Genetics Exam 4

If there are two alleles of a gene, B and b, and the frequency of the B allele (p) is 0.90, the frequency of the b allele (q) is 0.09. 0.01. 0.10. 0.81. 0.30.

.10

25. If the genotypic frequencies for an allele in a population at Hardy-Weinberg equilibrium are 0.635 homozygous dominants, 0.430 heterozygotes, and 0.125 homozygous recessives, what is the frequency of the recessive allele? A) 0.35 B) 0.65 C) 0.125 D) 0.87

.35

Solid black, black with tan belly, and agouti coat color in mice are all caused by alleles of the agouti gene. All three colors can be true-breeding. When using mice from true-breeding strains: (1) Black — Agouti F1s are all agouti, (2) Black — Black with Tan belly F1s are all black and tan, and (3) Black with Tan belly — Agouti F1s are all agouti. If you were to cross the F1s from (1) with the F1s from (2), what proportion of the resulting offspring would you expect to be black with a tan belly? 1/4 2/4 3/4 all none

1/4

For alleles of genes in Hardy-Weinberg equilibrium, the frequency of heterozygotes is represented as q2. 2pq. p2. q. p.

2pq

With respect to the chromosomes involved in the translocation, 14 and 21, what is the total number of different gametes possible for a heterozygous carrier parent to produce? Hints 4 2 3 6

6

Hemophilia is a recessive, X-linked condition in which a person's blood does not clot properly. Suppose that a man and woman are planning to have a child and want to calculate the risk that their child will have hemophilia. Neither the man nor the woman has the disease, but the woman knows she is a carrier (heterozygous) for the hemophilia allele. 11. If they have a daughter, what are the odds that she will have hemophilia? A) 0 B) ¼ C) ½ D) ¾

A) 0

6. ABO blood type is determined by alleles that show A) complete penetrance. B) incomplete penetrance. C) variable expressivity. D) incomplete penetrance and variable expressivity

A) complete penetrance.

19. In pseudodominance, the dominant allele of a gene is ______, and the recessive allele is _________. A) deleted; expressed B) expressed; masked C) expressed; deleted D) deleted; masked

A) deleted; expressed

22. One difference between epistasis and dominance is that A) epistasis occurs between two different genes while dominance occurs between alleles at one gene locus. B) only epistasis is influenced by environmental interactions. C) dominant traits are completely penetrant, while epistatic interactions may not be. D) dominant traits may show variable penetrance, while epistatic interactions may not.

A) epistasis occurs between two different genes while dominance occurs between alleles at one gene locus.

13. Thirty people are selected for a long-term mission to colonize a planet many light years away from Earth. The mission is successful and the population rapidly grows to several hundred individuals. However, certain genetic diseases are unusually common in this group, and their gene pool is quite different from that of the Earth population they have left behind. Which of the following phenomena has left its mark on this population? A) founder effect B) high rates of mutation C) bottleneck effect D) natural selection

A) founder effect

Chromosomal mutations in prokaryotes or eukaryotes may occur as the result of exposure to chemicals. Therefore, all the choices listed are correct. as the result of exposure to radiation. spontaneously All of the choices listed are correct.

All of above

A man with the A blood type marries a woman with blood type B. Which blood type or types could their children have? A B O A, B, AB, or O

All of the Above

Nondisjunction of chromosomes may result in the loss of one homologous chromosome pair. the addition of a single chromosome. the loss of a single chromosome. the addition of one homologous chromosome pair. All of these

All of these

Which of the following traits is determined by programmed transposition? Mating types in yeast All of these Eye color in Drosophila Pattern baldness in humans None of these

All of these

Which of the following will result in modifications to the expected Mendelian ratios? Gene interaction Epistasis Incomplete penetrance Incomplete dominance All of these

All of these

What is the genetic consequence of a homozygous translocation? An alteration in the linkage relationships of genes Formation of abnormal chromatids following crossing-over Gene duplications and deletions Abnormal pairing during meiosis Inviable gamete formation (semisterility)

An alteration in the linkage relationships of genes

A person with type B blood could safely receive a transfusion of blood from someone with blood type B. AB. O. Both A and C Any of these

