Genetics Final

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Cystic fibrosis is a human recessive autosomal condition. If two heterozygous parents have two children, what is the probability that they will be born in the order: normal boy and affected girl?

1/16

Consider the following three-factor (trihybrid) testcross: Calculate the number of expected individuals of a+a bb c+c genotype if 1000 progeny result from this testcross

About 46

A mother with blood type AB has a child with blood type B. Give all possible blood types for the father of this child.

A. A, B, AB, O

An individual has the following genotype. Gene loci (A) and (B) are 15 cM apart. What are the CORRECT frequencies of some of the gametes that can be made by this individual?

AB = 7.5%; aB = 42.5%

Which of the following crosses would produce a 3:1 ratio of phenotypes in the next generation?

Aa × Aa

Which of the following crosses would produce a 1:1 ratio of phenotypes in the next generation?

Aa × aa

Consider the following three-point (trihybrid) testcross: Calculate the number of double crossovers you would expect to observe if 1000 progeny result from this testcross assuming a coefficient of coincidence of 0.25.

About 4

Which of the following was NOT one of Mendel's conclusions based on his monohybrid crosses?

Genes are carried on chromosomes.

A testcross includes

one parent who shows the dominant phenotype for one or more genes and a second parent who is homozygous recessive for these genes

A single nucleotide polymorphism can be associated with a disease trait based on its genetic _____ to that trait

phenotype

A couple has six daughters and is expecting a seventh child. What is the probability that this child will be a boy?

1/2

Freckles are caused by a dominant allele. A man has freckles but one of his parents does not have freckles. The man has fathered a child with a woman that does not have freckles. What is the probability that their child has freckles?

1/2

The ability to roll the tongue is caused by a dominant allele. A woman is a "roller," but one of her parents is not. The woman is expecting a child with a man who is a "nonroller." What is the probability that their first child will be a "roller"?

1/2

Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an AB gamete from an AABb individual?

1/2

In rabbits, an allelic series helps to determine coat color: C (full color), cch (chinchilla; gray color), ch (Himalayan; white with black extremities), and c (albino; all white). The C allele is dominant to all others, cch is dominant to ch and c, ch is dominant to c, and c is recessive to all the other alleles. This dominance hierarchy can be summarized as C > cch > ch > c. Indicate the phenotypic ratios expected in rabbits with the cross Ccch × Cch.

3 full color:1 chinchilla

You are studying body color in an African spider and have found that it is controlled by a single gene with four alleles: B (brown), br (red), bg (green), and by (yellow). B is dominant to all the other alleles, and by is recessive to all the other alleles. The bg allele is dominant to by but recessive to br. You cross a pure-breeding brown spider with a pure-breeding green spider. Predict the phenotype of the progeny.

All brown

Which of the following statements is TRUE?

All of these statements are true.

Which term refers to mating between closely related people?

Consanguinity

The R locus determines flower color in a new plant species. Plants that are genotype RR have red flowers, and plants that are rr have white flowers. However, Rr plants have pink flowers. What type of inheritance does this demonstrate for flower color in these plants?

Incomplete dominance

What is the apparent purpose for X inactivation in humans and other mammals?

It allows for the levels of expression of genes on the X chromosome to be similar in males and females.

What is the role of the SRY gene in humans?

It is located on the Y chromosome and initiates the developmental pathway toward the male phenotype.

A eukaryotic diploid cell from an organism with the XX-XO sex determination system has two pairs of autosomes and one X chromosome, shown below. https://utclearn.blackboard.com/courses/1/SP18.BIOL.3250.25247/ppg/d6/brg001884517a/q19-1.png From what type of individual is this cell?

Male

Honeybees have a haplo-diploid sex determination system where females develop from a fertilized egg (they are diploid, having one allele from the female queen and one allele from the male), and males develop from unfertilized eggs (they are haploid, having only one allele from the queen). Assuming that the queen is heterozygous for a particular gene, what is the probability that a female will inherit the recessive allele from her mother? What is the probability that a male will inherit a recessive allele from his mother?

The probability that a daughter will inherit a recessive allele from her mother is 50%; the probability that a son will inherit a recessive allele from his mother is 50%.

