Genetics Exam 4

If someone has a complement of sex chromosomes that is XXX, resulting in showing that this individual has Triplo-X syndrome, how many number(s) of barr bodies in their human cells are present? A. 1 (Incorrect, this would be correct if they did not have a syndrome (XX), had Klinefelter (XXY) or Klinefelter (XXYY)). B. 2 (This correctly represents the right number of barr bodies in human cells within this syndrome). C. 3 (Incorrect, This would be correct if one had Klinefelter (XXXXY) or Poly-X Female (XXXX) D. 4 (Incorrect, The syndrome Poly-X Female (XXXXX) contains 4 barr bodies). E. None of the above are correct (B contains the right answer making this option false).

B

If we know the recombination frequency of two linked genes we can predict the outcomes of crosses with the two linked genes.

False, we need to know the RF and the repulsion or coupling, need to know two conditions

The higher the coefficient of coincidence the higher the crossover interference

False. relationship is 1-coc=interference,thereforethegreaterthecocthesmallertheinterference

From the cross AB/ab x ab/ab, what is the recombination frequency if the progeny numbers are 72 AB/ab, 68 ab/ab, 17 Ab/ab, and 21 aB/ab? a. 0.213 b. 0.271 c. 0.500 d. 0.787 e. cannot be determined

a

You calculate an interference of 0.59. What does this number tell you? a. You will not observe 59% of expected double crossovers. b. You will observe 59% double crossovers. c. You will observe 41% double crossovers. d. You will observe 59% of expected double crossovers.

a

For the X-linked dominant trait, affected fathers normally pass the trait to daughters, but will not pass the trait to sons.

true

Height in all organisms is always a continuous trait.

true

Heritability indicates the degree to which a characteristic is genetically determined.

true

Heritability is used to estimate what proportion of a traits variance in a population is genetic variance.

true

In humans SRY is the male determining gene.

true

In humans there are about 5% pseudo autosomal regions at both tips of the X and Y chromosomes.

true

Linked genes with a low recombination frequency generally are closer than genes with higher recombination frequency.

true

Most continuously varying characteristics are both polygenic and influenced by environmental factors.

true

Standard deviation is calculated in the same units as the original measurements, while variance is calculated in units squared.

true

Temperature during embryonic development determines sex in reptiles like turtles and alligators.

true

The heritability of an individual cannot be estimated.

true

When both parents are heterozygous for an autosomal recessive trait, 1/4 of their children will inherit the trait.

true

When narrow-sense heritability is high for a particular trait offspring tend to resemble their parents for that trait.

true

crossovers on chromosomes are frequently not independent of events. The interference occurs when one crossover inhibits another.

true

What is the most likely order of the linked genes R, S, and T if the distance between R and S is 22 m.u., the distance between S and T is 8 m.u., and the distance between R and T is 14 m.u.? a. R S T b. S T R c. T R S d. cannot be determined

...

Two linked genes, (A) and (B) in human have a recombination frequency of 18%. A man with genotype AB/ab marries a woman who is ab/ab.What is the probability that their first two children will both be ab/ab? (use percentage, rounded to one decimal, e.g. 3.5%, 5.0%) 16.8%

16.8%

If a heterozygous parents (AB/ab) is test-crossed to a homozygous recessive (ab/ab), what will the progeny phenotypic ratio be if genes A and B are completely linked?

1AB: 1ab

In Drosophila melanogaster, cut wings (ct) is recessive to normal wings (ct+), sable body (s) is recessive to gray body (s+), and vermilion eyes (v) is recessive to red eyes (v+). All three recessive mutations are X-linked. A female fly with cut wings, sable body, and vermilion eyes is crossed to a male with normal wings, gray body, and red eyes. The F1 females produced by this cross were mated with cut, sable, vermilion males in a testcross. The following are the progeny resulting from the testcross. v ct s 510 v+ ct s 1 v+ ct+ s 14 v+ ct+ s+ 500 v+ ct s+ 73 v ct s+ 20 v ct+ s 81 v ct+ s+ 1 Total -> 1200 Determine the interference among these genes.

