Required Practical 2 - Mitotic Index

Question 1

What is the mitotic index?

Answer 1

The ratio of cells undergoing mitosis: total cells

Question 2

Why did you use hydrochloric acid (5 mol dm -cubed to initially soak the garlic root tip?

Answer 2

To stop all enzyme activity in the cell, as the acidic pH breaks the ionic bonds in tertiary structure of enzymes

Question 3

What made the chromosomes visable?

Answer 3

Toluidene blue stain

Question 4

Why did you macerate the garlic root tip on the slide?

Answer 4

To separate the layers of cells, making it easier to see under the light microscope

Question 5

Why did you rinse the root tip in distilled water in a watch glass after leaving it in the hydrochloric acid for 15 minutes?

Answer 5

To rinse it

Question 6

Why did you use the root tip, not a slice from the main body?

Answer 6

The roots grow the fastest in a plant, so it is more likely to see cells undergoing mitosis there

Question 7

Why did you have to immediately add the root tip to the acid as soon as it had been chopped off the main garlic?

Answer 7

This stops any reactions from continuing any further - leaving it lying around would cause cells in mitosis to finish, and no more to continue as it is separate from the main body so can;t grow any more

Question 8

What was my conclusion?

Answer 8

Most of the cells were in interphase, so mitosis wasn’t visable. It was random too - no order or patterns in the samples.
For me, mitotic index around 1:6 / 10/4% - 16.7%
Online, 37.14% in mitosis.