In a cross between pure-breeding tall plants with pure-breeding short plants, all of the F1 are tall. When these plants are allowed to fertilize themselves, the F2 plants occur in a ratio of 3 tall:1 short. Which of the following is NOT a valid conclusion from these results?

The tall and short traits assort independently of each other in this cross.

If an organism of genotype Aa is used for a testcross, what is the genotype of the other individual used in the cross?

A low coefficient of coincidence indicates that:

far fewer double crossover recombinant progeny were recovered from a testcross than would be expected from the map distances of the genes involved.

A linkage group

is formed between one or more genes residing close together on a chromosome

If a female Drosophila that is heterozygous for a recessive X-linked mutation is crossed to a wild-type male, what proportion of female progeny will have the mutant phenotype?

If a male bird that is heterozygous for a recessive Z-linked mutation is crossed to a wild type female, what proportion of the progeny will be mutant males?

A chi-square test was performed and indicated that the observed numbers of offspring were significantly different from the expected. Which of the following P-values would support this conclusion?

0.004

A student researcher conducted a cross between Aabb X aaBb. The student found 92 AaBb, 97 Aabb, 101 aaBb, and 89 aabb. Calculate the Chi-Square value based on these findings and input your exact number of your result with at least two decimal points in the answer box

0.1

Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an AABB zygote from a cross AaBb × AaBb?

1/16

You are studying a gene that controls ossicone (horn) length in giraffes. The wild-type long-ossicone allele (L) is dominant to the mutant short-ossicone (l) allele. However the L allele is only 60% penetrant. You cross two heterozygous giraffes. What proportion of offspring would you expect to exhibit the long ossicone phenotype? Assume the penetrance of L applies equally to both homozygotes and heterozygotes.

0.45

Use the following information to answer Questions 44 and 45. A space capsule crashes to Earth with an alien life-form aboard. Two creatures emerge from the capsule, one with green skin and one with yellow skin. The yellow creature soon gives birth to offspring fathered by the green creature, producing 12 green and 8 yellow offspring. Green skin in these diploid creatures is dominant to yellow skin. You are curious to find out if the number of offspring is significantly different from expected Mendelian ratios, so you perform a chi-square test. What is the chi-square value for this cross?

0.8

Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an A_B_ phenotype from a cross aabb × AABB?

1 (100%)

1 full color:1 Himalayan

In animals, the inability to make the pigment melanin results in albinism, a recessive condition. Two unaffected parents, who have decided to have three children, have a first child that has albinism (genotype aa). What is the probability that the second and third children will also have albinism?

1/16

Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an AB gamete from an AaBb individual?

1/4

Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an AaBb zygote from a cross AaBb × AABB?

1/4

A eukaryotic diploid cell from an organism with the XX-XO sex determination system has two pairs of autosomes and one X chromosome, shown below. https://utclearn.blackboard.com/courses/1/SP18.BIOL.3250.25247/ppg/d6/brg001884517a/q21-1.png What is the probability of a gamete from this individual that has the following genotype: alleles A and b, chromosome X?

1/8

Joan is phenotypically normal but had a child with the autosomal recessive disease cystic fibrosis (CF) from a previous marriage. Joan's father has hemophila A, a sex-linked recessive condition where the blood fails to clot properly. Her father has survived due to recent treatment advances. Joan now intends to marry Bill, who is also phenotypically normal but who has a sister, Jill, with CF. Bill's parents are phenotypically normal, and there is no history of hemophilia A in his family. Assume that Joan and Bill do marry and have a child. What is the probability that this child will have CF, but will not have hemophilia A ? (Hint: This problem requires that you utilize concepts from Chapter 3 as well as Chapter 4.)

1/8

2 full color:1 Himalayan:1 albino

A chi-square test is done to test the hypothesis that a set of data represents a F2 ratio of 9:3:3:1. The degree(s) of freedom that should be used is:

A woman is phenotypically normal, but her father had the sex-linked recessive condition of red-green color blindness. If she has children with a man with normal vision, what is the probability that their first child will have normal vision and their second child will be color blind?

3/16

In a cross between AaBbCcDdEe and AaBbccDdee, what proportion of the offspring would be expected to be A_bbC_ddE_? (A_ means AA or Aa.)

