The checkpoint in cell cycle plays important role in

• repair DNA damage

• apoptosis initiation

• assess DNA damage

• inhibit cell damage.

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.

Which is the longest phase of the cell cycle

• M-phase

• interphase

• Leptotene

• S-phase

54.

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

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

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.

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.

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