Here below some basic MCQ’s about “cell cycle and cell division” with answer which is explained in details. Let’s check one by one which is given below.
Question 1
Which of the following phases of the cell cycle is characterized by the duplication of DNA?
A) G1 Phase
B) S Phase
C) G2 Phase
D) M Phase
Answer: B) S Phase
Explanation: The S (Synthesis) Phase is where DNA replication occurs, leading to the duplication of the cell’s genetic material in preparation for cell division.
Question 2
During which phase of mitosis do the sister chromatids separate and move toward opposite poles of the cell?
A) Prophase
B) Metaphase
C) Anaphase
D) Telophase
Answer: C) Anaphase
Explanation: In Anaphase, the sister chromatids are pulled apart by the spindle fibers and move toward opposite poles, ensuring that each daughter cell will receive an identical set of chromosomes.
Question 3
What is the main purpose of the G1 checkpoint in the cell cycle?
A) To ensure DNA is replicated accurately
B) To prevent cells from dividing when conditions are unfavorable
C) To check for spindle fiber attachment
D) To initiate cytokinesis
Answer: B) To prevent cells from dividing when conditions are unfavorable
Explanation: The G1 checkpoint assesses whether the cell is ready to enter the S phase. It checks for factors such as cell size, nutrient availability, and DNA integrity. If conditions are not favorable, the cell can enter a resting state (G0).
Question 4
Which of the following events occurs during prophase?
A) Chromosomes align at the equatorial plane
B) Nuclear envelope breaks down
C) Cytokinesis begins
D) DNA is replicated
Answer: B) Nuclear envelope breaks down
Explanation: During prophase, chromatin condenses into visible chromosomes, and the nuclear envelope disintegrates, allowing the mitotic spindle to interact with the chromosomes.
Question 5
Cytokinesis in animal cells occurs through the formation of a:
A) Cell wall
B) Cleavage furrow
C) Cell plate
D) Centrioles
Answer: B) Cleavage furrow
Explanation: In animal cells, cytokinesis involves the formation of a cleavage furrow, which pinches the cell membrane and divides the cytoplasm into two daughter cells.
Question 6
What is the role of cyclins in the cell cycle?
A) To provide energy for mitosis
B) To facilitate DNA replication
C) To regulate the progression of the cell cycle
D) To form the mitotic spindle
Answer: C) To regulate the progression of the cell cycle
Explanation: Cyclins are proteins that regulate the cell cycle by activating cyclin-dependent kinases (CDKs), which are essential for the transition between different phases of the cell cycle.
Question 7
Which phase of the cell cycle is primarily focused on protein synthesis and cell growth?
A) S Phase
B) G1 Phase
C) G2 Phase
D) M Phase
Answer: B) G1 Phase
Explanation: The G1 phase is primarily for cell growth and the synthesis of proteins necessary for DNA replication.
Question 8
During which phase does the mitotic spindle form?
A) Telophase
B) Metaphase
C) Prophase
D) Anaphase
Answer: C) Prophase
Explanation: The mitotic spindle begins to form during prophase, helping to organize and separate the chromosomes.
Question 9
What is the end result of meiosis?
A) Two diploid cells
B) Four haploid cells
C) One diploid cell
D) Two haploid cells
Answer: B) Four haploid cells
Explanation: Meiosis results in four haploid cells, each with half the chromosome number of the original cell, which is crucial for sexual reproduction.
Question 10
In which phase of meiosis does crossing over occur?
A) Prophase I
B) Metaphase I
C) Anaphase I
D) Telophase I
Answer: A) Prophase I
Explanation: Crossing over, or genetic recombination, occurs during Prophase I of meiosis, increasing genetic diversity.
Question 11
What is the primary function of the G2 phase?
A) Cell growth
B) DNA synthesis
C) Preparation for mitosis
D) Chromosome segregation
Answer: C) Preparation for mitosis
Explanation: The G2 phase is a period of preparation for mitosis, where the cell ensures all DNA has been replicated and repairs any damage.
Question 12
The mitotic phase consists of:
A) Mitosis only
B) Cytokinesis only
C) Mitosis and cytokinesis
D) Interphase only
Answer: C) Mitosis and cytokinesis
Explanation: The mitotic phase includes both mitosis (nuclear division) and cytokinesis (cytoplasmic division).