3/256

In a cross between AaBbCc and AaBbcc, what proportion of the offspring would be expected to be A_bbcc? (A_ means AA or Aa.)

3/32

Which of the following statements is TRUE?

A testcross can be used to determine whether an individual is homozygous or heterozygous for a dominant allele.

Round seeds (R) is dominant to wrinkled seeds (r), and yellow seeds (Y) is dominant to green seeds (y). A true-breeding pea plant with round and yellow seeds is crossed to a true-breeding plant with wrinkled and green seeds. The F1 progeny are allowed to self-fertilize. What is the probability of obtaining a yellow seed in the F2?

3/4

In a cross between AABbCcDD and AaBbccdd, what proportion of the offspring would be expected to be A_B_C_D_? (A_ means AA or Aa.)

3/8

In Mendel's peas, yellow seeds are dominant to green. A pure-breeding yellow plant is crossed with a pure-breeding green plant. All of the offspring are yellow. If one of these yellow offspring is crossed with a green plant, what will be the expected proportion of plants with green seeds in the next generation?

50%

Assume that A and B are two linked genes on an autosome in Drosophila. A testcross is made where AB/ab flies are crossed to ab/ab flies and the progeny are counted and shown below. However, it is known that the Aa/bb genotype is lethal before the flies hatch and does not appear among the testcross progeny counted. What is the most precise map distance that can be calculated from these data? Aa Bb = 235 aa bb = 225 aa Bb = 20

8.0 cM

Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an A_B_ phenotype from a cross AaBb × AaBb?

9/16

Red-green color blindness is X-linked recessive. A woman with normal color vision has a father who is color blind. The woman has a child with a man with normal color vision.Which phenotype is NOT expected?

A color-blind female

Which of the following is NOT a typical characteristic of human traits that follow an autosomal recessive inheritance pattern?

All of these are characteristic of autosomal recessive inheritance.

A mother with blood type A has a child with blood type A. Give all possible blood types for the father of this child.

B. A, B, AB, O

In humans, blood types A and B are codominant to each other and each is dominant to O. What blood types are possible among the offspring of a couple of blood types AB and A?

B. A, B, and AB only

You are studying body color in an African spider and have found that it is controlled by a single autosomal gene with four alleles: B (brown), br (red), bg (green), and by (yellow). B is dominant to all the other alleles, and by is recessive to all the other alleles. The bg allele is dominant to by but recessive to br. You cross a pure-breeding brown spider with a pure-breeding green spider. Predict the genotype of the progeny.

B/bg

In dogs, black coat color (B) is dominant over brown (b), and solid coat color (S) is dominant over white spotted coat (s). A cross between a black, solid female and a black, solid male produces puppies with only black, solid coats. This same female was then mated with a brown, spotted male. Half of the offspring from this cross were black and solid, and half of the offspring were black and spotted. What is the genotype of the female?

BBSs

While doing field work in Madagascar, you discover a new dragonfly species that has either red (R) or clear (r) wings. Initial crosses indicate that R is dominant to r. You perform three crosses using three different sets of red-winged parents with unknown genotype and observe the following data: Cross Phenotypes 1 72 red-winged, 24 clear-winged 2 12 red-winged 3 96 red-winged Which cross is likely to have at least one parent with the genotype RR?

Crosses 2 and 3

If the characteristic followed in the pedigree is autosomal recessive, what is III-1's genotype?

Definitely heterozygous

The Lyon hypothesis helps us to understand which phenomenon in mammals?

Dosage compensation between males and females

In a germ-line cell from a female grasshopper (XX-XO sex determination system), when do the homologous X chromosomes segregate?

During meiosis

Assume that an individual of AB/ab genotype is testcrossed and four classes of testcross progeny are found in equal frequencies. Which of the following statements is TRUE?

Either b or d could be correct

Freckles are caused by a dominant allele. A man has freckles but one of his parents does not have freckles. What is his genotype?

Heterozygous

The ability to roll the tongue is caused by a dominant allele. A woman is a "roller," but one of her parents is not. What is the woman's genotype?

