Biology Chapter 9 and 10

Their position, or _________, on the chromosome is fixed.

locus

Sickle-cell disease is caused by a single mutation in the DNA of a particular gene. A person with this disease has red blood cells that lose their original donut shape and form a sickle shape. People with this disorder suffer from low energy levels, blood clots, and strokes. This is an example of Multiple Choice incomplete dominance. polygenic inheritance. pleiotropy. codominance. a multifactorial trait.

pleiotropy. Explanation Pleiotropy occurs when a single gene has more than one effect. Often, this leads to a syndrome, a group of symptoms that appear together and indicate the presence of a particular genetic mutation.

Sister chromatids divide in Multiple Choice meiosis I and meiosis II. neither meiosis I nor meiosis II. meiosis I only. meiosis II only.

meiosis II only.

In a monohybrid cross, how many traits are examined? Multiple Choice 5 4 2 3 1

1 Explanation "Mono" refers to one.

How many bivalents are formed in a cell with 20 chromosomes at the beginning of meiosis I? Multiple Choice 1 5 10 20 40

10

Consider a cell that has four pairs of chromosomes. What is the number of possible chromosome orientations in that cell? Multiple Choice 4 8 16 24 32

16

Which of the following describes meiosis II in humans? Multiple Choice 4N → 2N 2N → 2N 2N → 1N 1N → 2N 1N → 1N

1N → 1N

arrange the following events in the proper order in which they occur during meiosis I. 1 = Separation of homologous chromosomes 2 = Crossing-over 3 = Independent assortment Multiple Choice 1, 2, 3 1, 3, 2 2, 3, 1 3, 2, 1

2, 3, 1

If a parent is heterozygous for a gene, 1/2 of the time they will contribute a dominant allele to their offspring and 1/2 of the time they will contribute a recessive allele to their offspring. The phenotypes of the resulting offspring will be _____ dominant and _____ recessive. Multiple Choice 1/4; 3/4 1/2; 1/2 3/4; 1/4 all (4/4); no (0/4)

3/4; 1/4

which of the following processes contributes to creating genetic variability in the offspring? Multiple Choice having different alleles of the same gene independent assortment of chromosomes crossing-over pairing of homologous chromosomes All of the answers describe processes that contribute to genetic variability.

All of the answers describe processes that contribute to genetic variability.

Metaphase I

Tetrads line up at the spindle equator Chromosomes are shuffled into new combinations Homologous chromosomes face opposite spindle poles

In humans, there are 22 pairs of chromosomes called _________, which are the same in both males and females, and one pair of chromosomes called _________________, which contain genes that determine gender.

autosomes, sex chromosomes

both recessive and dominant

both females and males are affected equally

When conducting dihybrid crosses, it is assumed that the traits assort independently of one another. This is because they are on _____ chromosomes. Multiple Choice different homologous the same

different

The sex chromosomes in males are X and ____.

Y

Which of the following is an inaccurate statement about human blood types? Multiple Choice IA represents antigen A on red blood cells. Human blood genetics involves multiple alleles and an individual can have up to three different blood alleles. The allele representing blood type O is recessive. A person with AB blood has two different antigens on their red blood cells. When inherited together, A and B blood types exhibit codominance.

Human blood genetics involves multiple alleles and an individual can have up to three different blood alleles. Explanation It is true that human blood genetics involves multiple alleles (A, B, or O), but each individual only ever has two alleles (one from their father and one from their mother). The two alleles might be the same (ex. IBIB) or they might be different (ex. IBi).

The autosomal dominant disorder called ____________ leads to progressive degeneration of neurons in the brain.

Huntington disease

Determine if the following statement is true or false. A man with blood type A and a woman with blood type B can have a baby with blood type O. Multiple Choice False, the child must have type AB blood. True, because only one O allele is needed. True, because although A and B are the dominant blood types, both individuals could carry a type O allele. True, because A and B are codominant. False, because type A and B are dominant blood types and these individuals cannot have offspring with the recessive blood type.

True, because although A and B are the dominant blood types, both individuals could carry a type O allele. Explanation Type O blood is recessive, so parents that are AO (IAi) and BO (IBi) could have a child that is OO (ii).

