9th – Biology – Chapter 4 – CELL CYCLE

MCQs

1. How does meiosis increase genetic diversity?
   a) By producing identical cells b) By keeping chromosome numbers unchanged c) By crossing over and producing new gene combinations d) By preventing mutations
2. During which stage do homologous chromosomes separate?
   a) Anaphase I b) Anaphase II c) Metaphase I d) Telophase II
3. What is the main activity during the S phase of the cell cycle?
   a) DNA replication b) Cell division c) Cytoplasmic division d) Organelle growth
4. What is an important function of mitosis?
   a) Growth through an increase in cell number b) Gamete production c) Reduction of chromosome number d) Generation of genetic diversity
5. During which stage does crossing over take place?
   a) Prophase I b) Metaphase I c) Anaphase I d) Telophase I
6. What happens during prophase?
   a) Chromosomes condense and spindle fibers form b) Chromosomes line up at the equator c) Chromatids separate d) DNA is replicated
7. What is produced as a result of mitosis?
   a) Four identical daughter cells b) Two identical daughter cells c) One large cell d) Four haploid cells
8. What takes place during anaphase of mitosis?
   a) Chromatin condenses b) Sister chromatids separate and move toward opposite poles c) Nuclear envelope reforms d) Spindle fibers disappear
9. Which organism can regenerate lost body parts through mitosis?
   a) Hydra b) Starfish c) Bacteria d) Viruses
10. In which cells do centrosomes form the mitotic spindle?
    a) Plant cells b) Prokaryotic cells c) Animal cells d) All of these
11. Mitosis is mainly important for:
    a) Growth and repair b) Gamete formation c) Reduction of chromosome number d) Genetic variation
12. Where do chromosomes align during metaphase of mitosis?
    a) At the poles b) Randomly inside the cell c) Near the centrosomes d) Along the equator forming the metaphase plate
13. What occurs during prophase of mitosis?
    a) Chromosomes align at the equator b) Sister chromatids separate c) A new nuclear envelope forms d) Chromatin condenses into chromosomes and the nuclear envelope breaks down
14. What occurs during prophase I of meiosis?
    a) Sister chromatids separate b) Chromosomes align at the equator c) Nuclear envelope reforms d) Homologous chromosomes pair and crossing over occurs
15. Which event occurs in meiosis but not in mitosis?
    a) Nuclear division b) Chromosome alignment c) Crossing over d) DNA replication
16. Which process is essential for replacing cells in the body?
    a) Meiosis b) Mitosis c) Binary fission d) Crossing over
17. Which process allows some animals to regenerate body parts?
    a) Meiosis b) DNA replication c) Cytokinesis alone d) Mitosis
18. What may result from non-disjunction during meiosis?
    a) Normal gametes are produced b) A baby with an abnormal chromosome number may result c) Mitosis occurs instead d) Chromosome number doubles
19. Which phase occupies approximately 90% of the cell cycle?
    a) Mitosis phase b) G0 phase c) Interphase d) S phase
20. What is meant by metastasis?
    a) Shrinking of tumors b) Repair of DNA damage c) Formation of benign tumors d) Spread of malignant tumors
21. Meiosis occurs mainly in:
    a) Somatic cells b) Germ cells c) Skin cells d) Red blood cells
22. Asexual reproduction in Hydra commonly occurs through:
    a) Binary fission b) Fragmentation c) Spore formation d) Budding
23. What happens to chromosome number during mitosis?
    a) It is reduced by half b) It doubles c) It remains the same as in the parent cell d) It becomes zero
24. What is the major activity during the G2 phase?
    a) DNA replication b) Cell division c) Spindle formation only d) Growth and preparation for division, including DNA repair checks
