Chapter 15 practice, dynamic

deletion

A ________ is the loss of part of a chromosomal segment.

X chromosome inactivation

A genetic defect in humans results in the absence of sweat glands in the skin. Some men have this defect all over their bodies, but in women it is usually expressed in a peculiar way: A woman with this defect typically has small patches of skin with sweat glands and other patches without sweat glands. In women, the pattern of sweat-gland distribution can best be explained by __________. a mutation Recombination Nondisjunction Linkage X chromosome inactivation

black-bodied, normal-winged ... black-bodied, vestigial-winged

A gray-bodied, vestigial-winged fly is crossed with a black-bodied, normal-winged fly. The F1 progeny is testcrossed. Among the resulting offspring, __________ is a parental type, and __________ is a recombinant type. black-bodied, normal-winged ... black-bodied, normal-winged gray-bodied, normal-winged ... black-bodied, vestigial-winged gray-bodied, normal-winged ... black-bodied, normal-winged gray-bodied, vestigial-winged ... black-bodied, normal-winged black-bodied, normal-winged ... black-bodied, vestigial-winged

orders genes on a chromosome based on recombination frequencies

A linkage map __________. orders genes on a chromosome based on their location with respect to a stained band can be constructed only for sex chromosomes shows the ordering and exact spacing of genes on a chromosome orders genes on a chromosome based on recombination frequencies predicts the probability that you will have a male or female child

D) deletion and duplication

A nonreciprocal crossover causes which of the following products? A) deletion only B) duplication only C) nondisjunction D) deletion and duplication

male

A person with two X chromosomes and one Y chromosome would appear to be __________. female both male and female male neither male nor female any of the listed responses, depending on the number of other chromosomes

one of the couple's other children

A person's remains are found, and officials are trying to identify them. A couple believes that the remains belong to their missing daughter. Because the remains have decayed considerably, mitochondrial DNA is being used to determine the person's identity. In order to determine if the remains belong to someone in this couple's family, whose mitochondrial DNA should be used for comparison? either the husband's or the wife's the husband's mother one of the couple's other children the husband's Anyone from the same family will have nearly identical mitochondrial DNA.

0%

A woman is a carrier for red-green color blindness, a sex-linked trait. Her husband is normal (not color-blind) for this trait. What are the chances that their newborn daughter will be red-green color-blind? 0% 25% 50% 75% 100%

He is red-green color-blind.

A woman is red-green color-blind. What can we conclude, if anything, about her father? We have too little information to tell. He is red-green color-blind. He has two Y chromosomes. There is a 50% probability that he has normal vision. None of the listed responses is correct.

duplication

A_______ is the repetition of a segment. The repeated segment may be located next to the original or at a different location, and its orientation may be the same as the original or the reverse.

translocation

A________ is the transfer of a segment to a nonhomologous chromosome. This may be reciprocal (two nonhomologous chromosomes exchange segments) or nonreciprocal (one chromosome transfers a segment without receiving one).

inversion

An__________ is the removal of a segment followed by its reinsertion into the same chromosome in the reverse orientation.

map units do not necessarily correlate to physical distances along the chromosome

Because the frequency of crossing over is not uniform along the length of a chromosome, __________. recombination frequency cannot be used to determine the number of map units separating two genes map units do not necessarily correlate to physical distances along the chromosome the recombination frequency between two genes cannot be used to calculate the number of map units separating them the map unit is an unreliable unit of measurement, and is rarely used today pairs of homologous chromosomes contain small but significant differences in gene order

carry extranuclear genes

Both chloroplasts and mitochondria __________. display a Mendelian pattern of inheritance carry extranuclear genes are found within the nucleus are inherited from both parents have linear DNA

aneuploid

Cells that have an abnormal number of some particular chromosome are said to be __________. nanoploid diploid aneuploid polyploid trisomy

male white-eyed; Morgan

Compared to peas, fruit flies were thought to have no variations, until the discovery of a __________ fly by __________. male red-eyed; Morgan female white-eyed; Morgan female white-eyed; Krebs female red-eyed; Krebs male white-eyed; Morgan

Either her mother was a carrier or her father had hemophilia.