If an individual within the parental generation was heterozygous for both traits, what combinations of traits could their gametes possess? Multiple Choice WS and ws WS, Ws, wS, and ws WwSs, WWSS, and wwss WW, Ww, ww, SS, Ss, and ss

WS, Ws, wS, and ws

autosomal recessive

affected children can have unaffected parents heterozygotes have normal phenotype

The autosomal recessive disorder called ___________ causes urine to be black.

alkaptonuria

Alleles are Multiple Choice alternate versions of the same gene. sister chromatids. recessive genes. dominant genes. two versions of the same gene.

alternate versions of the same gene. Explanation There may be more than two versions of a gene (e.g., blood types). Alleles are the alternate forms of the gene (such as A, B and O alleles of the human blood gene).

You are looking at a cell under a microscope and see what appears to be several "X" structures being pulled to each side of the cell. What stage of meiosis are you looking at? Multiple Choice anaphase I metaphase I prophase I prophase II anaphase II

anaphase I Explanation The X structure is composed of two sister chromatids. Therefore, you are looking at homologous chromosomes separating which occurs during anaphase I.

During metaphase I, the homologous chromosomes align at the spindle equator with each homologue Multiple Choice facing opposite spindle poles. facing both spindle poles. facing the same spindle pole. being separated into two sister chromatids. not facing either spindle pole.

facing opposite spindle poles. Explanation In metaphase I, homologous chromosomes face opposite spindle poles. This ensures that each daughter nucleus will receive one chromosome from each homologous pair.

Independent assortment occurs in prophase I.

false

What is the name of the process in which haploid gametes fuse to form diploid offspring? Multiple Choice fertilization meiosis I meiosis II prophase I

fertilization

Because they reside so close together on the chromosome, there is a reduced chance that _______________ will occur and therefore they do not follow the traditional Mendelian genotypic ratios.

independent assortment

During meiosis, each pair of alleles on the homologous chromosomes sorts independently from all other pairs of alleles. This statement corresponds to Multiple Choice the law of independent assortment. gene theory. the law of probability. the law of segregation. the rule of multiplication.

the law of independent assortment. Explanation Tthe law of independent assortment states that each pair of alleles assorts independently of the other pairs during meiosis. Because of this, all possible combinations of alleles can occur in the gametes.

Which of the following statements about crossing-over is true? Multiple Choice It occurs only in males. It occurs only in females. It occurs only between alleles that are the same. It results in reduced genetic variation among gametes. Crossing-over allows for the reassortment of linked genes.

Crossing-over allows for the reassortment of linked genes.

prophase II, n

Explanation The cell is in prophase II. There are no longer any homologous pairs (characteristic of meiosis II) and the chromosomes, which each still consist of two sister chromatids, are not yet aligned at the metaphase plate (characteristics of prophase II). Since homologous chromosomes split and separate into different daughter cells during Meiosis I, cells in meiosis II are haploid (n).

What are all possible gametes that can be produced by an individual with the following genotype: FFGg? Multiple Choice Fg, fG Fg FG, Fg, fG, fg FF, Gg FG, Fg

FG, Fg Explanation Every gamete will receive one "F" allele and one "g" allele. In this case, since there is only one version of the F allele and 2 versions of the G allele, there are only two possible combinations of F and G alleles in the gametes: FG and Fg.

autosomal dominant

affected children have at least one affected parent heterozygotes are affected

All of the alleles on a chromosome form a(n) ______________ because they tend to be inherited together.

linkage group

The autosomal recessive disorder called ___________________ causes blue-colored skin.

methemoglobinemia

The sex chromosomes in females are two _____ chromosomes.

X

Which of the following events occur during prophase I? Multiple Choice breakdown of nuclear envelope condensation of chromosomes movement of centrosomes breakdown of the nuclear envelope and condensation of chromosomes breakdown of the nuclear envelope, condensation of chromosomes, and movement of centrosomes

breakdown of the nuclear envelope, condensation of chromosomes, and movement of centrosomes

Which of the following is a sex-linked recessive disorder? Multiple Choice cystic fibrosis Marfan syndrome color blindness alkaptonuria sickle-cell disease .

color blindness Explanation Color blindness is the only trait listed that has been identified as being associated with the X chromosome and is sex-linked recessive.

