LS 7B Midterm 1 PEQs

Among the progeny of a heterozygous round (Aa) x homozygous wrinkled (aa) testcross, three seeds are chosen at random. What is the probability that all three seeds are round? 2(1/2)3 (1/2)3 3(1/2)3 4(1/2)3

(1/2)3

Given equal probabilities of the birth of a boy or girl, what is the probability that a group of four siblings includes all boys? All girls? All boys or all girls? 1/16; 1/16; 1/8 1/8; 1/16; 3/8 1/16; 1/8; 3/8 1/16; 1/16; 1/64

1/16; 1/16; 1/8

A normal XY male has a son with the karyotype XYY. The likely explanation is: second-division nondisjunction. first-division nondisjunction. copy-number variation. translocation.dosage compensation.

second-division nondisjunction.

An individual who is heterozygous for two linked genes (with alleles A, a and B, b) is crossed with an AB/ab individual, and among the progeny are: 14 AB/ab 36 Ab/ab 34 aB/ab 16 ab/ab What is the frequency of recombination? 0.35 0.70 0.60 0.30 0.40

0.30

The pedigree shown pertains to a trait due to a rare, X-linked recessive mutation. Individual 1 has an affected brother and husband, but the genotypes and phenotypes of individuals 1, 3, and 4 are unknown. What is the probability that individual 1 is heterozygous? What is the probability that individual 3 is affected? What is the probability that individual 4 is affected? 1/2; 0; 1/2 1; 1/2; 1/2 1; 1/4; 1/4 1/2; 1/4; 1/4 1; 1/2; 1/4

1/2; 1/4; 1/4

According to the figure shown, the average number of new mutations that occur across an entire human genome in one generation is approximately _____ times higher than in nematodes. 2 1000 10,000 100 10

100

In genetics, the dash symbol (-) is a "wild card" that stands for either the dominant allele or the recessive allele; for example, A- means the individual has either the genotype AA or Aa. Two genes that undergo independent assortment affect fruit color in summer squash. Each gene has two alleles, one of which is dominant for fruit color. Genotypes of the form A- B- and A- bb have white fruit, genotypes of the form aa B- have yellow fruit, and genotype aa bb has green fruit. What ratio of white : yellow : green is expected from the cross Aa Bb x Aa Bb? 9:3:4 10:3:3 9:6:1 12:3:1

12:3:1

In genetics, the dash symbol (-) is a "wild card" that stands for either the dominant allele or the recessive allele; for example, A- means the individual has either the genotype AA or Aa. Two genes that undergo independent assortment affect the shape of the seed capsule in the broadleaf weed known as shepherd's purse. Each gene has two alleles, one of which is dominant for the shape of the seed capsule. Genotypes of the form A- B-, A- bb, and aa B- have triangular seed capsules, whereas the seed capsules of aa bb genotypes are ovoid. What ratio of triangular : ovoid is expected from the cross Aa Bb x Aa Bb? 10:6 13:3 9:7 12:4 15:1

15:1

A true-breeding black rabbit is crossed with a true-breeding white rabbit to produce an F1 generation of 16 individuals. If the black color trait is dominant, which of the outcomes represents the expected phenotype of an F1 generation cross? 0 black rabbits, 0 white rabbits, 16 gray rabbits 0 black rabbits, 16 white rabbits, 0 gray rabbits 9 black rabbits, 3 white rabbits, 3 gray rabbits, and 1 spotted rabbit 5 black rabbits, 4 white rabbits, 7 gray rabbits 16 black rabbits, 0 white rabbits, 0 gray rabbits

16 black rabbits, 0 white rabbits, 0 gray rabbits

The pedigree shown here pertains to a trait due to a rare, X-linked recessive mutation. Individual 1 has an affected father, but the genotypes and phenotypes of individuals 1-4 are unknown. What is the probability that individual 1 is heterozygous? What is the probability that individual 3 is heterozygous? What is the probability that individual 4 is affected? 1; 1/2; 1/2 1/2; 1/4; 1/4 1; 1/2; 1/4 1; 1/4; 1/2 1/2; 1/4; 1/2

