RP2 - Calculating Mitotic Index using Plant Cells

Question 1

Where in plants can cells undergoing mitosis be found?

Answer 1

Meristem tissue at shoot and root tips.

Question 2

What is the mitotic index?

Answer 2

The ratio of cells undergoing mitosis to the total number of cells in a sample.

Question 3

Outline the procedure to prepare a root tip slide.

Answer 3

1. Warm 1M HCl to 60°C in a water bath.
2. Cut a root tip using a scalpel and add to the HCl. 3. Leave for 5 minutes.
3. Remove from HCl and wash with distilled water.
4. Cut the tip of the root tip sample and place on a slide.
5. Add a few drops of stain to make chromosomes visible.

Question 4

State the formula for the mitotic index.

Answer 4

Mitotic index = Number of cells with visible chromosomes / Number of cells in sample

Question 5

State the hazards and precautions for reagents used in this procedure.

Answer 5

HCl - corrosive, avoid skin contact, wear eye protection
Toluidine Blue O stain - irritant, avoid contact with
skin, wear eye protection
Scalpel - cut away from fingers