CELL CYCLE Flashcards
What is the approximate duration of the cell cycle in human cells?
a) 24 minutes
b) 24 hours
c) 90 minutes
d) 12 hours
b) 24 hours
How long does it take for yeast to progress through the cell cycle?
a) 90 minutes
b) 24 hours
c) 12 hours
d) 30 minutes
a) 90 minutes
Which of the following phases represents the actual cell division?
a) G1 phase
b) Interphase
c) M Phase (Mitosis)
d) G2 phase
M Phase (Mitosis)
What is the phase between two successive M phases called?
a) G1 phase
b) G0 phase
c) S phase
d) Interphase
d) Interphase
During a 24-hour human cell cycle, how long does the actual cell division last?
a) 24 hours
b) 1 hour
c) 12 hours
d) 90 minutes
b) 1 hour
What happens during the G1 phase of interphase?
a) DNA replication occurs
b) The cell prepares for mitosis
c) The cell grows and remains metabolically active
d) Chromosomes separate
c) The cell grows and remains metabolically active
During the S phase, what happens to the amount of DNA in the cell?
a) It doubles
b) It remains the same
c) It halves
d) It triples
a) It doubles
What is the quiescent stage (G0) of the cell cycle?
a) A phase where DNA replication occurs
b) A phase where cells stop dividing and become metabolically inactive
c) A phase where cells exit G1 and become metabolically active but stop proliferating
d) A phase where cells continue dividing rapidly
c) A phase where cells exit G1 and become metabolically active but stop proliferating
In animals, where is mitotic cell division usually seen?
a) Haploid cells
b) Diploid somatic cells
c) Germ cells
d) All types of cells
b) Diploid somatic cells
Which cells in plants can undergo mitosis?
a) Only diploid cells
b) Only haploid cells
c) Both haploid and diploid cells
d) None of the above
c) Both haploid and diploid cells
Why is mitosis called equational division?
a) Because the number of chromosomes in parent and progeny cells is halved
b) Because the number of chromosomes in parent and progeny cells remains the same
c) Because it only occurs in haploid cells
d) Because the DNA content is doubled
b) Because the number of chromosomes in parent and progeny cells remains the same
Which of the following is not one of the four stages of karyokinesis?
a) Prophase
b) Interphase
c) Metaphase
d) Telophase
b) Interphase
What is the first stage of karyokinesis?
a) Anaphase
b) Telophase
c) Prophase
d) Metaphase
c) Prophase
What is a key event that occurs during prophase?
a) Chromosomes align at the equator
b) Chromosomal material condenses to form compact mitotic chromosomes
c) Cytokinesis occurs
d) Nuclear envelope reforms
b) Chromosomal material condenses to form compact mitotic chromosomes
During prophase, which structures begin moving toward opposite poles of the cell?
a) Chromatids
b) Kinetochores
c) Centrosomes
d) Golgi complexes
c) Centrosomes
In which phase does the nuclear envelope completely disintegrate?
a) Prophase
b) Anaphase
c) Metaphase
d) Telophase
c) Metaphase
What structures attach to the kinetochores during metaphase?
a) Chromosomes
b) Centrioles
c) Spindle fibres
d) Asters
c) Spindle fibres
What is the name of the plane where chromosomes align during metaphase?
a) Kinetochore plate
b) Spindle plate
c) Metaphase plate
d) Equatorial plate
c) Metaphase plate
What key feature defines the metaphase stage of mitosis?
a) Chromosomes begin to condense
b) Chromosomes align at the spindle equator
c) Cytoplasmic division begins
d) Chromosomes move toward opposite poles
b) Chromosomes align at the spindle equator
What marks the end of prophase when observed under a microscope?
a) Disappearance of the Golgi complex, endoplasmic reticulum, nucleolus, and nuclear envelope
b) Chromosomes condense into chromatin
c) Formation of the nuclear envelope
d) Spindle fibres attach to kinetochores
Disappearance of the Golgi complex, endoplasmic reticulum, nucleolus, and nuclear envelope
Which event characterizes the onset of anaphase?