During crossing-over, Multiple Choice genetic material is exchanged between sister chromatids, resulting in new combinations of alleles. sister chromatids from each homologous chromosome of a tetrad are exchanged, resulting in new combinations of alleles. genetic material is exchanged between nonsister chromatids, resulting in new combinations of alleles. one homologous chromosome of a tetrad is exchanged with another tetrad, resulting in new combinations of alleles. nonsister chromatids from each homologous chromosome of a tetrad are exchanged, resulting in new combinations of alleles.

genetic material is exchanged between nonsister chromatids, resulting in new combinations of alleles. Explanation Crossing-over occurs between nonsister chromatids of a tetrad, and results in new combinations of alleles. Crossing-over of sister chromatids would not result in new allele combinations.

Centromeres divide in Multiple Choice mitosis and meiosis I. mitosis and meiosis II. meiosis II only. meiosis I and meiosis II. mitosis, meiosis I, and meiosis II.

mitosis and meiosis II.

The failure of sister chromatids to separate during meiosis is called Multiple Choice disjunction. crossing-over. nondisjunction. synapsis. tetrad formation.

nondisjunction. Explanation Nondisjunction is the failure of homologous chromosomes to separate during meiosis I, or failure of daughter chromosomes to separate during meiosis II.

A cross-over in meiosis is an exchange of genetic material between Multiple Choice sister chromatids of the same chromosome. sister chromatids of homologous chromosomes. sister chromatids of nonhomologous chromosomes. nonsister chromatids of homologous chromosomes. nonsister chromatids of nonhomologous chromosomes.

nonsister chromatids of homologous chromosomes

In a one-trait testcross, a homozygous dominant individual is crossed with a homozygous recessive individual. Which phenotype will be absent in the F1 generation? Multiple Choice heterozygote. negative trait. homozygote. recessive trait. dominant trait.

recessive trait Explanation All the F1 progeny are heterozygotes, which means that the recessive trait is masked.

Meisosis II

result in four genetically diverse haploid nuclei a haploid number of dyads align at the spindle equator during metaphase

meisosis I

result in two genetically diverse haploid nuclei crossing over occurs in synapse homologous chromosomes pair up during prophase tetrads align at the spindle equator during metaphase

Mitosis

result in two genetically identical diploid nuclei a diploid number of dyads align at the spindle equator during metaphase

The autosomal recessive disorder called _____________ causes irregularly shaped hemoglobin that leads to poor circulation.

sickle-cell disease

Which genetic disorder is associated with an irregular shape of the red blood cells? Multiple Choice cystic fibrosis (CF) phenylketonuria (PKU) sickle-cell disease Huntington disease Marfan syndrome

sickle-cell disease Explanation Sickle-cell disease is an irregular shape of the red blood cells. Marfan syndrome is associated with a defect in the elastic connective tissue protein called fibrillin. Huntington disease is caused by a mutation to the protein huntingtin. Phenylketonuria (PKU) is associated with the lack of the enzyme necessary for the metabolism of phenylalanine. Cystic fibrosis (CF) is associated with a faulty protein channel in the cell membrane.

A homologous pair is composed of Multiple Choice two chromosomes with two sister chromatids each. four sister chromatids, each with its own centromere. four sister chromatids attached at a common centromere. four chromosomes with two sister chromatids each. two sister chromatids with separate centromeres.

two chromosomes with two sister chromatids each Explanation A homologous pair consists of two homologous chromosomes that each consist of two sister chromatids, for a total of four chromatids per homologous pair.

A tetrad is made up of Multiple Choice four nonhomologous chromosomes. four nonhomologous chromatids. four homologous pairs of chromosomes. two homologous pairs of chromosomes. two homologous chromosomes, each consisting of two chromatids.

two homologous chromosomes, each consisting of two chromatids

Which of the following statements is true? Multiple Choice Chromosomes are classified into two categories: the sex chromosomes that determine gender and autosomes that determine non-gender related traits. Chromosomes are classified into two categories: autosomes that determine gender and the sex chromosomes that determine non-gender related traits. In humans all 46 chromosomes have an identical match called the homologue. While sex chromosomes determine different genders, they look the same until they are stained. Homologous chromosomes differ in banding patterns, the traits they code for, and size.

