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Cell cycle, mitosis and meiosis: NEET MCQs with answers

82 questions on this topic of Cell Structure and Function (NEET 2027 syllabus). Here are 12; tap one to see its answer and explanation.

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easy

1. A typical human cell in culture divides about once every:

  1. 24 hours
  2. 90 minutes
  3. 24 minutes
  4. 7 days
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Answer: (A) 24 hours

Cell cycle duration varies: a typical human cell in culture divides once in approximately every 24 hours, while yeast can complete the cycle in about 90 minutes.

NCERT Class 11

medium

2. Interphase lasts for about what fraction of the duration of a cell cycle?

  1. About 10 per cent
  2. More than 95 per cent
  3. About 50 per cent
  4. Less than 5 per cent
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Answer: (B) More than 95 per cent

The M phase (mitosis) lasts only about an hour of a 24-hour human cell cycle. Interphase, the phase between two successive M phases, lasts more than 95 per cent of the cycle.

NCERT Class 11

hard

3. Assertion (A): Anaphase I of meiosis reduces the chromosome number by half. Reason (R): In anaphase I, homologous chromosomes separate while sister chromatids remain associated at their centromeres. Choose the correct option.

  1. Both A and R are true and R is the correct explanation of A
  2. Both A and R are true but R is not the correct explanation of A
  3. A is true but R is false
  4. A is false but R is true
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Answer: (A) Both A and R are true and R is the correct explanation of A

Because whole homologues, not chromatids, go to each pole, each daughter nucleus receives half the chromosome number.

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4. At the start of anaphase in mitosis:

  1. Homologous chromosomes pair
  2. Centromeres split and chromatids separate
  3. The nuclear envelope reforms
  4. DNA replicates
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Answer: (B) Centromeres split and chromatids separate

In anaphase, each chromosome's centromere splits and the chromatids (now daughter chromosomes) move to opposite poles.

easy

5. In a typical eukaryotic cell cycle, which phase is the actual period of cell division?

  1. G2 phase
  2. G1 phase
  3. S phase
  4. M phase (mitotic phase)
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Answer: (D) M phase (mitotic phase)

The cell cycle is divided into interphase (G1, S and G2), the period of preparation, and the M phase, during which the actual division takes place.

hard

6. Cells in the quiescent G0 stage:

  1. Divide faster than other cells
  2. Are dead
  3. Replicate DNA continuously
  4. Remain metabolically active but no longer proliferate unless called on to do so
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Answer: (D) Remain metabolically active but no longer proliferate unless called on to do so

G0 cells exit G1, stay metabolically active, and divide only when the organism requires it.

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7. The process of meiosis involves:

  1. Two sequential cycles of nuclear and cell division but only a single cycle of DNA replication
  2. One division and two DNA replications
  3. Two divisions and two DNA replications
  4. One division and no DNA replication
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Answer: (A) Two sequential cycles of nuclear and cell division but only a single cycle of DNA replication

Meiosis has meiosis I and meiosis II but only one cycle of DNA replication. It pairs homologous chromosomes, allows recombination and produces four haploid cells.

NCERT Class 11

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8. Which is a significance of mitosis?

  1. It halves the chromosome number
  2. It increases genetic variability by crossing over
  3. It produces gametes in animals
  4. It produces diploid daughter cells with identical genetic complement and helps in growth and repair
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Answer: (D) It produces diploid daughter cells with identical genetic complement and helps in growth and repair

Mitosis gives genetically identical diploid daughter cells. It is essential for growth, restores the nucleo-cytoplasmic ratio, and repairs tissues such as epidermis, gut lining and blood cells.

NCERT Class 11

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9. Crossing over between non-sister chromatids of homologous chromosomes, mediated by the enzyme recombinase, occurs during:

  1. Diplotene
  2. Leptotene
  3. Pachytene
  4. Zygotene
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Answer: (C) Pachytene

Pachytene is characterised by recombination nodules, the sites of crossing over between non-sister chromatids. Crossing over is enzyme-mediated (recombinase) and leads to recombination.

NCERT Class 11

medium

10. A diploid cell has 2n = 20 chromosomes. Find the number of chromatids at metaphase of mitosis.

  1. 10
  2. 40
  3. 5
  4. 20
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Answer: (B) 40

With 2n = 20: mitosis keeps 20 chromosomes; meiosis I halves the number to 10 (each with two chromatids); gametes have 10; metaphase of mitosis shows 40 chromatids; there are 10 bivalents at metaphase I.

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11. A diploid cell has 2n = 20 chromosomes. Find the number of chromosomes in each gamete.

  1. 5
  2. 40
  3. 10
  4. 20
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Answer: (C) 10

With 2n = 20: mitosis keeps 20 chromosomes; meiosis I halves the number to 10 (each with two chromatids); gametes have 10; metaphase of mitosis shows 40 chromatids; there are 10 bivalents at metaphase I.

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12. A diploid cell has 2n = 14 chromosomes. Find the number of chromosomes in each cell after meiosis I.

  1. 28
  2. 7
  3. 14
  4. 3.5
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Answer: (B) 7

With 2n = 14: mitosis keeps 14 chromosomes; meiosis I halves the number to 7 (each with two chromatids); gametes have 7; metaphase of mitosis shows 28 chromatids; there are 7 bivalents at metaphase I.

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