Consider a woman who is a carrier of a recessive X-linked allele for hemophilia. Which of the following possibilities could explain the presence of the hemophilia allele in her genotype? Both her mother and her father had hemophilia. Either her mother was a carrier or her father had hemophilia. Either her mother was homozygous dominant or her father had hemophilia. Either her mother was a carrier or her father had a dominant allele. None of the listed responses is correct.

aneuploidy; trisomic

Down syndrome is an example of __________, and the child is __________ for chromosome 21. aneuploidy; trisomic aneuploidy; monosomic polyploidy; monosomic polyploidy; trisomic haploidy; monosomic

To express an X-linked recessive allele, a female must have two copies of the allele, one of which is contributed by the father.

Duchenne muscular dystrophy is caused by a sex-linked recessive allele. Its victims are almost invariably boys, who usually die before the age of 20. Why is this disorder almost never seen in girls? To express an X-linked recessive allele, a female must have two copies of the allele, one of which is contributed by the father. Nondisjunction occurs in males but not in females. A sex-linked allele cannot be passed from mother to daughter. Sex-linked traits are never seen in girls. The allele is carried on the Y chromosome.

nondisjunction

During meiosis, homologous chromosomes sometimes "stick together" and do not separate properly. This phenomenon is known as __________. sticky chiasmata nondisjunction gametic infertility meiotic failure cellular sterility

aneuploidy

Examples of alterations of chromosomal structures include all of the following except __________. duplications aneuploidy deletions translocations inversions

a mosaic

Female mammals have two X chromosomes, one from their mother and one from their father. During X inactivation, one X chromosome in each embryonic cell is randomly inactivated; therefore, all of the tissues that arise from that cell have the same inactivated X chromosome. Female mammals are therefore considered to be __________ of the maternal and paternal cells. a fusion a mosaic a blending a recombinant homozygotes

the mother

For an X-linked trait, it is the contribution of __________ that determines whether a son will display the trait. the mother the father the paternal grandfather the paternal grandmother None of the listed responses is correct.

ACBD

Four genes (A, B, C, and D) are on the same chromosome. The recombination frequencies are as follows: A-B: 19%; B-C: 14%; A-C: 5%; B-D: 2%; A-D: 21%; C-D: 16%. Based on this information, which sequence of genes is correct? ACDB ABCD ABDC ADBC ACBD

translocation occurred

Gene A is normally found on chromosome number 15 in humans. If amniocentesis reveals fetal cells containing gene A on chromosome 17, but not on 15, the best explanation would be that __________. a change in nucleotide sequence within Gene A occurred either during gametogenesis or in the mitotic divisions following fertilization at least one parent probably had a genetic abnormality an inversion of gene A occurred on chromosome 15 translocation occurred crossing over occurred during synapsis of meiosis I in one parent's gametes

genomic imprinting

Gene silencing is called __________. a translocation a mitochondrial effect genomic imprinting polyploidism a linkage analysis

embryonic development

Genomic imprinting in mammals appears to affect primarily genes involved in __________. sex determination vision embryonic development digestion function of the nervous system

embryonic development

Genomic imprinting in mammals appears to primarily affect genes involved in __________. function of the nervous system vision digestion embryonic development sex determination

50%

Hemophilia is an X-linked disorder. The daughter of a father with hemophilia and a carrier mother has a __________ probability of having hemophilia. 0% 50% 33% 100% 25%

A) The two genes are closely linked on the same chromosome.

How would one explain a testcross involving F1 dihybrid flies in which more parental-type offspring than recombinant-type offspring are produced? A) The two genes are closely linked on the same chromosome. B) The two genes are linked but on different chromosomes. C) Recombination did not occur in the cell during meiosis. D) Both of the characters are controlled by more than one gene

Half of their sons will show the recessive trait.

