Genetics Final Notecards

A male mouse of genotype A/a . B/b is testcrossed multiple times. Overall, these testcrosses produce 11 mice of phenotype A B, 81 A b, 77 a B, and 14 a b. Based on these data, the genotypes of the male mouse's parents are most likely:

Ab/Ab and aB/aB.

Ascospores from a cross a X b c (all auxotrophic markers) are analyzed. If genes a and b are linked, 10 map units apart, but gene c is located on a different chromosome, what proportion of ascospores is expected to be a+b+c+?

About 22.5%

A dihybrid in cis is crossed to a dihybrid in trans (the two genes of interest, A and B, are linked). What proportion of the progeny is expected to be homozygous recessive with respect to the two genes of interest?

6.25%

How many different DNA molecules eight nucleotide pairs long are theoretically possible?

65,536

A plant is heterozygous at three loci. How many different gamete genotypes can it theoretically produce with respect to these three loci?

8

In a trihybrid, how many different gamete genotypes can be produced with respect to the three genes of interest?

8

In a linear tetrad analysis, the second division segregation (MII) frequency of the cyh locus is 16%. The map distance from this locus to its centromere is:

8 mu

Which of the following is a component of DNA?

Guanidine

A female Drosophila with the mutant phenotype a is crossed to a male who has the mutant phenotype b. In the resulting F1 generation all females are wild-type and all males have the a mutant phenotype. Based on these results, we can conclude that the mode of inheritance of the phenotypes of interest is:

recessive for both a and b.

In a haploid fungus similar to Neurospora, a red-colored mutant is crossed to an alanine-requiring mutant. Assuming independent assortment, what proportion of the spores produced will be alanine-requiring?

1/2

Mendel crossed Y/Y;R/R (yellow wrinkled) peas with y/y;r/r (green smooth) peas and selfed the F1 to obtain an F2. What proportion of the F2 individuals were pure-breeding?

1/4

Two genes, A and B, are linked. An individual of genotype A b/A b is crossed to one that is a B/a B. The F1 is selfed and an F2 is obtained. Which of the following ratios most likely represents the phenotypic ratio observed in this F2?

51:24:24:1

In maize, the genes W and D are so tightly linked that virtually no crossovers occur between them. A dihybrid W d/w D is testcrossed to w d/w d. The percent of progeny with W-/D- phenotype will be:

0

A laboratory mouse homozygous for an RFLP marker is mated to a wild mouse that is heterozygous for that marker. One of the heterozygous individuals resulting from this cross is mated back to the wild parent. What proportion of the offspring will have the same RFLP pattern as the original laboratory mouse?

1/2

"Dumpy" is a commonly used mutant phenotype in the nematode worm C. elegans. Two "Dumpy" individuals are crossed to each other and this cross produces 210 "Dumpy" and 68 wild-type individuals. If one of the "Dumpy" individuals used in this cross was mated with a wild-type, what ratio of "Dumpy": wild-type would we observe in the offspring?

1:1

A very common type of red/green colorblindness in humans is caused by a mutation in a gene located on the X chromosome. Knowing that the mutant allele is recessive to the wild-type, what is the probability that the son of a woman whose father is colorblind is going to also be colorblind?

50%

The maximum second division segregation frequency normally possible is

66.7%

A rare, curly winged mutant of Drosophila was found in nature. A mating of this fly with a true-breeding, normal laboratory stock produced progeny in the ratio 1 curly winged to 1 normal (both sexes had the same ratio). All curly winged progeny of this cross, mated with normal progeny of the same cross, again yielded 1 curly winged to 1 normal fly. When mated with one another, the curly winged progeny of the first cross yield a progeny of 623 curly: 323 normal. This ratio strongly suggests which of the following:

Flies homozygous for the curly allele are lethal and never survive.

In unordered tetrad analyses of two linked loci, a nonparental ditype is an indication of:

Four chromatid double crossover

The nuclear genome of a mouse nerve cell is compared to that of a mouse skin cell. What differences can we expect to see between these two cells' nuclear genomes?