25. What can uncontrolled mitosis cause?
    a) Genetic diversity b) Haploid cells c) Regeneration d) Formation of tumors
26. What is the result of meiosis?
    a) Two identical daughter cells b) Four daughter cells with half the chromosome number c) Two cells with double the chromosome number d) Four identical daughter cells
27. What is the significance of crossing over?
    a) It doubles chromosome number b) It exchanges genetic material, causing recombination c) It prevents chromosome pairing d) It occurs during mitosis
28. In mitosis, the chromosome number:
    a) Is halved b) Doubles c) Remains the same d) Becomes zero
29. During which stage of meiosis do sister chromatids separate?
    a) Anaphase I b) Anaphase II c) Telophase I d) Prophase I
30. Which structures form the mitotic spindle in animal cells?
    a) Chromosomes b) Centrosomes c) Nucleolus d) Golgi apparatus
31. What happens during anaphase of mitosis?
    a) Homologous chromosomes separate b) Sister chromatids separate c) Chromosomes duplicate d) DNA condenses
32. Which type of cells generally does not enter the G0 phase?
    a) Neurons b) Liver cells c) Epithelial cells d) Kidney cells
33. During which phase of interphase does DNA replication occur?
    a) G2 phase b) G1 phase c) S phase d) G0 phase
34. What is a major difference between prophase of mitosis and prophase I of meiosis?
    a) Crossing over occurs in mitosis but not meiosis b) Homologous chromosomes pair in meiosis but not mitosis c) Chromatin condenses only in meiosis d) Spindle fibers form only in mitosis
35. Homologous chromosomes pair with each other during:
    a) Mitosis b) Meiosis c) Cytokinesis d) Interphase
36. What is the G0 phase?
    a) A phase of rapid cell division b) The phase of DNA replication c) The final phase of mitosis d) A stage in which cells stop dividing and perform specialized functions
37. Which cells typically remain permanently in the G0 phase?
    a) Epithelial cells b) Liver cells c) Neurons d) Skin cells
38. During which stage of mitosis do chromosomes line up at the center?
    a) Prophase b) Anaphase c) Metaphase d) Telophase
39. How many divisions occur in meiosis compared with mitosis?
    a) One in meiosis and two in mitosis b) One in both c) Two in both d) Two in meiosis and one in mitosis
40. Which statement correctly describes a major difference between mitosis and meiosis?
    a) Mitosis has one division, while meiosis has two b) Mitosis forms reproductive cells c) Meiosis has one division d) Meiosis occurs only in body cells
41. Genetic variation in meiosis is mainly introduced through:
    a) Chromosome alignment b) Crossing over c) Nuclear division d) Spindle fiber formation
42. Cytokinesis in animal cells occurs through:
    a) Cell plate formation b) Furrow formation c) Chromosome duplication d) Spindle fiber breakdown
43. Which of the following is NOT a characteristic of mitosis?
    a) It occurs in somatic cells b) It produces genetically identical daughter cells c) Chromosome number is halved in daughter cells d) It produces two daughter cells
44. What is a malignant tumor?
    a) A harmless mass of cells b) A tumor that remains in its original location c) A tumor that invades other tissues and is cancerous d) A tumor caused by meiosis errors
45. Which statement correctly describes the S phase?
    a) The cell grows and prepares for division b) The cell replicates its DNA c) The cell stops dividing d) The cell divides into two new cells
46. Meiosis produces:
    a) Two identical cells b) Four genetically different cells c) One large cell d) No cells
47. What happens during metaphase?
    a) Chromosomes condense b) Chromosomes line up at the center c) Chromosomes split d) Nuclear envelope reforms
48. Who discovered mitosis?
    a) Gregor Mendel b) Walther Flemming c) Charles Darwin d) Robert Hooke
49. How does cytokinesis differ between plant and animal cells?
    a) A furrow forms in plant cells b) Plant cells use vesicles to form a cell plate or phragmoplast instead of a furrow c) Cytokinesis does not occur in plant cells d) Animal cells use vesicles instead of a furrow
50. What happens during the G1 phase?
    a) DNA replication occurs b) The cell grows and produces proteins and organelles c) Chromosomes separate d) The cell divides into two daughter cells