B or O

7. Which of the following types of chromosomal mutation cannot revert to the wild-type state as it results in a loss of genetic material? A) Tandem duplication B) Deletion C) Reciprocal interchromosomal translocation D) Intrachromosomal translocation

B) Deletion

12. In certain types of sheep, horns are only expressed in males, never in females although both male and female sheep carry the genes for horns. This is an example of a ___ trait A) Sex-influenced B) Sex-limited C) Sex-linked D) Sex- determined

B) Sex-limited

18. In clover leaves, chevron pattern (a light-colored triangular leaf pattern) is controlled by seven different alleles at a single gene. From this information alone, what can be said about this trait? A) Alleles at this gene show incomplete dominance. B) There is a multiple allelic series with seven alleles that controls chevron pattern. C) This gene shows epistasis. D) One allele at this gene must be completely dominant.

B) There is a multiple allelic series with seven alleles that controls chevron pattern.

21. The order of genes on a particular DNA segment is A-B-C-D-E. After a chromosomal mutation, the order is A-B-C-B-C-D-E. This mutation is a(n) A) translocation. B) duplication. C) inversion. D) deletion.

B) duplication.

14. Neurofibromatosis is a dominantly inherited disease that can show mild, moderate, or severe symptoms. Every individual that inherits the dominant allele shows at least mild symptoms. This means that the disease allele shows A) variable penetrance and complete expressivity. B) variable expressivity and complete penetrance. C) variable penetrance and variable expressivity. D) complete penetrance and complete expressivity

B) variable expressivity and complete penetrance.

Two true-breeding mutant strains of Drosophila have black body color instead of the wild-type gray yellow. When the two strains are crossed, all the F1 flies have wild-type body color. How can these data be interpreted? Recombination occurred. Complementation occurred. The mutations involved are on two different genes. A new mutation occurred in all the offspring. Both B and C

Both B and C

. In Labrador retrievers, three coat color phenotypes are observed: brown, black and yellow. The coat color B gene (B=black & b= brown) is hypostatic to the recessive epistatic E gene. What coat color do you expect for genotype Bbee? A) Black B) Brown C) Yellow D) Black and brown

C) Yellow

3. An isolated population of prairie dogs has longer than average teeth. As a result they can eat more grass with less effort and are better able to survive. The mutation(s) that resulted in longer teeth: A) allowed the teeth to grow longer over several generations until they reached an optimal length for eating grass. B) arose in many members of the population at the same time. C) happened by chance. D) occurred because the prairie dogs needed to be more efficient at eating grass to survive and reproduce.

C) happened by chance.

24. In a chi-square test, a P value equal to 0.04 tells one that A) there is a 4% chance the hypothesis is correct. B) there is a 4% chance the hypothesis is incorrect. C) if the experiment were repeated, chance deviations from the expected values as large as those observed would be seen only 4% of the time. D) if the experiment were repeated, chance deviations from the expected values as large as those observed would be seen at least 96% of the time

C) if the experiment were repeated, chance deviations from the expected values as large as those observed would be seen only 4% of the time.

5. Dicentric or acentric chromosomes may arise in meiosis after crossing over as a result of which kind of chromosomal mutation? A) deletion B) translocation C) inversion D) duplication

C) inversion

Hemophilia is a recessive, X-linked condition in which a person's blood does not clot properly. Suppose that a man and woman are planning to have a child and want to calculate the risk that their child will have hemophilia. Neither the man nor the woman has the disease, but the woman knows she is a carrier (heterozygous) for the hemophilia allele. 10. If they have a son, what are the odds that he will have hemophilia? A) 0 B) ¼ C) ½ D) ¾

C) ½

4. Which of the following is not possible? A) Two blood type A parents having a child that is blood type O B) A blood type A and a blood type B parent having a child that is blood type O C) A blood type AB and a blood type B parent having a child that is blood type A D) A blood type AB and a blood type B parent having a child that is blood type O

D) A blood type AB and a blood type B parent having a child that is blood type O

9. Red-green color blindness in humans is an X-linked recessive trait. What will the progeny ratios be if a carrier female is mated with a normal male? A) All the sons and all the daughters will be normal. B) All the sons will be color blind; all the daughters will be normal. C) Half the sons will be color blind; all the daughters will be carriers. D) Half the sons will be color blind; half the daughters will be carriers

D) Half the sons will be color blind; half the daughters will be carriers

17. Which of the following is not a typical characteristic of extranuclear traits? A) They show uniparental inheritance. B) They cannot be mapped relative to nuclear genes. C) They show non-Mendelian segregation in crosses. D) They are affected by substitution of a nucleus with a different genotype.

