2nd Year Biology Chapter 21 Cell Cycle Notes

biology 12th notes chapter 21

1. The microtubules of mitotic apparatus are composed of protein tubulin and traces of:


2. Cells from an advanced malignant tumor most often have very abnormal chromosomes, and often an abnormal total number of chromosomes.Why might this occur?


3. Crossing over occurs during


4. Meiosis occurs in


5. Interphase


6. The two main stages of cell division are called


7. The process of meiosis is completed in how many divisions?


8. Besides the ability of some cancer cells to over proliferate, what else could logically result in a tumor?


9. Which is the longest of the mitotic stages?


10. An enzyme that attaches a phosphate group to another molecule is called


11. A cell containing 92 chromatids at metaphase of mitosis would, at its completion, produce two nuclei each containing how many chromosome?


12. A female lacking ovaries and germ cells is probably affected with


13. In order for anaphase to begin, which of the following must occur?


14. The length of chromosomes is


15. Tetrad


16. The vesicle forming phragmoplast originate during:


17. The autosomal non-disjunction in man in which 21 pair of chromosome fail to segregate resulting in gametos with 24 chromosome is:


18. For a newly evolving protist, what would be the advantage of using eukaryote-like cell division rather than binary fission?


19. When during the cell cycle is a cell’s DNA replicated?


20. Chromatids start moving towards the respective poles in


21. In non-disjunction chromosomes fail to segregate during.


22. In which group of eukaryotic organisms does the nuclear envelope remain intact during mitosis?


23. Phragmoplast


24. Which is the shortest part of the cell cycle?


25. Tumor cells


26. All of the following are problems that growth causes for cells except


27. Synapsis


28. Which of the following is not a way that cell division solves the problems of cell growth?


29. Cytokinesis usually, but not always, follows mitosis.If a cell complet mitosis but not cytokinesis, the result would be a cell with


30. Tissue culture


31. Cell cycle involves:


32. A network of very fine threads called chromatin material can be visualized in cell during:


33. Programmed and organized process of cell death is also called


34. Regarding mitosis and cytokinesis, one difference between higher plants and animals is that in plants


35. During which phase of mitosis do the chromosomes line up along the middle of the dividing cell?


36. Karyokinesis


37. How do the daughter cells at the end of mitosis and cyclokinesis compare with their parent cell when it was in G1 of the cell cycle?


38. Which of the following does not occur during mitosis?


39. Karyokinesis involves division of


40. Which of the following questions might be answered by such a method?


41. Small localized tumors are called


42. Apoptosis is:


43. Which term describes centromeres uncoupling, sister chromatids separating and the two new chromosomes moving to opposite poles of the cell?


44. The interphase of meiosis lacks


45. Tubulin


46. The affected individuals have one missing X-chromosome with only 45 chromsomes in:


47. The formation of a cell plate is beginning across the middle of a cell and nuclei are re-forming at opposite ends of the cell.What kind of cell is this?


48. Cancer is caused mainly by mutations in


49. The best conclusion concerning delta is that the cells


50. The number of sets of microtubules originate from each pair of centriole is 


51. The chromosomes of many of the squashed onion root tip cells are plainly visible.In some cells, replicated chromosomes are aligned along the center of the cell.These particular cells are in which stage of mitosis?


52. Cells that are in a non-dividing state are in which phase?


53. The vesicles forming phragmoplast originate during


54. Chromatin network is visible during


55. Nerve and muscle cells are in this phase


56. Mongolism is also known as


57. The somatic cells derived from a single-celled zygote divide by which process?


58. If a cell has 8 chromosomes at metaphase of mitosis, how many chromosomes will it have during anaphase?


59. The division of whole cell is called:


60. The chances of teenage mother having Down’s syndrome child is:


61. Meiosis I


62. The period of life cycle of cell between two consecutive divisions is termed as


63. Taxol, anticancer drug, disrupts microtubule formation by binding to microtubules and accelerating their assembly so surprisingly, this stops mitosis.Specifically, taxol must affect


64. Cell death due to tissue damage is called:


65. Malignant tumor


66. DNA is replicated at which stage of the cell cycle?


67. Which of the following is a factor that can stop normal cells from growing?


68. During which phases of mitosis are chromosomes composed of two chromatids?


69. Microtubules are composed of


70. As a cell becomes larger, its


71. The proteins which become activated during cytokinesis are


72. Mitotic spindle


73. In the cells of some organisms, mitosis occurs without cytokinesis.This will result in


74. The kinetochore fibres of spindle attach to chromosome at region:


75. Which term describes centrioles beginning to move apart in animal cells?


76. Reduction in the chromosome number occurs during


77. The measured DNA levels ranged from 3 to 6 picograms per nucleus.In which stage of the cell cycle was the nucleus with 6 picograms of DNA?


