Genetics Exam 2 Study Set

Explain why inversions and reciprocal translocations do not usually cause a phenotypic effect. Also name and explain the two primary circumstances that do cause phenotypic effects.

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Regarding the ABO blood group system in humans. An individual is genetically I(Bi) and yet expresses the O blood type. What is this specific phenomenon in blood types known as? What type of genetic interaction is this an example of? Explain fully how this can be so?

Bombay Phenotype

Many of the color varieties of summer squash are determined by several interacting loci: AA or Aa gives white, aaBB or aaBb gives yellow, and aabb produces green. Assume that two fully heterozygous plants are crossed. Give the phenotypes and frequencies of the offspring.

White, yellow, or green in a 12:3:1 ratio

How many Barr bodies would an individual with XYY genotype possess a. 0 b. 1 c. 2 d. None of the answers are correct

a. 0

Manx cats are heterozygous for a dominant mutation that results in no tails (or very short tails), large hind legs, and a distinctive gait. Homozygous dominant individuals are not viable (they die before birth). A male Manx cat and a female Manx cat produce a live/viable kitten. What is the probability that this viable kitten has a non-manx tail? a. 1/3 b. 1/2 c. 1/4 d. 2/3

a. 1/3

The Notch mutation is a deletion on the X chromosome of Drosophila melanogaster. Female flies heterozygous for Notch have an indentation on the margins of their wings. Notch is lethal in the homozygous and hemizygous conditions. The Notch deletion covers the region of the X chromosome that contains the locus for white eyes, an X-linked recessive trait. Determine the phenotypes and proportions of progeny produced by the crosses listed in the table. (Image in messenger) a. 1/3 red-eyed Notch females, 1/3 wild-type females, and 1/3 white-eyed males b. 1/3 white-eyed females, 1/3 white-eyed Notch females, and 1/3 white-eyed males c. 1/4 Notch males, 1/4 red-eyed Notch females, 1/4 white-eyed females, 1/4 white-eyed males d. 1/3 wild-type males, 1/3 wild-type females, 1/3 white-eyed Notch females e. 1/3 wild-type males, 1/3 red-eyed Notch females, 1/3 white-eyed females What proportion of progeny would you expect from cross A?

a. 1/3 red-eyed Notch females, 1/3 wild-type females, and 1/3 white-eyed males

Trisomy 8 usually leads t o early miscarrieage of a fetus. However, adult individuals have been found with cells with three copies of chromosome 8 in them. How can this be? a. The trisomic cells underwent a mitotic nondisjunction. b. The trisomic cells underwent complete nondisjunction c. The trisomic cells underwent a meiotic nondisjunction d. This individual must be triploid

a. The trisomic cells underwent a mitotic nondisjunction.

Polydactyly is the condition of having extra fingers or toes. Some polydactylous persons possess extra fingers or toes that are fully functional, whereas others possess only a small tag of extra skin. This is an example of a. Variable expressivity b. Complete dominance c. Independent assortment d. Complementation e. Incomplete penetrance

a. Variable expressivity

The F1 mother of these progeny (F2) resulted from a cross between two lies from true breeding lines (P generation). What are the genotypes of these two P generation lines? a. prprcn+cn+ and pr+pr+cncn b. pr+pr+cn+cn+ and prprcncn c. pr+prcn+cn and prprcncn d. pr+prcncn and prprcn+cn e. Eithere a or b could be true

a. prprcn+cn+ and pr+pr+cncn

What proportion of progeny would you expect from cross B?

b. 1/3 white-eyed females, 1/3 white-eyed Notch females, and 1/3 white-eyed males

