on a gel. The bands in the gel constitute a:

A)genotype.
B)karyotype.
C)phenotype.
D)DNA type.
E)diagnosis.

Question 35

If a population has only one allelic form of the gene, every individual is:

A)conserved.
B)nondisjoined.
C)homozygous.
D)heterozygous.
E)identical.

Question 36

If there are 3 different alleles for a particular gene in a population of diploid organisms, how many different genotypes are possible in the population?

A)2
B)3
C)6
D)9
E)12

Question 37

In the diagram below, the horizontal lines represent DNA strands in a double-stranded molecule, the vertical lines mark the positions of cleavage sites for a particular restriction enzyme, the arrows show the positions of primers used in the polymerase chain reaction (PCR) to amplify the region, and the numbers are the number of nucleotides between successive restriction sites. If this particular DNA molecule is amplified and then cleaved with the restriction enzymes, what size band(s) would be observed in a gel?

A)5 kb
B)5 kb and 3 kb
C)5 kb, 3 kb, and 2 kb
D)3 kb and 2 kb
E)None of the answer options is correct.

Question 38

All of the phenotypes listed below are determined at least partially by genotype. Which trait is MOST likely to be influenced by the environment as well?

A)eye color
B)sex
C)weight
D)Klinefelter syndrome
E)None of the other answer options is correct.

Question 39

Only those mutations that occur in somatic (body) cells can be passed on to progeny.

Question 40

The 32 allele of the CCR5 receptor protein implicated in long-term HIV survival has which of the following properties?

A)It makes it more difficult to be exposed to HIV.
B)It makes it more difficult for HIV to get into its target cells.
C)It makes it more difficult for HIV to replicate inside target cells.
D)It reduces the number of HIV particles that come out of target cells.

Question 41

If an individual is homozygous for a certain allele, it means that the:

A)allele is rare in the population.
B)allele is neutral.
C)individual received the same allele from each parent.
D)allele is beneficial.
E)None of the answer options is correct.

Question 42

While a mutation will not always change the phenotype of an individual, it will always change the genotype.

Question 43

Genetic studies have identified an allele (32) that seems to provide protection against HIV. Which of the following would MOST likely explain the reason why our population has this mutation?

A)Our bodies are designed to protect us against a myriad of pathogens, and the immune system was preparing for future viruses similar to HIV.
B)This mutation likely benefited the human population against some other related pathogen.
C)This mutation was likely induced in the genome by the presence of the HIV virus.
D)This mutation is very likely a neutral mutation.

Question 44

The ability to perceive a bitter taste from certain chemicals, including PTC, has been linked to certain alleles. Which of the following would provide an explanation for the fact that almost all nonhuman primates have the "taster" phenotype, whereas the human population has a significant percentage of "nontaster" phenotypes?

A)The advantage to being able to taste bitter compounds would keep you from eating poisonous compounds, an advantage not needed in the human population anymore.
B)The advantage to not being able to taste bitter compounds means that humans are more likely to eat vegetables and thus live longer than nonhuman primates.
C)Nonhuman primates only eat foods that are not bitter, so the phenotype of tasting bitter compounds was not selected against.
D)Humans needed the ability to not taste bitter compounds, so the mutation happened.

Question 45

Phenotypes:

A)can be subject to environmental conditions.
B)only result from gene transcription.
C)are always expressed in the same way.
D)always result solely from the actions of a single gene.
E)None of the other answer options is correct.

Question 46

Alleles are alternate molecular forms of a gene.

Question 47

What is the difference between a gene and an allele?

A)A gene is a segment of DNA that codes for a protein or RNA; alleles are alternate forms of a gene.
B)An allele is a segment of DNA that codes for a protein or RNA; genes are alternate forms of an allele.
C)An allele is a segment of DNA that codes for a gene; genes are alternate forms of an allele.
D)A gene is a segment of DNA that codes for a protein or RNA; the term allele refers to all of the DNA in a cell or organism.

