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60 Cards in this Set
- Front
- Back
1. Edouard van Beneden proposed that an egg and a sperm, each containing half the complement of chromosomes found in somatic cells, fuse to produce a single cell called a(n) ______. |
A. zygote |
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2. ______ is a process of nuclear division which reduces the number of chromosomes per cell from 2 sets to 1 set. |
B. Meiosis |
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3. ______ cells contain one set of chromosomes. |
D. Haploid |
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4. In life cycles that alternate between haploid and diploid stages, fertilization doubles the number of chromosomes per cell while ______ reduces it in half. |
B. meiosis |
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5. Homologous chromosomes pair along their length during prophase I of meiosis. While two homologues are paired, genetic exchange may occur between them in a process called ________. |
D. crossing over |
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6. Compared to asexual reproduction, the main advantage of sexual reproduction is that it |
B. increases the genetic diversity of the offspring |
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7. If there were no suppression of DNA replication between meiotic divisions but cytokinesis proceeded normally, what is the most likely outcome of meiosis? |
A. 4 diploid cells |
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8. Evidence of crossing over can often be seen under the light microscope as a structure called a _______. |
C. chiasma |
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9. The fusion of a male gamete with a female gamete is called |
A. syngamy. |
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10. Diploid organisms use meiosis to produce haploid cells. Meiosis consists of how many rounds of nuclear division? |
B. two |
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11. The pairing of chromosomes along their lengths, which is essential for crossing over, is referred to as |
B. synapsis. |
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12. The cell produced by the fusion of an egg and a sperm is the |
C. zygote. |
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13. The zygote has |
E. two copies of each chromosome. |
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14. All animal cells are diploid except |
A. gametes. |
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16. Which of the following produces new cells that are genetically identical to the original cell? |
C. centromere. |
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17. In animals, the cells that will eventually undergo meiosis to produce gametes are set aside early in development. These are called |
B. germ-line cells. |
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18. Which of the following events occurs first during meiosis? |
D. synapsis of homologous chromosomes |
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19. Chromosomes exchange genetic information by |
E. crossing over. |
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20. Crossing over between homologous chromosomes takes place during |
E. crossing over. |
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21. The synaptonemal complex is |
C. a network of proteins that holds homologues together. |
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22. At the end of meiosis II, each of the four resulting cells contains |
C. one full set of chromosomes, each with 1 molecule of DNA. |
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23. Which best describes the process of independent assortment? |
A. The way one pair of homologues lines up along the metaphase plate does not affect how any other pair lines up. |
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24. In plants and animals, the zygote develops by which of the following processes? |
A. mitosis |
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25. The pairing of homologous chromosomes is called |
B. synapsis. |
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26. Which best explains the process of meiosis? |
B. The cells that result from meiosis I are haploid, and each chromosome consists of 2 chromatids. |
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27. During meiosis, sister chromatids are held together by |
D. a common centromere and a protein called cohesion. |
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28. What immediately follows meiosis I? |
B. prophase II |
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29. All of the following increase genetic variation EXCEPT |
D. mitosis. |
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30. One of a pair of chromosomes with similar genetic information and from different sources like the sperm and egg. |
B. homologue |
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31. Which structures indicate where crossing over has occurred. |
A. chiasmata |
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32. Which structure holds two homologous chromosomes together? |
E. synaptonemal complex |
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33. During anaphase I, which best represents segregation of the chromatids that make up one pair of homologues? (M represents a maternal chromatid and P represents a paternal chromatid. Assume no crossing over occurs.) |
A. M and M to one pole; P and P to the other pole. |
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34. You are studying meiosis in an organism where 2n= 28. How many chromosomes will be present in each cell after meiosis I is complete but before meiosis II begins? |
B. 14 |
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35. You are studying meiosis in an organism where 2n=24. How many chromosomes will each nucleus have after meiosis II is complete? |
B. 12 |
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36. You are comparing the events of meiosis I in cells from several different organisms. You come across one species in which you do not observe any chiasmata. The best conclusion to make is |
A. there is no crossing over between non-sister chromatids |
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37. Which statement about the reductive division of meiosis is false? |
B. During the reductive division, sister chromatids migrate to opposite poles of the cell. |
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38. The Rec8 protein holds sister chromatids together during meiosis. If an individual has a mutation that prevents degradation of Rec8, this would most likely prevent |
B. normal segregation during meiosis II |
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39. Which of the following is likely to occur if you were to prevent cyclin B from associating with its cyclin-dependent kinase near the end of meiosis I? |
D. activation of DNA replication |
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40. Which of the following statements about crossing over is false? |
