12th Class Biology Mcqs with Answers Chapter 21 | 2nd year Biology Mcqs With Answers

Chapter 21

Cell Cycle

Encircle the most appropriate answer among the following options

1. The centromere is a region in which choose which one is correct:

Chromatids remain attached to one another until anaphase
Metaphase chromosomes become aligned at the metaphase plate
Chromosomes are grouped during telophase
The nucleus is located prior to mitosis

2. What is a chromatid?

A chromosome in G1 of the cell cycle
A replicate chromosome
A chromosome found outside the nucleus
A special region that holds two centromeres together

3. Starting with a fertilized egg (zygote), a series of five cell divisions would

produce an early embryo with how many cells?

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

5. For a newly evolving protist, what would be the advantage of using

eukaryote-like cell division rather than binary fission?

Binary fission would not allow for the formation of new organisms
Cell division would allow for the orderly and efficient segregation of multiple linear chromosomes
Cell division would be faster than binary fission
Binary fission would not allow the organism to have complex cells

6. 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?

The daughter cells have half the amount of cytoplasm and half the amount of DNA
The daughter cells have half the number of chromosomes and half the amount of DNA
The daughter cells have the same number of chromosomes and half the amount of DNA
The daughter cells have the same number of chromosomes and the same amount of DNA

7. Cytokinesis choose which one is correct:

Missing X
Diplotene
Rapid division
Cell cleavage

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

Telophase
Anaphase
Metaphase
Interphase

9. Which is the longest of the mitotic stages?

Telophase
Anaphase
Metaphase
Interphase

10. Which term describes centromeres uncoupling, sister chromatids separating

and the two new chromosomes moving to opposite poles of the cell?

Telophase
Anaphase
Prometaphase
Metaphase

11. If cells in the process of dividing are subjected to drug colchicine, at which

stage will mitosis be arrested?

Anaphase
Prophase
Telophase
Metaphase

12. A cell containing 92 chromatids at metaphase of mitosis would, at its

completion, produce two nuclei each containing how many chromosome?

13. Malignant tumor choose which one is correct:

Diplotene
Rapid division
Cell cleavage
Missing X

14. If there are 20 centromeres in a cell at anaphase, how many chromosomes

are there in each daughter cell following cytokinesis?

16. The best conclusion concerning delta is that the cells choose which one is correct:

Contain no DNA
Contain no RNA
Contain only one chromosome that is very short
Are actually in the G0 phase

17. Where do the microtubules of the spindle originate during mitosis in both

plant and animal cells?

Centromere
Centrosome
Centriole
Chromatid

18. If a cell has 8 chromosomes at metaphase of mitosis, how many chromosomes

will it have during anaphase?

19. Cytokinesis usually, but not always, follows mitosis. If a cell complet mitosis

but not cytokinesis, the result would be a cell with choose which one is correct:

A single large nucleus
High concentrations of actin and myosin
Two abnormally small nuclei
Two nuclei

20. Regarding mitosis and cytokinesis, one difference between higher plants and

animals is that in plants choose which one is correct:

The spindles contain microfibrils in addition to microtubules, whereas animal spindles do not contain microfibrils
Sister chromatids are identical, but they differ from one another in animals
A cell plate begins to form at telophase, whereas in animals a cleavage furrow is initiated at that stage
Chromosomes become attached to the spindle at prophase, whereas in animals chromosomes do not become attached until anaphase

21. 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?

An animal cell in telophase
An animal cell undergoing cytokinesis
A plant cell in metaphase
A plant cell undergoing cytokinesis

22. Taxol, anticancer drug, disrupts microtubule formation by binding to

microtubules and accelerating their assembly so surprisingly, this stops

mitosis. Specifically, taxol must affect choose which one is correct:

The fibers of the mitotic spindle
Anaphase
Formation of the centrioles
The S phase of the cell cycle

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

Kinetochores
Golgi-derived vesicles
Actin and myosin
Centrioles and basal bodies

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

Telophase
Prophase
Metaphase
Anaphase

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

From G1 of interphase through metaphase
From metaphase through telophase
From anaphase through telophase
From G2 of interphase through metaphase

26. In which group of eukaryotic organisms does the nuclear envelope remain

intact during mitosis?

Seedless plants
Dinoflagellates
Diatoms
(B) and (C) only
(A), (B) and (C)

27. 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?

28. A group of cells is assayed for DNA content immediately following mitosis

and is fond to have an average of 8 picograms of DNA per nucleus. Those

cells would have how many picograms at the end of the S phase and at the

end of G2.