Question 13
Which of the following is NOT a stage of mitosis?
A) Prophase
B) Interphase
C) Metaphase
D) Anaphase
Answer: B) Interphase
Explanation: Interphase is not a stage of mitosis; it is the phase where the cell prepares for division, occurring before mitosis begins.
Question 14
What triggers the transition from G1 to S phase?
A) Cyclin D
B) Cyclin A
C) Cyclin B
D) Cyclin E
Answer: D) Cyclin E
Explanation: Cyclin E is crucial for the transition from the G1 phase to the S phase, where DNA synthesis occurs.
Question 15
During which stage of the cell cycle do organelles duplicate?
A) S Phase
B) G1 Phase
C) G2 Phase
D) M Phase
Answer: C) G2 Phase
Explanation: In the G2 phase, the cell prepares for mitosis, which includes the duplication of organelles.
Question 16
What structure is responsible for the movement of chromosomes during mitosis?
A) Centromere
B) Nucleus
C) Spindle fibers
D) Chromatin
Answer: C) Spindle fibers
Explanation: Spindle fibers, formed from microtubules, are responsible for pulling chromosomes apart during mitosis.
Question 17
What is the main purpose of meiosis?
A) Growth and repair
B) Asexual reproduction
C) Genetic variation and sexual reproduction
D) DNA replication
Answer: C) Genetic variation and sexual reproduction
Explanation: Meiosis produces gametes with genetic variation, essential for sexual reproduction.
Question 18
During which phase of the cell cycle does the chromatin condense into visible chromosomes?
A) G1 Phase
B) Prophase
C) Anaphase
D) Telophase
Answer: B) Prophase
Explanation: Chromatin condenses into distinct chromosomes during prophase, making them visible under a microscope.
Question 19
What occurs during telophase?
A) Chromosomes are pulled apart
B) The nuclear envelope re-forms
C) Spindle fibers disassemble
D) All of the above
Answer: D) All of the above
Explanation: During telophase, chromosomes reach the poles, the nuclear envelope re-forms, and spindle fibers disassemble.
Question 20
Which of the following statements about cyclin-dependent kinases (CDKs) is TRUE?
A) They are activated without cyclins.
B) They phosphorylate target proteins to regulate the cell cycle.
C) They are inactive throughout the cell cycle.
D) They function only in meiosis.
Answer: B) They phosphorylate target proteins to regulate the cell cycle.
Explanation: CDKs require binding to cyclins for activation, and once activated, they phosphorylate target proteins to drive the cell cycle forward.
Question 21
What is the function of the centromere?
A) To hold sister chromatids together
B) To organize microtubules
C) To assist in cytokinesis
D) To synthesize proteins
Answer: A) To hold sister chromatids together
Explanation: The centromere is the region of the chromosome where sister chromatids are joined, playing a critical role during cell division.
Question 22
Which of the following statements about cancer cells is TRUE?
A) They undergo normal cell cycle regulation.
B) They are immortal and do not stop dividing.
C) They have a normal number of chromosomes.
D) They cannot invade other tissues.
Answer: B) They are immortal and do not stop dividing.
Explanation: Cancer cells often bypass normal regulatory mechanisms, leading to uncontrolled division and immortality.
Question 23
What role do checkpoint proteins play in the cell cycle?
A) They accelerate the cell cycle.
B) They slow down the cell cycle.
C) They monitor the integrity of the cell’s DNA and overall condition.
D) They facilitate organelle duplication.
Answer: C) They monitor the integrity of the cell’s DNA and overall condition.
Explanation: Checkpoint proteins assess DNA integrity and other factors, ensuring cells only proceed to the next phase when conditions are right.
Question 24
What is a key difference between mitosis and meiosis?
A) Mitosis produces four cells; meiosis produces two.
B) Mitosis is for growth; meiosis is for reproduction.
C) Mitosis involves crossing over; meiosis does not.
D) Mitosis occurs in somatic cells; meiosis occurs in germ cells.
Answer: D) Mitosis occurs in somatic cells; meiosis occurs in germ cells.
Explanation: Mitosis results in two genetically identical daughter cells and occurs in somatic (body) cells, while meiosis produces four genetically diverse gametes from germ cells.