If a woman is heterozygous for a recessive sex-linked allele and her husband has the dominant allele, which one of the following is true about the probabilities for their children? All of their sons will show the recessive trait. All of their daughters will be heterozygous. Half of their sons will show the recessive trait. None of their sons will show the recessive trait. None of the listed responses is correct.

they are on the same chromosome

If two genes are linked, __________. they are on different chromosomes they are on sex chromosomes they are on the same chromosome they assort independently they code for the same protein

Aneuploidy

In Klinefelter syndrome, individuals are phenotypically male, but have reduced sperm production and may have some breast development in adolescence. The cells of Klinefelter individuals have two X chromosomes and one Y (they are XXY instead of XY). This occurs because of what meiotic error? Translocation Monosomy Aneuploidy Polyploidy Duplication

nondisjunction

In Klinefelter syndrome, individuals are phenotypically male, but they have reduced sperm production and may have some breast development in adolescence. The cells of Klinefelter individuals have two X chromosomes and one Y (they are XXY instead of XY). This occurs because of what meiotic error? duplication polyploidy nondisjunction monosomy translocation

fathers pass X-linked alleles only to their daughters, and mothers pass X-linked alleles to both their daughters and their sons

In X-linked patterns of inheritance, __________. fathers pass X-linked alleles only to their daughters, and mothers pass X-linked alleles only to their daughters fathers pass X-linked alleles only to their sons, and mothers pass X-linked alleles only to their daughters fathers pass X-linked alleles to both their daughters and their sons, and mothers pass X-linked alleles to both their daughters and their sons fathers pass X-linked alleles to both their daughters and their sons, and mothers pass X-linked alleles only to their sons fathers pass X-linked alleles only to their daughters, and mothers pass X-linked alleles to both their daughters and their sons

Matings of soft ray males and bony ray females give different results from the matings of bony ray males and soft ray females.

In a certain fish, fin rays (supporting structures for the fins) can be either bony or soft in adult fish. Sex linkage in a fish is similar to that in humans. What evidence would most strongly support the idea that the ray locus is on the X chromosome? Females with either bony or soft rays can reproduce, but males with soft rays cannot transfer sperm to the female. All of the listed responses are correct. Bony ray males can pass on bony rays only to their male offspring. Females with bony rays cannot pass bony rays to female offspring even if they are mating with a bony ray male. Matings of soft ray males and bony ray females give different results from the matings of bony ray males and soft ray females.

Matings of soft ray males and bony ray females give different results from the matings of bony ray males and soft ray females.

In a certain fish, fin rays (supporting structures for the fins) can be either bony or soft in adult fish. Sex linkage in a fish is similar to that in humans. What evidence would most strongly support the idea that the ray locus is on the X chromosome? Matings of soft ray males and bony ray females give different results from the matings of bony ray males and soft ray females. Females with either bony or soft rays can reproduce, but males with soft rays cannot transfer sperm to the female. Females with bony rays cannot pass bony rays to female offspring even if they are mating with a bony ray male. Bony ray males can pass on bony rays only to their male offspring. All of the listed responses are correct.

red; red

In a cross between wild-type (red-eyed) female flies and mutant white-eyed male flies, the F1 generation should always produce females with __________ eyes and males with __________ eyes. white; red red; pink red; red red; white white; white

The genes for hair color and eye color are linked.

In a particular species of mammal, black hair (B) is dominant to green hair (b), and red eyes (R) are dominant to white eyes (r). When a BbRr individual is mated with a bbrr individual, offspring are produced in a ratio of 5 black hair and red eyes:5 green hair and white eyes:1 black hair and white eyes:1 green hair and red eyes. The expected result would be equal numbers of these four phenotypes. Which of these explanations accounts for this ratio? The genes for hair color and the genes for eye color are carried on different chromosomes. The genes for hair color and eye color are linked. The genes for both of these traits are carried on the autosomes. Green-haired individuals have a higher prenatal mortality than black-haired individuals. The expected results did not take genetic recombination into account.

