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.
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