Consider the following statements regarding the quantitative changes in chromosome number and DNA content during the cell cycle of a diploid human somatic cell (2n = 46):
(I) During the G1 phase, the cell contains 46 chromosomes and a DNA content of 2C. (II) At the completion of the S phase, the cell contains 92 chromosomes and a DNA content of 4C. (III) During the G2 phase, the cell contains 46 chromosomes and a DNA content of 4C. (IV) At the completion of Telophase and Cytokinesis, each daughter cell receives 46 chromosomes and a DNA content of 2C.
Which of the above statements are correct?
Statement (I) is correct because a normal human somatic cell in G1 has 46 chromosomes and 2C DNA content. Statement (II) is incorrect because DNA content doubles during S phase but chromosome number remains 46. Statement (III) is correct because G2 cells possess 46 chromosomes with 4C DNA content. Statement (IV) is correct because mitosis restores each daughter cell to 46 chromosomes with 2C DNA content.
Question 92 of 100
📘 CLASS XI
Consider the following statements regarding Centrosomes and Spindle Assembly in Mitosis:
(I) Centrosome duplication takes place in the cytoplasm during the S phase of interphase. (II) Microtubules radiating outward from each centrosome during prophase are termed asters. (III) Asters are formed during mitotic spindle assembly in higher plant cells. (IV) The two asters together with spindle fibres form the mitotic apparatus.
Which of the above statements are correct?
Statement (I) is correct because centrosome duplication occurs during the S phase. Statement (II) is correct because asters are microtubule arrays radiating from centrosomes. Statement (III) is incorrect because higher plant cells lack centrosomes and asters. Statement (IV) is correct because two asters together with spindle fibres constitute the mitotic apparatus.
Question 93 of 100
📘 CLASS XI
Consider the following statements regarding the substages of Meiotic Prophase I:
(I) Synapsis is the pairing of homologous chromosomes occurring during Zygotene. (II) The synaptonemal complex forms during Zygotene and dissolves at the beginning of Diplotene. (III) Crossing over is the exchange of genetic material between non-sister chromatids of homologous chromosomes during Pachytene. (IV) Chiasmata are X-shaped structures representing crossover sites, which undergo terminalisation during Diakinesis.
Which of the above statements are correct?
All four statements are correct. Synapsis occurs during zygotene, the synaptonemal complex dissolves during diplotene, crossing over occurs between non-sister chromatids during pachytene, and chiasmata undergo terminalisation during diakinesis.
Question 94 of 100
📘 CLASS XI
Consider the following comparative statements regarding Anaphase events in Mitosis, Meiosis I, and Meiosis II:
(I) During mitotic Anaphase, centromeres split simultaneously and sister chromatids separate to opposite poles. (II) During Anaphase I of Meiosis, centromeres split simultaneously to separate sister chromatids. (III) During Anaphase I of Meiosis, homologous chromosomes separate while sister chromatids remain attached at centromeres. (IV) During Anaphase II of Meiosis, centromeres split simultaneously, allowing sister chromatids to move to opposite poles.
Which of the above statements are correct?
Statement (I) is correct because mitotic anaphase involves centromere splitting and separation of sister chromatids. Statement (II) is incorrect because centromeres do not split during Anaphase I. Statement (III) is correct because homologous chromosomes separate while sister chromatids remain attached. Statement (IV) is correct because centromeres split during Anaphase II.
Question 95 of 100
📘 CLASS XI
Consider the following statements regarding Mitotic and Meiotic Divisions across organisms:
(I) In animals, mitotic division is restricted mainly to diploid somatic cells, with male honey bees being a haploid exception. (II) In plants, mitotic divisions occur in both haploid and diploid cells, giving rise to alternation of generations. (III) Meiosis occurs in specialized diploid cells destined to form haploid gametes. (IV) Meiosis can take place directly in haploid cells to double their chromosome count.
Which of the above statements are correct?
Statement (I) is correct because mitosis generally occurs in diploid somatic cells, with haploid male honey bees as an exception. Statement (II) is correct because plants undergo mitosis in both haploid and diploid generations. Statement (III) is correct because meiosis occurs in specialized diploid cells to produce haploid gametes. Statement (IV) is incorrect because meiosis is a reductional division and does not occur in haploid cells.
