FINAL 07 2020, questions and answers PDF

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Module_8_ Ch_13...

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6/13/2020

Module #8: Ch 13

Module #8: Ch 13 Due: 11:59pm on Thursday, July 1, 2021 You will receive no credit for items you complete after the assignment is due. Grading Policy

Activity: Asexual and Sexual Life Cycles

Click here to complete this activity. Then answer the questions.

Part A What name is given to this process? To view the animation, click here. Then click on the image to start the animation. ANSWER:

asexual reproduction meiosis gametogenesis fertilization sexual reproduction

Correct A single individual is reproducing.

Part B Human gametes are produced by _____. ANSWER:

the cell cycle fertilization asexual reproduction meiosis mitosis

Correct Meiosis produces haploid gametes from a diploid parental cell.

Part C Normal human gametes carry _____ chromosomes.

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Module #8: Ch 13

ANSWER:

23 pairs of 46 46 pairs of 23 5

Correct This is the number of chromosomes in a single set of human chromosomes.

Part D Which of these cells is (are) haploid?

ANSWER:

D B A and D C and D B and C

Correct Once meiosis I is completed, cells are haploid.

Part E A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes. ANSWER:

30 8 32 16 64

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Correct 16 is half of 32.

Chapter 13 Pre-Lecture Question 3 Part A For what purpose(s) might a karyotype be prepared?

Hint 1. A karyotype provides a display of all the chromosomes from a diploid cell.

ANSWER:

for prenatal screening, to determine if a fetus has the correct number of chromosomes to determine whether a fetus is male or female to detect the possible presence of chromosomal abnormalities such as deletions, inversions, or translocations The first and second answers are correct. The first three answers are correct.

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.

Activity: Meiosis Animation

Click here to complete this activity. Then answer the questions.

Part A Meiosis I produces _____ cells, each of which is _____. ANSWER:

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Module #8: Ch 13 two ... haploid two... identical to the other two... diploid four ... haploid four ... diploid

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

Part B Meiosis II typically produces _____ cells, each of which is _____. ANSWER: two ... haploid four ... identical to the other four ... diploid two... diploid four ... haploid

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

Part C Click on the diagram to view an animation. This animation illustrates the events of _____.

ANSWER: telophase II and cytokinesis prophase II anaphase II telophase I and cytokinesis prophase I

Correct The events of prophase II are essentially the same as those of mitotic prophase except that prophase II cells are haploid.

Part D Click on the diagram to view an animation. This animation illustrates the events of _____.

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ANSWER: prophase II interphase anaphase II telophase I and cytokinesis anaphase I

Correct During anaphase II sister chromatids separate and migrate to opposite poles.

Part E Click on the diagram to view an animation. This animation illustrates the events of _____.

ANSWER:

telophase II and cytokinesis telophase I and cytokinesis telophase and cytokinesis telophase I telophase II

Correct Four haploid cells are present at the end of telophase II and cytokinesis.

Part F During _____ sister chromatids separate. ANSWER:

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Module #8: Ch 13 prophase II metaphase I interphase anaphase II prophase I

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

Part G Click on the diagram to view an animation. This animation illustrates the events of _____.

ANSWER: prophase II and cytokinesis interphase telophase and cytokinesis telophase I and cytokinesis telophase II and cytokinesis

Correct At the end of telophase I and cytokinesis there are two haploid cells.

Part H At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids. ANSWER: metaphase II interphase telophase I telophase telophase II

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

Part I Click on the diagram to view an animation. This is an animation of _____.

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ANSWER: prophase I telophase II and cytokinesis metaphase II prophase II metaphase I

Correct Homologous chromosomes pair during prophase I..

Part J Click on the diagram to view an animation. This animation illustrates the events of _____.

ANSWER: anaphase II interphase metaphase II anaphase I prophase I

Correct Metaphase II is essentially the same as mitotic metaphase except that the cells are haploid.

Part K Click on the diagram to view an animation. This animation illustrates the events of _____.

ANSWER:

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Module #8: Ch 13 telophase I and cytokinesis anaphase I metaphase II metaphase I prophase II

Correct During metaphase I tetrads align along the metaphase plate.

Part L Synapsis occurs during _____. ANSWER: prophase II metaphase II prophase I anaphase II telophase I and cytogenesis

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

Part M Homologous chromosomes migrate to opposite poles during _____. ANSWER: metaphase I telophase II and cytokinesis prophase II anaphase I metaphase II

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

Part N During _____ chromosomes align single file along the equator of a haploid cell. ANSWER:

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Module #8: Ch 13 prophase I anaphase I telophase I and cytokinesis metaphase I metaphase II

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

Part O Click on the diagram to view an animation. This animation illustrates the events of _____.

