required practical 2

Question 1

where in plant can cells undergoing mitosis be found?

Answer 1

meristem tissue at roots and shoots

Question 2

mitotic index equation

Answer 2

number of cells with visible chromosomes/total number of cells in sample

Question 3

method

Answer 3

1. heat 1moldm-3 HCl at 60c in a water bath
2. cut a small sample of the root tip using a scalpel
3. transfer root tip to HCl
4. remove and wash tip in cold distilled water
5. place tip on microscope slide and stain (e.g toluidine blue O)
6. lower cover and make no air bubbles and don’t damage chromosomes
7. place under microscope and set objective lens to lowest magnification
8. use coarse adjustment knob to move lens to above slide
9. use fine adjustment knob to re-adjust focus until image is clear
10. calculate mitotic index

Question 4

why is HCl used?

Answer 4

the root tip is treated with acid to break up the tissues into individual cells

Question 5

why do you only use the first 5mm from the tip?

Answer 5

this is where cells are undergoing mitosis

Question 6

why do you press down firmly on the cover slip?

Answer 6

to get a thin layer of cells so light can pass through

Question 7

why is a stain used?

Answer 7

to stain the chromosomes to make them visible