1; 1/2; 1/2

Consider a gene with four alleles: A1, A2, A3, and A4. In the cross A1A2 × A3A3, how many offspring genotypes are possible? 6 4 3 5 2

2

In the F2 generation of a homozygous round (AA) × homozygous wrinkled (aa) cross in peas, two seeds are chosen at random. What is the probability that one is round and the other is wrinkled? (1/4)2 2 × (3/4) × (1/4) (3/4)2 (3/4) × (1/4)

2 × (3/4) × (1/4)

Diploid somatic cells of elephants have 56 chromosomes. If nondisjunction of one of an elephant's chromosomes occurs in meiosis I, the resulting sperm are expected to have the chromosome complement: 28, 28, 28, 28. 29, 29, 27, 27. 29, 29, 28, 28. 56, 56, 57, 55. 28, 28, 29, 27.

29, 29, 27, 27

Consider a gene with four alleles: A1, A2, A3, and A4. In the cross A1A2 x A3A4, how many offspring genotypes are possible? 4 6 5 3 2

4

Consider a gene with four alleles: A1, A2, A3, and A4. How many distinct heterozygous genotypes are possible? 4 3 6

6

In genetics, the dash symbol (-) is a "wild card" that stands for either the dominant allele or the recessive allele; for example, A- means the individual has either the genotype AA or Aa. Two genes that undergo independent assortment affect coat color in mice. Each gene has two alleles, one of which is dominant for coat color. Genotypes of the form A- B- have a brownish color called agouti, A- bb are black, and aa B- and aa bb are albino (white). What ratio of agouti : black : white is expected from the cross Aa Bb x Aa Bb? 9:6:1 9:3:4 10:3:3 12:3:1

9:3:4

In a diploid individual, there are two genes called "A" and "B" on one chromosome. One homolog of that chromosome carries A and B alleles of those genes, and the homologous chromosome carries different forms (alleles) of these same genes, a and b. If there is a single crossover between these two genes involving one pair of non-sister chromatids during metaphase I of meiosis, the resulting four gametes would be: Ab, Ab, aB, aB. AB, AB, ab, ab. AB, ab, AB, ab. AaBb, AaBb, AaBb, AaBb. AB, Ab, aB, ab.

AB, Ab, aB, ab

With independent assortment, the ratio of genotypes in the F2 generation of a cross between true-breeding strains (AA bb x aa BB) can be described as 1:2:1:2:4:2:1:2:1. To what genotype does the "4" in the ratio refer? Aa Bb AA Bb Aa BB None of the other answer options are correct.

Aa Bb

If you crossed two heterozygous yellow-seed pea plants (genotypes Aa), the relative frequency of: All of these choices are correct. the a allele in each parent's gametes would be 1/2. homozygous yellow-seed plants (genotype AA) would be 1/4. the A allele in each parent's gametes would be 1/2. green-seed plants (genotype aa) would be 1/4.

All of these choices are correct

Flower color in snapdragons is due to a gene with incomplete dominance: CRCR plants have red flowers, CRCW have pink flowers, and CWCW plants have white flowers. Which cross is expected to yield progeny that all have pink flowers? CRCW x CRCW CWCW x CWCW CRCR x CRCW CRCR x CWCW CRCW x CWCW

CRCR x CWCW

Hemophilia is a sex-linked recessive trait in humans. If a carrier female (heterozygous for the trait) mated with a non-affected male, what would be the expected outcome(s)? Select all that apply. Half the sons would have hemophilia. None of the offspring would have hemophilia. None of the daughters would have hemophilia. Half the daughters would have hemophilia.

Half the sons would have hemophilia. None of the daughters would have hemophilia.

Gene A exists in five forms in the human population. Each form, or allele, has a different number of tandem repeats. The alleles are amplified using PCR and then run on a polyacrylamide gel for analysis, yielding the banding pattern shown on the gel. Which of the lanes in the gel could represent the alleles found in one individual? Lanes 2, 4, and 5 are possible. Lanes 2, 3, 4, and 5 are possible. Lanes 1, 2, 3, and 4 are possible. All 5 lanes are possible.

