Bio Chapters 12-15

A man has six fingers on each hand and six toes on each foot. His wife and their daughter have the normal number of digits. Remember that extra digits is a dominant trait. What fraction of this couple's children would be expected to have extra digits? Express your answer using the slash symbol and no spaces (for example, 1/16).

1/2

Imagine that you are a genetic counselor, and a couple planning to start a family comes to you for information. Charles was married once before, and he and his first wife had a child with cystic fibrosis. The brother of his current wife, Elaine, died of cystic fibrosis. Neither Charles, Elaine, nor their parents have cystic fibrosis. What is the probability that Charles and Elaine will have a baby with cystic fibrosis? Express your answer as a fraction using the slash symbol and no spaces (for example, 1/16).

1/6

Karen and Steve each have a sibling with sickle-cell disease. Neither Karen nor Steve nor any of their parents have the disease, and none of them have been tested to see if they have the sickle-cell trait. Based on this incomplete information, calculate the probability that if this couple has a child, the child will have sickle-cell disease. Express your answer as a fraction using the slash symbol and no spaces (for example, 1/16).

1/9

For tall heterozygotes with antennae, the offspring are: tall-antennae 46 dwarf-antennae 7 dwarf-no antennae 42 tall-no antennae 5 Calculate the recombination frequency between T and A. Enter your answer as a percentage (for example, 10%).

12%

In maize (corn plants) a dominant allele I inhibits kernel color, while the recessive allele i permits color when homozygous. At a different locus, the dominant allele P causes purple kernel color, while the homozygous recessive genotype pp causes red kernels. If plants heterozygous at both loci are crossed, what will be the phenotypic ratio of the offspring? _____ colorless: _____ purple: _____ red Express your answer as three whole numbers separated by colons (for example, 5:2:1).

12:3:1 The dominant allele I is epistatic to the P/p locus, and thus the genotypic ratio for the F1 generation will be 9 I_P_ (colorless) : 3 I_pp (colorless) : 3 iiP_ (purple) : 1 iipp (red). Overall, the phenotypic ratio is 12 colorless : 3 purple : 1 red.

A wild-type fruit fly (heterozygous for gray body color and normal wings) is mated with a black fly with vestigial wings. The offspring have the following phenotypic distribution: wild-type 778 black-vestigial 785 black-normal 158 gray-vestigial 162 What is the recombination frequency between these genes for body color and wing size? Express your answer as a percentage.

17%

Telophase and Cytokinesis

2 daughter nuclei form surrounded by the fragments of the parent's nuclear envelope, nucleoli reappear, cytokinesis begins

Two genes of a flower, one controlling blue (B) versus white (b) petals and the other controlling round (R) versus oval (r) stamens, are linked and are 10 map units apart. You cross a homozygous blue-oval plant with a homozygous white-round plant. The resulting F1 progeny are crossed with homozygous white-oval plants, and 1,000 F2 progeny are obtained. How many F2 plants of each of the four phenotypes do you expect? _____ blue-oval : _____ white-round : _____ blue-round : _____ white-oval Express your answer as four whole numbers separated by colons (for example, 400:300:200:100).

450:450:50:50

Assume that genes A and B are on the same chromosome and are 50 map units apart. An animal heterozygous at both loci is crossed with one that is homozygous recessive at both loci. What percentage of the offspring will show recombinant phenotypes resulting from crossovers?

50%

A wild-type fruit fly (heterozygous for gray body color and red eyes) is mated with a black fruit fly with purple eyes. The offspring are: wild-type 721 black-purple 751 gray-purple 49 black-red 45 What is the recombination frequency between these genes for body color and eye color? Express your answer as a percentage.

6%

locus

A specific place along the length of a chromosome where a given gene is located.