approximately 14%

In a particular species of mammal, black hair (B) is dominant to green hair (b), and red eyes (R) are dominant to white eyes (r). When a BbRr individual was mated with a bbrr individual, the observed distribution of offspring was as follows: black-red 1,070; black-white 177; green-red 180; green-white 1,072. Based on these data, what is the recombination frequency? 86% 30% 7% approximately 17% approximately 14%

tortoiseshell females; black males

In cats, black fur color is caused by an X-linked allele; the other allele at this locus causes orange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male? black females; orange males tortoiseshell females; tortoiseshell males orange females; black males tortoiseshell females; black males

A) how far apart they are on the chromosome

In general, the frequency with which crossing over occurs between two linked genes depends on what? A) how far apart they are on the chromosome B) the characters the genes code for C) the phase of meiosis in which the crossing over occurs D) whether the genes are on the X or some other chromosome E) whether the genes are dominant or recessive

two; X; Y; one; haploid

In humans, a normal male's somatic cells will have __________ set(s) of chromosomes and sex chromosomes designated as __________ and __________, while in bees and ants, a normal male's somatic cells have __________ set(s) of chromosomes, which are __________. two; X; X; one; haploid two; X; Y; one; haploid two; X; Z; two; diploid two; X; Y; two; diploid two; X; X; two; diploid

C) The male gamete determines sex because each male gamete can contribute either an X or a Y chromosome.

In humans, what determines the sex of offspring and why? A) The male determines sex because the sperm can fertilize either a female egg or a male egg. B) The female gamete determines sex because only the female gamete provides cytoplasm to the zygote. C) The male gamete determines sex because each male gamete can contribute either an X or a Y chromosome. D) The chromosome contribution from both parents determines sex because the offspring uses all the parents' chromosomes. E) The female gamete determines sex because only the female gametes can have one of two functional sex chromosomes.

50%

In werewolves (hypothetically), the pointy ear allele (P) are dominant over the round ear allele (p). The gene for ear shape is on the X chromosome. (Sex determination in werewolves is the same as for "other" humans.) A certain female werewolf has pointy ears even though her father had round ears. What percentage of her sons will have round ears if she mates with a werewolf with round ears? 0% 25% 50% 75% 100%

may have subnormal intelligence or be at risk for learning disabilities

Individuals with an extra X chromosome __________. may have subnormal intelligence or be at risk for learning disabilities have distinguishing physical features are generally sterile are always female None of the listed responses is correct.

b. n+1; n+1; n-1; n-1

Inheritance patterns cannot always be explained by Mendels models of inheritance. If a pair of homologous chromosomes fails to separate during meiosis I, select the choice that shows the chromosome number of the four resulting gametes with respect to the normal haploid number (n)? a. n+1; n+1; n; n b. n+1; n+1; n-1; n-1 c. n+1; n-1; n-1; n-1 d. n+1; n-1; n; n

Fathers with the disorder pass it on to all their children, but mothers with the disorder do not pass it along.

It is proposed that a certain disorder affecting the inner ear is caused by mitochondrial DNA. Which of the following observations would be the most decisive evidence against this idea? Females and males have the disorder in equal numbers. Fathers with the disorder pass it on to all their children, but mothers with the disorder do not pass it along. Mothers pass the disorder on to their offspring, but fathers do not. The precise cause of the disorder is found to involve the nervous system. All of the listed responses are correct.

are located near each other on the same chromosome

Linked genes __________. are located near each other on the same chromosome are located on the same chromosome, but one gene is closer to the centromere while the other gene is closer to the end of the arm are found only on sister chromatids Unselected are found only in Drosophila are located on the same chromosome but at opposite ends of the arms

E) males are hemizygous for the X chromosome.