8; 16
16; 8
16; 16
12; 16

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

Meiosis
Mitosis
Replication
Cytokinesis alone

30. The chromosomes of many of the squashed onion root tip 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?

Telophase
Prophase
Anaphase
Metaphase

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

Chromatids must lose their kinetochores
Cohesin must attach the sister chromatids to each other
Cohesin must be cleaved enzymatically
Kinetochores must attach to the metaphase plate

32. Why do chromosomes coil during mitosis?

To increase their potential energy
To allow the chromosomes to move without becoming entangled and breaking
To allow the chromosomes to fit within the nuclear envelope
To provide for the structure of the centromere

33. Which of the following best describes how chromosomes move toward the

poles of the spindle during mitosis?

The chromosomes are “reeled in” by the contraction of spindle microtubules
Motor proteins of the kinetochores move the chromosomes along the spindle microtubules
Non-kinetochore spindle fibers serve to push chromosomes in the direction of the poles
Both (A) and (B)

34. Which of the followings is a function of those spindle microtubules that do

not attach to kinetochores?

Maintaining an appropriate spacing among the moving chromosomes
Providing the ATP needed by the fibers attached to kinetochores
Maintaining the region of overlap of fibers in the cell’s center
Pulling the poles of the spindles closer to one another

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

How many cells are produced by the culture per hour?
What is the length of the S phase of the cell cycle?
When is the S chromosome synthesized?
How many picograms of DNA are made per cell cycle?

36. 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?

The presence of the pathogen made the experiment too contaminated to trust the results
Their tissue culture methods needed to be relearned
Infection causes lymphocytes to divide more rapidly
Infection causes cell cultures in general to reproduce more rapidly
Infection causes lymphocyte cultures to skip some parts of the cell cycle

37. If mammalian cells receive a go-ahead signal at the G1 checkpoint, they will choose which one is correct:

Move directly into telophase
Complete the cycle and divide
Exit the cycle and switch to a non-dividing state
Complete cytokinesis and form new cell walls

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

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

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

41. The “restriction point” occurs here choose which one is correct:

42. Nerve and muscle cells are in this phase choose which one is correct:

43. Meiosis I choose which one is correct:

Rapid division
Cell cleavage
Diplotene
G1 phase

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

45. Which number represents the point in the cell cycle during which the

chromosomes are replicated in the figure above?

46. An enzyme that attaches a phosphate group to another molecule is called choose which one is correct:

Phosphatase
Phosphorylase
Kinase
ATPase

47. Which of the following are true concerning cells?

They do not exhibit density-dependent inhibition when growing in culture
When they stop dividing, they do so at random points in the cell cycle
They are not subject to cell cycle controls
(B) and (C) only

48. 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?

The elderly person’s samples demonstrated their lowered immune responses
The young men had higher response because they are generally healthier
The patient samples should have had the lowest response but did not, so the experiment is invalid
The elderly donor samples represent cells no longer capable of any cell division

49. Cells from an advanced malignant tumor most often have very abnormal

chromosomes, and often an abnormal total number of chromosomes. Why

might this occur?

Cancer cells are no longer density dependent
Cancer cells are no longer anchorage dependent
Chromosomally abnormal cells can still go through cell cycle checkpoints
Transformation introduces new chromosomes into cells

50. Besides the ability of some cancer cells to over proliferate, what else could

logically result in a tumor?

Metastasis
Changes in the order of cell cycle stages
Lack of appropriate cell death
Inability to form spindles

51. 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 choose which one is correct:

An animal cell in the process of cytokinesis
A plant cell in the process of cytokinesis
An animal cell in the S phase of the cell cycle
A bacterial cell dividing

52. 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 choose which one is correct:

G1
G2
Prophase
Metaphase

53. One difference between cancer cells and normal cells is that cancer cells choose which one is correct:

Are arrested at the S phase of the cell cycle
Continue to divide even when they are tightly packed together
Cannot function properly because they are affected by density dependent inhibition
Are always in the M phase of the cell cycle

54. In the cells of some organisms, mitosis occurs without cytokinesis. This will

result in choose which one is correct:

Cells with more than one nucleus
Cells that are unusually small
Cells lacking nuclei
Destruction of chromosomes

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

Condensation of the chromosomes
Replication of the DNA
Separation of sister chromatids
Separation of the spindle poles

56. As a cell becomes larger, its choose which one is correct:

Volume increases faster than its surface area
Surface area increases faster than its volume
Volume increases, but its surface area stays the same
Surface area stays the same, but its volume increases

57. All of the following are problems that growth causes for cells except choose which one is correct:

DNA overload
Obtaining enough food
Excess oxygen
Expelling wastes

58. Which of the following is not a way that cell division solves the problems of

cell growth?

Cell division provides each daughter cell with its own copy of DNA
Cell division increases the mass of the original cell
Cell division increases the surface area of the original cell
Cell division reduces the original cell’s volume

59. Which pair is correct?

G1 phase, DNA replication
G2 phase, preparation for mitosis
S phase, cell division
M phase, cell growth

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

G1 phase
G2 phase
S phase
M phase

61. During which phase of mitosis do the chromosomes line up along the middle

of the dividing cell?