D) They are affected by substitution of a nucleus with a different genotype.

16. Pedigrees showing rare recessive traits A) have about half of the progeny affected when one parent is affected. B) have heterozygotes that are phenotypically affected. C) have about 3⁄4 of the progeny affected when both parents are affected. D) often skip a generation.

D) often skip a generation.

Dextral (D) and sinistral (d) shell coiling in the water snail Limnaea peregra is genetically determined by a maternal effect gene. From a population of mixed sinistral and dextral snails, a sinistral female and a dextral male are chosen. All the offspring are dextral. When the female offspring are mated, 50% produce only sinistral snails and the other 50% produce only dextral snails. What were the genotypes of the sinistral female and dextral male that were initially chosen? Dd female and Dd male dd female and DD male Dd female and dd male DD female and dd male dd female and Dd male

Dd female and dd male

Which of the following types of chromosomal mutation cannot revert to the wild-type state? Deletion Inversion Duplication Translocation Any of these may revert to wild-type

Deletion

Which of the following statements regarding familial Down syndrome is false? It accounts for approximately 5% of all Down syndrome cases. If one parent is a translocation heterozygote for chromosomes 14/21, a child born to this parent is as likely to have Down syndrome as he is to be normal. Heterozygous carriers of the Robertsonian translocation that cause familial Down syndrome can have children who are also carriers of the translocation. Heterozygous carriers of the Robertsonian translocation that causes familial Down syndrome can have children who are phenotypically normal and are not carriers of the translocation.

Down syndrome cases. If one parent is a translocation heterozygote for chromosomes 14/21, a child born to this parent is as likely to have Down syndrome as he is to be normal.

Many scientists believe that the evolution of multigene families, such as the genes for hemoglobin, is a result of which type of genetic rearrangement? Inversion Reciprocal translocation Duplication Deletion Nonreciprocal translocation

Duplication

According to the Hardy-Weinberg principle, at equilibrium the allele frequencies are dependent on the genotypic frequencies. True False

False

An allele that exhibits incomplete dominance is usually haplosufficient. True False

False

For eukaryotic organisms, polyploidy is always a lethal condition. True False

False

Inversion loops do NOT form during meiosis in paracentric inversion heterozygotes. Hints True False

False

Mutants that make up a complementation group complement each other. True False

False

Sex-limited traits are caused by genes that are on sex chromosomes. True False

False

The Hardy-Weinberg relationship cannot be used to compute allele frequencies when one or more alleles are recessive. True False

False

Which of the following syndromes is not paired with its causative chromosomal aberration? Cri du chat syndrome - deletion Fragile X syndrome - deletion Huntington disease - duplication Down syndrome - Robertsonian translocation

Fragile X syndrome - deletion

The chemical colchicine prevents the formation of microtubules. It is commonly used in certain experimental procedures to cause changes in cellular chromosomes. Which of the following changes is it likely to be used to create? Induction of mutant aneuploid individuals Induction of mutant polyploid individuals Induction of chromosomal duplications in experimental cell lines Prevention of nondisjunction in cell cultures Induction of chromosomal deletions in experimental cell lines

Induction of mutant polyploid individuals

Which of the following types of analysis allows scientists to visualize an individual's chromosomal makeup? Karyotype analysis Deletion mapping Inheritance analysis Genetic crosses Pedigree analysis

Karyotype analysis

Describe why mitochondrial DNA inheritance is uniparental

Mitochondrial DNA is inherited only through the mother (1 pt). Mother has most of the mitochondria is in the egg

A monosomic cell would produce gametes with how many chromosomes? N N and N+1 N+1 N-1 N and N-1

N and N-1

A child with type AB blood could not be the offspring of a man with type ___ blood. ANSWER: A B AB O

O

Which of the following methods is least useful for assessing levels of genetic variation in populations? DNA sequencing Protein electrophoresis VNTRs RFLP analysis Phenotypic observation