Question 25
In which stage of the cell cycle is DNA checked for damage before replication?
A) G1 Phase
B) S Phase
C) G2 Phase
D) M Phase
Answer: A) G1 Phase
Explanation: The G1 phase includes a checkpoint that checks for DNA damage before the cell enters the S phase for DNA replication.
Question 26
Which type of cell division is responsible for growth and repair in multicellular organisms?
A) Meiosis
B) Mitosis
C) Binary fission
D) Budding
Answer: B) Mitosis
Explanation: Mitosis is the process by which somatic cells divide for growth and tissue repair.
Question 27
Which of the following occurs during metaphase?
A) Chromosomes align along the equatorial plane.
B) Chromosomes condense.
C) Sister chromatids separate.
D) The nuclear envelope re-forms.
Answer: A) Chromosomes align along the equatorial plane.
Explanation: During metaphase, chromosomes line up at the cell’s equatorial plane, preparing for separation.
Question 28
How do plants achieve cytokinesis?
A) By forming a cleavage furrow
B) By forming a cell plate
C) By splitting the nucleus
D) By using centrioles
Answer: B) By forming a cell plate
Explanation: In plant cells, cytokinesis occurs through the formation of a cell plate that eventually develops into the cell wall.
Question 29
Which of the following checkpoints occurs at the end of G2?
A) G1 checkpoint
B) M checkpoint
C) G2 checkpoint
D) S checkpoint
Answer: C) G2 checkpoint
Explanation: The G2 checkpoint ensures that DNA has been completely and accurately replicated before the cell enters mitosis.
Question 30
What is the primary purpose of the G0 phase?
A) Active cell division
B) Resting state with no division
C) DNA synthesis
D) Preparation for meiosis
Answer: B) Resting state with no division
Explanation: The G0 phase is a quiescent state where cells are not actively dividing, allowing them to carry out specialized functions or remain inactive.
Question 31
What happens to the chromosomal number during meiosis?
A) It doubles
B) It remains the same
C) It is halved
D) It triples
Answer: C) It is halved
Explanation: Meiosis reduces the chromosome number by half, resulting in haploid gametes from diploid precursor cells.
Question 32
Which of the following is NOT a characteristic of cancer cells?
A) Uncontrolled growth
B) Differentiation
C) Ability to invade tissues
D) Abnormal nuclei
Answer: B) Differentiation
Explanation: Cancer cells often lose their ability to differentiate, whereas normal cells maintain specialized functions.
Question 33
During which phase does the spindle apparatus disappear?
A) Prophase
B) Anaphase
C) Telophase
D) Metaphase
Answer: C) Telophase
Explanation: The spindle apparatus disassembles during telophase as the cell prepares to complete division.
Question 34
What is the role of the kinetochore?
A) To organize chromosomes
B) To bind to spindle fibers
C) To assist in DNA replication
D) To synthesize RNA
Answer: B) To bind to spindle fibers
Explanation: The kinetochore is a protein structure on the centromere that attaches to spindle fibers to facilitate chromosome movement.
Question 35
What do you call the physical division of the cytoplasm during cell division?
A) Mitosis
B) Cytokinesis
C) Interphase
D) Chromatid separation
Answer: B) Cytokinesis
Explanation: Cytokinesis is the process of dividing the cytoplasm to form two distinct daughter cells after mitosis.
Question 36
Which phase is characterized by the reorganization of the nucleus and the reformation of the nuclear envelope?
A) Prophase
B) Metaphase
C) Anaphase
D) Telophase
Answer: D) Telophase
Explanation: During telophase, the nuclear envelope re-forms around the separated sets of chromosomes, completing the process of mitosis.
Question 37
What is the significance of apoptosis in the cell cycle?
A) It promotes cell division.
B) It prevents the proliferation of damaged cells.
C) It enhances DNA replication.
D) It is irrelevant to the cell cycle.
Answer: B) It prevents the proliferation of damaged cells.
Explanation: Apoptosis, or programmed cell death, eliminates damaged or unnecessary cells, maintaining healthy tissue function.
Question 38
Which of the following best describes anaphase?
A) Chromosomes condense and become visible.
B) Sister chromatids are pulled apart to opposite poles.
C) Chromosomes align at the equator of the cell.