Males are more often affected by sex-linked traits than females because A) X chromosomes in males generally have more mutations than X chromosomes in females. B) mutations on the Y chromosome often worsen the effects of X-linked mutations. C) female hormones such as estrogen often compensate for the effects of mutations on the X chromosome. D) male hormones such as testosterone often alter the effects of mutations on the X chromosome. E) males are hemizygous for the X chromosome. males are hemizygous for the X chromosome

C) translocation

One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome. What is this alteration called? A) deletion B) inversion C) translocation D) duplication

recessive, sex-linked

Pseudohypertrophic muscular dystrophy is a human disorder that causes gradual deterioration of the muscles. Only boys are affected, and they are always born to phenotypically normal parents. Due to the severity of the disease, the boys die in their teens. Is this disorder likely to be caused by a dominant or recessive allele? Is its inheritance sex-linked or autosomal? recessive, autosomal incomplete dominant, sex-linked recessive, sex-linked dominant, sex-linked

Either her mother was a carrier or her father had hemophilia.

Queen Victoria was a carrier of a recessive sex-linked allele for hemophilia. Which of the following possibilities could explain the presence of the hemophilia allele in her genotype? None of the listed responses is correct. Either her mother was homozygous dominant or her father had hemophilia. Either her mother was a carrier or her father had hemophilia. Both her mother and her father had hemophilia. Either her mother was a carrier or her father had a dominant allele.

D) Crossovers between these genes result in chromosomal exchange

Recombination between linked genes comes about for what reason? A) Nonrecombinant chromosomes break and then rejoin with one another. B) Independent assortment sometimes fails. C) Linked genes travel together at anaphase. D) Crossovers between these genes result in chromosomal exchange.

chromosomal theory of inheritance; segregation; independent assortment

The __________ states that genes have specific positions on chromosomes and that chromosomes undergo both __________ and __________. genetic theory of genes; segregation; independent assortment chromosomal theory of inheritance; segregation; independent assortment chromosomal theory of inheritance; segregation; dependent assortment chromosomal theory of genetics; desegregation; independent assortment genetic theory of inheritance; segregation; independent assortment

segregation; homologous pairs; independent assortment; alleles; independently

The ability to observe meiosis in gamete production supported Mendel's first law of __________, which applies when __________ separate, and supported Mendel's second law of __________, which applies when __________ sort __________. segregation; homologous pairs; independent assortment; alleles; independently independent assortment; homologous pairs; segregation; sister chromatids; independently segregation; sister chromatids; independent assortment; alleles; independently independent assortment; homologous pairs; segregation; alleles; independently segregation; homologous pairs; independent assortment; alleles; dependently

inversion

The chromosomal abnormality in which a fragment of a chromosome breaks off and then reattaches to the original chromosome in the same place but in the reverse direction is called __________. polyploidy inversion duplication deletion translocation

genes occupy specific positions on chromosomes, homologous chromosomes segregate from each other during meiosis, and chromosomes assort independently during meiosis

The chromosome theory of inheritance states that __________. genes occupy specific positions on chromosomes and homologous chromosomes segregate from each other during meiosis genes occupy specific positions on chromosomes genes occupy specific positions on chromosomes, homologous chromosomes segregate from each other during meiosis, and chromosomes assort independently during meiosis chromosomes assort independently during meiosis homologous chromosomes segregate from each other during meiosis

The first, second, and third answers are correct.

The chromosome theory of inheritance states that __________. genes occupy specific positions on chromosomes homologous chromosomes segregate from each other during meiosis chromosomes assort independently during meiosis The first and second answers are correct. The first, second, and third answers are correct.

greater as the distance between the two loci increases

The recombination frequency between two gene loci is __________. equal to the size of the chromosome greater as the distance between the two loci increases dependent on whether dominant or recessive alleles are carried at the two loci greater as the distance between the two loci decreases dependent on the sex of the parent

The two genes are unlinked and are assorting independently, leading to a 1:1:1:1 ratio of phenotypes in the offspring.