Question 48

The genotype of an organism constitutes its observable characteristics.

Question 49

Until 20-30 years ago, people with cystic fibrosis (CF) wouldn't live long enough to reproduce. CF is a homozygous recessive condition, leading researchers to think that, over time, the incidence of CF would decrease because the allele would be removed from the gene pool. The results actually indicate that the rate of CF is on the rise. Based on what you know about why certain genotypes and phenotypes persist in a population, which of the following could be a likely explanation for why the rate of CF is on the rise?

A)We are being subjected to more mutations as a population due to more pollution.
B)The population is increasing, and more people mean more mutations.
C)The heterozygous condition is beneficial, much like what we see with sickle cell trait.
D)People are traveling more, so when people from different areas reproduce, more mutations will result.

Question 50

Harmful mutations are always quickly weeded out of a population.

Question 51

When DNA with variable number tandem repeats (VNTRs) is visualized on a gel, the resulting fragments separate according to their:

A)A-T content.
B)G-C content.
C)color.
D)size.
E)shape.

Question 52

Imagine a region of DNA containing a variable number tandem repeat (VNTR) that is found in the genome of koalas. The possible number of VNTR alleles in the population equals the number of:

A)genes.
B)base pairs.
C)times a gene is repeated in tandem along the DNA.
D)times a short noncoding sequence is repeated in tandem along the DNA.
E)restriction fragment length polymorphisms there are in the genome.

Question 53

Imagine that you know two sistersRose and Samboth of whom smoke. Rose has a mutation in the gene for alpha-1 antitrypsin, whereas Sam does not. Which of the following statements is TRUE regarding these sisters?

A)Because both sisters smoke, Rose and Sam will certainly develop emphysema; however, given her mutation, Rose will likely develop a much more serious form of the disease.
B)Given that a mutation in alpha-1 antitrypsin serves a "protective" function against the development of emphysema, Rose will not develop this disease but Sam will.
C)It is possible that neither Rose nor Sam will develop emphysema; however, the fact that both sisters smokeadded to the mutation that Rose carriesincreases their chances of developing this disease.
D)Rose is predisposed to develop emphysema, but if Sam does, this will be a random occurrenceenvironmental factors or lifestyle choices (such as smoking)have not been associated with emphysema.

Question 54

A phenotype always refers to something that you can see with your eyes, such as hair color or eye color.

Question 55

An organism that has two different alleles of a given gene has a _____ genotype.

A)diploid
B)heterozygous
C)dizygous
D)merozygous
E)heteromorphic

Question 56

The figure below represents analysis of blood from a victim of a crime and two suspects. Criminologists created this Southern blot with restriction fragments from a variable number tandem repeat (VNTR) site. Which suspect could be convicted based on these data alone?

A)suspect 1
B)suspect 2
C)both
D)neither

Question 57

Which one of the following statements about restriction fragment length polymorphisms (RFLPs) is CORRECT?

A)RFLPs are the product of cleavage by restriction enzymes.
B)RFLPs are variations in restriction sites that result in DNA being cleaved into different-sized pieces.
C)RFLPs are numerous in the human population.
D)RFLPs can take the place of VNTRs in forensic analyses.
E)All of these choices are correct.

Question 58

Any mutation that has no effect on the organism is considered neutral.

Question 59

Can identical twins be distinguished by DNA typing? By DNA fingerprinting?

A)no; no
B)no; yes
C)yes; no
D)yes; yes

Question 60

Some alleles in the heterozygous state are beneficial, whereas in the homozygous state the same alleles can be harmful.

Question 61

An individual is charged with murder, based on DNA typing of a blood sample that is more than 20 years old. The accused claims that the evidence is no longer relevant because: (Select all that are legitimate arguments, even if unlikely.)