Chromosomes are classified into two categories: the sex chromosomes that determine gender and autosomes that determine non-gender related traits. Explanation While sex chromosomes both determine gender, they can code for different traits depending on if they are XX or XY. Autosomes code for the same traits whether the individual is male or female.

Red-green color blindness is a recessive X-linked trait. If a female is red-green color-blind, which of the following is true? Multiple Choice Women cannot exhibit red-green color blindness because they have two X chromosomes. Her mother must be color-blind. Both her parents are carriers of the recessive allele. Her father must be color-blind. Both her parents must be color-blind.

Her father must be color-blind. Explanation A woman who is color-blind must have received one recessive allele from both her parents. Because her mother has two copies of the gene, she could be either color-blind or a carrier. However, her father only has one copy, so he must exhibit red-green color blindness.

What does true-breeding mean? Multiple Choice When the plant is pollinated, all the offspring resemble the parent and are heterozygotes. The organism cannot be cultivated. When the plant self-pollinates, all the offspring resemble the parent, and are homozygous for that gene. The organism can be cross-pollinated. The organism is easy to cultivate.

When the plant self-pollinates, all the offspring resemble the parent, and are homozygous for that gene. Explanation True-breeding means an organism is homozgous for a particular gene and will only produce offspring with the same characteristic.

A human egg with 22 chromosomes that is fertilized by a normal sperm will result in Multiple Choice a zygote with trisomy. a zygote with a normal chromosome number. a zygote with monosomy. a zygote with disomy. a fertilized egg with 44 chromosomes.

a zygote with monosomy. Explanation The resulting zygote will contain 45 chromosomes (22 from the egg plus 23 from the sperm). Since one chromosome is missing (n-1), this results in a monosomy.

A chromosome contains a long series of different ________ that are in a definite ___________

alleles, sequence

The autosomal recessive disorder called _____________ causes abnormally thick mucus in the bronchial tubes and pancreatic ducts.

cystic fibrosis

All but which one of the following results from nondisjunction? Multiple Choice diploidy monosomy Down syndrome polyploidy trisomy

diploidy Explanation Nondisjunction leads to either additional chromosomes (trisomy), additional pairs of chromosomes (polyploidy), or missing chromosomes (monosomy).

Germ-line cells are haploid but gametes are diploid

false

Following telophase II and cytokinesis, meiosis II results in the formation of four ______ (haploid/diploid) daughter cells.

haploid

Which of the following is mismatched? Multiple Choice the specific alleles that an individual has - genotype physical expression of a trait - phenotype identical alleles - heterozygous allele that masks expression of alternate allele - dominant allele whose expression can be masked by an alternate allele - recessive

identical alleles - heterozygous Explanation Identical alleles refer to an individual that is homozygous, not heterozygous.

In the human life cycle, Multiple Choice mitosis produces haploid gametes, and fertilization creates a diploid cell that divides by meiosis to produce a new individual. diploid gametes are produced by mitosis, and fertilization results in tetrapolid daughter cells that divide by meiosis to produce a new individual. diploid gametes are produced by meiosis, and fertilization produces haploid daughter cells that divide by mitosis to produce a new individual. a haploid zygote is produced by meiosis and fertilization results in a diploid daughter cells that divide by mitosis to produce a new individual. meiosis produces haploid gametes, and fertilization creates a diploid cell that divides by mitosis to produce a new individual.

meiosis produces haploid gametes, and fertilization creates a diploid cell that divides by mitosis to produce a new individual. Explanation Meiosis is used to produce haploid gametes. During fertilization, gametes unite to form a single-celled zygote (fertilized egg), restoring the diploid chromosome number. The zygote then undergoes mitosis to produce the cells that will form a new individual.