Heterozygous

Gregor Mendel carried out a cross between two pea plants by taking pollen from a plant that was homozygous for round seeds and dusting the pollen onto the stigma of a plant homozygous for wrinkled seeds. Which of the following would be the reciprocal cross that Mendel had carried out for this experiment?

Homozygous round stigma pollinated with pollen from a homozygous wrinkled plant

Which of the following statements about X inactivation in mammalian females is FALSE?

In an individual with three X chromosomes, one of the three will become inactivated.

In humans there is a genetic disorder that results from a dominant mutation present in a gene located in the pseudoautosomal region of the Y chromosome and on the X chromosome.Which of the following statements is CORRECT?

None of the statements is correct.

A eukaryotic diploid cell from an organism with the ZZ-ZW sex determination system has two pairs of autosomes and a pair of sex chromosomes, Z and W, shown below. https://utclearn.blackboard.com/courses/1/SP18.BIOL.3250.25247/ppg/d6/brg001884517a/q16-1.png A diploid cell from this individual begins to go through meiosis. After the completion of meiosis I, it becomes two cells. One of these two cells now undergoes meiosis II. Which of the following is a possible normal combination of chromosomes in one of the subsequent two cells after the completion of meiosis II?

One chromosome with an a allele, one chromosome with a B allele, one W

In sesame, the one-pod condition (P) is dominant to three-pod (p), and normal leaf (W) is dominant to wrinkled (w). These characteristics assort independently. A one-pod, wrinkled leaf × one-pod, normal leaf cross gave a progeny of 654 one-pod, normal leaf plants and 224 three-pod, normal leaf plants. What are the likely genotypes of the parents in this cross?

Pp ww × Pp WW

In Mendel's peas, purple flower color is dominant to white. From which of the following descriptions can you NOT infer the genotype at this locus completely?

Purple

Women known to be heterozygous or carriers for the sex-linked recessive condition of hemophilia A were studied to determine the time required for their blood to clot. It was found that the time required for their blood to clot varied from individual to individual. The values obtained ranged from normal clotting at one extreme to clinical hemophilia at the other extreme. What is the most probable CORRECT explanation for these findings?

Random X inactivation probably results in individuals with different proportions of cells in their bodies expressing the normal allele at the hemophilia locus.

Round seeds (R) is dominant to wrinkled seeds (r), and yellow seeds (Y) is dominant to green seeds (y). A plant of unknown genotype is testcrossed to a true-breeding plant with wrinkled and green seeds. The offspring produced were 53 round and yellow, 49 round and green, 44 wrinkled and yellow, 51 wrinkled and green. What is the likely genotype of the parent in question?

RrYy

Round seeds (R) is dominant to wrinkled seeds (r), and yellow seeds (Y) is dominant to green seeds (y). A true-breeding plant with round and yellow seeds is crossed to a true-breeding plant with wrinkled and green seeds. What is the genotype of the F1 progeny?

RrYy

The trait shown below is expressed only in males in the family. What is the BEST explanation for the inheritance of this trait?https://utclearn.blackboard.com/courses/1/SP18.BIOL.3250.25247/ppg/d6/brg001884517a/q22-1.jpg

Sex-linked (X-linked) recessive inheritance

Why was the pea plant an ideal plant for Mendel to use?

Simple traits that are easy to identify

Normal males (XY) and Klinefelter males (XXY) both possess only one active X chromosome. Nonetheless there are clearly phenotypic differences between the two. What is the MOST reasonable explanation as to why such differences exist?

Some genes remain active on inactive X chromosomes, so XXY males would produce higher expression levels for these genes compared to XY males.

Women with Turner syndrome (XO) and normal women (XX) are clearly different phenotypically. In addition, the vast majority of XO conceptions abort before birth. However, both XO and XX women have one active X chromosome since the X in XO women remains active and one might expect that they would therefore have similar phenotypes. What is the MOST reasonable explanation for their different phenotypes?

Some genes remain active on the inactive X chromosome, and XX women will have two copies of these genes expressed while XO women only have one copy expressed.

Familial vitamin-D-resistant rickets is an X-linked dominant condition in humans. If a man is afflicted with this condition and his wife is normal, it is expected that among their children, all the daughters would be affected and all the sons would be normal. In families where the husband is affected and the wife is normal, this is almost always the outcome among their children when such families have been studied. Very rarely an unexpected result occurs in such families where a boy is born with the disorder. If the chromosomes of such unusual boys are examined, what might be expected to be found?