a) Chromosomes align at the equatorial plate
b) Centromeres split, and chromatids move to opposite poles
c) Nuclear envelope reappears
d) Chromosomes condense into visible structures
b) Centromeres split, and chromatids move to opposite poles
What direction do centromeres move during anaphase?
a) Away from the poles
b) Toward the poles, leading the chromosome movement
c) Toward the equatorial plate
d) Randomly within the cell
b) Toward the poles, leading the chromosome movement
Which event marks the beginning of telophase?
a) Chromosomes align at the metaphase plate
b) Chromosomes decondense and lose their individuality
c) Centromeres split and chromatids separate
d) Cytoplasmic division occurs
b) Chromosomes decondense and lose their individuality
What key event occurs during telophase?
a) Chromosomes cluster at opposite spindle poles
b) Nuclear envelope disintegrates
c) Chromosomes align at the equator
d) Spindle fibres attach to kinetochores
a) Chromosomes cluster at opposite spindle poles
What structures reform during telophase?
a) Spindle fibres and kinetochores
b) Chromatids and centromeres
c) Nucleolus, Golgi complex, and endoplasmic reticulum
d) Chromosomes and centrioles
c) Nucleolus, Golgi complex, and endoplasmic reticulum
What is cytokinesis?
a) The division of the nucleus
b) The separation of chromatids into daughter chromosomes
c) The division of cytoplasm into two daughter cells
d) The condensation of chromatin material
c) The division of cytoplasm into two daughter cell
How does cytokinesis occur in animal cells?
a) By the formation of a cell plate
b) By the appearance of a cleavage furrow
c) By fragmentation of the plasma membrane
d) Through spindle fibre attachment
b) By the appearance of a cleavage furrow
In plant cells, cytokinesis is achieved by:
a) The appearance of a cleavage furrow
b) The formation of a cell plate starting at the center
c) Splitting of the nuclear envelope
d) Merging of spindle fibres at the poles
b) The formation of a cell plate starting at the center
What is the result of karyokinesis without cytokinesis?
a) The formation of a single nucleus
b) The formation of two identical daughter cells
c) A multinucleate condition called syncytium
d) A decrease in cell size
c) A multinucleate condition called syncytium
What structure acts as the middle lamella between two daughter cells in plant cytokinesis?
a) Centromere
b) Aster
c) Cell plate
d) Spindle fibre
c) Cell plate
In which types of cells does mitosis usually occur?
a) Only in haploid cells
b) Only in diploid cells
c) In both haploid and diploid cells
d) Only in prokaryotic cells
b) Only in diploid cells
What is one significant contribution of mitosis in multicellular organisms?
a) Gamete formation
b) Reduction of chromosome number
c) Cell repair and growth
d) Genetic variation
c) Cell repair and growth
Why is mitosis essential for cells in tissues like the epidermis and the gut lining?
a) To reduce the size of the cells
b) To constantly replace cells that are lost or damaged
c) To generate genetic diversity
d) To increase the number of chromosomes
b) To constantly replace cells that are lost or damaged
What role does mitosis play in the growth of plants?
a) It helps in forming haploid gametes
b) It occurs only in mature tissues
c) It leads to continuous growth through divisions in meristematic tissues
d) It replaces non-dividing cells in leaves
c) It leads to continuous growth through divisions in meristematic tissues
Meiosis reduces the chromosome number by half. What is this process crucial for?
a) Asexual reproduction
b) Cell repair
c) Sexual reproduction
d) Growth of multicellular organisms
c) Sexual reproduction
How many haploid cells are formed at the end of meiosis?
a) One
b) Two
c) Four
d) Six
c) Four
Which phase of meiosis is characterized by the pairing of homologous chromosomes and recombination between non-sister chromatids?
a) Prophase I
b) Metaphase I
c) Anaphase II
d) Telophase II
a) Prophase I
Meiosis I is initiated after what event in the cell cycle?
a) DNA replication
b) Cytokinesis
c) Telophase I
d) Centromere splitting
a) DNA replication
What restores the diploid phase in the life cycle of sexually reproducing organisms after meiosis?
a) Mitosis
b) Fertilization
c) DNA replication
d) Crossing over
b) Fertilization
How many sequential cycles of nuclear and cell division occur during meiosis?
