#1
Which phase of the cell cycle is characterized by DNA replication?
S phase
ExplanationDNA replication occurs during this phase.
#2
What is the correct sequence of stages in the cell cycle?
G1 phase -> S phase -> G2 phase -> M phase
ExplanationThe cell cycle progresses through these stages: growth (G1), DNA replication (S), further growth and preparation (G2), and mitosis (M).
#3
What is the purpose of cytokinesis in the cell cycle?
To divide the cytoplasm and separate the daughter cells
ExplanationCytokinesis divides the cytoplasm, resulting in two daughter cells.
#4
Which enzyme is responsible for unwinding DNA during replication?
Helicase
ExplanationHelicase unwinds the DNA double helix.
#5
What is the purpose of the G1 checkpoint in the cell cycle?
To check for DNA damage
ExplanationThe G1 checkpoint assesses DNA integrity before committing to cell division.
#6
Which checkpoint ensures that the DNA is undamaged before entering mitosis?
G2 checkpoint
ExplanationThis checkpoint verifies DNA integrity before the cell proceeds to mitosis.
#7
What is the significance of meiosis in sexual reproduction?
To increase genetic variation
ExplanationMeiosis leads to the generation of genetically diverse gametes.
#8
What happens during interphase of the cell cycle?
DNA replication occurs
ExplanationInterphase is a period of cell growth and DNA replication.
#9
Which of the following is a characteristic of cancer cells?
Uncontrolled cell division
ExplanationCancer cells divide uncontrollably, leading to tumor formation.
#10
What is the role of cyclin-dependent kinases (CDKs) in cell cycle regulation?
To phosphorylate target proteins
ExplanationCDKs regulate cell cycle progression by phosphorylating specific proteins.
#11
During which phase of mitosis do chromosomes align at the metaphase plate?
Metaphase
ExplanationChromosomes line up along the metaphase plate during this phase.
#12
What is the role of spindle fibers during mitosis?
To separate sister chromatids and move them to opposite poles
ExplanationSpindle fibers ensure proper chromosome segregation during mitosis.
#13
What is the consequence of a mutation in a tumor suppressor gene?
Increased cell proliferation
ExplanationLoss of tumor suppressor function leads to uncontrolled cell division.
#14
What is the significance of crossing over during meiosis?
It leads to genetic diversity
ExplanationCrossing over exchanges genetic material between homologous chromosomes, increasing genetic variation.
#15
Which phase of mitosis is characterized by the physical separation of sister chromatids?
Anaphase
ExplanationAnaphase involves the separation of sister chromatids, moving towards opposite poles of the cell.