Required Practical: Identifying Mitotic Stages

Question 1

Growth in plants occurs in specific regions called

Answer 1

meristems

Question 2

The root tip meristem can be used to study mitosis

The root tip meristem can be found just behind the

Answer 2

protective root cap

Question 3

In the root tip meristem, there is a zone of cell division that contains cells undergoing mitosis

Pre-prepared slides of root tips can be studied or temporary slides can be prepared using the squash technique (root tips are

Answer 3

stained and then gently squashed, spreading the cells out into a thin sheet and allowing individual cells undergoing mitosis to be clearly seen)

Question 4

Apparatus

Answer 4

Scalpel
Forceps
Onion roots
Gloves
Ethanoic acid
Dilute hydrochloric acid
Water bath
Spotting tile
Microscope slides
Coverslips
Pipettes
Acetic orcein stain
Paper towels
Optical microscope

Question 5

step 1 Garlic or onion (Allium cepa) root tips are most commonly used (the bulbs can be encouraged to grow roots by………….

Remove the tips of the roots (about 1cm) and place them in ethanoic ……………
This helps to………….

Answer 5

by suspending them over water for a week or two)

alcohol

This helps to “fix” the tissue and prevent mitosis from continuing in the cells

Question 6

step 2 Place the root tips in warm (60oC) dilute ………………

this separates …….

Answer 6

hydrochloric acid

cells

Question 7

step 3 Transfer the root tip to a

Answer 7

microscope slide

Question 8

step 4 Using a pipette, add a suitable stain (eg. which does what

Answer 8

acetic orcein, which stains chromosomes a deep purple)

Question 9

Place a coverslip on top of the root tip and press down firmly using a ………… to make sure no air bubbles

Answer 9

mounted needle

Question 10

View the cells under a microscope start by using the lowest

Answer 10

Place under a microscope and set the objective lens on the lowest
magnification.

Use the coarse adjustment knob to move the lens down to just above the slide

Question 11

Transfer root tip to HCl and you can incubate for 5 minutes.

Answer 11

To drain some of the HCL / soften tissues

Question 12

Analysis
Cells undergoing mitosis (similar to those in the images below) can be seen and drawn
Annotations can then be added to these drawings to show the different stages of mitosis