58.3%

Two linked genes, (A) and (B) in human have a recombination frequency of 18%. A man with genotype AB/ab marries a woman who is ab/ab. What is the probability that their first child will be Ab/ab? (use percentage, rounded to one decimal, e.g. 3.5%, 5.0%)

9%

Which of the following is a FALSE statement? A. Turtles in warm temperatures are more likely to be female (this is a true statement because it can be linked to temperature of environment) B. Alligators in cold temperatures are more likely to be females (this is a true statement because it can be linked to temperature of environment) C. Alligators in warm temperatures are less likely to be females (this is a true statement because they are more likely to be male in warm temperatures) D. Turtles in cold temperatures are more likely to be male (this is a true statement because it can be linked to temperature of environment)

E. Temperature has nothing to do with the determination of sex of either of these animals (this is false because temperature does have to do with determining sex; Lecture 18: Sex Determination and Sex-Linked Characteristics)

Affected people with an autosomal dominant trait have 100% chance to pass the trait to their kids.

False, 50-100% depends on whether the transmitter is heterozygote or homozygote

Linked genes are allelic.

False, allelic means different alleles at the same locus, linked genes are different genes on the same chromosome

An X-linked recessive trait can be passed from father to son.

False, father only passes y chromosome to the son (can't pass an x recessive)

The components of phenotypic variance include only genetic variance and environmental variance.

False, genetic, environemt and interaction of both

When heritability is high, environmental factor will not influence a character.

False, heritability only explains if variation is influenced by genetics

Recombination frequencies can be predicted by a chi-square test.

False, just shows of the two genes are independently sorting or linked

Some linked genes can exhibit recombination frequencies of more then 50%.

False, max is 50%

For the X-linked recessive traits, normally there are more females than males affected.

False, more males than females

Recombination of different alleles can occur only though crossing over.

False, occur through independent assortment

Three point test crosses are only informative when both parents are true breeding.

False, one homozygote and one heterozygote, one has to be heterozygote

The condition XXXY is always lethal in humans.

False, shows Klinefelter syndrome

Linked genes segregate independently.

False, travel together

Completely linked genes on the same chromosomes can show independent assortment.

False, travel together so they can't independently assort

Which of the following, when portrayed on a pedigree fits the description? This trait tends to skip generations, is controlled by the X chromosome, and may be passed to females and males but more frequently in males. A. X-linked Dominant B. Y-linked C. Autosomal recessive D. X-linked Recessive E. Autosomal dominant

The correct answer is D. All the criteria fit an X-linked recessive trait. Not C or E because autosomal traits don't appear on the sex chromosomes. It is not Y-linked (B) because the criteria said it occurs on the X chromosome. Lastly, not A, X-linked Dominant, because those traits tend to appear in every generation, thus not skipping generations.

A chromosome map shows the linear order pf gene loci present on a chromosome and the relative distances between them.

True

A eukaryotic diploid cell from an organism with the XX (female) -XY (male) sex determination system has two pairs of autosomes and a pair of sex chromosomes, X and Y, shown below.From what type of individual is this cell? a. male b. female c. hermaphrodite d. monoecious e. can't tell

a

A human with an XY chromosome pair appears female. All of the following are possible explanations for this condition except: a. this person suffers from Turner syndrome. b. this person has a non-functional SRY gene. c. this person lacks the SRY gene. d. this person does not make testosterone.

a

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. (i) What was the genotype of the individual tested? a. Abc/aBC b. ABC/aBC c. abc/abC d. ABc/abC

a

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. (ii) What is the order of the gene loci? a. CAB (or BAC) b. ABC (or CBA) c. ACB (or BCA d. cannot be determined

a

Based on last question, were the genes in the heterozygous parent coupled or in repulsion? a. coupled b. repulsion c. neither d. both

a

If a female animal that is heterozygous for a recessive X-linked mutation is crossed to a wild type male, what proportion of the progeny will be mutant females? a. 0% b. 100% c. 75% d. 50% e. 25%