ANSWER: prophase I anaphase I prophase II metaphase II telophase I and cytokinesis

Correct During anaphase I homologous chromosomes, consisting of sister chromatids, migrate to opposite poles.

Part P At the end of _____ and cytokinesis there are four haploid cells. ANSWER: prophase I prophase II interphase telophase II anaphase I

Correct At the end of telophase II and cytokinesis there are four haploid cells.

Part Q During _____ a spindle forms in a haploid cell.

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Module #8: Ch 13

ANSWER:

prophase I anaphase II prophase II telophase I and cytokinesis metaphase II

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

Part R Click on the diagram to view an animation. This animation illustrates _____.

ANSWER:

anaphase I prophase II anaphase II prophase I interphase

Correct During interphase the centrosome duplicates and the chromosomes are not condensed.

Video Tutor Session Quiz: Mitosis vs. Meiosis Click the play icon on the Video Tutor Session to your right. You can also download the video or view the text of the tutor session to read while you are watching. After you have watched the tutor session, answer the questions. Estimated time: 9 minutes

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Part A

ANSWER:

mitosis meiosis gametogenesis both mitosis and meiosis none of the above

Correct Mitosis goes on continuously in most parts of the body, whereas meiosis takes place only in the gonads.

Part B

ANSWER: mitosis only meiosis I only meiosis II only either mitosis or meiosis I either meiosis I or meiosis II

Correct Meiosis I is the only time that chromosomes line up by homologous pairs.

Part C

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Module #8: Ch 13 Click here to review the figure

ANSWER:

tetrad telomere centromere chromosome centrosome

Correct The centromere is the point of attachment between two duplicated chromosomes.

Part D

ANSWER: 5 10 15 20 the answer cannot be determined

Correct If the hypothetical organism has 5 chromosomes in one of its gametes, then it must have 10 chromosomes in a body cell. Just before mitosis, the chromosomes in a body cell are duplicated, but the sister chromatids remain joined together. So you will see 10 (duplicated) chromosomes in a typical body cell.

Part E Click here to review the figure

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ANSWER:

just after meiosis I the start of meiosis I the start of meiosis II just before mitosis the start of mitosis

Correct We can see that the chromosomes are duplicated and lined up by homologous pair. That only happens at the start of meiosis I.

Meiosis (3 of 3): Determinants of Heredity and Genetic Variation (BioFlix tutorial) In this tutorial you will explore how chromosome movements during meiosis underlie both heredity and genetic variation, the two key characteristics of sexual reproduction. Before beginning the tutorial, watch the Meiosis animation. Pay particular attention to the processes that ensure that each daughter cell receives one full set of chromosomes, while at the same time mixing chromosomes of maternal and paternal origin. You can review relevant parts of the animation at any point in the tutorial.

Part A - Processes that determine heredity and contribute to genetic variation Meiosis guarantees that in a sexual life cycle, offspring will inherit one complete set of chromosomes (and their associated genes and traits) from each parent. The transmission of traits from parents to offspring is called heredity. Another important aspect of meiosis and the sexual life cycle is the role these processes play in contributing to genetic variation. Although offspring often resemble their parents, they are genetically different from both of their parents and from one another. The degree of variation may be tremendous. The following processes are associated with meiosis and the sexual life cycle: DNA replication before meiosis crossing over chromosome alignment in metaphase I and separation in anaphase I chromosome alignment in metaphase II and separation in anaphase II fertilization Sort each process into the appropriate bin according to whether it contributes to heredity only, genetic variation only, or both.

Hint 1. DNA replication

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DNA replication, which occurs before meiosis begins, produces replicated chromosomes. Assuming that no errors occur during the replication process, each replicated chromosome consists of two genetically identical sister chromatids. Hint 2. What is crossing over? Crossing over occurs at the beginning of meiosis. Which of the following statements is/are true about crossing over? Select all that apply. ANSWER: As a result of crossing over, the two sister chromatids of a replicated chromosome are no longer identical. Crossing over is a rare event and can only occur at one location along each pair of homologous chromosomes. Crossing over produces chromosomes with new combinations of maternal and paternal alleles. Crossing over involves the exchange of corresponding segments of DNA between sister chromatids.