D) The nuclear envelope reforms.
Answer: B) Sister chromatids are pulled apart to opposite poles.
Explanation: Anaphase is characterized by the separation of sister chromatids and their movement toward opposite ends of the cell.
Question 39
Which enzyme is crucial for unwinding DNA during replication?
A) DNA polymerase
B) Helicase
C) Ligase
D) Primase
Answer: B) Helicase
Explanation: Helicase is the enzyme responsible for unwinding the DNA double helix, allowing replication to occur.
Question 40
What happens during the S phase of the cell cycle?
A) The cell grows in size.
B) DNA is replicated.
C) Organelles are duplicated.
D) Chromosomes condense.
Answer: B) DNA is replicated.
Explanation: The S phase is specifically dedicated to the replication of DNA, resulting in two complete sets of chromosomes.
Question 41
What is a key feature of meiosis II compared to meiosis I?
A) It involves crossing over.
B) It results in the separation of homologous chromosomes.
C) It results in the separation of sister chromatids.
D) It occurs only in diploid cells.
Answer: C) It results in the separation of sister chromatids.
Explanation: Meiosis II is similar to mitosis, where sister chromatids are separated, whereas meiosis I separates homologous chromosomes.
Question 42
Which phase is characterized by the alignment of chromosomes along the equatorial plane?
A) Prophase
B) Metaphase
C) Anaphase
D) Telophase
Answer: B) Metaphase
Explanation: During metaphase, chromosomes are aligned at the cell’s equatorial plane, preparing for separation.
Question 43
What happens during the G1 checkpoint?
A) DNA replication is checked for errors.
B) The cell assesses its size and nutrient availability.
C) Chromosomes condense.
D) The nuclear envelope breaks down.
Answer: B) The cell assesses its size and nutrient availability.
Explanation: The G1 checkpoint ensures the cell is adequately prepared for DNA synthesis, checking size and nutrient status.
Question 44
In which type of cells does binary fission occur?
A) Plant cells
B) Animal cells
C) Prokaryotic cells
D) Fungal cells
Answer: C) Prokaryotic cells
Explanation: Binary fission is the asexual reproduction process used by prokaryotic cells, such as bacteria, to divide.
Question 45
Which process increases genetic diversity in sexually reproducing organisms?
A) Mitosis
B) Cytokinesis
C) Meiosis
D) Binary fission
Answer: C) Meiosis
Explanation: Meiosis introduces genetic variation through processes like crossing over and independent assortment of chromosomes.
Question 46
What is the main function of the mitotic spindle?
A) To condense chromatin
B) To facilitate organelle replication
C) To segregate chromosomes during cell division
D) To synthesize DNA
Answer: C) To segregate chromosomes during cell division
Explanation: The mitotic spindle is crucial for the accurate segregation of chromosomes during mitosis and meiosis.
Question 47
Which of the following structures holds sister chromatids together?
A) Spindle fibers
B) Kinetochore
C) Centromere
D) Chromatin
Answer: C) Centromere
Explanation: The centromere is the region of the chromosome that holds sister chromatids together until they are separated during cell division.
Question 48
In what phase does the nuclear envelope disintegrate?
A) Prophase
B) Metaphase
C) Anaphase
D) Telophase
Answer: A) Prophase
Explanation: The nuclear envelope breaks down during prophase, allowing spindle fibers to access the chromosomes.
Question 49
What is the role of telomeres?
A) To assist in DNA replication
B) To protect the ends of chromosomes from degradation
C) To regulate the cell cycle
D) To bind to spindle fibers
Answer: B) To protect the ends of chromosomes from degradation
Explanation: Telomeres are repetitive nucleotide sequences at the ends of chromosomes that protect them from deterioration and prevent fusion with other chromosomes.
Question 50
Which of the following is a feature of cancer cells?
A) Controlled growth
B) Limited division
C) Anchorage dependence
D) Loss of contact inhibition
Answer: D) Loss of contact inhibition
Explanation: Cancer cells often lose contact inhibition, allowing them to grow uncontrollably and invade surrounding tissues.
Question 51
During which phase do homologous chromosomes separate?
A) Anaphase I
B) Anaphase II
C) Telophase I
D) Metaphase II
Answer: A) Anaphase I
Explanation: During Anaphase I of meiosis, homologous chromosomes are pulled apart to opposite poles of the cell.
