#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 of the following is a characteristic of haploid cells?
They are produced by meiosis
ExplanationHaploid cells result from meiosis, containing half the chromosome number of the parent cell.
#7
What is the function of the protein complex APC/C in the cell cycle?
To degrade cyclins
ExplanationAPC/C marks specific proteins, including cyclins, for degradation during cell cycle progression.
#8
Which phase of the cell cycle follows mitosis?
Interphase
ExplanationInterphase is the phase between cell divisions, following mitosis.
#9
What is the role of the protein p53 in the cell cycle?
To arrest the cell cycle in response to DNA damage
Explanationp53 halts the cell cycle to repair DNA damage or induce apoptosis if the damage is irreparable.
#10
Which phase of the cell cycle is characterized by cell growth and preparation for DNA replication?
G1 phase
ExplanationG1 phase involves cellular growth and preparation for DNA synthesis.
#11
Which checkpoint ensures that the DNA is undamaged before entering mitosis?
G2 checkpoint
ExplanationThis checkpoint verifies DNA integrity before the cell proceeds to mitosis.
#12
What is the significance of meiosis in sexual reproduction?
To increase genetic variation
ExplanationMeiosis leads to the generation of genetically diverse gametes.
#13
What happens during interphase of the cell cycle?
DNA replication occurs
ExplanationInterphase is a period of cell growth and DNA replication.
#14
Which of the following is a characteristic of cancer cells?
Uncontrolled cell division
ExplanationCancer cells divide uncontrollably, leading to tumor formation.
#15
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.
#16
What is the primary function of the G2 checkpoint?
To check for DNA damage
ExplanationThe G2 checkpoint verifies DNA integrity before entering mitosis.
#17
During which phase of meiosis do homologous chromosomes separate?
Anaphase I
ExplanationHomologous chromosomes separate during Anaphase I of meiosis.
#18
What is the role of the enzyme telomerase in cell division?
To lengthen telomeres
ExplanationTelomerase maintains telomere length, preventing cellular senescence and promoting cell division.
#19
What is the outcome of meiosis II?
Formation of haploid daughter cells
ExplanationMeiosis II results in the formation of haploid daughter cells from haploid intermediates.
#20
What is the function of checkpoints in the cell cycle?
To ensure accurate progression through the cell cycle
ExplanationCheckpoints monitor key events and ensure proper progression through the cell cycle.
#21
During which phase of mitosis do chromosomes align at the metaphase plate?
Metaphase
ExplanationChromosomes line up along the metaphase plate during this phase.
#22
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.
#23
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.
#24
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.
#25
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.