Multiple Choice Questions

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Microtubule depolymerizing drug such as colchicine is expected to

  • inhibit spindle formation during mitosis

  • inhibit cytokinesis

  • allow mitosis beyond metaphase

  • induce formation of multiple contractile rings


A.

inhibit spindle formation during mitosis

Colchicine is an alkaloid derived from the autumn crocus, Colchicum autumnale. It inhibits spindle formation in cells during mitosis so that chromosomes cannot separate during anaphase, thus inducing multiple sets of chromosomes. It does not affect cytokinesis.


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Which is the longest phase of the cell cycle

  • M-phase

  • interphase

  • Leptotene

  • S-phase


When synapsis is complete all along the chromosome, the cell is said to have entered a stage called

  • zygotene

  • pachytene

  • diplotene

  • diakinesis


The importance of meiosis lies in :

  • bringing discontinuous variations

  • addition in the number of chromosomes

  • reduction in the number of chromosomes

  • maintaining the number of chromosomes


Barr Body is found in the cytoplasm during

  • interphase in cell of female mammal

  • interphase in cell of male mammal

  • prophase in cell of female mammal

  • prophase in cell of male mammal.


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The checkpoint in cell cycle plays important role in

  • repair DNA damage

  • apoptosis initiation

  • assess DNA damage

  • inhibit cell damage.


Assertion: Meiosis II is similar to mitosis.

Reason : Meiosis I cannot occur in haploid cells.

  • If both assertion and reason are true and reason is the correct explanation.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false

  • If both assertion and reason are false.


Which of the following is not a characteristic of meiosis

  • It involves two stages of DNA replication one before meiosis-I and another before meiosis-II

  • It involves recombination and crossing over

  • Sister chromatids separate during anaphase II

  • Nuclear membrane disappears during prophase.


Which of the following statements is incorrect about G0 phase

  • Mitosis occurs after G0 phase.

  • Biocatalysts can be used to exit G0 phase.

  • Cell volume keeps on increasing during this phase.

  • Cell metabolism occurs continuously in G0 phase.


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In a diploid cell, at which stage of cell cycle, the amount of DNA is doubled?

  • G1 and G2 phase

  • G0 phase

  • S, G2 and M phase

  • S phase


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