The sex of birds, some insects, and other organisms is determined by a ZW chromosomal arrangement in which the males have like sex chromosomes (ZZ) and females are ZW (similar to XY in humans). Assume that a recessive lethal allele on the Z chromosome causes death of an embryo in birds. What sex ratio would result in the offspring if a cross were made between a male heterozygous for the lethal allele and a normal female? a. 4:1 male to female b. 2:1 male to female c. 3:1 male to female d. 1:2 male to female e. 1:1 male to female

b. 2:1 male to female

The following information applies to problems 47-50. In fruit floes, the recessive pr and cn mutations cause brown and bright-red eyes, respectively (wild-type flies have bright-red eyes). The double mutant pr cn combination has orange eyes. An F1 female whos is a wild-type is crossed to an orange-eyed male. Their F2 progeny have the following distributions: wild-type 8 brown 241 bright-red 239 orange 12 TOTAL: 500 Which classes are the parental types (not the same thing as the parents)? a. Wild-type and orange b. Brown and bright-red c. Wild-type and brown d. Bright-red and orange e. There is no way to determine this

b. Brown and bright-red

(For numbers 53-55) Shell coiling of the snail Lymnaea peregra results from a genetic maternal effect. An autosomal allele for a right-handed shell, D, called dextral, is dominant over the allele for a left-handed shell, d, called sinistral. In general, snails are hermaphroditic and reproduce as both males and females. However, a pet snail named Martha is sinistral and reproduces only as a female a. DD b. Dd c. dd d. More than one of the above e. None of the above Martha's genotype?

b. Dd

Martha's Dad's genotype?

b. Dd

Which of the following definitions is FALSE? a. Penetrance - The percentage of individuals in the population carrying the allele who actually express the phenotype associated with it b. Expressivity - The percentage of individuals in the population carrying the allele who do not express the phenotype associated with it c. Incomplete dominance - Occurs when the phenotype of the heterozygote is an intermediate of the phenotypes of the homozygotes d. Codominance - Occurs when multiple alleles exist for a given gene and more than one of them is dominant

b. Expressivity - The percentage of individuals in the population carrying the allele who do not express the phenotype associated with it

Crossing over is more likely to occur between genes that are _____ on a chromosome a. Close together b. Far apart c. It depends on the types of genes d. There is no correlation

b. Far apart

Predict the potential effect of the Lyon hypothesis on the retina of a human female heterozygous for the X-linked red-green color blindness trait. a. X chromosome inactivation is influenced by methylation patterns inherited from the parents. When the chromosome with the X-linked red-green color blindness trait is obtained from the mother, then female offspring will not be affected. If its obtained from the father, then they will be affected. b. Females will display mosaic retinas with patches of defective color perception and surrounding areas with normal color perception c. If descendants of the cells with the X-linked red-green color blindness trait participate in the further development of the retina, females will not be affected. d. Females will be fully color blind

b. Females will display mosaic retinas with patches of defective color perception and surrounding areas with normal color perception

In Drosophila, an individual female fly was observed to be XXY and to have white eyes as contrasted with the normal red eye color of wild type. The female's parents were wild type. The mother, however, was heterozygous for the gene for white eyes. Knowing that white eyes are X-linked and recessive, in which parent and at what stage did nondisjunction occur to produce this XXY, white-eyed female fly? a. Meiosis I in the mother b. Meiosis II in the mother c. Meiosis I in the father d. Meiosis II in the father e. More than one of the above

b. Meiosis II in the mother

What is the gene order of linked genes M, N, O, and P, given the following recombination frequencies? M-N: 6% M-O: 12% M-P: 5% N-O: 18% N-P: 1% O-P: 17% a. MOPN b. NPMO c. ONPM d. PNMO

b. NPMO

(for numbers 20-23 below). Male-limited precocious puberty results from a rare, sex-limited autosomal allele (P) that is dominant over the allele for normal puberty (p) and is expressed only in males. Bill undergoes precocious puberty, but his brother Jack and his sister Beth underwent puberty at the usual time, between the ages of 10 and 14. Although Bill's mother and father underwent normal puberty, his two maternal uncles (his mother's brothers) underwent precocious puberty. All of Bill's grandparents underwent normal puberty. Match the most likely genotype(s) for each relative in his family below a. PP b. Pp c. pp d. PP or Pp e. Pp or pp Bill's genotype

b. Pp

Bill's mother

b. Pp

A cross between two pea plants with genotypes PpLl and PpLl results in an F1 generation that is 25% PPLL, 50% PpLl, and 25% ppll. What reason most likely explains why other possible genotypes are not present? a. The genes underwent independent assortment b. The loci of the genes are close together c. The loci of the genes are on different chromosomes d. Crossing over occurred between chromosomes

