MITOSIS ANSWERS

1. Read through the following passage on the cell cycle and mitosis, then write in the gaps the most appropriate word or words to complete the passage.
(a) In the cell cycle DNA synthesis occurs during  interphase .  At the beginning of prophase  chromatin  condenses and chromosomes become visible. The end of prophase is characterized by the breakdown of the  nuclear membrane . The chromosomes become attached to the equator of the  spindle  during  metaphase . At anaphase the chromosome splits at the centromere and one copy heads towards each pole of the spindle. The final phase is called  telophase  and it involves the formation of two new separate nuclei. In animal cells this phase is followed by cytokinesis.

(7)


2. (a) Explain why root tips are particularly suitable material to use for preparing slides to show mitosis. 
  • cells dividing/active growing region.

(1)

(b) Give a reason for carrying out each of the following steps in preparing a slide showing mitosis in cells from a root tip. 

(i)

The tissue should be stained. 

  • in order to distinguish the chromosomes / show up neclear material.

(1)

(ii) 

The stained material should be pulled apart with a needle and gentle pressure applied to the cover slip during mounting. 
  • seperate the cells / produce a thinner cell layer.
(1)
(c) The drawing has been made from a photograph showing a cell undergoing mitosis.

In which stage of mitosis is the cell shown in this drawing? 
  • Anaphase
(1)

3. The drawings A-E show stages of mitosis in an animal cell.

(a) Which of the drawings A -E shows

(i)

 anaphase;
  • A

(1)

(ii) telophase;
  • D

(1)

(iii) metaphase?
  • E

(1)

(b) Give two processes which occur during interphase and which are necessary for nuclear division to take place.
  • Replication of DNA;
  • ATP production;
  • Synthesis of spindle / proteins / replication of centrioles.

(any2)