A)20-year-old DNA cannot be typed reliably because it becomes chemically degraded.
B)his DNA has changed because of somatic mutation.
C)the chance of mislabeling an evidence sample from so long ago is too great.
D)a sample that old could no longer discern the accused from his brother.
E)None of the other answer options is correct.

Question 62

In the diagram below, the horizontal lines represent DNA strands in a double-stranded molecule, the vertical lines mark the positions of cleavage sites for a particular restriction enzyme, the arrows show the positions of primers used in the polymerase chain reaction to amplify the region, and the numbers are the number of nucleotides between successive restriction sites. Suppose that the population contains a restriction fragment length polymorphism (RFLP) for this region of DNA. Some DNA molecules contain the site Y, whereas other DNA molecules lack this site. If we use the symbol Y⁺ to denote the allele containing the Y site and Y^- to denote the allele lacking it, then what bands would be observed in the heterozygous genotype Y⁺/ Y^- after amplification and cleavage with the restriction enzyme?

A)5 kb
B)5 kb and 3 kb
C)5 kb, 3 kb, and 2 kb
D)3 kb and 2 kb
E)None of the answer options is correct.

Question 63

On police procedural TV shows, the brilliant detective sometimes gets a DNA sample from a paper coffee cup that the suspect has touched. Is this fantasy made up for television, or is it scientifically sound?

A)It is possible and fairly easy.
B)It might be possible, but would cost hundreds of thousands of dollars.
C)It is fantasy. DNA is destroyed by even mild heat.
D)It is possible but illegal. Discarded coffee cups are regarded as personal property.

Question 64

A genetic polymorphism that eliminates a restriction site in DNA is a:

A)single-nucleotide polymorphism.
B)copy-number variant.
C)mutation in noncoding DNA.
D)single-nucleotide polymorphism, a copy-number variant, or a mutation in noncoding DNA.
E)None of the answer options is correct.

Question 65

The accompanying gel diagram shows the bands obtained for a single variable number tandem repeat (VNTR) in evidence obtained at a crime scene (W) and genomic DNA from four suspects A-D. Which suspect CANNOT be ruled out as the source of the DNA in the sample?

A)suspect A
B)suspect B
C)suspect C
D)suspect D
E)All suspects can be ruled out.

Question 66

SNPs can be detected by microarrays, which are wafer-like substrates to which millions of short stretches of DNA are attached. A microarray consists of many different squares, each one containing a different sequence of single-stranded DNA to which fluorescently labeled strands of DNAs from patients with different SNPs can hybridize. If one square will hybridize with an SNP having a C-G base pair at a particular site and an adjacent square will hybridize with an SNP having a T-A base pair at the same site, which of the following genotypes will hybridize with both squares and make them fluoresce?

A)the homozygous C-G/C-G genotype
B)the homozygous T-A/T-A genotype
C)the heterozygous C-G/T-A genotype
D)None of the answer options is correct; all of the genotypes hybridize with both squares.

Question 67

The genotype of a fetus can be screened for SNPs associated with some diseases.

Question 68

Many SNPs are regarded as "neutral" in the sense of having little or no effect on the likelihood of survival or reproduction of the different genotypes. Could you ever say for certain that a particular SNP is "neutral"?

A)Yes, if the polymorphism is in noncoding DNA.
B)Yes, if the polymorphism is in a transposable element.
C)Yes, if the polymorphism results in synonymous codons.
D)No, because any effect may be too small to detect.
E)No, because you can never prove a negative.

Question 69

The gel diagram below shows the bands obtained for a single variable number tandem repeat (VNTR) in evidence obtained at a crime scene (W) and genomic DNA from four suspects (A-E). Which suspect CANNOT be ruled out as the source of the DNA in the sample?

A)suspect A
B)suspect B
C)suspect C
D)suspect D
E)suspect E

Question 70

Identical twins have the same:

A)phenotype.
B)genotype.
C)karyotype.
D)DNA type.
E)fingerprints.