The two cells have the same genome; there will be no differences.

In the cross mt+al+ X mt al, the mt locus shows an MII frequency of 12%, the al locus an MII frequency of 10%. Most asci were parental ditypes. The order of loci is:

centromere- al-mt

Wild cats (Felis silvestris) and common mice (Mus musculus) are diploid. In wild cats 2n = 38, while in common mice 2n = 40. Based on this information, we can conclude that wild cat cells have

fewer DNA molecules than common mouse cells.

In Labrador retrievers, black color coat (B/-) is dominant to brown color coat (b/b). A breeder crosses two black individuals who have previously produced some brown puppies. If the cross produces six puppies: a) What is the probability that the first born will be brown? b) What is the probability that four of them will be brown and two will be black? c) What is the probability that at least one of them will be brown?

(a) Both parents must be heterozygotes B/b because they have previously produced brown puppies. The probability that they produce a brown puppy is therefore . (b) Each pup has chance of being black and chance of being brown. The order in which the brown and black puppies are born does not matter, so there are 15 different permutations of 4 brown+2 black (5!). Hence, the probability is: 15((1/4)(1/4)(1/4)(1/4)(3/4)(3/4))=135/4096=3.3% (c) In this case, the only instance that does not satisfy the condition is the case in which all puppies are black. The probability of this event Modify Remove is (3/4)6 = 729/4096 = 17.8%. Therefore, the probability of obtaining at least one brow puppy is 1 - (729/4096) = 82.2%.

Consider the following pedigree of a rare autosomal recessive disease. Assume all people marrying into the pedigree do not carry the abnormal allele. (a) If individuals A and B have a child, what is the probability that the child will have the disease? (b) If individuals C and D have a child, what is the probability that the child will have the disease? (c) If the first child of C * D is normal, what is the probability that their second child will have the disease? (d) If the first child of C * D has the disease, what is the probability that their second child will have the disease?

(a) Choosing M for unaffected and m for the disorder, male B must be M/m, and female A has a 2/3 chance of being M/m. The overall chance of an affected child is 1 * 2/3 * 1/4 = 1/6. (b) If C's mother A is heterozygous, C stands a 1/2 chance of being heterozygous. D's mother must be heterozygous, and D stands a 1/2 chance of inheriting that heterozygosity. The overall chance of an affected child is 2/3 * 1/2 * 1 * 1/2 * 1/4 = 1/24. (c) The probability is still 1/24. (d) Now that we know individuals C and D must both be M/m, the chance of the second child being m/m is 1/4.

In a particular species of plants, flower color is dimorphic: Some individuals have red flowers, whereas others have yellow flowers. If flower color is controlled by a single gene with two alleles (cred and cyellow): (a) What would be the simplest way to determine which allele is dominant? (b) What will be the genotypic ratio in the offspring of a cross between a monohybrid and a pure-breeding individual?

(a) Crossing a pure-breeding red to a pure-breeding yellow individual, and assessing the phenotype of the monohybrid produced. If it makes red flowers, then cred is dominant, if it makes yellow flowers, then cyellow is dominant. (b) 1:1; half of the offspring will be heterozygous and half will be homozygous like the pure-breeding parent.

Suppose that red flower color (RR or Rr) is dominant to white flower color (rr) in Petunia. A friend has a Petunia plant with red flowers and wants to determine whether the plant is RR or Rr. (a) What cross could you perform to help your friend determine the genotype of his Petunia plant? (b) How will this cross help you determine the genotype of your friend's red flowered petunia? That is, how will the results from this cross differ if the red-flowered petunia is RR vs. Rr?

(a) Perform a testcross (test the red Petunia to a genotypically rr Petunia) (b) You will observe different segregation in the testcross progeny, depending on the genotype of the red petunia. If the red petunia is RR, then all testcross progeny will be red; If the red petunia is Rr, then of the testcross progeny will be red (Rr) and will be white (rr).

