Chapter 12: The Cell Cycle Review

1) The centromere is a region in which

2) What is a chromatid?

3) What is the name for the special region on a duplicated chromosome that holds the sister chromatids together?

4) If there are 20 chromatids in a cell, how many centromeres are there?

5) Regarding mitosis and cytokinesis, one difference between higher plants and animals is that in plants

The questions below refer to the following terms. Each term may be used once, more than once, or not at all.

A. telophase

B. anaphase

C. prometaphase

D. metaphase

E. prophase

6) Two centrosomes are arranged at opposite poles of the cell.

7) Centrioles begin to move apart in animal cells.

8) This is the longest of the mitotic stages.

9) Centromeres uncouple, sister chromatids are separated, and the two new chromosomes move to

10) Cytokinesis usually, but not always, follows mitosis. If a cell completed mitosis but not cytokinesis, the result would be a cell with

11) How do the daughter cells at the end of mitosis and cytokinesis compare with their parent cell when it was in G₁ of the cell cycle?

12) Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, taxol disrupts microtubule formation by binding to microtubules and accelerating their assembly from the protein precursor, tubulin. Surprisingly, this stops mitosis. Specifically, taxol must affect

13) Chromosomes first become visible during ________ of mitosis.

14) The correct sequence of steps in the M phase of the cell cycle is

15) In which group of eukaryotic organisms does the nuclear envelope remain intact during mitosis?

16) The somatic cells derived from a single-celled zygote divide by which process?

17) Imagine looking through a microscope at a squashed onion root tip. The chromosomes of many of the cells are plainly visible. In some cells, replicated chromosomes are aligned along the center (equator) of the cell. These particular cells are in which stage of mitosis?

18) Cells that are in a nondividing state are in which phase?

The questions below consist of five phrases or sentences concerned with the cell cycle. For each one, select the answer below that is most closely related to it. Each answer may be used once, more than once, or not at all.

A. G₀

B. G₁

C. S

D. G₂

E. M

19) The "restriction point" occurs here.

20) Nerve and muscle cells are in this phase.

21) the shortest part of the cell cycle

22) DNA is replicated at this time of the cell cycle.

23) The cyclin component of MPF is destroyed toward the end of this phase.

24) Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called

25) Which of the following is true concerning cancer cells? They do not exhibit density-dependent 26) Nucleoli are present during

27) Chromosomes become visible during

28) Spindle fibers attach to kinetochores during

29) During prophase a homologous pair of chromosomes consists of

Chapter 13: Meiosis and Sexual Life Cycles

30) In a cell in which 2n = 6, the independent assortment of chromosomes during meiosis can by itself give rise to ________ genetically different gametes.

31) What is a genome?

32) How do the two members of a pair of homologous chromosomes differ from each other?

33) What is a karyotype?

34) At which stage of mitosis are chromosomes photographed in the preparation of a karyotype?

35) The human X and Y chromosomes are

36) If the liver cells of an animal have 24 chromosomes, how many chromosomes do its sperm cells have?

37) Which of the following is true of a species that has a chromosome number of 2n = 16?

38) Eukaryotic sexual life cycles show tremendous variation. Of the following elements, which do all sexual life cycles have in common?

I. alternation of generations

II. meiosis

III. fertilization

IV. gametes

V. spores

39) In animals, meiosis results in gametes, and fertilization results in

40) Referring to a plant sexual life cycle, which of the following terms describes the process that leads directly to the formation of gametes?

41) In animals, somatic cells are produced by mitosis and ________ are produced by meiosis.

42) After telophase I of meiosis, the chromosomal makeup of each daughter cell is

43) How do cells at the completion of meiosis compare with cells that have replicated their DNA and are just about to begin meiosis?

44) Which of the following terms belongs with the words synapsis, tetrads, and chiasmata?

45) Which of the following happens at the conclusion of meiosis I?

46) Which of the following is true of the process of meiosis?

47) Crossing over occurs during which phase of meiosis?

48) How does the sexual life cycle increase the genetic variation in a species?

49) For a species with a haploid number of 23 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes?

50) Independent assortment of chromosomes is a result of

51) What name is given to the process that restores the diploid number of chromosomes?

52) At the end of ________ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.

53) Homologous chromosomes migrate to opposite poles during

For the following questions, match the key event of meiosis with the stages listed below.

I. prophase I V. prophase II

II. metaphase I VI. metaphase II

III. anaphase I VII. anaphase II

IV. telophase I VIII. telophase II

54) Centromeres of sister chromatids uncouple and chromatids separate.

55) Tetrads of chromosomes are aligned at the center of the cell; independent assortment soon follows.

56) Synapsis of homologous pairs occurs; crossing over may occur.

Use the following key to answer the following questions. Each answer may be used once, more than once, or not at all.

A. The statement is true for mitosis only.

B. The statement is true for meiosis I only.

C. The statement is true for meiosis II only.

D. The statement is true for mitosis and meiosis I.

E. The statement is true for mitosis and meiosis II.

57) A cell divides to produce two daughter cells that are genetically identical.

58) Homologous chromosomes synapse and crossing over occurs.

59) Centromeres uncouple and chromatids are separated from each other.

The following questions refer to the essential steps in meiosis described below.

1. formation of four new nuclei, each with half the chromosomes present in the parental nucleus

2. alignment of tetrads at the metaphase plate

3. separation of sister chromatids

4. separation of the homologues; no uncoupling of the centromere

5. synapsis; chromosomes moving to the middle of the cell in pairs

60) From the descriptions above, which of the following is the order that most logically illustrates a sequence of meiosis?

61) Which of the steps take place in both mitosis and meiosis?