Genetic variation occurs when chromosomes are shuffled in fertilization and what other process?. A.meiosis B.mitosis C.natural selection D.genetic drift E.mutation

A. Meiosis Variation is produced as a result of independent assortment and crossing over.

Centromeres divide and sister chromatids become full-fledged chromosomes during _____. A.anaphase B.interphase C.prometaphase D.metaphase E.telophase

A. anaphase During anaphase, sister chromatids separate and daughter chromosomes migrate to opposite poles

Two organisms with genotype AaBbCcDdEE mate. These loci are all independent. What fraction of the offspring will have the same genotype as the parents? A.1/16 B.1/4 C.3/4 D.4/3 E.9/64

A.1/16 Breaking the question down into individual loci makes it simpler. The offspring of Aa ×Aa will be Aa 50% (one-half) of the time. The same is true for Bb, Cc, and Dd. Two EE individuals can only have EE offspring, so that probability is 1. The chance of an offspring being identical to the parent is therefore (1/2)4, or 1/16.

What kind of cell results when a diploid and a haploid gamete fuse during fertilization? A.A triploid cell B.A monoploid cell C.A trisomic cell D.A monosomic cell

A.A triploid cell A triploid cell has three sets of chromosomes: the two from the diploid gamete and the one from the haploid gamete.

What is a nondisjunction? A.An error in cell division that causes homologous chromosomes or sister chromatids to move to the same side of the dividing cell B.An error in which a diploid cell or organism lacks a chromosome of one type, producing a chromosome number of 2n - 1 C.None of the above D.An error in which a diploid cell or organism has an extra chromosome of one type, producing a chromosome number of 2n + 1

A.An error in cell division that causes homologous chromosomes or sister chromatids to move to the same side of the dividing cell Nondisjunction refers to the failure of pairs of chromosomes or sister chromatids to separate during meiosis or mitosis.

Two sister chromatids are joined at the centromere prior to meiosis. Which statement is correct? A.Barring mutation, the two sister chromatids must be identical. B.These chromatids make up a diploid chromosome. C.The cell that contains these sister chromatids must be haploid.

A.Barring mutation, the two sister chromatids must be identical.

If a eukaryotic cell is in the G1 phase of the cell cycle, which statement about the cell's chromosomes must be correct? A.Each chromosome is made of a complex of DNA and associated proteins. B.The chromosomes are preparing for DNA synthesis. C.Each chromosome consists of two identical chromatids.

A.Each chromosome is made of a complex of DNA and associated proteins. Eukaryotic cells are made of chromatin, a complex of DNA and associated protein molecules. The proteins maintain the structure of the chromosome and help control gene activity.

How do cells acquire homologous chromosome pairs that carry the alleles that are independently assorted? A.Fusion of gametes B.Meiosis C.DNA replication D.Mitosis

A.Fusion of gametes During fertilization, gametes bring together homologous chromosomes to generate a diploid individual.

A particular cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question is most likely in A.G1. B.anaphase. C.G2. D.metaphase. E.prophase.

A.G1

Folk singer Woody Guthrie died of Huntington's disease, an autosomal dominant disorder. Which statement below must be true? A.It is very likely that at least one of Woody Guthrie's parents also have had the allele for Huntington's disease. B.His daughters will die of Huntington's disease but not his sons. C.All of his children will develop Huntington's disease. D.His sons will develop Huntington's disease but not his daughters. E.There is not enough information to answer the question.

A.It is very likely that at least one of Woody Guthrie's parents also have had the allele for Huntington's disease. Unless the disease is caused by a new mutation, which is quite rare, individuals with a dominant condition must have inherited the dominant allele from one of their parents. As it happens, Guthrie's mother also died of Huntington's disease.

A white-eyed female Drosophila is crossed with a red-eyed male Drosophila. Which statement below correctly describes the results? A.None of the females will have white eyes. B.Twenty-five percent of the females will have red eyes. C.Twenty-five percent of the females will have white eyes. D.Fifty percent of the females will have red eyes. E.None of the females will have red eyes.

A.None of the females will have white eyes. All of the females will have red eyes because they will inherit the dominant red-eye allele from their male parent.

You cross a true-breeding red-flowered snapdragon with a true-breeding white-flowered one. All of the F1 are pink. What does this say about the parental traits? A.Red shows incomplete dominance over white. B.Both red and white are pleiotropic. C.Red is completely dominant. D.Pink is dominant, and red and white are recessive.

A.Red shows incomplete dominance over white. Red shows incomplete dominance over white, and the F1 is therefore pink

Which syndrome is characterized by the XO chromosome abnormality? A.Turner syndrome B.Klinefelter syndrome C.Down syndrome D.Trisomy X

A.Turner syndrome Turner syndrome is characterized by a chromosome pattern of XO, or one X chromosome and no Y chromosome.