78. It is the period of extensive metabolic activity


79. Prophase I of meiosis is further divided into how many substages?


80. Which number represents the point in the cell cycle during which the chromosomes are replicated in the figure above?


81. Where do the microtubules of the spindle originate during mitosis in both plant and animal cells?


82. If cells in the process of dividing are subjected to drug colchicine, at which stage will mitosis be arrested?


83. The Syndrome in which individual has short stature, webbed neck, with-out ovaries and complete absence of germcells is


84. Apoptosis


85. Condensation of chromosomes reaches to its maximum during


86. Kinetochore


87. If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis?


88. Length of cell cycle in yeast cells is:


89. Which one is absent in animal cell


90. The centromere is a region in which


91. Why do chromosomes coil during mitosis?


92. XXY


93. Cytokinesis


94. The syndrome having trisomy of chromosome number 18 is:


95. If there are 20 chromatids in a cell, how many centromeres are there?


96. Starting with a fertilized egg , a series of five cell divisions would produce an early embryo with how many cells?


97. Chromosomes appear inside the nucleus at the time of


98. Chromosomes first become visible during which phase of mitosis?


99. Which number represents DNA synthesis in the figure above?


100. The sex chromosome complement in individuals with Klinefelter’s syndrome is


101. For the formation of phragmoplast, the vesicles originate from


102. Which of the following are true concerning cells?


103. Mitosis is divided into


104. The period of cell cycle between two consecutive division is termed as


105. Cell commits suicide in the absence of


106. Which of the following explains why normal cells grown in a petri dish tend to stop growing?


107. Unequal separation of chromosomes is called:


108. Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei re-forming on either side of the cell plate.This cell is most likely


109. One difference between cancer cells and normal cells is that cancer cells


110. In human cell, average cell cycle is about


111. Which of the followings is a function of those spindle microtubules that do not attach to kinetochores?


112. What is a chromatid?


113. The “restriction point” occurs here


114. The research team used the setup to study the incorporation of labeled nucleotides into a culture of lymphocytes and found that the lymphocytes incorporated the labeled nucleotide at a significantly higher level after a pathogen was introduced into the culture.What did they conclude?


115. The research team established similar lymphocyte cultures from a number of human donors, including healthy teenagers of both genders, patients already suffering from long-term bacterial infections, and elderly volunteers.They found that the increase in lymphocyte incorporation after pathogen introduction was slightly lower in some of the women teenagers and significantly lower in each of the elderly persons.They repeated the study with a larger number of samples but got the same results.What might be among their conclusions?


116. If mammalian cells receive a go-ahead signal at the G1 checkpoint, they will


117. The number of daughter cells produced at the end of meiosis is


118. G2 phase


119. Cyclins are a family of closely related proteins that


120. Which of the followings are primarily responsible for cytokinesis in plant cells?


121. Which pair is correct?


122. In the case of human cell, average cell cycle is about 


123. What is the role of the spindle during mitosis?


124. The most critical phase of mitosis is:


125. A particular cell has half as much DNA as some other cells in a mitotically active tissue.The cell in question is most likely in