The χ2 value means nothing on its own--it is used to find the probability that, assuming the hypothesis is true, the observed data set could have resulted from random fluctuations. A low probability suggests the observed data is not consistent with the hypothesis, and thus the hypothesis should be rejected. What is the hypothesis that you are testing? The two genes are unlinked and are assorting independently, leading to a 1:1:0:0 ratio of phenotypes in the offspring. The two genes are linked and are assorting together, leading to a ratio of phenotypes in the offspring that deviates significantly from 1:1:1:1. The two genes are linked and are assorting together, leading to a 1:1:1:1 ratio of phenotypes in the offspring. The two genes are unlinked and are assorting independently, leading to a 1:1:1:1 ratio of phenotypes in the offspring.

both the first and third listed responses

What appears to be the mechanism for genomic imprinting? DNA methylation that silences particular genes crossing over DNA methylation that activates particular genes nondisjunction both the first and third listed responses

DNA methylation that silences particular genes and DNA methylation that activates particular genes

What appears to be the mechanism for genomic imprinting? Nondisjunction DNA methylation that silences particular genes and DNA methylation that activates particular genes DNA methylation that silences particular genes Crossing over DNA methylation that activates particular genes

homologous chromosomes separating during meiosis I

What can we observe in order to visualize Mendel's Law of Segregation? homologous chromosomes separating during meiosis II the behavior of sex-linked genes sister chromatids separating during mitosis the replication of DNA homologous chromosomes separating during meiosis I

a) the 2 genes are likely to be located on different chromosomes

What does a frequency of recombination of 50% indicated? a) the 2 genes are likely to be located on different chromosomes b) the genes are located on sex chromosomes c) all of the offspring have combinations of traits that match one of the two parents d) abnormal meiosis has occurred

0%

What is the probability that a human male will inherit an X-linked recessive allele from his father? 25% 0% 100% 50% 75%

B) an inversion

What results if a fragment of a chromosome breaks off and then reattaches to the original chromosome at the same place but in the reverse direction? A) polyploidy B) an inversion C) a nondisjunction D) a deletion E) a translocation

aneuploidy ... nondisjunction of chromosome 21

When a person has Down syndrome, he or she has an extra chromosome 21. Therefore, Down syndrome is a kind of _________ and results from __________. replication error ... an extra cycle of DNA synthesis during the S phase genomic imprint ... excessive methylation of either the paternal or maternal chromosome 21 polyploidy ... occurrence of meiosis without cytokinesis aneuploidy ... nondisjunction of chromosome 21 None of the listed responses is correct.

trisomic; aneuploidy

When an individual has an additional chromosome, that chromosome set is called __________, and the condition is known as __________. trisomic; polyploidy monosomic; aneuploidy trisomic; haploidy trisomic; aneuploidy monosomic; haploidy

be greater than

When crossing over occurs between two linked genes in an F1 dihybrid testcross, the frequency of the parental types will always __________ the frequency of the recombinant types when compared to Mendel's unlinked genes. be less than be equal to be dominant to be greater than be recessive to

The XIST gene on the X chromosome that will be inactivated is expressed to produce multiple RNA transcripts that bind to that chromosome and effectively cover it up, thereby generating a Barr body.

Which of the following best describes the function of the XIST gene in X chromosome inactivation? The XIST gene codes for an enzyme that methylates DNA on the X chromosome being inactivated. The XIST gene on the X chromosome that will be inactivated is expressed to produce multiple RNA transcripts that bind to that chromosome and effectively cover it up, thereby generating a Barr body. The XIST gene on the X chromosome that will remain active is expressed to produce multiple RNA molecules that bind to the X chromosome to be inactivated and effectively cover it up, thereby generating a Barr body. Together with other proteins, the protein product of the XIST gene binds to histones and induces supercoiling of the DNA in one of the X chromosomes, thus inactivating it. The first and second listed responses are correct.

XO

Which of the following is the only known viable human monosomy? XXX XYY XY XXY XO

B) The gene is present in both males and females.

Which of the following is true of an X-linked gene, but not of a Y-linked gene? A) It is only expressed in female offspring. B) The gene is present in both males and females. C) It is expressed in half of the cells of either male or female. D) It does not segregate like other genes. E) Sister chromatids separate during mitosis.