51. Which phase is a resting stage in which some cells permanently stop dividing?
    a) G1 phase b) G2 phase c) S phase d) G0 phase
52. Which phase of the cell cycle lasts the longest?
    a) Mitosis b) Cytokinesis c) Interphase d) Telophase
53. Who discovered the events of mitosis?
    a) Oscar Hertwig b) Gregor Mendel c) Charles Darwin d) Walther Flemming
54. Which process occurs only during meiosis?
    a) Formation of two identical cells b) DNA replication c) Crossing over d) Cytokinesis
55. What happens to chromosome number during meiosis?
    a) It is halved b) It remains unchanged c) It increases d) It becomes tripled
56. What is produced after the first meiotic division?
    a) Two haploid cells b) Four haploid cells c) Two diploid cells d) Four diploid cells
57. What is a tetrad in meiosis?
    a) A single chromosome b) A pair of homologous chromosomes containing four chromatids c) A spindle fiber d) A separated chromatid
58. What structure reforms around chromosomes during telophase of mitosis?
    a) Centrosome b) Spindle fibers c) Phragmoplast d) Nuclear envelope
59. How does meiosis help maintain chromosome number in the next generation?
    a) By doubling chromosomes in gametes b) By producing haploid gametes that fuse to restore the diploid number c) By preventing DNA replication d) By keeping chromosome pairs intact
60. What occurs during G1 phase of interphase?
    a) DNA replication b) Cell growth and enzyme production c) Chromosome alignment d) Cytokinesis
61. What is the main purpose of meiosis?
    a) Producing gametes or spores for reproduction b) Growth and repair c) Cell replacement d) Asexual reproduction
62. What may happen if sister chromatids fail to separate during anaphase?
    a) Both daughter cells receive extra chromosomes b) One daughter cell receives both chromatids while the other receives none c) The cell enters G0 phase d) The cell undergoes meiosis
63. What happens during anaphase I of meiosis?
    a) Sister chromatids separate b) Homologous chromosomes move toward opposite poles c) Chromosomes align at the equator d) Nuclear envelopes form
64. What is the role of meiosis in flowering plants?
    a) Producing somatic cells b) Increasing cell size c) Replacing dead cells d) Producing spores with half the chromosome number
65. Why is meiosis II necessary after meiosis I?
    a) To replicate chromosomes b) To ensure genetic recombination c) To reduce chromosome number d) To separate sister chromatids
66. A cell with a nuclear membrane reforming around two chromosome sets is in which stage?
    a) Prophase b) Anaphase c) Metaphase d) Telophase
67. During metaphase I, chromosomes:
    a) Align as homologous pairs b) Line up individually c) Split into chromatids d) Form the mitotic spindle
68. What is the purpose of meiosis in plants?
    a) Growth b) Repair c) Production of spores d) Blood formation
69. What is the cell cycle?
    a) A random process of cell growth b) A series of events from cell formation through growth and division into two daughter cells c) The process of cell death d) DNA replication only
70. Malignant tumors:
    a) Remain in one place b) Spread and invade other tissues c) Always remain harmless d) Are always beneficial
71. What is the division of the nucleus called?
    a) Cytokinesis b) Karyokinesis c) Metastasis d) Binary fission
72. During which phase are chromatids pulled toward opposite poles?
    a) Prophase b) Metaphase c) Anaphase d) Telophase
73. What is the result of crossing over during meiosis?
    a) Identical gametes b) Double chromosome number c) New combinations of genes d) No genetic change
74. An organism has four pairs of chromosomes. After meiosis I, how many chromosomes and chromatids will each daughter cell contain?
