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Cell Cycle and Cell Division - XI

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Which of the following statements is/are false?

a. In only about 90 minutes, yeast can progress through the cell cycle. b. The M-phase lasts more than 95% of the duration of the cell cycle. c. During interphase, the cell undergoes both cell growth and DNA replication.

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

  5. Only c


Correct Option: C
Explanation:

This is the correct option as this statement is false. The interphase lasts more than 95% of the duration of the cell cycle.

Which of the following processes do(es) not take place during the division of a cell?

a. DNA replication b. Cell growth c. RNA replication

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

  5. Only c


Correct Option: E
Explanation:

This is the correct option as RNA replication does not take place during the division of a cell.

Which of the following statements is/are false?

a. Cells in the quiescent stage remain metabolically active, but no longer proliferate unless called on to do so. b. Mitotic cell division in animals is seen in the diploid somatic cells. c. Plants can show mitotic divisions in only haploid cells.

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

  5. Only c


Correct Option: E
Explanation:

This is the correct option as this statement is false. Plants show mitotic divisions in both haploid and diploid cells.

Which of the following features do(es) not belong to metaphase?

a. Spindle fibres attach to kinetochores of the chromosomes. b. At the end of metaphase, the cells do not show golgi complexes, endoplasmic reticulum, nucleolus and the nuclear envelope. c. Chromosomes are moved to spindle equator and get aligned along the metaphase plate.

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

  5. Only c


Correct Option: C
Explanation:

This is the correct option as this is not a feature of metaphase. At the end of prophase, the cells do not show golgi complexes, endoplasmic reticulum, nucleolus and the nuclear envelope.

Which of the following statements about the significance of mitosis is false?

  1. Multicellular organisms grow due to mitosis.

  2. Mitosis contributes towards the repair of cells.

  3. Mitosis increases the genetic variability in the population of organisms from one generation to the next.

  4. The production of diploid daughter cells with identical genetic complement is a resultant of mitosis.

  5. Mitotic divisions in the meristematic tissues result in a continuous growth of plants.


Correct Option: C
Explanation:

This is the correct option as this statement is false about the significance of mitosis. Meiosis increases the genetic variability in the population of organisms from one generation to the next.

Telophase is the final stage of mitosis. Which of the following is/are not the characteristic(s) of telophase?

a. Golgi complex and ER reform. b. Nuclear envelope assembles around the chromosome clusters. c. Chromosomes cluster at opposite spindle poles. d. Chromatids move to opposite poles.

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

  5. Only d


Correct Option: E
Explanation:

This is the correct option as the movement of chromatids towards the opposite poles is not a characteristic of telophase.

Chiasmata are x-shaped structures. Which of the following stages is marked by the terminalisation of chiasmata?

  1. Pachytene

  2. Zygotene

  3. Leptotene

  4. Diakinesis

  5. Diplotene


Correct Option: D
Explanation:

This is the correct option. Diakinesis is the final stage of meiotic prophase 1 and is marked by the terminalisation of chiasmata.

The kind of cell division that reduces the chromosome number by half and results in the production of haploid daughter cells is called meiosis. Which of the following is not a characteristic of meiosis?

  1. At the end of meiosis 2, three haploid cells are formed.

  2. It ensures the production of haploid phase in the life cycle of sexually reproducing organisms.

  3. It involves 2 sequential cycles of nuclear and cell division.

  4. Meiosis 1 is initiated after the parental chromosomes have replicated to produce identical sister chromatids at the S phase.

  5. It involves pairing of homologous chromosomes.


Correct Option: A
Explanation:

This is the correct option as this is not a characteristic of meiosis. At the end of meiosis 2, four haploid cells are formed.

Which of the following statements is/are false?

a. Prophase of the mitosis division is longer and more complex than the prophase of first meiotic. b. Mitosis accomplishes the segregation of duplicated chromosomes into daughter nuclei. c. During cytoplasmic division, mitochondria and plastids get distributed between the two daughter cells.

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

  5. Only c


Correct Option: A
Explanation:

This is the correct option as this statement is false. Prophase of the first meiotic division is longer and more complex than the prophase of mitosis.

Match the following:

 
a. Anaphase 2 1. In this stage, the chromosomes again become compact and by the end of this stage, the nuclear membrane disappears.
b. Metaphase 2 2. In this stage, the chromosomes align at the equator.
c. Prophase 2 3. This stage begins with the simultaneous splitting of the centromere of each chromosome.
  1. a - 1, b - 2, c - 3

  2. a - 1, b - 3, c - 2

  3. a - 2, b - 3, c - 1

  4. a - 3, b - 2, c - 1

  5. a - 3, b - 1, c - 2


Correct Option: D
Explanation:

This is the correct option. Anaphase 2 stage begins with the simultaneous splitting of the centromere of each chromosome. In metaphase 2, the chromosomes align at the equator. In prophase 2, the chromosomes again become compact and by the end of this stage, the nuclear membrane disappears.

In which of the following stages of mitosis do chromosomes decondense and lose their individuality after having reached their respective poles?

  1. Anaphase

  2. Metaphase

  3. Prophase

  4. Telophase

  5. None of these


Correct Option: D
Explanation:

This is the correct option. In telophase, chromosomes decondense and lose their individuality after having reached their respective poles.

In which of the following stages of mitosis does the centriole begin to move towards opposite poles of the cell?

  1. Prophase

  2. Metaphase

  3. Telophase

  4. Anaphase

  5. None of these


Correct Option: A
Explanation:

This is the correct option. In prophase, the centriole begins to move towards opposite poles of the cell.

In which of the following phases do sister chromatids separate forming two identical daughter chromosomes

  1. Anaphase

  2. Telophase

  3. Cytokinesis

  4. Karyokinesis

  5. Prophase


Correct Option: A
Explanation:

This is the correct option as the separation of the daughter chromatids occurs in this phase

Match the following:

 
a. Gap 1 phase 1. In this phase, DNA replication begins in the nucleus and the centriole duplicates in the cytoplasm.
b. Synthesis phase 2. In this phase, cell growth continues and proteins are synthesised in preparation for mitosis.
c. Gap 2 phase 3. In this phase, the cell is metabolically active and grows continuously, but does not replicate its DNA.
  1. a - 3, b - 2, c - 1

  2. a - 1, b - 3, c - 2

  3. a - 3, b - 1, c - 2

  4. a - 2, b - 1, c - 3

  5. a - 1, b - 2, c - 3


Correct Option: C
Explanation:

This is the correct option. In gap 1 phase, the cell is metabolically active and grows continuously, but does not replicate its DNA. In synthesis phase, DNA replication begins in the nucleus and the centriole duplicates in the cytoplasm. In gap 2 phase, cell growth continues and proteins are synthesised in preparation for mitosis.

Match the following:

a. Leptotene stage 1. During this stage, chromosomes start pairing together and this process is called synapsis.
b. Zygotene stage 2. During this stage, under a light microscope, chromosomes become gradually visible.
c. Pachytene stage 3. During this stage, bivalent chromosomes clearly appear as tetrads.
  1. a - 3, b - 1, c - 2

  2. a - 2, b - 1, c - 3

  3. a - 1, b - 2, c - 3

  4. a - 1, b - 3, c - 2

  5. a - 2, b - 3, c - 1


Correct Option: B
Explanation:

This is the correct option. During leptotene stage, under a light microscope, chromosomes become gradually visible. During zygotene stage, chromosomes start pairing together and this process is called synapsis. During pachytene stage, bivalent chromosomes clearly appear as tetrads.

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