Short Questions

1. At which stage of mitosis do the chromatids separate as independent chromosomes?
2. Define cancer or what are cancer cells?
3. Define cell cycle?
4. Define centrosome in an animal cell?
5. Define crossing over?
6. Define karyokinesis and cytokinesis. How do karyokinesis and cytokinesis phases of cell division differ?
7. Define meiosis and mitosis. What is the importance of mitosis and meiosis?
8. Define meiosis?
9. Define mitosis?
10. Define non-disjunction. What is non-disjunction or meiotic errors? What do you mean by non-disjunction?
11. Define non-disjunction?
12. Describe sub-phases of interphase.
13. Differentiate between benign and malignant tumor.
14. Differentiate between Go-phase and S-phase of interphase. Differentiate between interphase and mitotic phase. Describe changes occur during G1-phase.
15. Differentiate between mitotic and meiotic cell division?
16. Does Downs syndrome is related to the age of mother?
17. Explain a tumour?
18. Explain apoptosis?
19. Explain equatorial plate in cell division?
20. Explain non-disjunction?
21. Give events of Zygotene.
22. Give two main importance of meiosis.
23. How can you distinguish cancer cells from normal cells?
24. How can you identify Cancer cells? Cancer is uncontrolled cell division, explain.
25. How do karyokinesis and cytokinesis phases of cell division differ?
26. How does anaphase I of meiosis differs from that of mitosis?
27. How does cytokinesis take place in a plant cell?
28. How is the parent animal cell divided into two daughter cells at late telophase? OR How does cytokinesis take place in on animal cell?
29. How many chromosomes do occur in male affected by Klinefelter’s syndrome?
30. How meiosis maintains chromosome number constant generation after generation?
31. How much time is required for cell cycle in case of human?
32. How prophase of meiosis differs from that of mitosis?
33. How would you identify a metacentric chromosome?
34. In higher plants instead of visible centriole what is present?
35. In what respects does mitosis in plant cells differ from that in animal cells? Explain cytokinesis in plants. How cytokinesis occur in plants?
36. Name the different stages of interphase?
37. Name the microtubules which originate from centrioles?
38. Name the phases into which nuclear division (Karyokinesis) can be distinguished for convenience?
39. Name the substages of prophase I of meiosis?
40. Sketch and label cell cycle.
41. What are apparent symptoms or effects of Downs syndrome?
42. What are chromatids?
43. What are homologous chromosomes?
44. What are main causes of cancer?
45. What are mutagens? Give one example.
46. What are the apparent symptoms or effects of Down’s syndrome?
47. What are the chromosomes other than the sex chromosomes known as?
48. What are the durations of different stages of the human cell cycle?
49. What are the symptoms of Turner’s syndrome?
50. What are the two significant happenings of meiosis?
51. What are two basic types of tumours?
52. What do you know about chromatin?
53. What events occur in metaphase I of meiosis?
54. What events occur in prophase of mitosis?
55. What happens during metaphase I?
56. What happens in Diakinesis?
57. What happens in G2-phasw?
58. What happens in Telopase of mitosis?
59. What is a telocentric chromosome?
60. What is apoptosis?
61. What is autosomal non-disjunction?
62. What is benign tumours?
63. What is bivalent or tetrad?
64. What is chiasmata?
65. What is Downs Syndrome?
66. What is G1-phase?
67. What is Go?
68. What is karyotype in a cell?
69. What is kinetochore?
70. What is Klinefelter’s syndrome?
71. What is malignant tumour?
72. What is meant by cell cycle?
73. What is metastasis?
74. What is mitotic apparatus formed of in animal as well as in plant cells?
75. What is Necrosis?
76. What is Phragmoplast?
77. What is sex chromosomal non-disjunction?
78. What is S-phase of cell cycle?
79. What is synapsis?
80. What is the cause of Down’s syndrome?
81. What is the difference between the acrocentric and sub metacentric chromosomes?
82. What is the duration of Pachytene leptotene and zygotene?
83. What is the importance of bivalent formation?
84. What is Tumour?
85. What two conventional phases of Mitosis?
86. When in plants and animals the meiosis takes place?
87. Which kind of cell division is involved in asexual reproduction in plants and animals?
88. Why are the ‘X’ and ‘Y’ chromosomes known as the sex chromosomes?
89. Write down the cause of Turner’s syndrome in human beings?
90. Write down the chemical composition of the spindle fibers, including both the kinetochore fibers and the polar fibers?
91. Write down the duration of cell cycle in yeast cell?
92. Write down the effects of Klinefelter’s syndrome on the affected male humans?
93. Write down the two basic phases of cell cycle?

Long Questions

1. Define non-disjunction and discuss its effect with one example.
2. Explain about interphase of cell cycle.
3. Explain the stages of prophase I of meiosis I.
4. Write about Necrosis and Apoptosis.

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