biology chapter 11 Flashcards

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
B. karyotype
C. embryo
D. oocyte

2. ______ is a process of nuclear division which reduces the number of chromosomes per cell from 2 sets to 1 set.
A. Mitosis
B. Meiosis
C. Binary fission
D. Syngamy

3. ______ cells contain one set of chromosomes.
A. Germ-line
B. Somatic
C. Diploid
D. Haploid

4. In life cycles that alternate between haploid and diploid stages, fertilization doubles the number of chromosomes per cell while ______ reduces it in half.
A. mitosis
B. meiosis
C. binary fission
D. syngamy

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 ________.
A. syngamy
B. synapsis
C. independent assortment
D. crossing over

6. Compared to asexual reproduction, the main advantage of sexual reproduction is that it
A. requires less energy
B. increases the genetic diversity of the offspring
C. can produce more complex offspring
D. can produce a greater number of offspring

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
B. 2 diploid cells
C. 4 haploid cells
D. 2 haploid cells
E. 2 diploid cells and 2 haploid cells

8. Evidence of crossing over can often be seen under the light microscope as a structure called a _______.
A. kinetochore
B. centromere
C. chiasma
D. centriole

9. The fusion of a male gamete with a female gamete is called
A. syngamy.
B. meiosis.
C. mitosis.
D. recombination.
E. synapsis.

10. Diploid organisms use meiosis to produce haploid cells. Meiosis consists of how many rounds of nuclear division?
A. one
B. two
C. three
D. four
E. none of these

11. The pairing of chromosomes along their lengths, which is essential for crossing over, is referred to as
A. syngamy.
B. synapsis.
C. prophase.
D. recombination.
E. centromere.

12. The cell produced by the fusion of an egg and a sperm is the
A. gamete.
B. oocyte.
C. zygote.
D. germ line cell.
E. somatic cell.

13. The zygote has
A. one copy of each chromosome.
B. one full haploid complement of chromosomes.
C. chromosomes identical to those of a sperm cell.
D. chromosomes identical to those of an egg cell.
E. two copies of each chromosome.

14. All animal cells are diploid except
A. gametes.
B. muscle cells.
C. nerve cells.
D. germ-line cells.
E. somatic cells.

16. Which of the following produces new cells that are genetically identical to the original cell?
A. meiosis
B. mitosis
C. crossing over
D. independent assortment
E. fertilization

17. In animals, the cells that will eventually undergo meiosis to produce gametes are set aside early in development. These are called
A. somatic cells.
B. germ-line cells.
C. sex cells.
D. gametophytes.
E. reproductive cells.

18. Which of the following events occurs first during meiosis?
A. homologous chromosomes separate and are pulled to opposite poles of the cell
B. sister chromatids separate and are pulled to opposite poles of the cell
C. chromosomes decondense
D. synapsis of homologous chromosomes
E. pairs of homologous chromosomes align along the equatorial plate

19. Chromosomes exchange genetic information by
A. fertilization.
B. mitosis.
C. syngamy.
D. DNA replication.
E. crossing over.

20. Crossing over between homologous chromosomes takes place during
A. prophase II.
B. prophase I.
C. interphase II.
D. interphase I.
E. metaphase II.

21. The synaptonemal complex is
A. a cluster of microtubules at each pole of the cell.
B. a network of microtubules that forms the spindle apparatus.
C. a network of proteins that holds homologues together.
D. the area where microtubules attach to the centromere of each chromosome.
E. a region of highly coiled DNA.

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.
B. Segregation of chromosomes during meiosis I is independent of their segregation during meiosis II.
C. During synapsis, chromosomes pair up at random.
D. Crossing over along one pair of chromosomes is independent of crossing over along the other pairs.
E. During synapsis, homologues pair independently of each other.

22. At the end of meiosis II, each of the four resulting cells contains
A. one full set of chromosomes, each with 2 molecules of DNA.
B. two full sets of chromosomes, each with 2 molecules of DNA.
C. one full set of chromosomes, each with 1 molecule of DNA.
D. two full sets of chromosomes, each with 1 molecule of DNA.

24. In plants and animals, the zygote develops by which of the following processes?
A. mitosis
B. meiosis
C. syngamy
D. synapsis
E. reduction division

25. The pairing of homologous chromosomes is called
A. syngamy.
B. synapsis.
C. alignment.
D. independent assortment.
E. crossing over.

26. Which best explains the process of meiosis?
A. The cells that result from meiosis I are haploid, and each chromosome consists of 1 chromatid.
B. The cells that result from meiosis I are haploid, and each chromosome consists of 2 chromatids.
C. The cells that result from meiosis II are haploid, and each chromosome consists of 2 chromatids.
D. The cells that result from meiosis I are diploid, and each chromosome consists of 2 chromatids.
E. The cells that result from meiosis I are diploid, and each chromosome consists of 1 chromatid.

27. During meiosis, sister chromatids are held together by
A. a common centromere and kinetochore microtubules.
B. a common centromere and chiasmata.
C. a common centromere and polar microtubules.
D. a common centromere and a protein called cohesion.
E. the kinetochores and a protein called cohesion.

28. What immediately follows meiosis I?
A. DNA replication
B. prophase II
C. metaphase II
D. synapsis of homologues
E. crossing over of homologues

29. All of the following increase genetic variation EXCEPT
A. crossing over.
B. random fertilization.
C. independent assortment.
D. mitosis.
E. mutation.