a) One
b) Two
c) Three
d) Four
b) Two
Which of the following stages of Prophase I involves the formation of a synaptonemal complex?
a) Leptotene
b) Zygotene
c) Pachytene
d) Diakinesis
b) Zygotene
During which stage of Prophase I does crossing over occur?
a) Leptotene
b) Zygotene
c) Pachytene
d) Diplotene
c) Pachytene
What is the enzyme responsible for mediating the crossing over of genetic material during Prophase I?
a) Helicase
b) Ligase
c) Recombinate
d) Recombinase
d) Recombinase
Which of the following terms refers to the X-shaped structures formed at the sites of crossing over in diplotene?
a) Centromere
b) Bivalent
c) Chiasmata
d) Kinetochore
c) Chiasmata
What happens during the diakinesis stage of Prophase I?
a) Chromosomes start pairing together
b) Crossing over is initiated
c) Terminalisation of chiasmata occurs
d) Recombination is completed
c) Terminalisation of chiasmata occurs
During which stage do homologous chromosomes align on the equatorial plate in Meiosis I?
a) Prophase I
b) Metaphase I
c) Anaphase I
d) Telophase I
b) Metaphase I
In which stage of Meiosis I do homologous chromosomes separate, while sister chromatids remain together?
a) Leptotene
b) Metaphase I
c) Anaphase I
d) Telophase I
c) Anaphase I
What follows the separation of homologous chromosomes during Telophase I in meiosis?
a) Formation of chiasmata
b) DNA replication
c) Reformation of nuclear membrane and cytokinesis
d) Separation of chromatids
c) Reformation of nuclear membrane and cytokinesis
What is the stage between Meiosis I and Meiosis II called, where no DNA replication occurs?
a) Diakinesis
b) Interkinesis
c) Anaphase I
d) G1 Phase
b) Interkinesis
How is Prophase II different from Prophase I?
a) It is more complex
b) It is simpler and shorter
c) It involves crossing over
d) It involves recombination
b) It is simpler and shorter
During which phase of Meiosis II do the sister chromatids separate and move to opposite poles?
a) Prophase II
b) Metaphase II
c) Anaphase II
d) Telophase II
c) Anaphase II
Which of the following events occurs in Prophase II of meiosis?
a) Synapsis of homologous chromosomes
b) Reformation of the nuclear membrane
c) Disappearance of the nuclear membrane
d) Crossing over
c) Disappearance of the nuclear membrane
In which phase of Meiosis II do the chromosomes align at the equator of the cell?
a) Prophase II
b) Metaphase II
c) Anaphase II
d) Telophase II
b) Metaphase II
Which phase of Meiosis II is characterized by the simultaneous splitting of the centromeres?
a) Prophase II
b) Metaphase II
c) Anaphase II
d) Telophase II
c) Anaphase II
At the end of Meiosis II, what is the outcome in terms of the number and type of cells produced?
a) Two diploid cells
b) Four haploid cells
c) Two haploid cells
d) Four diploid cells
b) Four haploid cells
In Telophase II of meiosis, what event occurs after the chromosomes reach opposite poles?
a) Recombination of genetic material
b) Chromosome condensation
c) Nuclear envelope formation
d) Crossing over
c) Nuclear envelope formation
What is the primary significance of meiosis in sexually reproducing organisms?
a) Increase in the chromosome number
b) Reduction in genetic variability
c) Conservation of chromosome number across generations
d) Increase in body size
c) Conservation of chromosome number across generation
Which of the following processes contributes to the genetic variability seen in populations?
a) Mitosis
b) Cytokinesis
c) Meiosis
d) Binary fission
c) Meiosis
How many nuclear and cell divisions occur during meiosis?
a) One nuclear and one cell division
b) Two nuclear and two cell divisions
c) One nuclear and two cell divisions
d) Two nuclear and one cell division
b) Two nuclear and two cell divisions
In Meiosis II, how does the process differ from Meiosis I?
a) Meiosis II involves crossing over
b) Meiosis II involves homologous chromosome pairing
c) Meiosis II resembles mitosis and separates sister chromatids
d) Meiosis II involves synapsis
c) Meiosis II resembles mitosis and separates sister chromatids
