Consider the following statements regarding Interphase and its sub-stages (G1, S, G2, G0):
(I) G1 phase corresponds to the interval between mitosis and the initiation of DNA replication. (II) Most of the organelle duplication occurs during the G1 phase of interphase. (III) Cell growth (cytoplasmic increase) occurs exclusively during the S phase along with DNA replication. (IV) Cells in the G0 phase remain metabolically active but no longer proliferate unless called on to do so depending on the requirement of the organism.
Which of the above statements are correct?
Statement (I) is correct because G1 phase is the interval between mitosis and the start of DNA replication. Statement (II) is correct because most organelle duplication occurs during G1. Statement (III) is incorrect because cytoplasmic growth is continuous throughout the cell cycle and is not restricted to the S phase. Statement (IV) is correct because G0 cells remain metabolically active but do not proliferate unless stimulated.
Question 82 of 100
📘 CLASS XI
Consider the following statements regarding Prophase and Metaphase of Mitosis:
(I) Prophase is marked by the initiation of condensation of chromosomal material. (II) Microtubules radiating outward from centrosomes are called asters, and two asters together with spindle fibres form the mitotic apparatus. (III) Complete disintegration of the nuclear envelope marks the commencement of metaphase. (IV) During metaphase, individual centromeres split simultaneously to separate sister chromatids.
Which of the above statements are correct?
Statement (I) is correct because prophase begins with chromatin condensation. Statement (II) is correct because asters together with spindle fibres constitute the mitotic apparatus. Statement (III) is correct because metaphase begins after complete nuclear envelope breakdown. Statement (IV) is incorrect because centromere splitting occurs during anaphase, not metaphase.
Question 83 of 100
📘 CLASS XI
Consider the following statements regarding cellular events during Mitotic Anaphase and Telophase:
(I) At the onset of anaphase, centromeres split simultaneously and sister chromatids separate into daughter chromosomes. (II) As chromosomes move toward opposite poles in anaphase, centromeres lead toward the pole while chromosome arms trail behind. (III) During telophase, chromosomes cluster at opposite spindle poles, decondense, and lose their individual identity. (IV) Nuclear envelope, nucleolus, Golgi complex, and endoplasmic reticulum completely disappear during telophase.
Which of the above statements are correct?
Statement (I) is correct because anaphase begins with centromere splitting. Statement (II) is correct because centromeres lead chromosome movement toward the poles while arms trail. Statement (III) is correct because chromosomes decondense during telophase. Statement (IV) is incorrect because the nuclear envelope, nucleolus, Golgi complex, and ER reform during telophase.
Question 84 of 100
📘 CLASS XI
Consider the following statements regarding Cytokinesis in Plant vs. Animal Cells and Syncytium Formation:
(I) In animal cells, cytokinesis occurs via a plasma membrane furrow that deepens centripetally. (II) In plant cells, cell wall formation starts at the cell periphery and grows centripetally toward the center. (III) The simple precursor of the new cell wall in plant cells is the cell-plate, which represents the middle lamella. (IV) Syncytium formation occurs when karyokinesis is not followed by cytokinesis, as seen in liquid endosperm of coconut.
Which of the above statements are correct?
Statement (I) is correct because animal cytokinesis occurs by centripetal cleavage furrow formation. Statement (II) is incorrect because plant cytokinesis begins at the center and grows centrifugally. Statement (III) is correct because the cell plate develops into the middle lamella. Statement (IV) is correct because failure of cytokinesis after karyokinesis forms a syncytium, as seen in coconut liquid endosperm.
Question 85 of 100
📘 CLASS XI
Consider the following statements regarding the Significance of Mitotic Cell Division:
(I) Mitosis is an equational division that results in daughter cells with identical genetic complements. (II) Cell division by mitosis helps restore the nucleo-cytoplasmic ratio disturbed by cell growth. (III) Mitotic division in apical and lateral cambium meristems leads to continuous growth of plants throughout life. (IV) Mitotic division is responsible for replacing worn-out cells of the upper epidermis, gut lining, and blood cells.
Which of the above statements are correct?
All four statements are correct. Mitosis is an equational division producing genetically identical daughter cells, restores the nucleo-cytoplasmic ratio, enables continuous growth in apical and lateral meristems, and replaces worn-out cells in the epidermis, gut lining, and blood.