Phenotypic observation

Which of the following is not used to help identify individual chromosomes in a karyotype? Chromosome size Centromere position Point mutations Heterochromatin regions Banding pattern on staining

Point mutations

_________ results in multiple complete chromosome sets. Tandem duplication Nondisjunction Aneuploidy Polyploidy

Polyploidy

Both changes in chromosome number and chromosome structure are believed to have resulted in novel genomes, leading to new species. True False

True

Down syndrome (trisomy-21) is the only human autosomal trisomy in which the individuals may survive to adulthood. True False

True

For a gene with complete dominance, the recessive allele has no effect on the phenotype of a heterozygote. True False

True

In a dihybrid cross with independent assortment of the two genes, any deviation from the Mendelian 9:3:3:1 ratio indicates that the phenotype is the product of the interaction of two or more genes. True False

True

Recessive lethals are often mutations in essential genes. True False

True

Studies performed on identical twins separated at birth have shown that many phenotypes, such as IQ or alcoholism, are influenced by the person's genotype as well as by their environment. True False

True

The color dilution gene in horses is an example of incomplete dominance. Hints True False

True

What two other modes of inheritance (e.g. X-linked recessive) are consistent with the inheritance of this rare disease? Give a one sentence explanation to support each

X-linked dominant (1 pt) or Autosomal dominant (1pt) - all children affected, with one affected parent (1 pt- they can use this explanation for both). Autosomal recessive inheritance- If mother is homozygous recessive and Father heterozygous, children have a high change of getting two copies of the disease gene

In the multiple allelic system for eye color in Drosophila, the phenotypic expression of the alleles depends on a. how much pigment is produced by the alleles present. b. the temperature at which the flies are grown. c. the interaction of alleles from two different genes. d. the sex of the fly. Both A and B

a. how much pigment is produced by the alleles present.

Cultivated wheat is descended from three distinct species, each with a diploid set of 14 chromosomes. Thus, it is an autotetraploid with 28 chromosomes. an allotriploid with 21 chromosomes. an allotriploid with 42 chromosomes. an allohexaploid with 84 chromosomes. an allohexaploid with 42 chromosomes.

an allohexaploid with 42 chromosomes.

Which of the following is the most likely example of codominance? Hints a. A pure-breeding tall plant is crossed to a pure-breeding short plant. All their progeny are of medium height. b. A pure-breeding plant with red flowers is crossed to a pure-breeding plant with white flowers. All their progeny have pink flowers. c. A pure-breeding plant with red flowers is crossed to a pure-breeding plant with white flowers. All their progeny have flowers with some red patches and some white patches. d. A plant with red flowers is crossed to a plant with white flowers. Half their progeny have red flowers, the other half have white flowers.

c. A pure-breeding plant with red flowers is crossed to a pure-breeding plant with white flowers. All their progeny have flowers with some red patches and some white patches.

Which of the following arrangements would yield the greatest reduction in gamete viability? Hints a. An inversion homozygote for a large inversion b. An inversion homozygote for a small inversion c. An inversion heterozygote for a large inversion d. An inversion heterozygote for a small inversion

c. An inversion heterozygote for a large inversion

A dicentric chromosome has two mutations. centromeres. centrosomes. arms. telomeres.

centromeres.

All of the following could result from meiosis in a pericentric inversion heterozygote in which a single crossover occurred within the inversion loop except a _______. chromosome with two centromeres chromosome with some deleted regions chromosome with some duplicated regions completely normal chromosome

chromosome with two centromeres

wo persons who have recessive genetic deafness marry and have 6 children. All the children can hear. The reason they can hear is most likely due to pleiotropy. epistasis. partial penetrance. sex linkage. complementation.

complementation

Manx cats have no tails. When two Manx cats are bred together there is always a one third chance that a kitten will have a tail. When a Manx cat is bred to a cat with a normal tail there is a one-half chance that a kitten will have a tail. Which of the following is the best explanation for this? ANSWER: a. The Manx phenotype is dominant epistatic. b. The Manx genotype exhibits variable expression. c. The Manx phenotype is a result of heteroplasmy. d. The Manx phenotype is dominant, but the allele is a recessive lethal. e. The Manx phenotype is caused by gene interactions.

d. The Manx phenotype is dominant, but the allele is a recessive lethal.