Mendel's Y/y; R/r dihybrid pea plants were the F1 of the cross between a double homozygous dominant and a double homozygous recessive. If we testcrossed these dihybrids, what proportion of the offspring would be recombinant and phenotypically resemble the F1 dihybrid?

0%

In maize, two plants that are both heterozygous for the recessive alleles a and b are crossed. What frequency of double-mutant progeny will appear if a and b are 7.2 map units apart, and both parents carry a and b in repulsion (trans)?

0.001296

A corn plant of genotype A/a;B/B;C/c;D/d;E/e;f/f;G/g is selfed. What is the probability of producing a completely homozygous individual out of all possible offspring?

0.031

The maize genes sh and bz are linked, 40 map units apart. If a plant sh+bz/sh bz+ is selfed, what proportion of the progeny will be sh bz/sh bz?

0.04

The linkage relationships among the four mouse genes, A, B, C, and D, are shown in the map below. A 30mu B C 15mu D

0.064

Ascospores from a cross leu-2 X ad-7 met-3 (all auxotrophic markers) are plated on minimal medium (no adenine, leucine, or methionine). If the three genes are unlinked, what proportion of ascospores is expected to grow into a colony on this medium?

0.125

In a haploid organism, the loci leu and arg are linked, 30 map units apart. In a cross: leu+arg X leu arg+, what proportion of progeny will be leu arg?

0.15

Out of 800 progeny of a three-point testcross, there were 16 double crossover recombinants, whereas 80 had been expected on the basis of no interference. The interference is:

0.155

The F, G, and H loci are linked in the order written. There are 30 map units between F and G, and 30 map units between G and H. If a plant F G H/f g h is testcrossed, what proportion of progeny plants will be f g h/f g h if there is no interference?

0.245

The mouse autosomal genes B and S are linked and 38 map units apart. Genotypes B S/B S and b s/b s are intercrossed and the F1 is testcrossed to b s/b s. The proportion of B-S- progeny will be:

0.31

Fruit color in a particular plant is controlled by a set of three QTLs (quantitative trait loci, or "polygenes") that work in an equal and additive manner. Each QTL has two alleles (i.e., A and a); each allele represented by a capital letter produces "one dose" of yellow pigment, while alleles represent with lower case letters do not produce any pigment at all. A trihybrid plant (A/a; B/b; C/c) is selfed. Assuming no effects of the environment, what proportion of the offspring will have the same fruit colour phenotype as the dihybrid parent?

0.312

A corn plant known to be hybrid for three linked genes is testcrossed. The progeny phenotypes and frequencies are: The coefficient of coincidence in this genomic region is: +++ 74 abc 70 a++ 44 +bc 50 ++c 4 ab+ 2 a+c 368 +b+ 388

0.40

In Drosophila, the genes crossveinless-c and Stubble are linked, about 7 map units apart on chromosome 3. cv-c is a recessive mutant allele of crossveinless-c (cv-c+ is wild type), while Sb is a dominant mutant allele of Stubble (Sb+ is wild type). A dihybrid female Drosophila with genotype cv-c Sb+/cv-c+Sb is testcrossed. The proportion of phenotypically wild-type individuals in the progeny of the testcross will be:

0.465

What is the maximum number of heterozygous genotypes that could be produced by monohybrid self?

1

In a diploid invertebrate, genes D and E are closely linked. Single crossovers between these two genes occurs only in one out of 40 meioses, and multiple crossovers are never observed. If an individual has the genotype D e/d E, what percentage of its gametes are expected to be recombinant (either DE or de)?

1.25%

The following pedigree concerns the autosomal recessive disease phenylketonuria (PKU). The couple marked A and B are contemplating having a baby but are concerned about the baby having PKU. What is the probability of the first child having PKU? Unless you have evidence to the contrary, assume that a person marrying into the pedigree (i.e., not a descendant of the two parents at the top of the pedigree) is not a carrier. The filled-in individuals have PKU. Blank circle- dark square Blank circle-blank square blank circle blank square Black circle.... a and b are.