b. The loci of the genes are close together

Which of the following terms should NOT be used to describe a human with 3 copies of chromosome 12 but a normal set of 2 chromosomes for the remaining sets? a. Aneuploid b. Triploid c. 2n+1 d. Trisomy 12 e. All of these terms can be used to describe the situation

b. Triploid

(For numbers 39, 40, and 41) Suppose a graduate student is studying a loss-of-function mutation in the mouse gene zigzag. Whereas wild type mice have straight tails, zigzag mutant mice have tails with two sharp kinks, so that the tail looks like the letter Z. To determine how the zigzag phenotype is inherited, he performs the crosses listed in the first column of the table below, using parents from true breeding lines. Three possible sets of results from these crosses are shown. Determine the mode of inheritance of the zigzag gene that would yield each result set. (Image in messenger) a. Cytoplasmic inheritance b. maternal effect inheritance c. X-linked recessive inheritance d. Genomic imprinting (maternal allele is inactivated) e. Genomic imprinting (paternal allele is inactivated 39. Set #39

b. maternal effect inheritance

Common red-green color blindness is an X-linked recessive trait. A normal woman whose father is color blind married a normal man and they have one son. What is the probability that the son is color blind? a. 0 b. 1/4 c. 1/2 d. 3/4 e. 1

c. 1/2

Two parents with blood types A and B have a child who has O blood type. What is the chance that their next child will be A (don't consider the Bombay Phenotype)? a. 0 b. 1/2 c. 1/4 d. 3/4 e. 1

c. 1/4

A plant species has 2n = 18 chromosomes. How many chromosomes would you expect to find in a tetrasomic individual of this species? a. 17 b. 19 c. 20 d. 22 e. 36

c. 20

In humans, there are _____ autosomal linkage groups, plus X and Y linkage groups a. 23 b. 46 c. 22 d. 92

c. 22

Assuming there are no heteroplasmic individuals but that people from different families have different DNA, how many different mitochondrial DNAs are there in this entire pedigree? (Image in messenger) a. 2 b. 4 c. 5 d. 6 e. 7

c. 5

Assume that a dihybrid cross is made in which the genes' loci are autosomal, independently assorting, and incompletely dominant. How many different phenotypes are expected in the offspring? a. 3 b. 4 c. 9 d. 12 e. 16

c. 9

The condition that exists when an organism gains or loses one or more chromosomes but not a complete haploid set is known as ______. a. Polyploidy b. Euploidy c. Aneuploidy d. Triploidy e. Trisomy

c. Aneuploidy

What would be the consequence of a diploid gamete (resulting from meiotic nondisjunction) being fertilized by a haploid gamete from the same species? a. Allodiploid b. Allotriploid c. Autotriploid d. Allotetraploid e. Autotetraploid

c. Autotriploid

Which cromosomal change rarely has a phenotypic effect on resulting offspring? a. Insertions b. Unbalanced translocation c. Balanced translocation d. Chromosome loss

c. Balanced translocation

A spineless (no wing bristles) female fly is mated to a male that is claret (dark eyes) and hairless (no thoracic bristles). Phenotypically wild-type F1 female progeny were testcrossed, and the following progeny (1000) total were observed. Which gene is in the middle? (Image in messenger) a. Spineless b. Claret c. Hairless d. Cannot be determined

c. Hairless

Which type of chromosome mutation increases the amount of genetic material for all chromosomes? a. Translocation b. Aneuploidy c. Polyploidy d. Inversion e. Transversion

c. Polyploidy

Given your calculated p-value and expected values based on a null hypothesis with the assumption of linkage, what do you conclude about your observed and expected data? a. The difference between the observed and expected data was significant. We can reject the null hypothesis. The data are consistent with linkage b. The difference between the observed and expected data was insignificant. We can reject the null hypothesis. The data are inconsistent with linkage c. The difference between the observed and expected data was significant. We can reject the null hypothesis. The data are inconsistent with linkage d. The difference between the observed and expected data was insignificant. We cannot reject the null hypothesis. The data are consistent with linkage

c. The difference between the observed and expected data was significant. We can reject the null hypothesis. The data are inconsistent with linkage