The nuclear division used in sexual reproduction is called__________ and it serves two major functions: (1) reducing the chromosome number and (2) shuffling the chromosomes and genes to produce genetically different gametes, called _________ (males) and _________ (females).

meiosis, sperm ,eggs

Random orientation of homologous chromosomes occurs in ________ of meiosis. Multiple Choice prophase I metaphase I anaphase I prophase II metaphase II

metaphase I

The autosomal dominant disorder called ________________ causes defective collagen that leads to weakened, brittle bones.

osteogenesis imperfecta

Another level of genetic variation is added by ____________________, since we can't predict which sperm will fertilize a given egg.

random fertilization

Which of the following events occurs during anaphase I? Multiple Choice separation of homologous chromosomes formation of synaptonemal complex lengthening of kinetochore microtubules alignment of tetrads along equator replication of DNA

separation of homologous chromosomes

What is the inheritance pattern of hemophila? Multiple Choice sex-linked dominant sex-linked recessive polygenic codominance pleiotropic

sex-linked recessive Explanation Hemophilia is a sex-linked recessive disorder because the allele for the trait is found on the X chromosome.

During metaphase II, the ______ aligns the sister chromatids along the metaphase plate.

spindle

Meiosis II produces haploid cells because Multiple Choice the chromosomes do not replicate between meiosis I and meiosis II. the chromosomes are duplicated between meiosis I and meiosis II. meiosis II is actually a series of two additional cell division events. some of the chromosomes are spontaneously reabsorbed by the newly formed gametes.

the chromosomes do not replicate between meiosis I and meiosis II

At the end of meiosis I, there are two haploid cells, each with two sister chromatids per chromosome.

true

During metaphase II, sister chromatids attach to the spindle by kinetochore microtubules; each is attached to an opposite pole.

true

A tetrad consists of Multiple Choice one duplicated chromosome consisting of two nonsister chromatids. two homologous chromosomes each comprised of two nonsister chromatids. one duplicated chromosome consisting of two sister chromatids. two homologous chromosomes consisting of a single DNA strand each. two homologous chromosomes each comprised of two sister chromatids.

two homologous chromosomes each comprised of two sister chromatids. Explanation A tetrad consists of a pair of homologous chromosomes with each homologous chromosome comprised of two sister chromatids joined together by a centromere.

Consider a cell that has three pairs of chromosomes. What fraction of the gametes produced from this cell will contain only maternal chromosomes? Multiple Choice 1/2 1/4 1/6 1/8 1/12

1/8

Which pair of chromosomes on a karyotype would show you the sex of a baby? Multiple Choice 6th pair 18th pair 23rd pair 1st pair 21st pair

23rd pair Explanation On a karyotype the sex chromosomes are displayed last. This would be the 23rd pair of chromosomes.

The probability of having an offspring with both the dominant phenotypes for both genes is equal to the product of the individual probabilities. This means the probability of having a dominant phenotype for both traits would be Multiple Choice 3/4 × 3/4 = 9/16. 1/2 × 1/2 = 1/4. 3/4 × 1/4 = 3/16. 4/4 × 4/4 = 16/16.

3/4 × 3/4 = 9/16

Interphase differs from interkinesis because Multiple Choice homologous chromosomes separate during interphase, but not during interkinesis. DNA is duplicated during interkinesis, but not during interphase. DNA is duplicated during interphase, but not during interkinesis. homologous chromosomes separate during interkinesis, but not during interphase. interkinesis only occurs during mitosis, while interphase occurs during both meiosis and mitosis.

DNA is duplicated during interphase, but not during interkinesis. Explanation Interkinesis is the abbreviated cell cycle between meiosis I and II. The DNA is not duplicated during interkinesis.

If the parental genotype is EeWw, what are the potential allele combinations that could occur at the end of meiosis? Multiple Choice EW, Ew, eW, and ew EE, WW, ee, and ww WW, Ew, EW, and ew EW, Ew, ee and ww EW, EE, eW, and ww

EW, Ew, eW, and ew Explanation When the alleles assort during meiosis, there will be four different combinations possible from this individual: EW, Ew, eW and ew.

Which of the following is true in regards to an autosomal recessive pedigree? Multiple Choice Males are affected more often than females. The trait is carried on the Y chromosome. Heterozygotes are affected. Heterozygotes have a normal phenotype. Affected children will have at least one affected parent.