A(n) ___ within a chromosome changes the amount of DNA in that chromosome. translocation inversion deletion point mutation

deletion

A gene that masks the expression of a second gene is haplosufficient. incompletely dominant. epistatic. homeostatic.

epistatic

A human cell containing two sets of 23 chromosomes is euploid. polyploid. aneuploid. haploid. None of these

euploid.

An X-linked homozygous color-blind woman gives birth to a son who is not color blind. He could have normal vision because he has Turner syndrome. has triploidy. has Klinefelter syndrome. has Down syndrome. is XYY.

has Klinefelter syndrome.

If a small region of a chromosome containing a non-essential gene is completely deleted, and an organism has two identical chromosomes with this deletion, then the organism will exhibit pseudodominance. has recessive alleles of those genes. has more heterochromatin. has no alleles of that gene. is dead.

has recessive alleles of those genes.

A mutation event occurs in which two different (nonhomologous) chromosomes end up with a small piece of the other. This mutation is a(n) paracentric inversion. intrachromosomal translocation. intrachromosomal duplication. interchromosomal translocation.

interchromosomal translocation.

Dextral (D) and sinistral (d) shell coiling in the water snail Limnaea peregra is genetically determined. From a population of mixed sinistral and dextral snails, a sinistral female and a dextral male are chosen. All the offspring are dextral. When the female offspring are mated, 50% produce only sinistral snails and the other 50% produce only dextral snails. This form of inheritance is called sex-limited inheritance. partial penetrance. maternal effect. sex-linked inheritance. maternal inheritance.

maternal effect.

A ___ inversion is a rearrangement of DNA that involves the centromere. translocated pericentric submetacentric paracentric

pericentric

A(n) ________ inversion includes the centromere. paracentric pericentric epicentric concentric chromocentric

pericentric

Most monoploid individuals do not survive because their cells cannot divide properly. recessive lethal mutations cannot be masked by dominant alleles. they have only one sex chromosome. they have missing genes. they do not have the appropriate gene dosages.

recessive lethal mutations cannot be masked by dominant alleles.

How many different phenotypes are possible in a one gene/three allele system that displays codominance to each other? Hints three eight two six

six

Seedless bananas are produced from sterile triploid autopolyploid plants. sterile tetraploid allopolyploid plants. fertile diploid plants that are unfertilized. monoploid plants grown from unfertilized seeds. Both C and D

sterile tetraploid allopolyploid plants.

The distinctive fur pattern of Siamese cats results when genes that are responsible for the coat color are influenced by gender. age. X-inactivation. temperature. other genes.

temperature

A In familial Down syndrome resulting from Robertsonian translocation, the affected individual has two copies of the long arm of chromosome 21, one of which is attached to part of chromosome 14. the affected individual has three copies of the long arm of chromosome 21, one of which is attached to part of chromosome 14. the affected individual has three copies of the long arm of chromosome 14, one of which is attached to chromosome 21. the affected individual is missing a copy of chromosome 21. the affected individual has three copies of the complete chromosome 21.

the affected individual has three copies of the long arm of chromosome 21, one of which is attached to part of chromosome 14.

Comb shape in chickens is controlled by the epistatic interaction of two genes, resulting in two different phenotypes. the interaction of two genes with complete dominance, resulting in four different phenotypes. one gene with incomplete dominance, resulting in three different phenotypes. the interaction of three alleles and codominance, resulting in four different phenotypes. None of these

the interaction of two genes with complete dominance, resulting in four different phenotypes.

A Robertsonian translocation is considered non-reciprocal because _______. Hints an uneven number of gametes is produced in each meiosis the smaller of the two reciprocal products of translocated chromosomes is lost for every viable gamete formed, there are two inviable gametes formed trisomies of chromosome 21 are viable, whereas monosomies of the same chromosome are not

the smaller of the two reciprocal products of translocated chromosomes is lost

People affected by diseases caused by mtDNA defects show partial penetrance. typically have cells that are heteroplasmons. inherited them through maternal effect. are sterile. have epistatic respiration.

typically have cells that are heteroplasmons.

Individuals with neurofibromatosis may have a range of phenotypes, from pigment spots on the skin to tumorlike growths. This is an example of gene magnification. X-inactivation. variable expressivity. age of onset. incomplete penetrance.

variable expressivity.