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

A.aneuploidy An aneuploid individual has either too many or too few chromosomes, usually as a result of nondisjunction.

Meiosis II typically produces _____ cells, each of which is _____. A.four ... haploid B.two... diploid C.four ... identical to the other D.two ... haploid E.four ... diploid

A.four ... haploid At the end of meiosis II there are typically 4 haploid cells

During _____ chromosomes align single file along the equator of a haploid cell. A.metaphase II B.prophase I C.telophase I and cytokinesis D.anaphase I E.metaphase I

A.metaphase II Metaphase II is essentially the same as mitotic metaphase except that the cell is haploid

Synapsis occurs during _____. A.prophase I B.anaphase II C.metaphase II D.telophase I and cytogenesis E.prophase II

A.prophase I Synapsis, the pairing of homologous chromosomes, occurs during prophase I.

Which of the following does not occur during mitosis? A.replication of the DNA B.separation of sister chromatids C.separation of the spindle poles D.spindle formation E.condensation of the chromosomes

A.replication of the DNA

What is crossing over? A.the exchange of homologous portions of nonsister chromatids B.making an RNA copy of a DNA strand C.a direct consequence of the separation of sister chromatids D.also referred to as the "independent assortment of chromosomes" E.the movement of genetic material from one chromosome to a nonhomologous chromosome

A.the exchange of homologous portions of non sister chromatids The result is new combinations of genetic material (genetic recombination).

During prophase a homologous pair of chromosomes consists of _____. A.two chromosomes and four chromatids B.one chromosome and four chromatids C.one chromosome and two chromatids D.two chromosomes and two chromatids E.four chromosomes and two chromatids

A.two chromosomes and four chromatids At this point each of the chromosomes consists of two chromatids.

Mitosis results in the formation of how many cells; meiosis results in the formation of how many cells? A.two diploid cells ... four haploid cells B.two diploid cells ... two haploid cells C.four haploid cells ... two diploid cells D.four diploid cells ... four haploid cells E.two diploid cells ... two diploid cells

A.two diploid cells ... four haploid cells In mitosis a cell that has doubled its genetic material divides to produce two diploid daughter cells. In meiosis a cell that has doubled its genetic material undergoes two rounds of division, producing four haploid cells.

Various procedures can be used to detect genetic disorders before birth. Among the tests discussed in this chapter, which is the least invasive (list first), and which two allow the chromosomes of the fetus to be examined? A.ultrasound imaging ... chorionic villus sampling ... amniocentesis B.ultrasound imaging ... fetoscopy... amniocentesis C.amniocentesis ... ultrasound imaging ... chorionic villus sampling D.chorionic villus sampling ... fetoscopy ... amniocentesis E.amniocentesis ... fetoscopy ... chorionic villus sampling

A.ultrasound imaging ... chorionic villus sampling ... amniocentesis

If we continued to follow the cell lineage from question 4, then the DNA content of a single cell at metaphase of meiosis II would be A.x. B.4x. C.0.25x. D.2x. E.0.5x.

A.x.

Genome

All of a cells genetic information. Prokaryotes (single long DNA molecule) Eukaryotes (several DNA molecules)

Kinetochores

Anchor on the Sister Chromatid that attaches to the fiber that pulls the sister chromatids apart. Spindle fibers attach during pro metaphase

Chromosomes become visible during _____. A.anaphase B.prophase C.prometaphase D.interphase E.metaphase

B. Prophase During prophase, the chromatin fibers become discrete chromosomes.

Of the following chromosomal abnormalities, which type is most likely to be viable in humans? A.Monosomy B.Trisomy C.Haploidy D.Triploidy

B. Trisomy Some trisomies are viable in humans, but they result in developmental abnormalities, such as Down syndrome (trisomy 21). Only humans with trisomies of the small chromosomes (13, 18, or 21) or the sex chromosomes survive past birth

A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain? A.23 B.92 C.46 D.46 or 92, depending on the portion of prophase examined E.23 or 46, depending on the portion of prophase examined

B.92 Mitosis follows the duplication of the cell's DNA.