Question 71

In England, a man who is upset about the amount of dog feces on his lawn supposedly collected hair samples from neighborhood dogs and compared their DNA types with that of the feces, thereby identifying the offending dog (and the negligent owner). It this possible?

A)This is not only possible, but it is fairly easy.
B)This is ridiculous-no way.
C)It might be possible, but it would cost hundreds of thousands of dollars.
D)It's an urban legend, so forget it.

Question 72

Genomic regions with a variable number of tandem repeats (VNTRs) used in DNA typing are highly polymorphic with many different possible genotypes existing in a population. However, matching patterns of bands for any one VNTR between the DNA in a sample and the genomic DNA of a particular individual is not sufficient to establish that the two come from the same individual. The primary reason is that:

A)the DNA sample could be contaminated.
B)the gel may have been handled improperly.
C)the individual in question may have a twin.
D)any one VNTR could match in two individuals by chance.
E)VNTRs have multiple alleles and many possible genotypes.

Question 73

The figure below represents analysis of blood from a victim of a crime and from two suspects. Criminologists created this gel using restriction fragments from a variable number tandem repeat (VNTR) site. Which suspect is definitely innocent?

A)suspect 1
B)suspect 2
C)Both suspects are definitely innocent.
D)Neither suspect is definitely innocent.

Question 74

A weapon (W) left behind at a crime scene is typed for a variable number tandem repeat (VNTR). The DNA from the weapon includes bands from the victim (V) as well as those from the perpetrator. Which of the suspects A-E has VNTR bands that are consistent with those of the perpetrator?

A)suspect A
B)suspect B
C)suspect C
D)suspect D
E)suspect E

Question 75

The accompanying gel diagram shows the bands obtained for a single variable number tandem repeat (VNTR) in evidence obtained at a crime scene (W) and genomic DNA from three suspects A-C. Which suspect CANNOT be ruled out as the source of the DNA in the sample?

A)suspect A
B)suspect B
C)suspect C
D)All suspects can be ruled out.
E)No suspects can be ruled out.

Question 76

Using PCR to amplify the same region of the genome from different individuals can identify differing lengths due to different numbers of repeated sequences referred to as:

A)variable number tandem repeats.
B)restriction fragment length polymorphisms.
C)single-nucleotide polymorphisms.
D)copy-number variations.
E)first-division nondisjunctions.

Question 77

Although a match between the DNA in a sample and the genomic DNA of a particular individual for a single variable number tandem repeat (VNTR) is not sufficient to establish identity, a mismatch is definitive. The primary reason is that:

A)the DNA in the sample must match its origin.
B)VNTRs have multiple alleles and many possible genotypes.
C)the sample might have been contaminated.
D)any band in the sample could have been degraded by nucleases.
E)an individual could show an extra VNTR band merely by chance.

Question 78

A technician who is doing DNA typing uses the polymerase chain reaction to amplify genomic DNA corresponding to three different variable number tandem repeats (VNTRs) in the human genome. The pair of primers for each VNTR is labeled with a different fluorescent dye, so that the bands from one VNTR fluoresce blue, those from another fluoresce red, and those from the third fluoresce green. A sample (W) containing DNA from an unknown individual is compared to genomic DNA from five individuals (A-E). Which individual's VNTR bands match those in the sample?

A)individual A
B)individual B
C)individual C
D)individual D
E)individual E

Question 79

With regard to alleles that encode different forms of beta-hemoglobin in humans and their relation to malaria, which of the following are examples of phenotypes?

A)sickle-cell anemia
B)AA, AS, SS
C)susceptibility to malaria
D)sickled red blood cells
E)allele C

Question 80

An individual (T) is bequeathed a large amount of money, and five people (A-E) present themselves, each claiming to be T's long-lost twin. For the variable number tandem repeat (VNTR) shown below, which individual has genomic DNA that is consistent with the claim?

A)individual A
B)individual B
C)individual C
D)individual D
E)individual E