Lanes 2, 4, and 5 are possible

A pea plant is heterozygous (Aa) for seed color and heterozygous (Bb) for seed shape. Which statements are correct according to Mendel's principle of independent assortment? Select all that apply. Each gamete will contain either a seed-color allele or a seed-shape allele, but not both. Possible gamete genotypes are AB or ab; each is equally likely to occur. A gamete that contains the dominant allele for seed color must also contain the recessive allele for seed shape. A gamete that contains the dominant allele for seed color must also contain the dominant allele for seed shape. A gamete that contains the dominant allele for seed color is equally likely to contain the dominant or the recessive allele for seed shape.

Possible gamete genotypes are AB or ab; each is equally likely to occur. A gamete that contains the dominant allele for seed color is equally likely to contain the dominant or the recessive allele for seed shape.

Suppose that in humans the ability to roll the tongue (R) is dominant to being unable to roll it (r). Having freckles (F) is dominant to having no freckles (f). A freckled tongue-roller could have which genotypes? Select all that apply. rrFF All of these choices are correct. RRff and RrFf only RrFf RRFF

RrFf RRFF

Imagine that a rancher has a herd of cattle with brown hides and short horns. All of his cattle are also relatively short in stature. If all of these were true-breeding traits, what could you say about the progeny of these cattle? The progeny of these cattle will be short in stature and have brown hides and short horns. It is impossible to determine which traits will occur among the progeny—they will likely demonstrate different hide colors, horn lengths, and heights. The progeny of these cattle will have a mix of brown, black, white, and spotted hides. The progeny of these cattle will have short horns but a variety of hide colors and heights. Since the cattle are true breeding, the progeny of this herd will all be sterile.

The progeny of these cattle will be short in stature and have brown hides and short horns.

Considering an X-linked dominant trait, if an unaffected woman and an affected man decide to have children, which of the answer choices is possible for their children? Their daughters are not expected to show the dominant trait. All of their sons are expected to show the dominant trait. Their daughters are expected be heterozygous for the gene. All their children, whether male or female, are expected to show the dominant trait. Their sons are expected to be heterozygous for the gene.

Their daughters are expected be heterozygous for the gene.

Which of the examples would be good examples of genotype-by-environment interactions? Select all that apply. two different strains of corn that differ in height due to genotype a strain of corn whose yield varies with the amount of nutrients in the soil a strain of mutant mice that becomes obese regardless of feed amount a line of chickens whose eggshells are extra thick regardless of feed type two different mutants of mice that share similar fat metabolism abilities a line of dairy cows that increases milk yield in relation to feed amount

a strain of corn whose yield varies with the amount of nutrients in the soil a line of dairy cows that increases milk yield in relation to feed amount

An individual who is heterozygous for two linked genes has the genotype AB/ab, which means that the A and B alleles are in one chromosome and the a and b alleles are in the homologous chromosome. Among the products of meiosis listed, which would be the recombinant types? Select all that apply. AB aB Ab

aB Ab

An individual is heterozygous for two linked genes, but whether its genotype is AB/ab or Ab/aB is not known. The individual is crossed with an ab/ab individual, and among the progeny are: 16 AB/ab; 54 Ab/ab; 46 aB/ab; 24 ab/ab. These results imply that the genotype of the doubly heterozygous parent was AB/ab. false true

false

You are given two populations of true-breeding tomato plants with two simple dominant/recessive traits that sort independently. Using the multiplication rule, how many different phenotypic combinations would you expect to see in the F2 generation? In what phenotypic ratio? three; 9:6:1 two; 3:1 four; 9:3:3:1

four; 9:3:3:1

X-linked genes show crisscross inheritance because males: get their Y chromosomes from their father and transmit their Y chromosomes to their sons. transmit their Y chromosome to their sons. transmit their X chromosome to their sons. get their X chromosome from their father. get their Y chromosome from their father. get their X chromosomes from their mother and transmit their X chromosomes to their daughters.

get their X chromosomes from their mother and transmit their X chromosomes to their daughters.