Prophase
Metaphase
Telophase
Anaphase

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

It helps separate the chromosomes
It breaks down the nuclear membrane
It duplicates the DNA
It divides the cell in half

63. The two main stages of cell division are called choose which one is correct:

Mitosis and interphase
Synthesis and cytokinesis
The M phase and the S phase
Mitosis and cytokinesis

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

Contact with other cells
Growth factors
A cut in the skin
Cyclin that has been taken from a cell in mitosis

65. Which of the following explains why normal cells grown in a petri dish tend

to stop growing?

The cells lack cyclin
The petri dish inhibits cell growth
Contact with other cells stops cell growth
Most cells grown in petri dishes have a defective p53

66. Cyclins are a family of closely related proteins that choose which one is correct:

Regulate the cell cycle
Cause cancer
Produce p53
Work to heat wounds

67. It is the period of extensive metabolic activity choose which one is correct:

68. In human cell, average cell cycle is about choose which one is correct:

18 hours
6 hours
24 hours
12 hours

69. The period of cell cycle between two consecutive division is termed as choose which one is correct:

Prophase
Metaphase
Telophase
Interphase

70. The vesicles forming phragmoplast originate during choose which one is correct:

Prophase
Metaphase
Telephase
Inter phase

71. Cancer is caused mainly by mutations in choose which one is correct:

Sex cells
S-phase
Somatic cells
G2 stage

72. The interphase of meiosis lacks choose which one is correct:

G1 stage
G0 stage
G2 stage
S phase

73. Condensation of chromosomes reaches to its maximum during choose which one is correct:

Diplotane
Zygotenre
Leptotene
Diakinesis

74. The sex chromosome complement in individuals with Klinefelter’s syndrome is choose which one is correct:

XXY
XXYY
XYYY
Xy

75. Mitosis is divided into choose which one is correct:

Cytokinesis
Interphas
Both (A) and (D)
Karyokinesis

76. A female lacking ovaries and germ cells is probably affected with choose which one is correct:

Haemophilia
Klinefelter’s syndrome
Turner’s syndrome
Down’s syndrome

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

78. The number of daughter cells produced at the end of meiosis is choose which one is correct:

79. Meiosis occurs in choose which one is correct:

Viruses
Both plants and animals
Plants
Bacteria

80. Small localized tumors are called choose which one is correct:

Cancer
Benign
Malign
Interdigitate

81. Reduction in the chromosome number occurs during choose which one is correct:

Meiosis II
Mitosis
Both (A) and (B)
Meiosis I

82. Crossing over occurs during choose which one is correct:

Diplotene
Zygotene
Pachytene
Leptotene

83. Chromatids start moving towards the respective poles in choose which one is correct:

Metaphase
Prophase
Anaphase
Diplotene

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

85. The proteins which become activated during cytokinesis are choose which one is correct:

Globulin
Fibrin
Actin and myosin
Hemoglobin

86. The length of chromosomes is choose which one is correct:

0.40 0.80 um
1 um 3 um
0.25 0.50 um
0.60 1.2 um

87. Interphase choose which one is correct:

Aster and spindle
Resting phase
Chromatin
4.5 hours

88. Mitotic spindle choose which one is correct:

Resting phase
Chromatin
Centromere
Aster and spindle

89. Kinetochore choose which one is correct:

Centromere
Resting phase
Aster and spindle
4.5 hours

90. G2 phase choose which one is correct:

Resting phase
4.5 hours
Chromatin
Aster and spindle

91. Phragmoplast choose which one is correct:

Somatic cells
Plant cell
Zygotene
Pachytene

92. Cancer choose which one is correct:

Somatic cells
Anaphase I
Plant cell
Pachytene

93. Tetrad choose which one is correct:

Pachytene
Plant cell
Anaphase I
Zygotene

94. Crossing over choose which one is correct:

Plant cell
Pachytene
Anaphase I
Somatic cells

95. XXY choose which one is correct:

Turner’s syndrome
Necrosis
Klinefelter’s syndrome
Mitosis

96. Cell death choose which one is correct:

Necrosis
Klinefelter’s syndrome
Turner’s syndrome
Mitosis

97. Tissue culture choose which one is correct:

Klinefelter’s syndrome
Mitosis
Metastasis
Turner’s syndrome

98. Tumor cells choose which one is correct:

Klinefelter’s syndrome
Metastasis
Mitosis
Turner’s syndrome

99. Karyokinesis choose which one is correct:

Pairing
Leptotene
Division of nucleus
Protein

100. Tubulin choose which one is correct:

Leptotene
Protein
Pairing
Cell suicide

101. Apoptosis choose which one is correct:

Leptotene
Protein
Cell suicide
Division of nucleus

102. Synapsis choose which one is correct:

Protein
Pairing
Leptotene
Division of nucleus

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