If a diploid cell undergoes meiosis and produces two gametes that are normal, and one with n − 1 chromosomes, and one with n + 1 chromosomes, what type of error occurred? A.No error occurred; these are normal gametes. B.A nondisjunction error occurred in meiosis II, in which both sister chromatids of a chromosome migrated to the same pole of the cell. C.A nondisjunction error occurred in meiosis I, in which both members of all homologous pairs migrated to the same pole of the cell. D.A nondisjunction error occurred in meiosis I, in which both members of a homologous pair migrated to the same pole of the cell.

B.A nondisjunction error occurred in meiosis II, in which both sister chromatids of a chromosome migrated to the same pole of the cell. When this error occurs in meiosis II, only half of the gametes are affected.

Which of the following statements most accurately describes the process of independent assortment? A.Alleles found on separate chromosomes segregate based upon their origin. B.Alleles of different genes segregate from one another in a random manner. C.Dominant alleles segregate with recessive alleles. D.Genes located on the same chromosome assort as an independent unit.

B.Alleles of different genes segregate from one another in a random manner. The random distribution of alleles is required for independent assortment

True or false? The principle of independent assortment is best illustrated by events that take place during metaphase II, during which sister chromatids segregate independently of each other. A.True B.False

B.False The principle of independent assortment is best illustrated by events that take place during metaphase I, during which nonhomologous chromosomes segregate independently of each other.

Which of the following do you expect if an individual is heterozygous for the sickle-cell trait? A.He or she will not develop sickle-cell disease. B.He or she will show some symptoms of the disease. C.He or she will have full-blown sickle-cell disease because the allele is dominant. D.He or she will be more apt to acquire a serious case of malaria. E.None of the above.

B.He or she will show some symptoms of the disease. A heterozygote will produce both normal and abnormal hemoglobin

How are sister chromatids and homologous chromosomes different from each other? A.They are not different. Homologous chromosomes and sister chromatids are both identical copies of each other. B.Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication. C.Homologous chromosomes are identical copies of each other. One sister chromatid comes from the father, and one comes from the mother. D.Sister chromatids are only formed during mitosis. Homologous chromosomes are formed during meiosis. E.Homologous chromosomes are closely associated with each other in both mitosis and meiosis. Sister chromatids are only associated with each other during mitosis.

B.Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication. One homologous chromosome comes from the father, and the other comes from the mother. Sister chromatids are identical copies of each other.

What process is responsible for the independent assortment of alleles? A.Mitosis B.Meiosis. C.DNA replication. D.Cytokinesis.

B.Meiosis. The role of meiosis is to separate homologous chromosomes and their respective alleles, which are assorted in an independent manner.

Identify all possible products of meiosis in plant and animal life cycles. Select all that apply. A.Multicellular adult organisms B.Spores C.Gametes (sperm and eggs)

B.Spores C.Gametes (sperm and eggs) In most animal life cycles, the products of meiosis are gametes. However, in plants, the products of meiosis are spores

Which of the following occurs during meiosis but not during mitosis? A.Chromosomes align at the metaphase plate. B.Synapsis occurs. C.A spindle apparatus forms. D.Chromosomes migrate to opposite poles. E.Chromosomes condense.

B.Synapsis occurs. The pairing of homologous chromosomes that only occurs during prophase I of meiosis is called synapsis.

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

B.The male gamete determines sex because each male gamete can contribute either an X or a Y chromosome. In humans, the male produces both X- and Y-bearing sperm, whereas females only produce X-bearing eggs.

Which of the following is true of kinetochores? A.They interdigitate at the cell's equator and then move apart, causing the cell to elongate. B.They are sites at which microtubules attach to chromosomes. C.They are the primary centromere structures that maintain the attachment of the sister chromatids prior to mitosis. D.They attach to the ring of actin along the cytoplasmic surface of the plasma membrane, causing the actin to contract to form the cleavage furrow. E.They are located at the center of the centrosome; their function is to organize tubulin into elongated bundles called spindle fibers.

B.They are sites at which microtubules attach to chromosomes. As the spindle depolymerizes, the kinetochores appear to move along the spindle fiber, dragging the attached chromosomes with them.