1/12

The wild-type eye color in the fruitfly Drosophila melanogaster is dark red, as a result of a mixture of bright red and brown pigments. "Enzyme A" is encoded by the "a" gene, and is required to synthesize the bright red pigment. Lack of red pigment results in a somewhat brown eye color. You cross two fruitflies who are heterozygous for a recessive mutation that completely inactivates the "a" gene. What proportion of their offspring will have a recessive eye color phenotype?

1/4

Mendel crossed Y/Y;R/R (yellow wrinkled) peas with y/y;r/r (green smooth) peas and selfed the F1 to obtain an F2. In the F2 what proportion of the yellow wrinkled individuals were pure-breeding?

1/9

The pedigree below shows the inheritance patterns of two extremely rare, independent genetic conditions (represented with black and grey symbols, respectively). If individuals A and B have a child, what is the probability that it will have both conditions?

1/9

In an unordered ascus analysis of the Neurospora loci cot and fl, there were 42 tetratypes and 8 nonparental ditypes out of a total of 290 asci. These loci are linked at a distance of:

10 m.u

What is the probability that individual A is a heterozygous with respect to the condition depicted in the pedigree? 1 black circle-1 blank square ----------------1 black square 1 black circle 1 blank square

100%

Meiosis I is about to start in a cell of a plant in which 2n = 18. At this stage, the cell has

18 chromosomes, and a total of 36 chromatids.

If genes assort independently, a testcrossed dihybrid characteristically produces progeny phenotypes in the ratio:

1:1:1:1

Two genes, A and B, are linked. An individual of genotype A b/A b is crossed to one that is a B/a B. The F1 is testcrossed. Which of the following ratios most likely represents the phenotypic ratio observed in the progeny of this testcross?

1:4:4:1

A male Drosophila melanogaster has the genotype A/a; B/b; C/c; XD/Y. How many different sperm genotypes can it produce through meiosis of one single pre-gametic (2n) cell?

2

In Neurospora, a, b, and c are auxotrophic mutants (require particular compounds for growth). The mating a b+ X a+b gives 5% prototrophs (grown on unsupplemented medium). The mating b+c X b c+ gives 2.5% prototrophs, and the mating a+c X a c+ gives 2.5% prototrophs. Assuming complete interference prevails in the chromosome segment in question, what percentage of prototrophs would you expect in the mating a+b c+ X a b+c? (The order of mutations is not necessarily a,b,c: It can be determined on the basis of the two-point crosses above.)

2.5%

In a plant in which 2n = 24, what is the total number of chromosomes present at the end of interphase?

24

A phenotypically normal woman is heterozygous for the recessive Mendelian allele causing phenylketonuria, a disease caused by the inability to process phenylalanine in food. She is also heterozygous for a recessive X-linked allele causing red-green colorblindness. What percentage of her eggs will carry the dominant allele that allows normal processing of phenylalanine and the X-linked recessive allele that causes colorblindness?

25%

In the offspring of a dihybrid self, what percentage of the individuals are themselves dihybrid?

25%

A trihybrid cross is a cross between two individuals who are heterozygous for three genes. Assuming independent assortment and complete dominance, what phenotypic ratios would be observed in F1?

27:9:9:9:3:3:3:1

In one strand of DNA the nucleotide sequence is 5'-ATGC-3'. The complementary sequence in the other strand must be

3'-TACG-5'.

Two pure-breeding mutant plants were crossed: One had small leaves (wild-type leaves are large) and the other made pink flowers (wild-type flowers are purple). All F1 individuals had small leaves and purple flowers. Assuming independent assortment, what proportion of the F2 individuals are expected to be phenotypically wild-type?

