Consider the following statements regarding the specific biochemical and organelle duplication events in Interphase:
(I) Most of the organelle duplication occurs during the G1 phase of interphase. (II) Proteins required for mitosis are synthesized during the G2 phase while cell growth continues. (III) In animal cells, centriole duplication takes place in the cytoplasm during the S phase. (IV) DNA replication occurs a second time during the G2 phase to double the chromosomes for karyokinesis.
Which of the above statements are correct?
Statement (I) is correct because most organelle duplication occurs during G1. Statement (II) is correct because proteins required for mitosis are synthesized during G2 while growth continues. Statement (III) is correct because centriole duplication occurs during S phase in animal cells. Statement (IV) is incorrect because DNA replication occurs only during the S phase, not during G2.
Question 32 of 100
📘 CLASS XI
Consider the following statements regarding the Mitotic Apparatus and Spindle Structure:
(I) Centrosomes, which duplicate during the S phase, move toward opposite poles during prophase. (II) Microtubules radiating outward from each centrosome during prophase are termed asters. (III) The two asters along with spindle fibres collectively constitute the mitotic apparatus. (IV) Asters are prominent in both plant and animal cells during mitotic spindle formation.
Which of the above statements are correct?
Statement (I) is correct because centrosomes duplicate during S phase and migrate to opposite poles during prophase. Statement (II) is correct because the radiating microtubules are called asters. Statement (III) is correct because the mitotic apparatus consists of two asters together with spindle fibres. Statement (IV) is incorrect because higher plant cells lack asters.
Question 33 of 100
📘 CLASS XI
Consider the following statements regarding Metaphase and Anaphase of Mitosis:
(I) The complete disintegration of the nuclear envelope defines the beginning of metaphase. (II) At metaphase, each chromosome is connected to spindle fibres from both poles via kinetochores on its sister chromatids. (III) Anaphase onset is marked by simultaneous splitting of centromeres and separation of sister chromatids into daughter chromosomes. (IV) During anaphase, chromosome arms lead toward opposite poles while centromeres trail behind.
Which of the above statements are correct?
Statement (I) is correct because metaphase begins after complete nuclear envelope breakdown. Statement (II) is correct because spindle fibres attach to kinetochores of sister chromatids from opposite poles. Statement (III) is correct because centromeres split at the onset of anaphase, separating sister chromatids. Statement (IV) is incorrect because centromeres lead toward the poles while chromosome arms trail behind.
Question 34 of 100
📘 CLASS XI
Consider the following statements regarding Cytokinesis and Syncytium Formation:
(I) In animal cells, cytokinesis occurs via a plasma membrane furrow that deepens centripetally. (II) In plant cells, wall formation initiates in the cell centre and grows centrifugally toward lateral walls. (III) The simple precursor of the new plant cell wall is the cell plate, which develops into the middle lamella. (IV) Failure of cytokinesis following karyokinesis results in a multinucleate condition called a syncytium, as seen in coconut liquid endosperm.
Which of the above statements are correct?
Statement (I) is correct because animal cytokinesis proceeds by centripetal cleavage furrow formation. Statement (II) is correct because plant cytokinesis begins centrally and proceeds 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 35 of 100
📘 CLASS XI
Consider the following statements regarding the Significance of Mitosis in Living Organisms:
(I) Mitosis typically results in the production of diploid daughter cells with identical genetic complements. (II) Mitosis restores the nucleo-cytoplasmic ratio disturbed during cell growth. (III) Continuous growth in plants throughout life is driven by mitotic divisions in apical and lateral cambium meristems. (IV) Cell replacement in the upper epidermal layer, gut lining, and blood cells depends on continuous mitotic division.
Which of the above statements are correct?
Statement (I) is correct because mitosis produces genetically identical diploid daughter cells. Statement (II) is correct because mitosis restores the nucleo-cytoplasmic ratio after cell growth. Statement (III) is correct because lifelong plant growth depends on mitotic divisions in apical and lateral meristems. Statement (IV) is correct because mitosis continuously replaces worn-out cells in the epidermis, intestinal lining, and blood.