E. aneuploidy

Which of the following results in a situation in which the chromosome number is either 2n+1 or 2n-1 ? A. inversion B. methylation C. polyploidy D. gene linkage E. aneuploidy

Among the F2 progeny, only males had white eyes. All of the females had red eyes.

Which of the following results of Thomas Hunt Morgan's experiments with white-eyed mutant flies was unexpected in light of Mendelian genetics? The F1 flies were crossed with each other, and the F2 progeny included red-eyed and white-eyed flies in a 3:1 ratio. In the parental cross, a white-eyed male was crossed with a red-eyed female. The F1 progeny all had red eyes. Among the F2 progeny, only males had white eyes. All of the females had red eyes. The mutant allele (white eyes) was recessive. All of the listed responses are correct.

B. The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them.

Which of the following statements is true of linkage? A. All of the traits that Mendel studied-seed color, pod shape, flower color, and others-are due to genes linked on the same chromosome. B. The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them. C. The observed frequency of recombination of two genes that are far apart from each other has a maximum value of 100%. D. Crossing over occurs during prophase II of meiosis. E. Linked genes are found on different chromosomes.

The first three responses are correct.

Which of the following would result in genetic variation by way of new combinations of alleles? independent alignment of homologous chromosomes during meiosis I the exchange of alleles between homologous chromosomes during meiosis I random fertilization increasing the number of possible allele combinations in an individual The first and second responses are correct. The first three responses are correct.

B. The arrangement of each pair of homologous chromosomes on the metaphase plate during metaphase I is random with respect to the arrangements of other pairs.

Which of these descriptions of the behavior of chromosomes during meiosis explains Mendel's law of segregation? A. The two alleles for each gene separate as homologous chromosomes move apart during anaphase I. B. The arrangement of each pair of homologous chromosomes on the metaphase plate during metaphase I is random with respect to the arrangements of other pairs. C. Sister chromatids separate during anaphase II.

All eight possible phenotypes could occur, but a greater proportion of the offspring would have the parental phenotypes.

Which statement best predicts the results of the cross MmDdPp x mmddpp assuming that all three genes are linked? Lack of independent assortment means that you cannot predict the frequencies of phenotypes in the offspring. Only the parental phenotypes could possibly occur in the offspring. All eight possible phenotypes would occur in equal numbers in the offspring (1:1:1:1:1:1:1:1). All eight possible phenotypes could occur, but a greater proportion of the offspring would have the parental phenotypes.

deletion

Which type of chromosomal alteration is responsible for the cri du chat syndrome? translocation inversion deletion duplication genetic imprinting

Extra copies of the other chromosomes are probably fatal to the developing embryo.

Why are individuals with an extra chromosome 21, which causes Down syndrome, more numerous than individuals with an extra chromosome 3 or chromosome 16? Nondisjunction of chromosomes 3 and 16 probably occurs much less frequently. Down syndrome is not more common, just more serious. Chromosome 21 is a sex chromosome, and 3 and 16 are not. Extra copies of the other chromosomes are probably fatal to the developing embryo. There are probably more genes on chromosome 21 than on the others.

Both the second and fourth answers are correct.

Why did Morgan choose Drosophila for his genetics experiments? They have a long generation time. A single mating can produce many offspring. They have a large number of chromosomes. Drosophila chromosomes can be easily distinguishable under a light microscope. Both the second and fourth answers are correct.

the most common phenotype thought to be found in the natural population

Wild type refers to __________. any mutant genotype the most extreme mutant phenotype observed in an experiment extranuclear genes a kind of chromosomal deletion the most common phenotype thought to be found in the natural population

She is XXX.

With a microscope, you examine some somatic cells from a woman and notice that each nucleus has two Barr bodies. What can you infer about the sex chromosomes in this individual? She is XXXX. She is XXX. None of the listed responses is correct. She is XXY, but the Y chromosome lacks the SRY gene. She is XX.

two; Barr body; random

X inactivation occurs when there is/are at least __________ X chromosomes present in an individual, forming a structure called a __________ by a __________ event. two; chromosomal body; random two; chromosomal body; specific one; Barr body; random two; Barr body; random one; Barr body; specific

Sons and daughters have equal probabilities in inheriting a recessive allele of an X-linked gene from their mother, but only sons can inherit rare Y-linked genetic disorders from their father.