a

In Drosophila melanogaster, cut wings (ct) is recessive to normal wings (ct+), sable body (s) is recessive to gray body (s+), and vermilion eyes (v) is recessive to red eyes (v+). All three recessive mutations are X-linked. A female fly with cut wings, sable body, and vermilion eyes is crossed to a male with normal wings, gray body, and red eyes. The F1 females produced by this cross were mated with cut, sable, vermilion males in a testcross. The following are the progeny resulting from the testcross. v ct s 510 v+ ct s 1 v+ ct+ s 14 v+ ct+ s+ 500 v+ ct s+ 73 v ct s+ 20 v ct+ s 81 v ct+ s+ 1 Total -> 1200 Which is the correct genetic map for these genes:(shown as gene1 --(genetic distance between 1 and 2)-- gene2 --(genetic distance between 2 and 3)-- gene3) a. ct --(13cM)-- v --(3cM) -- s b. ct --(12cM)-- v --(6cM) -- s c. v --(3cM) -- s --(13cM)-- ct d. v --(13cM)-- ct --(3cM) -- s

a

Recombination frequencies can be calculated by a. counting the number of recombinant and parental offspring when an individual who is heterozygous for two genes is testcrossed. b. performing a chi-square test on the F2 progeny when an individual who is homozygous for two genes is initially crossed to an individual who is homozygous recessive for these two genes. c. counting the number of offspring who are expressing the dominant phenotype when a heterozygous individual for two genes is testcrossed. d. performing a chi-square test of the progeny of a cross between parents who are both heterozygous for the same two genes. e. counting the number of offspring that are found in the cross of an individual who is heterozygous for two genes with another parent who is homozygous dominant for one of these genes and homozygous recessive for the other gene.

a

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? a. homozygous dominant b. heterozygous c. homozygous recessive d. cannot be determined from this information

b

An XXY chromosome constitution produces ________ development in humans. a. female b. male c. hermaphrodite d. premature

b

How many Barr bodies are present in an individual with Klinefelter syndrome (XXYY)? a. 0 b. 1 c. 2 d. 3 e. 4

b

If a color-blind female has children, what do we know about all of her sons? a. Half of the sons will be color-blind. b. All sons will be color blind. c. All sons will have normal color vision. d. She would not be able to have a son. e. It is impossible to know without knowing the father's genotype.

b

If a mother is a carrier for color blindness (an X-linked recessive trait) and her husband has normal vision, what is the probability that their children will have color blindness? A- 1/2 B- 1/4 (cross XX^c with XY, result is one affected male) C- 0 D- 1 E- 3/4

b

If someone has sex chromosomes of XXY, then how many Barr bodies are present in human cells? A. 0 B. 1 (the correct number of Barr bodies associated with this syndrome) C. 2 D. 3 E. 4

b

Linked genes always exhibit a. phenotypes that are similar. b. recombination frequencies of less than 50%. c. homozygosity when involved in a testcross. d. a greater number of recombinant offspring than parental e. offspring when involved in a testcross. e. a lack of recombinant offspring when a heterozygous parent is testcrossed.

b

Which of the following is false regarding an X-linked recessive trait? (Lecture 19: Pedigree Analysis) A. the X-linked recessive trait tends to skip generations (incorrect: recessive traits do tend to skip generations) B. An affected male will pass the trait to his sons (correct: an affected male will NOT pass the trait to his sons because his sons will inherit his Y chromosome, not his X chromosome in which the recessive trait is carried) C. the X-linked recessive trait appears more frequently in males (incorrect: X-linked recessive traits do appear more frequently in males because they only need one recessive allele to show the trait, whereas females need two recessive alleles) D. A heterozygous female will produce about 1/2 affected males (incorrect: this is a true statement because heterozygous females will pass their recessive allele to about 1/2 of their sons) E. Y chromosomes are unable to mask the X-linked recessive trait (incorrect: this a true statement because Y chromosomes do not have an allele to mask the recessive allele on the X chromosome)

b

A genetic map shows which of the following? a. The distance in numbers of nucleotides between two genes b. The number of genes on each of the chromosomes of a species c. The linear order of genes on a chromosome d. The location of chromosomes in the nucleus when they line up at metaphase during mitosis e. The location of double crossovers that occur between two genes

c

A three-point testcross is used to determine the order of three linked genes. The following crossover progeny result: single crossovers, double crossovers, and no crossovers. To determine the order, one needs to compare the no-crossover progeny to what other class of progeny? a. the no-crossover class b. the single-crossover class c. the double-crossover class d. All classes need to be considered in determining gene order.

