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.
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