Height in humans generally shows a normal (bell-shaped) distribution. What type of inheritance most likely determines height? A.incomplete dominance B.a combination of polygenic inheritance and environmental factors C.a combination of complete dominance and environmental factors D.a combination of epistasis and environmental factors E.a combination of multiple alleles and codominance

B.a combination of polygenic inheritance and environmental factors Several genes (polygenic inheritance) control height in humans, giving an overall normal distribution. Environmental factors such as nutrition smooth out the curve

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.a translocation B.an inversion C.polyploidy D.a deletion E.a nondisjunction

B.an inversion

During _____ sister chromatids separate. A.prophase II B.anaphase II C.prophase I D.metaphase I E.interphase

B.anaphase II Anaphase II is essentially the same as mitotic anaphase except that the cell is haploid.

Cytochalasin B is a chemical that disrupts microfilament formation. How would this interfere with cell division? A.formation of the cell plate B.cleavage C.binary fission D.DNA replication E.formation of the mitotic spindle

B.cleavage In animal cells, the cleavage furrow forms when a ring of microfilaments contracts, causing the parent cell to be pinched in two

Heritable variation is required for which of the following? A.mitosis B.evolution C.asexual reproduction D.the production of a clone E.meiosis

B.evolution Variation is the raw material of evolution.

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

B.how far apart they are on the chromosome The farther apart two genes are, the greater the probability that a crossover will occur between them, and therefore the greater the recombination frequency.

Nucleoli are present during _____. A. prometaphase B.interphase C.metaphase D.prophase E.anaphase

B.interphase

In some organisms, such as certain fungi and algae, cells undergo the cell cycle repeatedly without subsequently undergoing cytokinesis. What would result from this? A.division of the organism into many cells, most lacking nuclei B.large cells containing many nuclei C.a rapid rate of gamete production D.a decrease in chromosome number E.inability to duplicate DNA

B.large cells containing many nuclei

During _____ a spindle forms in a haploid cell. A.telophase I and cytokinesis B.prophase II C.metaphase II D.prophase I E.anaphase II

B.prophase II Prophase II is essentially the same as mitotic prophase except that the cells are haploid.

Meiosis II is similar to mitosis in that A.the chromosome number is reduced. B.sister chromatids separate during anaphase. C.the daughter cells are diploid. D.DNA replicates before the division. E.homologous chromosomes synapse.

B.sister chromatids separate during anaphase.

At the end of _____ and cytokinesis there are four haploid cells. A.prophase I B.telophase II C.anaphase I D.interphase E.prophase II

B.telophase II

Bacteria reproduce by:

Binary Fission

Which of the following parental genotypes would yield a 1:1:1:1 phenotypic ratio in the offspring? A. aaBb, AaBb B. AaBb, AaBb C. AaBb, aabb D. aaBb, aabb

C. AaBb, aabb The offspring of these parents would have a phenotypic ratio of 1:1:1:1.

Why do some species employ both mitosis and meiosis, whereas other species use only mitosis? A.They need only mitosis to make large numbers of cells such as sperm. B.They need only meiosis if they produce egg cells. C.They need both if they are producing animal gametes. D.A single-celled organism only needs mitosis. E.They need meiosis if the cells are producing organs such as ovaries.

C. They need both if they are producing animal gametes The form of cell division that produces animal gametes is meiosis, not mitosis. The production of gametes in plants is a function of both mitosis and meiosis.

A human cell containing 22 autosomes and a Y chromosome is A.a somatic cell of a female. B.an egg. C.a sperm. D.a somatic cell of a male. E.a zygote.

C. a sperm.

Spindle fibers attach to kinetochores during _____. A.anaphase B.metaphase C.prometaphase D.telophase E.interphase

C. prometaphase Attachment of spindle fibers to kinetochores is one of the events of prometaphase

When can nondisjunction occur? Choose the best answer. A.In meiosis, when homologous chromosomes fail to separate B.In mitosis, when sister chromatids fail to separate C.All three answers are correct. D.In meiosis, when sister chromatids fail to separate

C.All three answers are correct. Nondisjunction errors can occur in meiosis I, when homologous chromosomes fail to separate, or in either mitosis or meiosis II, when sister chromatids fail to separate.