c

Consider the following three-point cross:ABC/abc x abc/abcWhich of the following is not a possible progeny genotype? (Consider both recombinant and non-recombinant progeny.) a. ABC/abc b. aBC/abc c. ABC/ABC d. AbC/abc e. abc/abc

c

If a heterozygous parent (AB/ab) is test-crossed to a homozygous recessive (ab/ab), what will the progeny phenotypic ratio be if genes A and B are completely linked? a. 1AB:1Ab:1aB:1ab b. 9AB:3Ab:3aB:1ab c. 1AB:1ab d. none of the above

c

If genes A and B are linked, what is the maximum percentage of recombinant gametes that can be produced if a single crossover occurs during Meiosis? a. 0% b. 25% c. 50% d. 75% e. 100%

c

In a three-point testcross the nonrecombinant progeny are A+ B+ C+ and a b c. The double-crossover progeny are A+ B+ c and a b C+. Which locus (A, B, or C) is in the middle? a. A b. B c. C d. A or B

c

In soreflies (a hypothetical insect), the dominant allele, L, is responsible for resistance to a common insecticide called Loritol. Another dominant allele, M, is responsible for the ability of soreflies to sing like birds. A true-breeding mute, Loritol-resistant sorefly was mated to a true-breeding singing, Loritol-sensitive sorefly, and the singing, Loritol-resistant female progeny were test-crossed with true-breeding wild type (i.e., mute, Loritol-sensitive) males. Of the 400 total progeny produced, 117 were mute and Loritol-resistant, 114 could sing and were Loritol-sensitive, 83 could sing and were Loritol-resistant, and 86 were mute and Loritol-sensitive. A chi-square test is done to determine if there is equal segregation of alleles at the L locus. What will be the chi-square value obtained and how many degrees of freedom would be used to interpret this value? a. 0.09 and three degree of freedom b. 0.56 and one degrees of freedom c. 0 and one degree of freedom d. 9.72 and three degrees of freedom e. A chi-square test is not the appropriate statistical test to answer this question.

c

The Lyon hypothesis helps us to understand which phenomenon in mammals? a. X-linked inheritance b. evolution of the Y chromosome c. dosage compensation between males and females d. development of male and female secondary sexual characteristics

c

When Morgan crossed a red-eyed female with a white-eyed male, which results made Morgan think that the locus affecting eye color was on the X chromosome? a. All F1 male and female flies had red eyes. b. All F1 male and female flies had white eyes. c. In the F2, all females had red eyes, and half of the males had red eyes and the other half had white eyes. d. In the F2, half of males and females had red eyes and the other half had white eyes. e. F2 generations were sterile.

c

Which of the following is a true statement regarding X-inactivation? A. X-inactivation is predetermined (Incorrect; X-inactivation happens at random) B. X-inactivation happens later in life when the body is fully matured (Incorrect; it occurs eary in development during the first few weeks) C. X-inactivation yields a Barr body (Correct; a Barr body is an inactivated X chromosome formed during interphase) D. The Xist gene activates the genes on the X chromosome by altering the chromatin structure (Incorrect; the Xist gene inactivates the genes on the X chromosome) E. All of the above statements are false (Incorrect; answer choice C is a true statement)

c

Why are the progeny of a testcross generally used to map loci? Why not the F2 progeny from an F1 × F1 cross? a. Only recombinant offspring would be found in the progeny of an F1 X F1 cross. b. The progeny of an F1 X F1 cross would be found in a 9:3:3:1 ratio when two genes are involved, whereas the progeny of a testcross would result in a 1:1:1:1 ratio .c. It is easier to classify recombinant and parental offspring of a testcross than with the progeny of an F1 X F1 cross. d. In a testcross more of the progeny would be expected to display the dominant phenotype than in the progeny of an F1 X F1 cross. e. A testcross is more useful for mapping genes that are located near each other but when genes are quite far apart on the same chromosome, an F1 X F1 cross actually is more useful.

