Question

Given below are sets of five terms each. Rewrite the terms in correct order In a logical sequence.

(i) Anaphase, Telophase, Prophase. Metaphase, Interphase.

(ii) Karyokinesis, S - phase, Cytokinesis, G₁ phase, G₂ phase.

(iii) Metaphase, Telophase, Prophase, Anaphase, Cytokinesis.

Answer 1

Part (i)

Hint: Arrange the terms in chronological order depending on the occurrence of these events during karyokinesis.

Interphase, Prophase, Metaphase, Anaphase, Telophase

1. Cell cycle has two events – interphase and M – phase.
2. Interphase is the interval between two successive cell cycles.
3. After interphase, M – phase begins which is the stage of cell division.
4. Prophase is the first stage of mitosis where the chromatin threads condense to form chromosomes. Each chromosome has two sister chromatids attached with the help of centromere.
5. Prophase is followed by metaphase where all the chromosomes line up at the equator forming the metaphasic plate.
6. Anaphase follows metaphase where the centromere splits and each sister chromatid moves towards the opposite poles of the cell.
7. Telophase is the last stage of mitosis where each polar group of chromosomes decondense to form chromatin fibres and gives rise to a new nucleus.

Part (ii)

Hint: The concept of the sequential events which occur in a mitotic cell cycle is used.

G₁ phase, S – phase, G₂ phase, karyokinesis, cytokinesis

1. G₁ is the first growth phase where volume of the cytoplasm increases and RNA and proteins are synthesized.
2. G₁ phase is followed by the S – phase which is the synthetic phase for replication of DNA to form sister chromatin threads.
3. G₂ phase is the second growth phase where the nucleus grows in size and there is further synthesis of RNA and proteins. Multiplication of cell organelles is also completed in this phase.
4. After G₂ phase, M phase starts which is the phase of cell division. It comprises of two parts – karyokinesis and cytokinesis.
5. First karyokinesis occurs where the chromosomes get divided equally and two daughter nuclei are formed.
6. Next cytokinesis takes place to produce two daughter cells.

Part (iii)

Hint: The concept of the sequential events which occur during M – phase of cell cycle is used here.

Prophase, Metaphase, Anaphase, Telophase, Cytokinesis

1. After the G₂ phase, the cells enter the M – phase where two events occur – karyokinesis and cytokines.
2. Karyokinesis starts with the prophase stage where condensed chromosomes are formed from chromatin threads.
3. Prophase is followed by metaphase during which the centromere and their associated pair of sister chromatids align themselves at the equator of the cell.
4. Metaphase is followed by anaphase. The centromere then splits and each sister chromatid is pulled towards the pole of the cell in anaphase.
5. Finally, telophase occurs which is the last step of karyokinesis. Here two daughter nuclei are produced each with a set of diploid chromosomes from the parent cell. Also, the chromosomes decondensed back into chromatin threads.
6. Karyokinesis is followed by cytokinesis to produce two daughter cells.