3/16

Two pure lines obtained from Mendel's experiments are crossed to each other. The first line makes green smooth seeds (peas), and the second line has white flowers. All F1 individuals have purple flowers and produce yellow wrinkled seeds. What proportion of the F2 plants should have purple flowers and make green wrinkled seeds?

3/36

A leucine-requiring mutant strain of haploid yeast is crossed to a cysteine-requiring mutant strain. Assuming independent assortment, what proportion of the spores produced will be mutant?

3/4

Fruit color in a particular plant is controlled by a set of three QTLs (quantitative trait loci, or "polygenes") that work in an equal and additive manner. Each QTL has two alleles (i.e., A and a); each allele represented by a capital letter produces "one dose" of yellow pigment, while alleles represent with lower case letters do not produce any pigment at all. If a trihybrid plant (A/a; B/b; C/c) is testcrossed, what proportion of the offspring will have a fruit colour phenotype that is different from both the trihybrid and the tester parents? (Assume no environmental effects).

3/4

A corn plant of genotype A/a;B/B;C/c;D/d;E/e;f/f;G/g is selfed. How many different completely homozygous genotypes could be produced?

32

If two mice of genotype F/f;G/g;H/h;I/i;J/j are repeatedly mated, how many different phenotypes will be found in the progeny? (Assume complete dominance for all genes.)

32

A sample of normal double-stranded DNA was found to have a guanine content of 18%. What is the expected proportion of adenine?

32%

If a plant of genotype A/a;B/b;C/c;D/d is selfed and the genes assort independently, how many different genotypes will be found among the progeny?

4

In mountain rabbits, the EL-1 gene is located on chromosome 3. Four alleles of this gene have been identified in the population. With respect to EL-1, what is the maximum number of genotypes in the progeny of a single cross between two mountain rabbits?

4

A pure line of Guinea pigs with genotype A/A; b/b is crossed to a pure line with genotype a/a; B/B. The F1 male and female Guinea pigs are crossed to each other to generate the F2. What proportion of the F2 individuals are the result of a recombinant egg being fertilized by a recombinant sperm?

4/16

The following pedigree shows the inheritance of a mild, but very rare condition in Siberian Husky dogs. If individuals 1 and 2 are crossed, what is the probability that they will produce an affected pup?

4/36

A couple are both heterozygous for the autosomal recessive disease cystic fibrosis (CF). What is the probability that their first child will either be a boy or have CF?

5/8

A wild-type strain of haploid yeast is crossed to a mutant strain with phenotype d. What phenotypic ratios will be observed in the progeny?

50% wild-type and 50% mutant (d)

Mice (Mus musculus) have 40 chromosomes per diploid cell (2n=40). How many double- stranded DNA molecules, and how many chromosomes are there in a mouse cell that is in the G2 stage of the cell cycle?

80 DNA molecules and 40 chromosomes

The three genes, D, E, and F, are closely linked as indicated on the map below. In this region of the genome, there is no interference (the coefficient of coincidence is 1). D 5mu E 10mu F If a trihybrid with genotype ABC/abc is testcrossed, what is the expected percentage of "parentals" within the progeny?

85.5%

Cystic fibrosis is an autosomal recessive condition. If the parents of a boy with cystic fibrosis have two more children, what is the probability that both of these children will be unaffected?

9/16

In the cross between a female A/a;B/b;c/c;D/d;e/e and male A/a;b/b;C/c;D/d;e/e, what proportion of the progeny will be phenotypically identical to the female parent? (Assume independent assortment of all genes and complete dominance.)