Question 52
What is the primary role of RNA primers in DNA replication?
A) To synthesize DNA
B) To provide a starting point for DNA polymerase
C) To unwind the DNA double helix
D) To stabilize single-stranded DNA
Answer: B) To provide a starting point for DNA polymerase
Explanation: RNA primers are short strands that provide a starting point for DNA polymerase to begin DNA synthesis.
Question 53
Which phase of the cell cycle is the longest?
A) G1 Phase
B) S Phase
C) G2 Phase
D) M Phase
Answer: A) G1 Phase
Explanation: The G1 phase is often the longest phase, during which the cell grows and carries out normal functions.
Question 54
In which phase of the cell cycle does the cell ensure that DNA replication has occurred without errors?
A) G1 Phase
B) S Phase
C) G2 Phase
D) M Phase
Answer: C) G2 Phase
Explanation: The G2 phase includes checkpoints that assess whether DNA has been accurately replicated before the cell enters mitosis.
Question 55
What are the end products of meiosis I?
A) Two diploid cells
B) Four haploid cells
C) Two haploid cells
D) One diploid cell
Answer: C) Two haploid cells
Explanation: Meiosis I results in two haploid cells, each containing one set of chromosomes, as homologous chromosomes are separated.
Question 56
What happens to the DNA during the S phase of the cell cycle?
A) It is transcribed into RNA.
B) It is replicated.
C) It is repaired.
D) It is condensed.
Answer: B) It is replicated.
Explanation: During the S phase, the entire DNA content of the cell is duplicated in preparation for cell division.
Question 57
How does the cell cycle ensure proper chromosome segregation?
A) By increasing the number of centrioles
B) By using checkpoints to detect errors
C) By promoting uncontrolled cell division
D) By eliminating all checkpoints
Answer: B) By using checkpoints to detect errors
Explanation: The cell cycle employs checkpoints to monitor for errors, ensuring proper chromosome segregation during cell division.
Question 58
What occurs during cytokinesis in animal cells?
A) A cell plate forms.
B) Chromatin condenses into chromosomes.
C) A cleavage furrow forms and the cell pinches apart.
D) Homologous chromosomes are separated.
Answer: C) A cleavage furrow forms and the cell pinches apart.
Explanation: In animal cells, cytokinesis involves the formation of a cleavage furrow that pinches the cell membrane to separate the daughter cells.
Question 59
Which of the following statements about cancer is true?
A) Cancer cells have normal cell cycle regulation.
B) Cancer cells typically have a higher number of chromosomes.
C) Cancer cells do not undergo apoptosis.
D) Cancer cells are all identical.
Answer: C) Cancer cells do not undergo apoptosis.
Explanation: Cancer cells often evade apoptosis, allowing them to survive and proliferate despite being damaged or dysfunctional.
Question 60
In meiosis, what is the term for the exchange of genetic material between homologous chromosomes?
A) Independent assortment
B) Crossing over
C) Segregation
D) Recombination
Answer: B) Crossing over
Explanation: Crossing over is the process where homologous chromosomes exchange genetic material, increasing genetic diversity in gametes.
Question 61
What is the result of a failure in the spindle checkpoint during mitosis?
A) Accurate chromosome segregation
B) Formation of identical daughter cells
C) Aneuploidy or unequal distribution of chromosomes
D) Apoptosis
Answer: C) Aneuploidy or unequal distribution of chromosomes
Explanation: A failure in the spindle checkpoint can lead to errors in chromosome separation, resulting in daughter cells with an abnormal number of chromosomes.
Question 62
What happens during anaphase II of meiosis?
A) Sister chromatids are pulled apart.
B) Homologous chromosomes separate.
C) Chromosomes align at the equatorial plane.
D) The nuclear envelope forms.
Answer: A) Sister chromatids are pulled apart.
Explanation: Anaphase II is characterized by the separation of sister chromatids and their movement to opposite poles of the cell.
Question 63
Which phase of the cell cycle is involved in the repair of DNA damage?
A) G1 Phase
B) S Phase
C) G2 Phase
D) M Phase
Answer: C) G2 Phase
Explanation: The G2 phase includes mechanisms for repairing any DNA damage that may have occurred during replication before the cell proceeds to mitosis.