What happens physically during the normal process of crossing over? a. Two homologous chromatids break and rejoin at random sites along the chromosome b. The genetic information on one chromatid is replaced by copying genetic information from a homologous chromatid without any physical exchange between the chromosomes c. Two homologous chromatids break and rejoin at precisely the same site along the chromosome so that there is no loss or gain of material on either product d. It is not known what occurs during crossing over

c. Two homologous chromatids break and rejoin at precisely the same site along the chromosome so that there is no loss or gain of material on either product

In Drosophila, sex is determined by a balance between the number of haploid sets of autosomes and the number of _____. a. telomeres b. centromeres c. X chromosomes d. Y chromosomes e. Nucleolar organizers

c. X chromosomes

Martha's Mom's genotype?

c. dd

Bill's father

c. pp

What is the genotype of the heterozygous F1 mother of these F2 progeny? a. prcn/pr+cn+ b. pr+cn/pr+cn c. pr+cn/prcn+ d. prcn+/prcn+ e. prcn/prcn

c. pr+cn/prcn+

What proportion of progeny would you expect from cross C?

d. 1/3 wild-type males, 1/3 wild-type females, 1/3 white-eyed Notch females

In Labrador retrievers, the allele for black coat color (B) is dominant to the allele for brown coat color (b). However, if a lab has two copies of the recessive allele for a pigment-depositing gene (e), it can only have yellow coat color. In a cross of two doubly heterozygous black labs (BbEe x BbEe), what fraction of the next generation would one expect to be yellow? a. 3/16 b. 1/8 c. 1/16 d. 1/4 e. None of the above

d. 1/4

While mapping two genes in Drosophila, you observe 30 recombinants among 200 total offspring. What is the distance between these genes? a. 30 map units b. 6.67 map units c. 60 map units d. 15 map units

d. 15 map units

A newly discovered species of dung beetle has 2n = 16 chromosomes. It mates with a closely related beetle species that has 2n = 12 chromosomes. How many chromosomes would there be in an allotriploid beetle produced from this cross? a. 3 or 17 b. 19 or 25 c. 18 or 24 d. 20 or 22 e. 36 or 48

d. 20 or 22

What is the map distance between the pr and cn genes? a. 20 m.u. b. 0.02 m.u. c. 0.04 m.u. d. 4 m.u. e. 8 m.u.

d. 4 m.u.

The X-linked recessive trait of color-blindness is present in 5% of males. If a mother who is a carrier and father who is unaffected plan to have 2 children, what is the probability the children will both be male and color-blind? a. 50% b. <1% c. 25% d. 6.25% e. None of the above

d. 6.25%

In chickens, a condition referred to as "creeper" exists whereby the bird has very short legs and wings, and appears to be creeping when it walks. If creepers are bred to normal chickens, one-half of the offspring are normal and one-half and creepers. Creepers never breed true. If bred together, they yield two-thirds creepers and one-third normal. Propose an explanation for the inheritance of this condition. a. According to the given data, one would expect the creeper trait to be recessive but dominant lethal. Normal birds would be homozygous for the dominant trait. b. According to the given data, one would expect the creeper trait to be dominant and a dominant lethal. Normal birds would be homozygous for the recessive trait. c. According to the given data, one would expect the creeper trait to be recessive and normal birds are heterozygous. The lethal phenotype is homozygous dominant. d. According to the given data, one would expect the creeper trait to be dominant and a recessive lethal. Normal birds would be homozygous for the recessive trait.

d. According to the given data, one would expect the creeper trait to be dominant and a recessive lethal. Normal birds would be homozygous for the recessive trait.

Set #40

d. Genomic imprinting (maternal allele is inactivated)