9/64

Neurospora loci d and f are located on the same chromosome. The d locus always segregates at MI, while the e locus segregates at MII at a frequency of 10%. Assuming complete interference, the expected frequency of parental ditypes in the progeny of a cross d+e+ X d e is:

90%

An SSLP is located 2 map units away from the X-linked locus responsible for red-green color blindness. Three alleles of this SSLP are known: "4 repeats," "5 repeats," and "7 repeats." A woman with normal colour vision, but whose father is color blind, marries a man with normal vision, and they have a son. Given the SSLP genotypes of the various family members shown above, what is the probability that the couple's son is color blind? Modify Remove Family member SSLP genotype Family member SSLP genotype Woman's father "5 repeats" Woman's husband "3 repeats" Woman "5 repeats"/"7 repeats" Couple's child "5 repeats"

98%

A second-division segregation ascus is an indication of:

A crossover between ventromere and locus

In loppins (small, diploid invertebrates), chocolate-dependent problem-solving ability is an autosomal recessive trait. You have been hired to map the position of the gene controlling this phenotype (called "lu") using two SSLP markers (called "A" and "B"). You first cross two pure-breeding loppins: lu+A[3 repeats] B[5 repeats]/lu-A[3 repeats] B[5 repeats] X lu- A[6 repeats] B[8 repeats]/lu-A[6 repeats] B[8 repeats]. The F1 is then crossed back to the lu-/lu- parent. Which of the following results would indicate that the lu gene is much closer to SSLP "A" than to SSLP "B"?

A higher proportion of lu+A[6 repeats]/lu-A[6 repeats] than lu+B[8 repeats]/lu-B[8 repeats] individuals

A gene is transcribed into an mRNA and this mRNA is 110 nucleotides long. Which of the following proteins could it encode?

A signalling protein that is 10 amino acids long

In hogs, a dominant allele B results in a white belt around the body. At a separate locus the dominant allele S causes fusion of the two parts of the normally cloven hoof resulting in a condition known as syndactyly. A belted syndactylous sow was crossed to an unbelted cloven-hoofed boar, and in the litter there were: 25% belted syndactylous25% belted cloven. The genotypes of the parents can best be represented as:

B/b;S/s * b/b;s/s

The following is known about the inheritance of size and fur color in Holland lop rabbits: • Crosses between large individuals only produce large individuals. • Crosses between dwarf individuals produce both large and dwarf rabbits in a ratio of 1:2. Such crosses also produce some very small kits (baby rabbits) that generally die within a few days. • Crosses between brown rabbits only produce brown kits. • Some crosses between black rabbits produce only black kits, whereas others produce both black and brown kits. • The size and fur-color phenotypes segregate independently. Based on the information above, what are the expected phenotypes in the F1 of a cross between a dwarf rabbit that breeds true for brown fur color and a large rabbit that breeds true for black fur color?

Black dwarf only

Using molecular techniques, researchers have knocked out both copies of gene "G" in a series of genetically identical mouse embryos. These mice develop normally, except for their forelimbs, which are missing several small bones. What can be concluded from the results of this experiment?

Gene "G" is necessary for proper development of forelimbs' small bones in mice.

A sweet pea plant of genotype A/A . B/B is crossed to one that is a/a . b/b to produce a dihybrid F1. One cell of one F1 individual (genotype A/a . B/b) goes through meiosis and produces four gametes of the following genotypes: A.b, A.b, a.B and a.B. What can be concluded regarding the linkage relationship between the two genes?

Genes A and B could be linked or unlinked; the result is not indicative of either as in both cases it's possible to obtain 100% recombinant gametes form one meiosis.

A diploid plant is a trihybrid for flower color (gene "F"), leaf size (gene "L") and seed weight (gene "S"); its phenotype includes red flowers, large leaves, and heavy seeds. This plant is crossed to a tester plant (which has white flowers, small leaves, and light seeds). The progeny is as follows: 23 Red, heavy, large 232 White, heavy, large 25 Red, heavy, small 228 White, heavy, small 230 Red, light, large 25 White, light, large 235 Red, light, small 26 White, light, small What can be concluded about the linkage relationships of the three genes in question?

Genes F and S are linked, while L assorts independently.