c

You are doing lab work with a new species of beetle. You have isolated lines that breed true for either blue shells and long antenna, or green shells and short antenna. Crossing these lines yields F1 progeny with blue shells and long antenna. Crossing F1 progeny with beetles that have green shells and short antenna yield the following progeny:Blue shell, long antenna 82Green shell, short antenna 78Blue shell, short antenna 37Green shell, long antenna 43Total 240Assuming that the genes are linked, what is the map distance between them in cM? a. 33.3 cM b. 25.0 cM c. 49.5 cM d. 8.0 cM e. The genes are actually assorting independently.

c

A eukaryotic diploid cell from an organism with the XX (female) -XY (male) sex determination system has two pairs of autosomes and a pair of sex chromosomes, X and Y, shown below. What is the probability of a gamete from this individual that has the following genotype: alleles A and b, chromosome X? a. 1/2 b. 1/4 c. 1/6 d. 1/8

d

A eukaryotic diploid cell from an organism with the XX (female) -XY (male) sex-determination system has two pairs of autosomes and a pair of sex chromosomes, X and Y, shown below. A cell from this individual begins to go through meiosis. After meiosis I, as it goes through meiosis II, it becomes two cells. Which of the following is a possible combination of chromosomes in one of the two cells before it goes through meiosis II? a. one chromosome with A allele, one with B allele, one X, one Y b. one chromosome with A allele, one with 'a' allele, one with B allele, one with b allele, one X, one Y c. a pair of sister chromatids with A allele, a pair of sister chromatids with B allele, a pair of sister chromatids X a pair of sister chromatids Y d. a pair of sister chromatids with 'a' allele, a pair of sister chromatids with B allele, a pair of sister chromatids Y e. C and D are both possible.

d

A testcross includes a. one parent who is homozygous recessive for one gene pair and a second parent who is homozygous recessive for a second gene pair. b. one parent who is homozygous dominant for one or more genes and a second parent who is homozygous recessive for these same genes. c. two parents who are both heterozygous for two or more genes. d. one parent who shows the dominant phenotype for one or more genes and a second parent who is homozygous recessive for these genes. e. one parent who shows the recessive phenotype for one or more genes and a second parent who is homozygous dominant for these genes.

d

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 child will be a "roller"? a. 1/4 b. 1/3 c. 3/4 d. 1/2 e. 2/3

d

Assume A and B are dominant alleles. If this individual (as show in figure) were crossed to an individual of genotype Aa Bb, what is the probability of a female offspring with the two dominant traits given by alleles A and B? a. 1/8 b. 1/16 c. 9/16 d. 9/32

d

In cats, the allele (B) produces black color but (b) produces a yellow color. These alleles are incompletely dominant to each other. A heterozygote produces a tortoiseshell color. The alleles (B) and (b) are sex-linked as well. Cross a tortoiseshell female with a yellow male. What percent of their offspring will be tortoiseshell? a. 25% b. 75% c. 0% d. 50%

d

Is it possible for two different genes located on the same chromosome to assort independently? a. No, if two genes are on the same chromosome, they will be linked and the recombination frequency will be less than 50%. b. Yes, if the two genes are close enough to each other, there are a limited number of crossover events between them. c. No, there will be a very high crossover interference such that the recombination frequency will be reduced significantly. d. Yes, if the genes are far enough apart on the same chromosome, a crossover occurs between them in just about every meiotic event. e. Yes, but only if the two genes are both homozygous.

d

Which of the following human genotypes is associated with Klinefelter syndrome? a. XXY b. XXYY c. XXXY d. All of the above. e. None of the above.