The graphs shown depict the relative proportions of individuals affected with a certain condition (darker shaded bar) and individuals not affected (lighter bar), in individuals carrying either the A - T or the G - C allele of a single-nucleotide polymorphism (SNP). Heterozygous genotypes carry both alleles and are included in both categories. Which graph shows a pattern that suggests that the G - C allele is a risk factor for the disease? graph L graph H graph Q graph K graph M

graph L

The mitochondrial DNA sequences of a large extended family were analyzed and compared to a single male in the family. Which of the relatives' mitochondrial DNA should be a match to this person? his maternal grandfather his children his brother's daughter his sister's son his paternal grandmother

his sister's son

The data shown are the results of growing one strain of a crop plant in soils with different nitrogen concentrations. If a different strain of the same crop plant were grown in the same soil conditions, you would predict that: it would respond the same way to soil nitrogen concentrations because they are the same type of crop plant. it could respond the same way or differently because the environment has too many variables to predict. it could respond the same way or differently; different genotypes can, but may not always, respond differently to soil nitrogen concentrations. it would respond completely differently to soil nitrogen concentrations because they are different strains.

it could respond the same way or differently; different genotypes can, but may not always, respond differently to soil nitrogen concentrations.

Which lane in the gel represents an individual who is homozygous for the nonmutant allele? lane 4 lane 2 lane 1 lane 3

lane 1

Hairy cell leukemia is a cancer of the white blood cells that responds to treatment with drugs that inhibit DNA synthesis. A mutation in the BRAF gene, designated BRAF V600E, is associated with hairy cell leukemia. BRAF V600E differs from the nonmutant BRAF gene in a single base pair. Imagine that this change to the single base-pair added a Hae III restriction site indicated by the arrow on the gene below. You decide to identify hairy cell leukemia with PCR and the restriction enzyme Hae III. Which lane on the gel represents DNA from cells heterozygous for the BRAF V600E allele? lane 2 lane 4 lane 1 lane 3

lane 2

Which lane in the gel represents an individual who is homozygous for the Hae III restriction site? lane 1 lane 3 lane 4 lane 2

lane 3

In the gel shown, which lane represents an individual homozygous for the hypertension allele? lane A lane D lane C lane E lane B

lane A

In the gel shown, which lane represents an individual heterozygous for the hypertension allele? lane D lane B lane C lane A lane E

lane B

Which lane in the gel represents an individual heterozygous for this SNP? lane E lane B lane C lane A lane D

lane B

Shown are two alleles of a single-nucleotide polymorphism (SNP), one of which is associated with a higher risk of developing high blood pressure (hypertension). Normal allele: 5′-ATTCGCGGAATTCTGG-3′ 3′-TAAGCGCCTTAAGACC-5′ Allele associated with hypertension: 5′-ATTCGCGGGATTCTGG-3′ 3′-TAAGCGCCCTAAGACC-5′ You amplify DNA from multiple patients at a cardiologist's office and digest each with EcoRI in order to determine the patients' genotypes for this SNP. EcoRI recognizes the sequence shown and cuts each strand at the locations indicated by the arrows. In the gel shown, which lane represents an unaffected individual? lane B lane A lane C lane D lane E

lane C

Red-green color blindness is due to a mutant gene in the X chromosome. An XX female with normal color vision and an XY male with normal color vision have a child with karyotype XXY who is color blind. The likely explanation is that the: father had CNV of the color-blind mutation. None of the other answer options is correct. mother was heterozygous for the color-blind mutation. father was heterozygous for the color-blindness mutation. mother had CNV of the color-blind mutation.

mother was heterozygous for the color-blind mutation.

Consider a gene with n alleles A1, A2, ..., An. How many distinct heterozygous genotypes are possible? n2/2 n2 n(n-1) n(n + 1)/2 n(n- 1)/2

n(n- 1)/2

Assuming that the trait represented by the filled symbols in the pedigree shown is a rare inherited trait with complete penetrance due to a single gene with alleles A and a, what mode of inheritance does the pedigree suggest? recessive dominant

recessive

Which of the traits depicted in the graph shown has the lowest heritability? trait M trait K trait L trait H

trait L