Heterozygotes have a normal phenotype. Explanation Features of autosomal recessive pedigrees include: 1. affected children can have unaffected parents. 2. heterozygotes have a normal phenotype. 3. males and females are equally likely to be affected.

Metaphase I (2n)

Homologous chromosomes are aligned together at the metaphase plate, so this represents metaphase I. Since the homologous chromosomes have not yet been separated into two new daughter cells, the cell is still diploid (2n).

Which of the following human syndromes is a monosomy? Multiple Choice Barr body syndrome Swyer syndrome Turner syndrome Down syndrome Klinefelter syndrome

Turner syndrome Explanation Turner syndrome results from an individual with a single X chromosome (45, X) and is thus a monosomy.

The human life cycle consists of Multiple Choice adults that are diploid who produce zygotes that are also diploid. adults who are haploid and produce diploid gametes; these gametes fuse to produce a haploid zygote which grows into an adult. zygotes who are haploid fuse to produce a diploid gamete which grows into an adult. gametes that are diploid and produce haploid zygotes; these grow into haploid adults. adults who are diploid and produce haploid gametes; these gametes fuse to produce a diploid zygote which grows into an adult.

adults who are diploid and produce haploid gametes; these gametes fuse to produce a diploid zygote which grows into an adult. Explanation The human life cycle describes the process of a diploid adult producing haploid gametes (sperm and egg) via meiosis which then fuse and produce a diploid zygote.

The filled-in squares of a Punnett square represent Multiple Choice an exact ratio that must always occur when the same parents have four offspring. examples of some of the offspring that can arise from a one-trait cross. all possible combinations of gametes based on a cross between the two parents the gametes from both parents. the gametes from one parent.

all possible combinations of gametes based on a cross between the two parents Explanation The gametes from each parent are found on the vertical and horizontal axes and these combine to provide all possible combinations that might occur in offspring.

If a homozygous black bull is mated with a homozygous white cow and the calf is gray, this would be an example of ________. However, if the calf has black and white spots, this would be an example of ________. Multiple Choice codominance; homology incomplete dominance; a sex-linked trait complete dominance; polygenic trait a sex-linked trait; a recessive trait incomplete dominance; codominance

incomplete dominance; codominance Explanation With incomplete dominance, there are three phenotypes and the heterozygote phenotype is intermediate between the two homozygous phenotypes. With codominance, both alleles are expressed in the heterozygote.

During which stage of meiosis will the pairs of homologous chromosomes line up? Multiple Choice metaphase I metaphase II metaphase anaphase I prophase II

metaphase I Explanation During metaphase I, the tetrads (pairs of homologous chromosomes) attach to the spindle and align at the spindle equator.

Which of the following processes and products are paired correctly? Multiple Choice oogenesis - 2n zygote oogenesis - 1n gamete spermatogenesis - 2n zygote meiosis - 2n zygote mitosis - 1n gamete

oogenesis - 1n gamete Explanation Both spermatogenesis and oogenesis result in haploid (1n) gametes.

Which of the following is a function only of mitosis? Multiple Choice reducing the chromosome number in gametes organismal growth producing gametes keeping the chromosome number constant from one generation to the next creating genetic variability

organismal growth Explanation Meiosis produces gametes and creates genetic variability, whereas mitosis increases cell numbers of an organism.

People who suffer from Marfan syndrome have disproportionately long limbs, a weakened aorta, and poor eyesight. All of these characteristics are due to the production of abnormal connective tissue, resulting from a single defective gene. Marfan syndrome is an example of Multiple Choice codominance. epistasis. multiple allelism. polygenic inheritance. pleiotropy.

pleiotropy. Explanation Pleiotropy occurs when a single gene has more than one effect. Often, this leads to a syndrome, a group of symptoms that appear together and indicate the presence of a particular genetic mutation. For example, people with Marfan syndrome have disproportionately long arms, legs, hands, and feet; a weakened aorta; and poor eyesight.

Metaphase II

the dyads align at the spindle equator sister chromatids face opposite spindle poles