Required Practical 2

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

Why is the stain used on the root tip?

Answer 3

The stain is used to make the chromosomes visible and easier to see the cells undergoing mitosis

Question 4

What is the procedure to prepare a root tip slide?

Answer 4

1. Heat 1moldm at 60*C in a water bath
2. Cut a small sample of the root tip, using a scalpel
3. Transfer root tip to HCl and incubate fro 5 minutes
4. Remove root tip from HCl and wash sample in cold distilled water and remove the very tip, using a scalpel
5. Place tip on a microscope scale and add a few drops of stain (toluidine blue o)

Question 5

What is the method for required practical two?

Answer 5

1. Heat 1moldm at 60*C in a water bath
2. Cut a small sample of the root tip, using a scalpel
3. Transfer root tip to HCl and incubate fro 5 minutes
4. Remove root tip from HCl and wash sample in cold distilled water and remove the very tip, using a scalpel
5. Place tip on a microscope scale and add a few drops of stain (toluidine blue o)
6. Lower the cover slip onto the slide, making sure there is no air bubbles in the slide
7. Place coverslip under microscope and set objective les= s on the lowest magnification
8. Using the coarse adjustment knob, move the lens down to just above the stick
9. Use the fine adjustment knob to readjust focus until the image is cleared
10. Then calculate the mitotic index

Question 6

Why should you avoid air bubbles in the slide?

Answer 6

You want to avoid the air bubbles because they could distort the image

Question 6

Why should the coverslip not slide over the sample?

Answer 6

If the coverslip slides sideways the chromosomes could become damaged

Question 7

How do you calculate the mitotic index?

Answer 7

You count the number of cells with visible chromosomes and divide that number by the total number of cells in a sample

Question 8

What are the hazards and precautions fro reagents used in this procedure?

Answer 8

Hydrochloric acid (HCl) - Is corrosive so avoid contact with skin and wear eye protection

Toluidine blue O stain - Is irritant so avoid contact wit skin and wear eye protection

Scalpel - It is sharp so cut away from your fingers