    a) 4 chromosomes and 8 chromatids b) 8 chromosomes and 8 chromatids c) 4 chromosomes and 4 chromatids d) 8 chromosomes and 16 chromatids
75. Which process uses mitosis for asexual reproduction?
    a) Budding in Hydra b) Gamete production c) Spore formation in plants d) Crossing over
76. What is a major similarity between mitosis and meiosis?
    a) Both produce four daughter cells b) Both reduce chromosome number c) Both involve crossing over d) DNA replication occurs in S phase before both processes
77. During which phase are chromosomes duplicated?
    a) Mitosis b) G1 phase c) S phase d) G2 phase
78. What does the cell cycle describe?
    a) A random series of events in a cell b) A series of events leading to cell growth and division c) The destruction of old cells d) The process of forming tumors
79. Who discovered meiosis?
    a) Gregor Mendel b) Robert Hooke c) Walther Flemming d) Oscar Hertwig
80. What is mitosis?
    a) A division producing cells with half the chromosome number b) A process exclusive to prokaryotes c) A division producing four daughter cells d) A division producing two identical daughter cells with the same chromosome number
81. During which phases do sister chromatids separate in both mitosis and meiosis?
    a) Anaphase of mitosis and anaphase II of meiosis b) Anaphase of mitosis and anaphase I of meiosis c) Metaphase of both processes d) Telophase of both processes
82. Uncontrolled mitosis can result in:
    a) Tumor formation b) DNA replication c) Cell repair d) Asexual reproduction
83. During which phase does maximum cell growth occur?
    a) M phase b) S phase c) G2 phase d) G1 phase
84. What is the main purpose of meiosis?
    a) Maintaining chromosome number b) Helping growth c) Repairing damaged cells d) Replacing old cells
85. What is the G2 phase responsible for?
    a) Checking DNA for damage and preparing for mitosis b) DNA replication c) Cell division d) Formation of spindle fibers only
86. What is a consequence of non-disjunction during meiosis?
    a) Gametes receive abnormal chromosome numbers b) Genetic diversity increases c) Chromosomes fail to condense d) Crossing over stops
87. What happens during telophase?
    a) The nuclear envelope reforms b) Cell growth occurs c) Chromosomes condense d) Spindle fibers form
88. How does the centrosome contribute to mitosis?
    a) It duplicates organelles b) It forms the mitotic spindle c) It initiates DNA replication d) It forms the nuclear envelope
89. Who discovered meiosis?
    a) Walther Flemming b) Thomas Morgan c) James Watson d) Oscar Hertwig

SHORT QUESTIONS