Question 36 of 100
📘 CLASS XI
Consider the following statements regarding the sequential substages of Meiotic Prophase I:
(I) Compaction of chromosomes continues throughout the leptotene stage. (II) Synapsis and synaptonemal complex formation take place during zygotene. (III) Recombination nodules appear and crossing over occurs between non-sister chromatids of homologous chromosomes in pachytene. (IV) Dissolution of synaptonemal complexes and terminalisation of chiasmata occur simultaneously during diakinesis.
Which of the above statements are correct?
Statement (I) is correct because chromosome compaction continues throughout leptotene. Statement (II) is correct because synapsis and synaptonemal complex formation occur during zygotene. Statement (III) is correct because recombination nodules appear and crossing over occurs between non-sister chromatids during pachytene. Statement (IV) is incorrect because synaptonemal complex dissolution occurs in diplotene, whereas terminalisation of chiasmata occurs in diakinesis.
Question 37 of 100
📘 CLASS XI
Consider the following statements regarding Diplotene and Diakinesis of Meiosis I:
(I) Diplotene can persist for months or years in the oocytes of certain vertebrates. (II) Terminalisation of chiasmata and maximum condensation of chromosomes characterize diakinesis. (III) By the end of diakinesis, the nucleolus disappears and the nuclear envelope breaks down. (IV) Diakinesis marks the final stage of meiotic prophase I and represents the transition to metaphase I.
Which of the above statements are correct?
Statement (I) is correct because diplotene may persist for months or years in vertebrate oocytes. Statement (II) is correct because diakinesis is characterized by terminalisation of chiasmata and maximum chromosome condensation. Statement (III) is correct because the nucleolus disappears and the nuclear envelope breaks down by the end of diakinesis. Statement (IV) is correct because diakinesis is the final stage of Prophase I before Metaphase I.
Question 38 of 100
📘 CLASS XI
Consider the following statements regarding Metaphase I and Anaphase I of Meiosis:
(I) Bivalent chromosomes align on the equatorial plate during Metaphase I. (II) Spindle fibres attach to kinetochores of homologous chromosomes from opposite poles during Metaphase I. (III) During Anaphase I, homologous chromosomes separate, but sister chromatids remain associated at centromeres. (IV) Centromeres split during Anaphase I to allow homologous chromosomes to move to opposite poles.
Which of the above statements are correct?
Statement (I) is correct because bivalents align at the metaphase plate during Metaphase I. Statement (II) is correct because spindle fibres attach to kinetochores of homologous chromosome pairs. Statement (III) is correct because homologous chromosomes separate while sister chromatids remain joined at the centromeres. Statement (IV) is incorrect because centromeres split only during Anaphase II.
Question 39 of 100
📘 CLASS XI
Consider the following statements regarding Interkinesis and Meiosis II:
(I) Interkinesis is the stage between Meiosis I and Meiosis II and is generally short-lived. (II) Active replication of chromosomal DNA takes place during interkinesis. (III) Meiosis II is an equational division that resembles normal mitosis. (IV) Centromeres split simultaneously during Anaphase II, enabling sister chromatids to separate to opposite poles.
Which of the above statements are correct?
Statement (I) is correct because interkinesis is the brief interval between Meiosis I and Meiosis II. Statement (II) is incorrect because DNA replication does not occur during interkinesis. Statement (III) is correct because Meiosis II is an equational division similar to mitosis. Statement (IV) is correct because centromeres split during Anaphase II, allowing sister chromatids to separate.
Question 40 of 100
📘 CLASS XI
Consider the following statements regarding Chromosome and DNA Quantities during Meiotic Stages in a cell with 2n = 20 and DNA content 2C at G1:
(I) After S phase preceding Meiosis I, the cell has 20 chromosomes and 4C DNA content. (II) At Telophase I (after cytokinesis I), each dyad daughter cell has 10 chromosomes (haploid) and 2C DNA content. (III) At Telophase II (after cytokinesis II), each of the four daughter cells has 10 chromosomes and 1C DNA content. (IV) DNA content doubles during interkinesis to ensure proper distribution during Meiosis II.
Which of the above statements are correct?
Statement (I) is correct because DNA content doubles from 2C to 4C during S phase while chromosome number remains 20. Statement (II) is correct because after Meiosis I each haploid daughter cell has 10 chromosomes and 2C DNA. Statement (III) is correct because after Meiosis II each daughter cell has 10 chromosomes and 1C DNA. Statement (IV) is incorrect because DNA replication does not occur during interkinesis.