Which statement provides the best description of the interphase portion of the cell cycle? A.Interphase is a resting stage prior to cell division. B.Interphase is a brief period between mitosis and chromosome duplication. C.During interphase, a cell is metabolically active.

C.During interphase, a cell is metabolically active. Interphase accounts for about 90% of the cell cycle and includes many key events critical to the cell cycle. It is not a resting stage; the cell is metabolically active during this phase.

Which of the following correctly matches a phase of the cell cycle with its description? A.G2: cell division B.M: duplication of DNA C.G1: follows cell division D.S: immediately precedes cell division E.All of the above are correctly matched.

C.G1: follows cell division After mitosis and cytokinesis, the newly formed daughter cells enter the G1 phase.

Which of the following is true about a plant with the genotype AABbcc? A.It will not express the recessive c allele. B.It is triploid. C.It is homozygous at two loci. D.It is heterozygous at two loci. E.It has recessive alleles at three loci.

C.It is homozygous at two loci. An organism having a pair of identical alleles at a given locus is said to be homozygous for that locus. Here, the plant is homozygous at loci A and C.

Why is it difficult to observe individual chromosomes with a light microscope during interphase? A.Sister chromatids do not pair up until division starts. B.They leave the nucleus and are dispersed to other parts of the cell. C.They have uncoiled to form long, thin strands. D.The spindle must move them to the metaphase plate before they become visible. E.The DNA has not been replicated yet.

C.They have uncoiled to form long, thin strands. Except during the M phase, the DNA is extended, allowing its genes to be transcribed for protein synthesis.

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of micro-tubules, its effectiveness must be related to A.myosin denaturation and inhibition of cleavage furrow formation. B.inhibition of DNA synthesis. C.disruption of mitotic spindle formation. D.suppression of cyclin production. E.inhibition of regulatory protein phosphorylation.

C.disruption of mitotic spindle formation.

Consider pea plants with the genotypes GgTt and ggtt . These plants can each produce how many type(s) of gametes? A.one ... two B.two... one C.four ... one D.one ... one E.four ... two

C.four ... one GgTt individuals can produce the following gametes: GT, Gt, gT, and gt. A ggtt plant can produce only gt.

What phenomenon occurs when a particular allele will either be expressed or silenced, depending on whether it is inherited from a male or a female? A.extranuclear inheritance B.polyploidy C.genomic imprinting D.aneuploidy E.sex linkage

C.genomic imprinting The sex of the parent transmitting a given chromosome can affect the chromosome's expression in the offspring

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

C.homologous chromosomes separating during meiosis I Homologous chromosomes each carry an allele for every gene. Those alleles may be the same or different, but they are segregated during meiosis I and distributed to each gamete.

Condensed Chromatin

Chromosomes

Prophase

Chromosomes condense, chromosomes appear as sister chromatids joined at centromere, nucleoli disappear, mitotic spindle begins to form, spindle pushes the centrosomes to poles of the cell

If a diploid cell undergoes meiosis and produces two gametes with n + 1 chromosomes and two gametes with n− 1 chromosomes, what type of error occurred? A.A nondisjunction error occurred in meiosis II, in which both sister chromatids of a chromosome migrated to the same pole of the cell. B.No error occurred; these are normal gametes. C.A nondisjunction error occurred in meiosis I, in which both members of all homologous pairs migrated to the same pole of the cell. D.A nondisjunction error occurred in meiosis I, in which both members of a homologous pair migrated to the same pole of the cell.

D.A nondisjunction error occurred in meiosis I, in which both members of a homologous pair migrated to the same pole of the cell. When this type of error occurs, half of the gametes receive one too many chromosomes, and the other half receive one too few. When all of the gametes are affected, the error probably occurred in meiosis I.

How many genetically unique types of gametes could be produced by an individual with the genotype RrYY? A.One B.Three C.Eight D.Two

D.Two The gametes would be either RY or rY.

Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely A.a plant cell in metaphase. B.an animal cell in the process of cytokinesis. C.an animal cell in the S phase of the cell cycle. D.a plant cell in the process of cytokinesis. E.a bacterial cell dividing.

D.a plant cell in the process of cytokinesis.