30. One of a pair of chromosomes with similar genetic information and from different sources like the sperm and egg.
A. chiasma
B. homologue
C. kinetochore
D. synapsis
E. synaptonemal

31. Which structures indicate where crossing over has occurred.
A. chiasmata
B. centromeres
C. kinetochores
D. centrioles
E. spindle fibers

32. Which structure holds two homologous chromosomes together?
A. centromere
B. kinetochore
C. polar microtubules
D. spindle apparatus
E. synaptonemal complex

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.
B. M and P to one pole; M and P to the other pole.
C. M to one pole; P to the other pole.
D. half of M and half of P to each pole.
E. the segregation of these chromatids is completely random.

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?
A. 7
B. 14
C. 28
D. 56

35. You are studying meiosis in an organism where 2n=24. How many chromosomes will each nucleus have after meiosis II is complete?
A. 24
B. 12
C. 6
D. 48

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
B. kinetochores of sister chromatids do not fuse
C. the chromosome pairs will not assort independently
D. chiasmata will form during meiosis II

22. At the end of meiosis II, each of the four resulting cells contains
A. one full set of chromosomes, each with 2 molecules of DNA.
B. two full sets of chromosomes, each with 2 molecules of DNA.
C. one full set of chromosomes, each with 1 molecule of DNA.
D. two full sets of chromosomes, each with 1 molecule of DNA.

37. Which statement about the reductive division of meiosis is false?
A. During the reductive division, homologues migrate to opposite poles of the cell.
B. During the reductive division, sister chromatids migrate to opposite poles of the cell.
C. During the reductive division, centromeres do not divide.
D. At the end of the reductive division, each daughter nucleus has one-half as many centromeres as the parental nucleus.

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
A. normal segregation during meiosis I
B. normal segregation during meiosis II
C. synapsis of homologous chromosomes
D. crossing over during prophase I

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?
A. failure to maintain sister chromatid cohesion at the centromere
B. failure to form initiation complexes necessary for DNA replication to proceed
C. suppression of DNA replication
D. activation of DNA replication

40. Which of the following statements about crossing over is false?
A. Crossing over takes place between non-sister chromatids.
B. Crossing over takes place between sister chromatids.
C. Crossing over occurs during prophase I.
D. Sites of crossing over are called chiasmata.
E. Crossing over is also called genetic recombination.

41. A life cycle that regularly alternates between haploid and diploid stages is found in all of the following EXCEPT
A. dogs
B. the bacterium E. coli
C. alfalfa plants
D. the mold N. crassa

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
A. failure to suppress DNA replication between meiosis I and meiosis II
B. failure of the chromosomes to assort independently during meiosis
C. failure of 1 homologous pair to segregate during meiosis.
D. failure of 2 homologous pairs to segregate during meiosis
E. failure of the cytoplasm to divide at the end of meiosis II

43. Why does sexual reproduction require both meiosis and syngamy?
A. The process of meiosis results in the production of gametes in which the number of chromosomes remains the same. 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.
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.
C. The process of meiosis results in the production of gametes in which the number of chromosomes is doubled. During syngamy, gametes are reduced by half, 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.

44. Which cells never divide by meiosis? (Check all that apply.)
__X__ haploid cells
_____ diploid cells
__X__ somatic cells
_____ germ-line cells
__X__ zygotes

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
__X__ Produce 4 daughter cells that are genetically different from the original parental cell
__X__ Reduce the number of chromosomes per cell from 10 to 5
_____ Reduce the number of chromosomes per cell from 20 to 10

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
_____ Increase the number of chromosomes per cell from 16 to 32
__X__ Increase the number of chromosomes per cell from 8 to 16
__X__ Combine the chromosomes from 2 haploid cells into a single diploid cell

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
A. blood cells
B. germ-line cells
C. somatic cells in the testes
D. bone marrow cells

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.)

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.)

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.)

51. How many tetrads are present in a single elephant cell (2n=56) during metaphase I of meiosis?

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
A. 8 chromosomes with 8 DNA molecules
B. 8 chromosomes with 16 DNA molecules
C. 4 chromosomes with 4 DNA molecules
D. 4 chromosomes with 8 DNA molecules

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
A. 2 pairs of sister chromatids failed to separate during meiosis II
B. 1 pair of sister chromatids failed to separate during meiosis II
C. 2 pairs of homologous chromosomes failed to separate during meiosis I
D. 1 pair of homologous chromosomes failed to separate during meiosis I

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
A. 3 cells with 20 chromosomes and 1 cell with 18
B. 2 cells with 20 chromosomes and 2 cells with 18
C. 2 cells with 19 chromosomes, 1 with 20, and 1 with 18
D. 3 cells with 18 chromosomes and 1 cell with 20

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?

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?

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?
A. 1/2
B. 1/4
C. 1/8
D. 1/16

58. A cell in G2 before meiosis begins, compared with one of the four cells produced at the end of meiosis II, has
A. twice as much DNA and twice as many chromosomes
B. four times as much DNA and twice as many chromosomes
C. twice as much DNA but the same number of chromosomes
D. four times as much DNA and four times as many chromosomes
E. twice as much DNA and half as many chromosomes

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
B. sister chromatids would migrate to opposite poles during anaphase II
C. sister chromatids would migrate to the same pole during anaphase I
D. sister chromatids would migrate to the same pole during anaphase II

60. Sister chromatids move to opposite poles of the cell during (Check all that apply.)
_____ anaphase I of meiosis
_____ metaphase I of meiosis
__X__ anaphase II of meiosis
__X__ anaphase of mitosis

15. The point of connection between two sister chromatids, before anaphase II of meiosis separates them, is called the
A. centriole
B. kinetochore.
C. centromere.
D. spindle apparatus.
E. centrosome.