Question 64
What is the purpose of the cell plate formation in plant cells?
A) To initiate cytokinesis
B) To condense chromosomes
C) To replicate DNA
D) To create spindle fibers
Answer: A) To initiate cytokinesis
Explanation: The cell plate forms during cytokinesis in plant cells and eventually develops into a new cell wall that separates the daughter cells.
Question 65
What is the role of DNA polymerase in DNA replication?
A) To unwind the DNA double helix
B) To synthesize new DNA strands
C) To ligate Okazaki fragments
D) To create RNA primers
Answer: B) To synthesize new DNA strands
Explanation: DNA polymerase synthesizes new strands of DNA by adding nucleotides complementary to the template strand during replication.
Question 66
What type of cell division occurs in somatic cells?
A) Meiosis
B) Mitosis
C) Budding
D) Binary fission
Answer: B) Mitosis
Explanation: Somatic cells undergo mitosis for growth and repair, producing two identical daughter cells.
Question 67
In which phase do the chromosomes decondense back into chromatin?
A) Prophase
B) Metaphase
C) Anaphase
D) Telophase
Answer: D) Telophase
Explanation: During telophase, chromosomes decondense into chromatin as the cell prepares to complete division.
Question 68
Which type of cell is produced by meiosis?
A) Somatic cell
B) Gamete
C) Stem cell
D) Prokaryotic cell
Answer: B) Gamete
Explanation: Meiosis produces gametes (sperm and egg cells), which are essential for sexual reproduction.
Question 69
How many chromosomes does a human gamete have?
A) 23
B) 46
C) 92
D) 48
Answer: A) 23
Explanation: Human gametes are haploid and contain 23 chromosomes, half the diploid number of 46 found in somatic cells.
Question 70
What is the primary checkpoint of the cell cycle that ensures DNA is intact before replication?
A) G1 checkpoint
B) S checkpoint
C) G2 checkpoint
D) M checkpoint
Answer: A) G1 checkpoint
Explanation: The G1 checkpoint assesses DNA integrity and cell conditions before the cell commits to DNA synthesis.
Question 71
What is the outcome of a single mitotic division?
A) Two diploid cells
B) Four haploid cells
C) One diploid cell
D) Two haploid cells
Answer: A) Two diploid cells
Explanation: A single mitotic division produces two genetically identical diploid daughter cells.
Question 72
What occurs during prophase I of meiosis that does not occur in mitosis?
A) Chromosome condensation
B) Nuclear envelope breakdown
C) Crossing over
D) Spindle formation
Answer: C) Crossing over
Explanation: Crossing over occurs during prophase I of meiosis, allowing genetic material exchange between homologous chromosomes, a feature not present in mitosis.
Question 73
What is the role of the checkpoints in the cell cycle?
A) To accelerate cell division
B) To ensure that each phase is completed accurately
C) To replicate DNA
D) To assist in chromatin condensation
Answer: B) To ensure that each phase is completed accurately
Explanation: Checkpoints monitor the cell cycle progression and ensure each phase is completed correctly before moving to the next.
Question 74
Which of the following phases is part of interphase?
A) M Phase
B) Cytokinesis
C) G2 Phase
D) Anaphase
Answer: C) G2 Phase
Explanation: Interphase includes the G1, S, and G2 phases, during which the cell grows and prepares for division.
Question 75
What is a characteristic of prokaryotic cell division?
A) It occurs through mitosis.
B) It involves meiosis.
C) It occurs by binary fission.
D) It requires a spindle apparatus.
Answer: C) It occurs by binary fission.
Explanation: Prokaryotic cells divide through binary fission, a simple and rapid process without mitosis or meiosis.
Question 76
What is the significance of checkpoints in the cell cycle?
A) They allow rapid cell division.
B) They ensure cells do not divide with damaged DNA.
C) They promote tumor formation.
D) They initiate apoptosis only.
Answer: B) They ensure cells do not divide with damaged DNA.
Explanation: Checkpoints play a critical role in preventing the division of cells with damaged or incomplete DNA, thus maintaining genomic integrity.
Question 77
What happens to a cell if it fails the G1 checkpoint?
A) It proceeds to S phase.