Question 86 of 100
📘 CLASS XI
Consider the following statements regarding Leptotene, Zygotene, and Pachytene of Meiotic Prophase I:
(I) Chromosomes become gradually visible under the light microscope during leptotene due to continuous compaction. (II) Synapsis and synaptonemal complex formation occur during zygotene, forming bivalents or tetrads. (III) Recombination nodules appear and crossing over occurs during pachytene. (IV) Crossing over is an exchange of genetic material between sister chromatids of non-homologous chromosomes.
Which of the above statements are correct?
Statement (I) is correct because chromosome compaction during leptotene makes chromosomes gradually visible under the light microscope. Statement (II) is correct because synapsis and synaptonemal complex formation occur during zygotene, producing bivalents. Statement (III) is correct because recombination nodules appear during pachytene where crossing over occurs. Statement (IV) is incorrect because crossing over occurs between non-sister chromatids of homologous chromosomes, not sister chromatids of non-homologous chromosomes.
Question 87 of 100
📘 CLASS XI
Consider the following statements regarding Diplotene, Diakinesis, and Metaphase I of Meiosis:
(I) Dissolution of the synaptonemal complex and appearance of X-shaped chiasmata occur at diplotene. (II) In oocytes of some vertebrates, diplotene can last for months or years. (III) Diakinesis is marked by terminalisation of chiasmata and breakdown of the nuclear envelope. (IV) During Metaphase I, bivalents line up at the equator and spindle fibres attach to kinetochores of sister chromatids from opposite poles.
Which of the above statements are correct?
Statement (I) is correct because diplotene begins with dissolution of the synaptonemal complex and visible chiasmata. Statement (II) is correct because vertebrate oocytes may remain arrested in diplotene for months or years. Statement (III) is correct because diakinesis involves terminalisation of chiasmata and nuclear envelope breakdown. Statement (IV) is incorrect because in Metaphase I spindle fibres attach to homologous chromosomes, whereas attachment to sister chromatids from opposite poles characterizes Metaphase II/mitosis.
Question 88 of 100
📘 CLASS XI
Consider the following statements regarding Anaphase I, Telophase I, and Interkinesis:
(I) During Anaphase I, homologous chromosomes separate, while sister chromatids remain attached at centromeres. (II) Telophase I followed by cytokinesis results in a dyad of cells. (III) Interkinesis is the stage between Meiosis I and Meiosis II, during which a second round of DNA replication takes place. (IV) Chromosomes in telophase I do not usually reach the extremely extended state of the interphase nucleus.
Which of the above statements are correct?
Statement (I) is correct because homologous chromosomes separate during Anaphase I while sister chromatids remain attached. Statement (II) is correct because Telophase I and cytokinesis produce a dyad of haploid cells. Statement (III) is incorrect because interkinesis does not include DNA replication. Statement (IV) is correct because chromosomes do not fully decondense to the interphase state during Telophase I.
Question 89 of 100
📘 CLASS XI
Consider the following statements regarding Meiosis II substages:
(I) Meiosis II is initiated immediately after cytokinesis I, usually before chromosomes have fully elongated. (II) Meiosis II resembles a normal mitosis. (III) During Anaphase II, centromeres split simultaneously, allowing sister chromatids to move to opposite poles. (IV) Telophase II concludes meiosis with the formation of a tetrad of four haploid daughter cells.
Which of the above statements are correct?
All four statements are correct. Meiosis II begins soon after cytokinesis I before complete chromosome elongation, resembles mitosis, involves centromere splitting during Anaphase II, and ends with Telophase II and cytokinesis producing four haploid daughter cells.
Question 90 of 100
📘 CLASS XI
Consider the following statements regarding the Significance of Meiosis and Key Meiotic Features:
(I) Meiosis conserves the specific chromosome number of each species across generations in sexually reproducing organisms. (II) Meiosis increases genetic variability in populations from one generation to the next, providing raw material for evolution. (III) Meiosis involves two sequential cycles of nuclear and cell division (Meiosis I and II) but only a single cycle of DNA replication. (IV) Meiosis involves pairing of homologous chromosomes and recombination between sister chromatids of the same chromosome.
Which of the above statements are correct?
Statement (I) is correct because meiosis halves chromosome number so fertilization restores the species chromosome number. Statement (II) is correct because meiosis increases genetic variation through recombination and independent assortment. Statement (III) is correct because meiosis includes two successive divisions but only one round of DNA replication before Meiosis I. Statement (IV) is incorrect because recombination occurs between non-sister chromatids of homologous chromosomes, not sister chromatids of the same chromosome.