1. What role can errors in cell-cycle checkpoints play in the development of cancer?
2. Why is anaphase important during mitosis?
3. What is the difference between metaphase I and metaphase II?
4. What would happen to life if mitosis did not occur?
5. How does crossing over increase genetic variation during meiosis?
6. How is mitosis involved in regeneration?
7. What is a gamete?
8. What structure reforms around chromosomes during telophase?
9. Why do some cells, such as neurons, remain permanently in G0?
10. What are tumors?
11. How does chromosome arrangement differ between metaphase of mitosis and metaphase I of meiosis?
12. What happens when mitosis becomes uncontrolled?
13. How does meiosis produce genetic diversity?
14. How is meiosis II different from mitosis?
15. Why is meiosis necessary for sexual reproduction?
16. What is mitosis?
17. What is karyokinesis?
18. How does cytokinesis differ in plant and animal cells?
19. What is cytokinesis?
20. Why is genetic variation important for survival?
21. In which types of cells does mitosis occur?
22. What are chiasmata?
23. What is the cell cycle?
24. What are the two main phases of the cell cycle?
25. Why do some cells stop dividing after reaching maturity?
26. How does mitosis maintain genetic stability?
27. What happens when non-disjunction occurs?
28. Give three differences between mitosis and meiosis.
29. During which phase of mitosis do sister chromatids separate?
30. What could result from an error during DNA replication in the S phase?
31. Who discovered mitosis?
32. Why must DNA be replicated before cell division?
33. What is the role of spindle fibers in mitosis?
34. What is non-disjunction?
35. What controls the events of the cell cycle?
36. How does mitosis help replace cells?
37. What are the main events of anaphase in mitosis?
38. Why do cancer cells divide uncontrollably?
39. Why are gametes haploid?
40. What are homologous chromosomes?
41. Why do sperm and egg cells contain genetic material different from their parent cells?
42. What role does mitosis play in growth?
43. Why is interphase the longest part of the cell cycle?
44. What can happen as a result of errors in mitosis?
45. What would happen if homologous chromosomes failed to separate during meiosis?
46. What happens to chromatin during prophase?
47. What is the function of the cleavage furrow during animal-cell division?
48. What is the final outcome of meiosis?
49. Why does meiosis involve two successive cell divisions?
50. What is the difference between prophase of mitosis and prophase I of meiosis?
51. How does meiosis help maintain the chromosome number of a species?
52. What is the purpose of meiosis?
53. Why do meiotic daughter cells contain half the original chromosome number?
54. What happens during synapsis in meiosis?
55. What are sister chromatids, and when do they separate during meiosis?
56. Why do skin cells continue dividing throughout life, whereas nerve and muscle cells permanently leave the cell cycle?
57. What is the function of the cell plate in plant-cell division?
58. What function does the centrosome perform during cell division?
59. Why does crossing over not normally occur during mitosis?
60. What is binary fission, and how does it differ from mitosis?
61. How does meiosis differ from mitosis?
62. What is regeneration? Give one example.
63. State three similarities between mitosis and meiosis.
64. Differentiate between benign and malignant tumors.
65. What role do spindle fibers play during mitosis?
66. What occurs during anaphase I of meiosis?
67. List the main events that occur during the G1 phase of interphase.
68. Name the two major phases of mitosis.
69. What is metastasis?
70. How does cytokinesis in animal cells differ from cytokinesis in plant cells?
71. What is checked during the G2 phase?
72. What is meiosis?
73. What happens during the G1 phase?
74. Who discovered meiosis?
75. How does mitosis contribute to asexual reproduction?
76. Why is mitosis essential for growth?
77. What could happen if an error occurs during anaphase?
78. What happens during metaphase?
79. What is crossing over, and why is it important?
80. How does meiosis differ from mitosis in terms of chromosome number?
81. What is the role of meiosis in reproduction?
82. Why is the S phase important?
83. What is the G0 phase, and which cells enter it?
84. What is the main purpose of the S phase in the cell cycle?

LONG QUESTIONS

1. How does meiosis ensure the proper distribution of chromosomes into gametes?
2. Describe the roles of mitosis and meiosis in the life cycles of plants and animals.
3. Explain how crossing over contributes to genetic variation.
4. Describe the role of spindle fibers during cell division.
5. Explain the major differences between mitosis and meiosis.
6. How does meiosis contribute to genetic diversity?
7. Describe the major events that occur during the phases of meiosis I.
8. Explain the different phases of interphase.
9. Compare prophase of mitosis with prophase I of meiosis.
10. Explain the role of centrioles and spindle fibers in cell division.
11. What is cytokinesis? Explain how it takes place in animal and plant cells.
12. Describe the cell cycle in detail.
13. Explain how uncontrolled mitosis can lead to cancer, giving examples.
14. Describe the events that take place during the different phases of mitosis.
15. What is mitosis? Explain its phases with a suitable diagram.
16. Describe cytokinesis in animal and plant cells.
17. Explain the consequences of errors occurring during mitosis and meiosis.
18. Describe the significance of mitosis.
19. Differentiate among chromatin, chromatids, and chromosomes.
20. What are the different types of tumors, and how do they spread?
21. What is meiosis? Describe its stages with a suitable diagram.
22. Explain the importance of mitosis in growth, repair, and reproduction.
23. Describe the significance of meiosis.
24. Discuss the importance of meiosis in maintaining chromosome number in organisms.
25. Describe the differences between anaphase of mitosis and anaphase I of meiosis.

ANSWER KEY

1. c)
2. a)
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36. d)
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89. d)