B) It enters the G0 phase.
C) It undergoes apoptosis.
D) It immediately divides.
Answer: B) It enters the G0 phase.
Explanation: If a cell does not meet the requirements at the G1 checkpoint, it may enter the G0 phase, a state of dormancy where it does not divide.
Question 78
Which of the following occurs during metaphase II?
A) Homologous chromosomes separate.
B) Chromosomes line up at the equator.
C) Sister chromatids are pulled apart.
D) The nuclear envelope re-forms.
Answer: B) Chromosomes line up at the equator.
Explanation: During metaphase II, individual chromosomes line up along the cell’s equatorial plane in preparation for separation.
Question 79
Which protein complex is essential for the formation of the mitotic spindle?
A) Kinetochore
B) Centromere
C) Centrioles
D) Chromatin
Answer: C) Centrioles
Explanation: Centrioles are essential for the formation of the mitotic spindle, which is responsible for chromosome movement during cell division.
Question 80
What is the role of ligase during DNA replication?
A) To synthesize RNA primers
B) To unwind the DNA double helix
C) To seal gaps between Okazaki fragments
D) To synthesize new DNA strands
Answer: C) To seal gaps between Okazaki fragments
Explanation: Ligase is responsible for sealing the nicks between Okazaki fragments on the lagging strand during DNA replication.
Question 81
What is the result of cytokinesis in plant cells?
A) Two identical daughter cells
B) A cleavage furrow forms
C) A cell plate forms, creating two separate cells
D) Chromosomes condense
Answer: C) A cell plate forms, creating two separate cells
Explanation: In plant cells, cytokinesis results in the formation of a cell plate that develops into a new cell wall, dividing the two daughter cells.
Question 82
Which phase of mitosis is characterized by the alignment of chromosomes along the metaphase plate?
A) Anaphase
B) Prophase
C) Telophase
D) Metaphase
Answer: D) Metaphase
Explanation: During metaphase, chromosomes are aligned at the metaphase plate, preparing for separation during anaphase.
Question 83
What occurs during prophase II of meiosis?
A) Chromosomes condense, and the nuclear envelope breaks down.
B) Homologous chromosomes separate.
C) Sister chromatids align at the equatorial plane.
D) The nuclear envelope re-forms.
Answer: A) Chromosomes condense, and the nuclear envelope breaks down.
Explanation: During prophase II, chromosomes condense again, and the nuclear envelope disintegrates in preparation for the second meiotic division.
Question 84
What is the function of the G2 checkpoint?
A) To ensure DNA is replicated properly.
B) To monitor cell size.
C) To check for spindle fiber attachment.
D) To initiate apoptosis.
Answer: A) To ensure DNA is replicated properly.
Explanation: The G2 checkpoint verifies that DNA replication is complete and that there are no damages before the cell enters mitosis.
Question 85
In what type of cells does meiosis occur?
A) Somatic cells
B) Prokaryotic cells
C) Germ cells
D) Stem cells
Answer: C) Germ cells
Explanation: Meiosis occurs in germ cells, which give rise to gametes for sexual reproduction.
Question 86
What is the significance of the cleavage furrow in animal cells during cytokinesis?
A) It initiates DNA replication.
B) It allows for the synthesis of RNA.
C) It helps in the physical separation of the two daughter cells.
D) It promotes the formation of the mitotic spindle.
Answer: C) It helps in the physical separation of the two daughter cells.
Explanation: The cleavage furrow is the indentation that forms in the cell membrane, facilitating the physical separation of the daughter cells during cytokinesis.
Question 87
Which of the following is true about tumor suppressor genes?
A) They promote cell division.
B) They are always active.
C) They inhibit uncontrolled cell growth.
D) They only function in cancer cells.
Answer: C) They inhibit uncontrolled cell growth.
Explanation: Tumor suppressor genes regulate cell division and can prevent the formation of tumors by inhibiting uncontrolled growth.
Question 88
What structure forms at the centromere during cell division?
A) Kinetochore
B) Spindle apparatus
C) Chromatin
D) Cell plate
Answer: A) Kinetochore
Explanation: The kinetochore forms at the centromere and is crucial for the attachment of spindle fibers during cell division.
Question 89
What process occurs during telophase?
A) Chromosomes are pulled apart.