Homologous chromosomes migrate to opposite poles during _____. A.metaphase II B.metaphase I C.prophase II D.anaphase I E.telophase II and cytokinesis

D.anaphase I During anaphase I sister chromatids remain attached at their centromeres, and homologous chromosomes move to opposite poles

Homologous chromosomes move toward opposite poles of a dividing cell during A.fertilization. B.binary fission. C.meiosis II. D.meiosis I. E.mitosis.

D.meiosis I.

In alternation of generations, what is the diploid stage of a plant that follows fertilization called? A.karyotype B.spore C.gametophyte D.sporophyte E.chiasmata

D.sporophyte The sporophyte is the diploid, multicellular stage of the plant that produces haploid spores by meiosis.

At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids. A.telophase B.interphase C.metaphase II D.telophase I E.telophase II

D.telophase I At the end of telophase I and cytokinesis, there are two haploid cells with chromosomes that consist of two sister chromatids each

Meiosis I produces _____ cells, each of which is _____. A.four ... diploid B.two... diploid C.four ... haploid D.two ... haploid E.two... identical to the other

D.two ... haploid At the end of meiosis I there are two haploid cells.

Chromatin

DNA protein complex

Cytokinesis often, but not always, accompanies _____. A.metaphase B.prometaphase C.interphase D.anaphase E.telophase

E. telophase

If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be A.0.5x. B.0.25x. C.4x. D.x. E.2x.

E.2x.

What number and types of chromosomes are found in a human somatic cell? A.21 autosomes and 2 sex chromosomes B.22 autosomes and 1 sex chromosome C.n chromosomes D.45 autosomes and 1 sex chromosome E.44 autosomes and 2 sex chromosomes

E.44 autosomes and 2 sex chromosomes Human somatic cells contain 22 pairs of autosomes and either two X chromosomes (in females) or an X and a Y chromosome (in males).

Which of the following is found in binary fission but not in mitosis? A.Replication of DNA begins at an origin. B.Replicated strands of DNA separate. C.The result produces 2 nuclei. D.Following the process, a membrane separates the 2 copies. E.Duplicated chromosomes attach to the plasma membrane.

E.Duplicated chromosomes attach to the plasma membrane. This is not true of mitosis.

For what purpose(s) might a karyotype be prepared? A.for prenatal screening, to determine if a fetus has the correct number of chromosomes B.to determine whether a fetus is male or female C.to detect the possible presence of chromosomal abnormalities such as deletions, inversions, or translocations D.The first and second answers are correct. E.The first three answers are correct.

E.The first three answers are correct. Karyotypes can show if all of the chromosomes are present, and whether an individual is male (XY) or female (XX). In addition, by staining the chromosomes and examining the resulting banding patterns, it is possible to detect defects such as deletions, translocations, and inversions.

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.It is expressed in half of the cells of either male or female. C.It does not segregate like other genes. D.Sister chromatids separate during mitosis. E.The gene is present in both males and females.

E.The gene is present in both males and females. All cells have at least one functional X chromosome.

The drug cytochalasin B blocks the function of actin. Which of the following aspects of the animal cell cycle would be most disrupted by cytochalasin B? A.DNA synthesis B.cell elongation during anaphase C.spindle formation D.spindle attachment to kinetochores E.cleavage furrow formation and cytokinesis

E.cleavage furrow formation and cytokinesis

How are human mitochondria inherited? A.from the father only B.as an X-linked trait C.without DNA D.as linear DNA E.from the mother only

E.from the mother only An individual's mitochondria are all derived from those found in the ovum.

Asexual reproduction _____. A.leads to a loss of genetic material B.requires both meiosis and mitosis C.is limited to plants D.is limited to single-cell organisms E.produces offspring genetically identical to the parent

E.produces offspring genetically identical to the parent Only one individual makes a genetic contribution to the offspring.

Interphase

G1, S, G2 phases, DNA has been replicated, membrane bound nucleus, centrosome has replicated

Anaphase

Microtubules shorten and separate chromatids to form complete chromosomes, chromosomes pulled to opposite poles

Prometaphase

Nuclear envelope breaks down, microtubules from spindle interact with the chromosomes at one of two Kinotochores

Metaphase

Spindle fibers align chromosomes at metaphase plate

How do sister chromatids separate?

proteins holding sister chromatids together inactive and/ or degrade allowing separate chromatids to move to opposite poles