B. Crossing over takes place between sister chromatids. |
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41. A life cycle that regularly alternates between haploid and diploid stages is found in all of the following EXCEPT |
B. the bacterium E. coli |
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42. In 95% of cases of Down's syndrome, there is one extra chromosome (number 21) in every cell. This aneuploid condition is most likely the result of |
C. failure of 1 homologous pair to segregate during meiosis. |
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43. Why does sexual reproduction require both meiosis and syngamy? |
B. The process of meiosis results in the production of gametes in which the number of chromosomes is reduced by half. During syngamy, two gametes fuse to form a new cell, and the number of chromosomes is restored to the full amount. Therefore, by coupling meiosis and syngamy, the organism ensures that the proper number of chromosomes will be maintained. |
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44. Which cells never divide by meiosis? (Check all that apply.) |
__X__ haploid cells __X__ somatic cells __X__ zygotes |
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45. A cell biologist examines a skin cell from a lizard during metaphase of mitosis and determines that 20 chromatids are present. The role of meiosis in this species is to (Check all that apply) |
__X__ Produce 4 daughter cells that are genetically different from each other |
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46. A cell biologist examines a leaf cell from an alfalfa plant during metaphase of mitosis and determines that 32 chromatids are present. The role of fertilization in this species is to (Check all that apply) |
__X__ Produce a new cell that has a combination of chromosomes from 2 different parents __X__ Increase the number of chromosomes per cell from 8 to 16 |
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47. The most common form of gene therapy involves inserting a normal gene into cells that contain a defective version of the gene. In order to use gene therapy to prevent a man from passing a defective gene on to future generations, you should try to insert normal copies of the gene into |
B. germ-line cells |
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48. If a germ-line cell from an owl contains 8 picograms of DNA during G1 of interphase, how many picograms of DNA would be present in each cell during prophase I of meiosis? (Enter the number only, not the units.) |
16 |
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49. If a somatic cell from a cat contains 40 picograms of DNA during G2 of interphase, how many picograms of DNA would be present in each cell during metaphase II of meiosis? (Enter the number only, not the units.) |
20 |
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50. If a germ-line cell from a salamander contains 10 picograms of DNA during G1 of interphase, how many picograms of DNA would be present in each gamete produced by this species? (Enter the number only, not the units.)
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5 |
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51. How many tetrads are present in a single elephant cell (2n=56) during metaphase I of meiosis? |
28 |
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52. A geneticist examines a somatic cell from a fly during metaphase of mitosis and determines that 16 chromatids are present. If a germ-line cell from this species divides by meiosis, then at the end of meiosis I (including the first cytokinesis) each cell will contain |
D. 4 chromosomes with 8 DNA molecules |
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53. Nondisjunction is the failure of homologous chromosomes to separate during meiosis I, or the failure of sister chromatids to separate during meiosis II or mitosis. As a result, both homologous chromosomes or both sister chromatids migrate to the same pole of the cell. This produces daughter cells with an imbalance of chromosomes. A cell biologist examines the final products of meiosis in an earthworm (2n=36) and finds 2 cells with 20 chromosomes, and 2 cells with 16 chromosomes. Most likely this was because |
C. 2 pairs of homologous chromosomes failed to separate during meiosis I |
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54. Nondisjunction is the failure of homologous chromosomes to separate during meiosis I, or the failure of sister chromatids to separate during meiosis II or mitosis. As a result, both homologous chromosomes or both sister chromatids migrate to the same pole of the cell. This produces daughter cells with an imbalance of chromosomes. If 18 pairs of sister chromatids segregate normally during meiosis II in cats (n=19) but we have nondisjunction of 1 pair, then at the end of meiosis II we will have |
C. 2 cells with 19 chromosomes, 1 with 20, and 1 with 18 |
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55. A cell biologist examines a diploid cell from a particular species of during metaphase of mitosis and determines that 8 centromeres are present. Based on this finding, how many centromeres should be present in a single cell from this species during anaphase II of meiosis? |
8 |
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56. A cell biologist examines a diploid cell from a particular species of butterfly during prometaphase of mitosis and determines that 10 centromeres are present. Based on this finding, how many chromatids should be present in a single cell from this species in metaphase I of meiosis?
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20 |
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57. Meiosis results in a reassortment of maternal chromosomes (inherited from the mother) and paternal chromosomes (inherited from the father.) If n=4 for a given species, and ignoring the effects of crossing over, what is the probability that a gamete will receive only paternal chromosomes? |
D. 1/16 |
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58. A cell in G2 before meiosis begins, compared with one of the four cells produced at the end of meiosis II, has |
B. four times as much DNA and twice as many chromosomes |
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59. In meiosis, sister kinetochores are attached to the same pole of the cell during meiosis I, and sister chromatid cohesion is released during anaphase II. What would be the likely result if sister kinetochores were attached to different poles of the cell during meiosis I and sister chromatid cohesion was released during anaphase I? |
A. sister chromatids would migrate to opposite poles during anaphase I |
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60. Sister chromatids move to opposite poles of the cell during (Check all that apply.) |
__X__ anaphase II of meiosis |
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15. The point of connection between two sister chromatids, before anaphase II of meiosis separates them, is called the |
C. centromere. |