In pet rabbits, brown coat color is recessive to black coat color. A black female rabbit gives birth to four black-coated and three brown-coated baby rabbits. What can be deduced about the genotype of the baby rabbits' father?

He could be heterozygous black/brown or homozygous brown.

You have come across a dog (named Cindy) that does not have a tail. Interestingly, all the puppies produced by this dog don't have a tail either. If the lack of tail is caused by a genetic mutation, where has this mutation most likely taken place?

In Cindy's gametes

Which of the following is true with respect to haploid and diploid cells?

In diploid cells, meiosis I results in the formation of two haploid cells.

Beside DNA, which of the following are major components of chromatin?

Proteins

What is the mechanism that ensures Mendel's First Law of segregation?

Segregation of homologous chromosomes during meiosis I

A plant with small red flowers is crossed to a plant with large white flowers. The resulting F1 is comprised of 75 plants with small red flowers and 72 plants with small white flowers. If flower color and flower size are controlled by a single gene each, what can be concluded from these results?

Small size is dominant to large size, but we can't determine which color is dominant.

Suppose that a single gene controls fruit color in mango. Yellow fruit (Y-) is dominant to red fruit (yy). Suppose a true breeding yellow mango plant was crossed with a red-fruited plant and the resulting F1 was selfed. The F2 segregated as expected. If one of the yellow-fruited plants was randomly selected and selfed, what is the probability that its progeny would segregate for fruit color? Explain your logic.

The F2 consists of YY: Yy : yy. Thus, the yellow-fruited plant that was randomly picked could be either YY or Yy. There is a chance that it was YY and chance that it was Yy. If a YY plant was selected and selfed, the progeny would not segregate for fruit color. If a Yy plant was selected, the progeny would segregate for fruit color.

What process occurring during meiosis ensures independent assortment?

The arrangement of homologous chromosomes on the metaphase plate

What is the most likely mode of inheritance of the exceptionally rare condition represented in the pedigree below, and why? (only one black square in the second down in pedigree)

X linked recessive because this would require the smallest number of rare alleles in the pedigree.

A female Drosophila with singed bristles is crossed to a male with sepia (dark brown) eyes. In the F1, all females are wild-type and all males have singed bristles. F1 males and females are crossed together, and the following F2 phenotypic ratios are obtained: 748 wild-type females 753 wild-type males 742 singed females 747 singed males 249 sepia females 250 sepia males 244 singed, sepia females 246 singed, sepia males If sn and se represent the mutant alleles of the singed and sepia gene, respectively, and sn+ and se+ are their wild-type counterparts, what are the most likely genotypes of the original parents?

Xsn/Xsn; se+/se+ and Xsn+/Y; se/se

The diagram below shows a part of the biochemical pathway responsible for fruit color in peppers (Caspicum annuum). Enzyme 1 is responsible for catalyzing the reaction that turns the colorless precursor into yellow pigment, whereas Enzyme 2 catalyzes the step that turns the yellow pigment into red pigment. A breeder crosses a pure-breeding plant that makes yellow peppers to a pure-breeding plant that makes red peppers. What proportion of the offspring will make red peppers? Colorless precursor (enzyme 1)>> yellow pigment >>>red pigment (enzyme 2)

all

The following pedigree shows the inheritance of attached earlobes (black symbols) and unattached earlobes (white symbol). Both alternative phenotypes are quite common in human populations. 2 black one blank circle

autosomal dominant trait

In an experimental plant, the genes t and q are linked. A pure breeding t/t individual is crossed to a pure breeding q/q individual to obtain a dihybrid F1. Genotypically, the F1 individuals can be described as:

dihybrids in trans

A plant of genotype C/C . d/d is crossed to c/c . D/D, and the F1 is testcrossed. If the genes in question are linked, the percentage of double homozygous recessive individuals in the offspring of the testcross will be:

less than 25%

The following pedigree depicts the inheritance of a rare hereditary disease affecting muscles: Two blanks. 2 black squares 2 black squares

x-linked recessive