d

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: Genes in cross Progeny (NR) Progeny (R) a, bw 2224 117 a, cv 2609 823 a, e 3200 3200 a, vg 5172 2379 bw, cv 4614 1706 bw, e 4150 4150 bw, vg 2796 1434 cv, e 3116 3116 cv, vg 2102 305 vg, e 4559 4559 Using these data from two-point crosses, what it the best genetic map (in cM) that can be developed? a. cv 5 bw 13 a 34 vg with e assorting independently b. bw 5 cv 24 vg 32 a with e assorting independently c. a 5 bw 13 vg 24 e with vg assorting independently d. cv 13 bw 5 a 27 vg with e assorting independently e. bw 5 a 24 cv 13 vg with e assorting independently

e

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? a. The genes A and B are on the same chromosome and closely linked. b. The genes A and B are on the same chromosome and very far apart. c. The genes A and B are probably between 10 and 20 map units apart on the same chromosome. d. The genes A and B are likely located on different chromosomes. e. Either b or d could be correct.

e

Genetic distances within a given linkage group a. cannot exceed 100 cM. b. are dependent on crossover frequencies between paired, non-sister chromatids. c. are measured in centiMorgans. d. cannot be determined. e. Both b and c are correct.

e

Qualitative traits demonstrate a discontinuous characteristic that exhibits only a few, easily distinguishable phenotypes; whereas, quantitative traits are a continuous characteristic that exhibits a continuous range of phenotypes. Which of the following is true regarding Quantitative traits? A. Can not be separated into distinct classes of phenotypes. B. Polygenic, multiple, or complex traits are known as quantitative traits. C. Statistical methods could be used to analyze these traits D. Mean and variance are major features of distribution in the analysis process E. All of the above (Correct answer; all of the statements are true)

e

Recombination occurs through a. crossing over and chromosome interference. b. chromosome interference and independent assortment. c. somatic-cell hybridization and chromosome interference. d. complete linkage and chromosome interference. e. crossing over and independent assortment.

e

Which of the following shows a Repulsion (trans) linkage phase? A) AB/ab B) Ab/aB C) aB/Ab D) A and B E) B and C

e. Both B and C show a Repulsion linkage phase since there is one dominant and one recessive allele on one of the homologous chromosomes. Answer choice A shows chromosomes in a Coupling linkage phase since both dominant alleles are on one of the homologous chromosomes and both recessive alleles are on the other.

One centiMorgan (cM) is one map unit and 100% recombination frequency.

false, 1%

An X-linked recessive trait is never seen in females.

false, Females can get an X-linked recessive disorder, but this is very rare. An abnormal gene on the X chromosome from each parent would be required, since a female has two X chromosomes

X and Y chromosomes can't pair and segregate into different cells in meiosis.

false, X and Y pair

Absence of Y chromosome in humans is lethal and results in embryo abortion.

false, also known as Y chromosome microdeletion, or YCM, produces no symptoms but is observed in men who experience reduced fertility/ low sperm count

The X and Y chromosomes are named after their characteristic shape.

false, corresponding letters in the alphabet

Odd numbers of crossover events between two genes can't be detected in the test cross.

false, evens cant be predicted

The cellular reason for X-inactivation is to reduce the amount of nondisjunction during meiosis.

false, just to balance

As the number of loci affecting a character increases, the number of phenotypic classes in the F2 decreases.

false, the number of phenotype classes in the F2 increases.

When ________ is high for a particular trait, offspring tend to resemble their parents for that trait.

narrow-sense heritability

A Y-linked trait is always passed from a father to a son.

true

A normal human female heterozygous for two X-linked alleles usually express only one of those alleles in any given cell in her body.

true

A testcross includes one parent that is homozygous recessive for all gene loci being examined

true

A woman with normal color vision must be a carrier (heterozygote) if she has a father who is color blind.

true

Autosomal recessive traits often appear to 'skip' generations.

true

Barr body is an inactivated X-chromosome visible in the nucleus of a cell in female mammals.

true

Both autosomal recessive and dominant traits appear equally in males and females.

true

Coupling and repulsion phases can result in the same phenotypes of the offspring but in very different numbers.

true

Cross between a white-eyed female and red-eyed male fruit fly will produce all red-eyed females and white-eyed males

true