Which of the following is primarily responsible for the maternal effect? a. Sperm cells b. Mitochondria c. Maternal phenotype d. Maternal genotype

d. Maternal genotype

The fruit fly Drosophila melanogaster has a haploid chromosome number of n=4 and 2n=8. Chromosome IV in this species is a tiny autosome. Flies trisomic for the chromosome IV are fertile and have no apparent defects. The eyeless (ey) and gawky (gw) loci are tightly linked on chromosome IV. Loss-of-function ey- and gw- alleles are recessive to ey and gw respectively. Flies homozygous for ey- lack eyes, and flies homozygous for gw- have disrupted circadian rhythms. Consider a male fly trisomic for chromosome IV, with each of the three chromosome copies bearing different allele combinations for these two loci: (Image in messenger) If this trisomic fly is the progeny of a male fly of genotype (ey+ey-, gw+gw-) crossed to a female fly with genotype (ey-ey-, gw-gw-), what can you conclude about the events that led to its formation? a. Nondisjunction occurred in the female parent at the meiosis I division to produce an (n+1) egg that fused with a normal (n) sperm. b. Nondisjunction occurred in the male parent at the meiosis II division to produce an (n+1) sperm that fused with a normal (n) egg. c. Nondisjunction occurred in the female parent at the meiosis II division to produce an (n+1) egg that fused with a normal (n) sperm. d. Nondisjunction occurred in the male parent at the meiosis I division to produce an (n+1) sperm that fused with a normal (n) egg.

d. Nondisjunction occurred in the male parent at the meiosis I division to produce an (n+1) sperm that fused with a normal (n) egg.

Which of the following is not correct concerning epistatic interactions? a. They can be associated with enzymatic pathways b. They produce variations in the expected 9:3:3:1 ratio of a dihybrid cross c. They involve a gene at one locus masking the effects of a gene at a different locus d. They always result in a 9:7 ratio of a dihybrid cross e. They are due to gene interactions

d. They always result in a 9:7 ratio of a dihybrid cross

Referring to question 6, how would you describe the configuration of alleles before recombination (c+d+ and cd)? a. repulsion b. complementation c. epistasis d. coupling e. homozygous

d. coupling

Given the following observed and expected data, using chi-squared calculate a p-value that corresponds with this data: (Image in messenger) a. 0.95>p>0.9 b. 0.9>p>0.75 c. 0.75>p>0.5 d. 0.25>p>0.1 e. 0.05>p

e. 0.05>p

Crossing two yellow mice results in 2/3 yellow offspring and 1/3 nonyellow offspring. What percentage of offspring would you expect to be nonyellow if you crossed two nonyellow mice? a. 25% b. 33% c. 66% d. 75% e. 100%

e. 100%

The Drosophila genes for white eyes (w), cut wings (ct), and tan body (t) lie at map positions 2.0, 20.0, and 28.0 respectively. Of 1000 progeny, 6 are double crossovers. What is the degree of interference? a. -1.4% b. 2.4% c. 14.4% d. 41.7% e. 58.3%

e. 58.3%

An individual with type A blood and an individual with type B blood mate and have offspring. What blood type is not possible in their offspring (don't consider the Bombay Phenotype)? a. Type O blood b. Type A blood c. Type B blood d. Type AB blood e. All blood types are possible

e. All blood types are possible

The semisterality of genotypes heterozygous for a reciprocal translocation results from the lethality due to the chromosomal abnormalities produced by a. Alternate segregation b. Adjacent-1 segregation c. Adjacent-2 segregation d. A and B e. B and C

e. B and C

Assume that genes c and d are located on the same chromosome. On one chromosome alleles c+ and d+ are found, while the homologue contains alleles c and d. Which of the following would be evidence of a recombination event? a. Alleles c+ and d+ together on one chromosome b. Alleles c and d together on one chromosome c. Alleles c+ and d together on one chromosome d. Alleles c and d+ together on one chromosome e. Both alleles c+ and d together on one chromosome and alleles c and d+ together on one chromosome

e. Both alleles c+ and d together on one chromosome and alleles c and d+ together on one chromosome

Set #41

e. Genomic imprinting (paternal allele is inactivated

Two chromosomes have the following segments, where the * represents the centromere: KLM*NOPQR STUV*WXYZ What type of chromosome mutation would result in the following chromosomes: KLM*NOPQR STXW*VUYZ a. Deletion b. Tandem duplication c. Paracentric inversion d. Reverse duplication e. Pericentric inversion

e. Pericentric inversion

Bill's sister Beth

e. Pp or pp

Which of the following types of inheritance have the feature that an affected male could have all affected daughters but no affected sons? a. Autosomal recessive b. Autosomal dominant c. Y-linked d. X-linked e. X-linked dominant

e. X-linked dominant