B) Chromosomes decondense, and the nuclear envelope re-forms.
C) Chromosomes line up at the metaphase plate.
D) DNA is replicated.
Answer: B) Chromosomes decondense, and the nuclear envelope re-forms.
Explanation: During telophase, chromosomes decondense back into chromatin, and the nuclear envelope re-forms around each set of chromosomes.
Question 90
How is genetic variation introduced during meiosis?
A) DNA replication
B) Chromosomal condensation
C) Crossing over and independent assortment
D) Mitosis
Answer: C) Crossing over and independent assortment
Explanation: Genetic variation in meiosis is introduced through crossing over during prophase I and the independent assortment of chromosomes during metaphase I.
Question 91
What is a primary characteristic of cancer cells?
A) Controlled growth
B) Normal apoptosis
C) High levels of differentiation
D) Ability to invade surrounding tissues
Answer: D) Ability to invade surrounding tissues
Explanation: Cancer cells are characterized by their ability to invade surrounding tissues and spread to other parts of the body, unlike normal cells that stay localized.
Question 92
What happens during S phase?
A) Cells grow and perform normal functions.
B) DNA is replicated.
C) Cells prepare for division.
D) Chromosomes condense.
Answer: B) DNA is replicated.
Explanation: The S phase is specifically for DNA replication, ensuring that each daughter cell will have a complete set of chromosomes after cell division.
Question 93
In which phase do chromatids separate and move towards opposite poles?
A) Telophase
B) Anaphase
C) Prophase
D) Metaphase
Answer: B) Anaphase
Explanation: During anaphase, sister chromatids are pulled apart and move toward opposite ends of the cell.
Question 94
What is the role of the spindle fibers?
A) To replicate DNA
B) To condense chromosomes
C) To pull chromosomes apart during cell division
D) To form the nuclear envelope
Answer: C) To pull chromosomes apart during cell division
Explanation: Spindle fibers are crucial for the separation of chromosomes during mitosis and meiosis, ensuring accurate distribution to daughter cells.
Question 95
What is the primary function of the G1 checkpoint?
A) To check for DNA damage
B) To assess cell size and nutrient availability
C) To ensure that DNA has been replicated
D) To monitor spindle fiber attachment
Answer: B) To assess cell size and nutrient availability
Explanation: The G1 checkpoint evaluates whether the cell is ready to enter the S phase by checking its size and available resources.
Question 96
Which of the following describes the process of meiosis?
A) A single division producing identical cells
B) A two-step division reducing chromosome number by half
C) A process that occurs only in prokaryotes
D) A process that produces diploid cells
Answer: B) A two-step division reducing chromosome number by half
Explanation: Meiosis consists of two rounds of division that reduce the chromosome number from diploid to haploid, producing gametes.
Question 97
What event occurs during metaphase I of meiosis?
A) Chromosomes align in pairs along the metaphase plate.
B) Sister chromatids are separated.
C) The nuclear envelope re-forms.
D) Crossing over occurs.
Answer: A) Chromosomes align in pairs along the metaphase plate.
Explanation: During metaphase I, homologous chromosome pairs align at the metaphase plate in preparation for separation.
Question 98
What is the consequence of uncontrolled cell division?
A) Normal tissue function
B) Cancer formation
C) Proper organ development
D) Cell senescence
Answer: B) Cancer formation
Explanation: Uncontrolled cell division can lead to cancer, where cells grow and proliferate inappropriately, forming tumors.
Question 99
How do mutations in proto-oncogenes affect cell behavior?
A) They reduce cell division.
B) They have no effect on cell behavior.
C) They promote uncontrolled cell growth.
D) They induce apoptosis.
Answer: C) They promote uncontrolled cell growth.
Explanation: Mutations in proto-oncogenes can convert them into oncogenes, leading to uncontrolled cell proliferation and potential cancer.
Question 100
What occurs during telophase II of meiosis?
A) Homologous chromosomes separate.
B) Sister chromatids are pulled apart.
C) Nuclear envelopes re-form around four haploid cells.
D) Chromosomes condense into chromatin.
Answer: C) Nuclear envelopes re-form around four haploid cells.
Explanation: During telophase II, the nuclear envelopes reform around the four haploid daughter cells that result from meiosis.
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