Hint 3. Chromosome alignment in metaphase I and separation in anaphase I In meiosis, the alignment of chromosomes in metaphase I and their separation in anaphase I ensures that each of the four daughter cells receives one complete set of chromosomes. At the same time, these processes also ensure that the chromosome set in each daughter cell consists of a mixture of maternal and paternal chromosomes. As shown in the diagram, the homologous pairs of chromosomes align in a random orientation at metaphase I. Each pair may orient with either its maternal or paternal homologue closer to a given pole. In the absence of crossing over, a diploid cell with a ploidy level of 2n can produce 2 n possible combinations of maternal and paternal chromosomes in the resulting gametes. The diagram shows meiosis in a cell where n = 2 with no crossing over.

Note that with crossing over, the number of possible chromosome combinations is even greater because sister chromatids (which separate in meiosis II) would no longer be identical (see Hint 4). Hint 4. How does the alignment and separation of chromosomes in metaphase II and anaphase II affect the outcome of meiosis? Which statement would be true about the four daughter cells of meiosis II if crossing over occurred during meiosis I? (Hint: Think about the sister chromatids that separate at anaphase II.) ANSWER:

All four daughter cells would be genetically identical. Two of the four daughter cells would be genetically identical to each other, while the other two daughter cells would be genetically identical to each other. All four daughter cells would be genetically different.

Hint 5. What is fertilization? Which of the following statements is/are true about the process of fertilization?

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Select all that apply. ANSWER: In sexually reproducing organisms, the number of chromosome sets (which is halved during meiosis) doubles at fertilization. The process of fertilization ensures that an organism receives a complete chromosome set from both its mother and its father. The process of fertilization is random, meaning that any of the possible male gametes can fuse with any of the possible female gametes, resulting in a zygote with a unique combination of genes. Fertilization is the fusion of a haploid male gamete and a haploid female gamete to produce a diploid zygote.

ANSWER:

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Correct In organisms that reproduce sexually, the processes of DNA replication, chromosome alignment and separation in meiosis I and II, and fertilization ensure that traits pass from one generation to the next. Crossing over, the exchange of maternal and paternal DNA segments that occurs during meiosis I, is not required to guarantee heredity. Unlike with asexual reproduction, offspring of sexual reproduction are genetically different from each other and from both of their parents. Mechanisms that contribute to genetic variation include the production of recombinant chromosomes due to crossing over the independent assortment of homologous chromosomes in meiosis I the separation of sister chromatids (which are no longer identical due to crossing over) in meiosis II the random fusion of male and female gametes during fertilization

Part B - Independent assortment and genetic variation Consider a diploid cell where 2n = 6. During metaphase I of meiosis, as the pairs of homologous chromosomes line up on the metaphase plate, each pair may orient with its maternal or paternal homologue closer to a given pole. There are four equally probable arrangements of the homologous pairs at metaphase I. (Note that this problem assumes that no crossing over has occurred.)

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The cells below show the eight possible combinations of chromosomes that the daughter cells of meiosis II can receive. Sort each daughter cell into the appropriate bin depending on which arrangement at metaphase I would create it.

Hint 1. Alignment on the metaphase plate The arrangement of chromosomes on the metaphase plate determines how the chromosomes will be distributed to the daughter cells. Because the positioning of chromosomes on the metaphase plate is completely random, maternal and paternal chromosomes assort independently among the daughter cells. The diagram shows the two possible arrangements of chromosomes at metaphase I in a cell where n = 2. The chromosomes to the left of the metaphase plate will be pulled to the left pole of the cell, and will end up in one daughter cell. Chromosomes to the right of the metaphase plate will be pulled to the right pole of the cell and end up in the other daughter cell.

ANSWER:

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Correct One aspect of meiosis that generates genetic variation is the random orientation of homologous pairs of chromosomes at metaphase I. Each pair can orient with either its maternal or paternal homologue closer to a given pole; as a result, each pair sorts into daughter cells independently of every other pair. Due to independent assortment alone, a diploid cell with 2n chromosomes can produce 2 n possible combinations of maternal and paternal chromosomes in its daughter cells. For the cell in this problem (n = 3), there are 23, or 8, possible combinations; for humans (n = 23), there are 223, or 8.4 million, possible combinations. Note that when crossing over occurs, the number of possible combinations is even greater.

Part C - Crossing over and genetic variation Assume that an organism exists in which crossing over does not occur, but that all other processes associated with meiosis...