Question 96 of 100
📘 CLASS XI
Consider the following statements regarding Cytokinesis and Middle Lamella Formation in Plant Cells:
(I) Plant cells undergo cytokinesis by forming a cell-plate that originates at the cell centre. (II) The cell-plate grows centrifugally outward to meet existing lateral walls. (III) The cell-plate represents the middle lamella between adjacent plant cell walls. (IV) Organelles such as mitochondria and plastids get distributed between daughter cells during cytokinesis.
Which of the above statements are correct?
All four statements are correct. Plant cytokinesis begins with formation of a centrally located cell plate that grows centrifugally to fuse with the lateral walls. The cell plate develops into the middle lamella, and cytokinesis distributes cytoplasmic organelles such as mitochondria and plastids between the daughter cells.
Question 97 of 100
📘 CLASS XI
Consider the following statements regarding the Disappearance and Reformation of Cellular Organelles during M Phase:
(I) Nucleolus, Golgi complex, and ER disappear by the end of Prophase. (II) The complete breakdown of the nuclear envelope defines the commencement of Metaphase. (III) Nuclear envelope, nucleolus, Golgi complex, and ER reform during Telophase. (IV) Chromosomes remain fully condensed throughout Telophase without losing their individual identity.
Which of the above statements are correct?
Statement (I) is correct because the nucleolus, Golgi complex, ER, and nuclear envelope disappear by late prophase. Statement (II) is correct because complete nuclear envelope breakdown marks the beginning of metaphase. Statement (III) is correct because these organelles reform during telophase. Statement (IV) is incorrect because chromosomes decondense and lose their distinct identity during telophase.
Question 98 of 100
📘 CLASS XI
Consider the following statements matching the substages of Meiotic Prophase I with their characteristic features:
(I) Leptotene is characterized by continuous compaction of chromosomes, making them visible under light microscopy. (II) Zygotene is characterized by synapsis (homologous chromosome pairing) and synaptonemal complex assembly. (III) Diplotene is recognized by the dissolution of synaptonemal complexes and appearance of X-shaped chiasmata. (IV) Diakinesis is marked by terminalisation of chiasmata, nucleolar disappearance, and transition to metaphase I.
Which of the above statements are correct?
All four statements are correct. Leptotene involves chromosome compaction, zygotene is marked by synapsis and synaptonemal complex formation, diplotene features dissolution of the synaptonemal complex with visible chiasmata, and diakinesis is characterized by terminalisation of chiasmata and transition to metaphase I.
Question 99 of 100
📘 CLASS XI
Consider the following statements regarding the Biological Significance of Mitosis:
(I) Mitosis yields diploid daughter cells with identical genetic complements. (II) Mitotic cell division restores the nucleo-cytoplasmic ratio disturbed by cell growth. (III) Constantly replaced cells of the skin epidermis, gut lining, and blood cells depend on continuous mitotic division. (IV) Mitotic divisions in apical and lateral cambium meristems result in continuous lifelong plant growth.
Which of the above statements are correct?
All four statements are correct. Mitosis preserves chromosome number and genetic identity, restores the nucleo-cytoplasmic ratio, replaces worn-out cells in tissues such as skin, gut lining, and blood, and enables continuous plant growth through apical and lateral meristems.
Question 100 of 100
📘 CLASS XI
Consider the following statements regarding the Significance and Key Features of Meiosis:
(I) Meiosis conserves the specific chromosome number of a species across generations in sexually reproducing organisms. (II) Meiosis increases genetic variability in populations from one generation to the next via crossing over and independent assortment. (III) Meiosis involves two sequential cycles of nuclear division accompanied by two cycles of DNA replication. (IV) Meiosis concludes with Telophase II and cytokinesis to yield a tetrad of four haploid daughter cells.
Which of the above statements are correct?
Statement (I) is correct because meiosis halves the chromosome number so fertilization restores the species-specific chromosome number. Statement (II) is correct because crossing over and independent assortment generate genetic variation. Statement (III) is incorrect because meiosis involves only one round of DNA replication before two successive nuclear divisions. Statement (IV) is correct because meiosis ends with Telophase II and cytokinesis, producing four haploid daughter cells.