X-linked genes differ from Y-linked genes in which of the following ways? Genes on the X chromosome are expressed only in females, and genes on the Y chromosome are expressed only in males. Sons and daughters can inherit alleles of X-linked genes from fathers proportionally but only sons inherit alleles of Y-linked genes from their fathers. Though most X-linked genes determine sex, Y-linked genes control for characters unrelated to sex. Sons and daughters have equal probabilities in inheriting a recessive allele of an X-linked gene from their mother, but only sons can inherit rare Y-linked genetic disorders from their father. Only X-linked genes are technically sex-linked because Y-linked genes affect characteristics unrelated to sex.

unlinked

You perform a testcross using F1 dihybrid flies. If, in the resulting offspring, the percentages of parental and recombinant offspring are about the same, this would indicate that the two genes are __________. imprinted linked similar in DNA sequence mutated unlinked

unlinked

You perform a testcross using F1 dihybrid flies. If, in the resulting offspring, the percentages of parental and recombinant offspring are about the same, this would indicate that the two genes are __________. similar in DNA sequence unlinked linked mutated imprinted

Nondisjunction; homologous chromosomes; sister chromatids

__________ is the failure of __________ to separate in meiosis I or the failure of __________ to separate in meiosis II. Nondisjunction; homologous chromosomes; sister chromatids Aneuploidy; sister chromatids; homologous chromosomes Disjunction; homologous chromosomes; sister chromatids Disjunction; sister chromatids; homologous chromosomes Nondisjunction; sister chromatids; homologous chromosomes

Polyploidy ... aneuploidy ... polyploid

__________ is usually less severe than __________, and __________ species have been observed in plants, fish, amphibians, and even mammals. Monosomy ... polyploidy ... monosomic Aneuploidy ... polyploidy ... aneuploid Polyploidy ... aneuploidy ... polyploid Nondisjunction ... disjunction ... nondisjunctional Trisomy ... polyploidy ... trisomic

none of the females will have white eyes

a white-eyed female Drosophilia is crossed with a red-eyed male Drisophilia. Which statement below correctly describes the results? none of the females will have red eyes 25% of the females will have white eyes none of the females will have white eyes 25% of the females will have red eyes 50% of the females will have red eyes

a) 1/4 of the gametes descended from cell X will be n+1, 1/4 will be n-1, and 1/2 will be n

if cell x enters meiosis, and nondisjunction of one chromosome occurs in one of its daughter cells during meiosis II, what will be the result at the completion of meiosis? a) 1/4 of the gametes descended from cell X will be n+1, 1/4 will be n-1, and 1/2 will be n b) half of the gametes descended from cell X will be n+1, and half will be n-1 c) all of the gametes descended from cell X will be diploid d) 2 of the 4 gametes descended from cell X will be haploid, and two will be diploid

c) a 1% frequency of recombination between 2 genes

what is the definition of one map unit? a) the physical distance between 2 linked genes b) the recombination frequency between 2 genes assorting independently c) a 1% frequency of recombination between 2 genes d) 1 nm of distance between 2 genes

wild type

what name is given to the most common phenotype in a natural population? autosome wild type genotype locus mutant phenotype

d) genomic imprinting

what phenomenon occurs when a particular allele will either be expressed or silenced, depending on whether it is inherited from a male or female? a) aneuploidy b) extranuclear inheritance c) sex linkage d) genomic imprinting e)polyploidy

-the gene involved is on the x chromosome

when Morgan crossed his red-eyed F1 generation flies to each other, the F2 generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result? -the gene involved is on the Y chromosome -the gene involved is on an autosome, but only in males -the gene involved is on the x chromosome -other male-specific factors influence eye color in flies