Some of the boys are XXY

In poodles, black fur is dominant to white fur. A black poodle is crossed with a white poodle. In a litter of seven, all of the puppies are black. What is the BEST conclusion?

The black poodle is probably homozygous.

In species of birds, males are the homogametic sex and females the heterogametic sex. Which if the following is TRUE in this system of sex determination?

The gender of the offspring is determined by the female parent.

In Labrador retrievers, black coat color is dominant to brown. Suppose that a black Lab is mated with a brown one, and the offspring are 4 black puppies and 1 brown. What can you conclude about the genotype of the black parent? (Assume that B is the allele for black and b is the allele for brown.)

The genotype must be Bb.

A genetic map shows which of the following?

The linear order of genes on a chromosome

A physical map often measures _____, whereas a genetic map measures _____.

distances in base pairs along the chromosome; centiMorgans

A testcross is performed on an individual to examine three linked genes. The most frequent phenotypes of the progeny were Abc and aBC, and the least frequent phenotypes were abc and ABC. What was the genotype of the heterozygous individual that is testcrossed with the correct order of the three genes?

bAc/BaC

A series of two-point crosses among fruit flies is carried out between genes for brown eyes (bw), arc wings (a), vestigial wings (vg), ebony body color (e), and curved wings (cv). The following number of nonrecombinant and recombinant progeny were obtained from each cross: Using these data from two-point crosses, what it the BEST genetic map (in cM) that can be developed?

bw 5 a 24 cv 13 vg with e assorting independently

The ability to curl one's tongue into a U-shape is a genetic trait. Curlers always have at least one curler parent but noncurlers can have one or both parents who are curlers. Using C and c to symbolize the alleles that control this trait, what is the genotype of a noncurler?

Human males, with XY chromosomes are _____ and produce two different kinds of gametes, whereas females with XX chromosomes are _____ and produce only one kind.

heterogametic; homogametic

Could the characteristic followed in the pedigree be caused by an autosomal dominant disease? Why or why not?

https://utclearn.blackboard.com/courses/1/SP18.BIOL.3250.25247/ppg/d6/brg0001f5124e3f225d4/f3q51-1.png No, the offspring of I-1 and I-2 contradict an autosomal dominant inheritance.

If the pedigree is for an autosomal recessive characteristic, which individuals are definitely heterozygous?

https://utclearn.blackboard.com/courses/1/SP18.BIOL.3250.25247/ppg/d6/brg0001f5124e3f225d4/f3q52-1.png I-1, I-2, II-4, II-5, III-1

A pedigree for a particular autosomal recessive human trait is shown below: What is the probability that if III-3 and III-4 marry, their first child will be affected with this trait?

https://utclearn.blackboard.com/courses/1/SP18.BIOL.3250.25247/ppg/d6/brg0001f5124e3f225d4/f3q54-1.png 1/6

The pedigree below shows the segregation of an autosomal recessive trait in humans. Unless there is evidence to the contrary, assume that individuals who marry into the family do not carry the recessive allele. If IV-1 and IV-2 marry, what is the probability that their first child will have this trait?

https://utclearn.blackboard.com/courses/1/SP18.BIOL.3250.25247/ppg/d6/brg0001f5124e3f225d4/f3q55-1.png 1/24

A Barr body is a(n):

inactivated X chromosome, visible in the nucleus of a cell that is normally from a female mammal.

A genome-wide association study helps identify genetic traits by:

linkage of genetic traits to haplotypes within a population

In pedigree analysis, consanguinity refers to:

mating between two closely related parents.

Compared to a physical map, a genetic map:

measures recombinant distance between genes

In pedigree analysis, the proband is:

the individual having the trait or disorder from whom the pedigree is initiated.

A pedigree shows that two parents are phenotypically normal, but one of their four biological children has a typical autosomal recessive trait. The other three children are phenotypically normal. It is very likely that:

the parents are both heterozygous for the trait.

A situation where the coefficient of coincidence is greater than 1.0 would indicate that

there were more double crossovers in the progeny than would be expected based on probability

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