front 1 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) ______. | back 1 zygote |
front 2 2. ______ is a process of nuclear division which reduces the number
of chromosomes per cell from 2 sets to 1 set. | back 2 meiosis |
front 3 3. ______ cells contain one set of chromosomes. | back 3 D. Haploid |
front 4 4. In life cycles that alternate between haploid and diploid stages,
fertilization doubles the number of chromosomes per cell while ______
reduces it in half. | back 4 meiosis |
front 5 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 ________. | back 5 crossing over |
front 6 6. Compared to asexual reproduction, the main advantage of sexual
reproduction is that it | back 6 B. increases the genetic diversity of the offspring |
front 7 7. If there were no suppression of DNA replication between meiotic
divisions but cytokinesis proceeded normally, what is the most likely
outcome of meiosis? | back 7 4 diploid cells |
front 8 8. Evidence of crossing over can often be seen under the light
microscope as a structure called a _______. | back 8 chiasma |
front 9 9. The fusion of a male gamete with a female gamete is called
| back 9 syngamy |
front 10 10. Diploid organisms use meiosis to produce haploid cells. Meiosis
consists of how many rounds of nuclear division? | back 10 two |
front 11 11. The pairing of chromosomes along their lengths, which is
essential for crossing over, is referred to as | back 11 synapsis |
front 12 12. The cell produced by the fusion of an egg and a sperm is the
| back 12 zygote |
front 13 13. The zygote has | back 13 E. two copies of each chromosome. |
front 14 14. All animal cells are diploid except | back 14 gametes |
front 15 16. Which of the following produces new cells that are genetically
identical to the original cell? | back 15 mitosis |
front 16 17. In animals, the cells that will eventually undergo meiosis to
produce gametes are set aside early in development. These are called
| back 16 germ-line cells |
front 17 18. Which of the following events occurs first during meiosis?
| back 17 D. synapsis of homologous chromosomes |
front 18 19. Chromosomes exchange genetic information by | back 18 crossing over |
front 19 20. Crossing over between homologous chromosomes takes place during
| back 19 B. prophase I. |
front 20 21. The synaptonemal complex is | back 20 C. a network of proteins that holds homologues together. |
front 21 23. Which best describes the process of independent assortment?
| back 21 A. The way one pair of homologues lines up along the metaphase plate does not affect how any other pair lines up. |
front 22 22. At the end of meiosis II, each of the four resulting cells
contains | back 22 C. one full set of chromosomes, each with 1 molecule of DNA. |
front 23 24. In plants and animals, the zygote develops by which of the
following processes? | back 23 mitosis |
front 24 25. The pairing of homologous chromosomes is called | back 24 synapsis |
front 25 26. Which best explains the process of meiosis? | back 25 B. The cells that result from meiosis I are haploid, and each chromosome consists of 2 chromatids. |
front 26 27. During meiosis, sister chromatids are held together by | back 26 D. a common centromere and a protein called cohesion. |
front 27 28. What immediately follows meiosis I? | back 27 B. prophase II |
front 28 29. All of the following increase genetic variation EXCEPT | back 28 mitosis |
front 29 30. One of a pair of chromosomes with similar genetic information and
from different sources like the sperm and egg. | back 29 homologue |
front 30 31. Which structures indicate where crossing over has occurred.
| back 30 chiasmata |
front 31 32. Which structure holds two homologous chromosomes together?
| back 31 E. synaptonemal complex |
front 32 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.) | back 32 A. M and M to one pole; P and P to the other pole. |
front 33 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? | back 33 B. 14 |
front 34 35. You are studying meiosis in an organism where 2n=24. How many
chromosomes will each nucleus have after meiosis II is
complete? | back 34 B. 12 |
front 35 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 | back 35 A. there is no crossing over between non-sister chromatids |
front 36 22. At the end of meiosis II, each of the four resulting cells
contains | back 36 C. one full set of chromosomes, each with 1 molecule of DNA. |
front 37 37. Which statement about the reductive division of meiosis is
false? | back 37 B. During the reductive division, sister chromatids migrate to opposite poles of the cell. |
front 38 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 | back 38 B. normal segregation during meiosis II |
front 39 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? | back 39 D. activation of DNA replication |
front 40 40. Which of the following statements about crossing over is
false? | back 40 B. Crossing over takes place between sister chromatids. |
front 41 41. A life cycle that regularly alternates between haploid and
diploid stages is found in all of the following EXCEPT | back 41 B. the bacterium E. coli |
front 42 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 | back 42 C. failure of 1 homologous pair to segregate during meiosis. |
front 43 43. Why does sexual reproduction require both meiosis and
syngamy? | back 43 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. |
front 44 44. Which cells never divide by meiosis? (Check all that
apply.) | back 44 __X__ haploid cells |
front 45 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) | back 45 _X__ Produce 4 daughter cells that are genetically different from
each other |
front 46 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) | back 46 __X__ Produce a new cell that has a combination of chromosomes from 2
different parents |
front 47 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 | back 47 B. germ-line cells |
front 48 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.) | back 48 16 |
front 49 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.) | back 49 20 |
front 50 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.) | back 50 5 |
front 51 51. How many tetrads are present in a single elephant cell (2n=56) during metaphase I of meiosis? | back 51 28 |
front 52 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 | back 52 D. 4 chromosomes with 8 DNA molecules |
front 53 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 | back 53 C. 2 pairs of homologous chromosomes failed to separate during meiosis I |
front 54 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 | back 54 C. 2 cells with 19 chromosomes, 1 with 20, and 1 with 18 |
front 55 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? | back 55 8 |
front 56 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? | back 56 20 |
front 57 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? | back 57 1/16 |
front 58 58. A cell in G2 before meiosis begins, compared with one of the four
cells produced at the end of meiosis II, has | back 58 B. four times as much DNA and twice as many chromosomes |
front 59 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? | back 59 A. sister chromatids would migrate to opposite poles during anaphase I |
front 60 60. Sister chromatids move to opposite poles of the cell during
(Check all that apply.) | back 60 __X__ anaphase II of meiosis |
front 61 15. The point of connection between two sister chromatids, before
anaphase II of meiosis separates them, is called the | back 61 C. centromere. |