Question

Questions about the cell cycle

1. Does the cell cycle really have a beginning and an end? Explain your answer.

2. Why is the spindle apparatus more complex in animal cells than in plant cells?

(it has something to do with differences in the structure of the different cell types)

3. What name is given to the plane in the center of the cell where chromosomes align during metaphase?

4. Which stage of mitosis is most often associated with the beginning of cytokinesis?

5. Why does pinching in of the cytoplasm not work for cytokinesis in plant cells?

Answer 1

Ans . (1) Since the cell cycle is a " cycle " it has no distinct beginning or ending. The cells are continually entering and exiting the various phases of the cycle.

Ans . (2) The differences are largely due to specialized structures in each type of cell. Plants have both a cell membrane and a cell wall , whereas the animal cells have no cell wall. Animals also have centrioles, but plants do not have centrioles.

The mitotic spindle in animal mitosis is formed with the help of two centrioles, whereas mitotic spindles in plant mitosis is formed without any centrioles.

Ans .(3) Metaphase plate or Equatorial plane.

During metaphase, the chromosomes line up at the metaphase plate under the tension from the mitotic spindle .

Ans .(4) Telophase.

Ans .(5) The pinching of cytoplasm is inadequate for cytokinesis , because plant cells also need to synthesize a new cell wall between the two new cells.