Edexcel International A Level Biology

Revision Notes

3.15 Core Practical 6: Observing the Stages of Mitosis

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Observing the Stages of Mitosis

  • Growth in plants occurs in specific regions called meristems
  • The root tip meristem can be used to study mitosis
  • The root tip meristem can be found just behind the protective root cap
  • 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 stained and then gently squashed, spreading the cells out into a thin sheet and allowing individual cells undergoing mitosis to be clearly seen)

Micrograph showing a stained root tip

A micrograph of a stained root tip, nuclei are clearly visible


  • Roots of onion or garlic
  • Microscope slide
  • Cover skip
  • 1 M hydrochloric acid
  • Stain (acetic orcein, toluidine blue for example)
  • Paper towel
  • Scalpel blade
  • Cutting tile
  • Water bath at 60oC
  • Boiling tube
  • Optical microscope


  1. Garlic or onion (Allium cepa) root tips are most commonly used (the bulbs can be encouraged to grow roots by suspending them over water for a week or two)
  2. Prepare a boiling tube of 1M hydrochloric acid and place in a water bath at 60oC for 10 minutes
  3. Remove the tips of the roots (about 1cm) and place in the warmed hydrochloric acid for 5 minutes
  4. Rinse the tips well in cold water using a pipette and blot dry with a paper towel 
  5. Cut approximately 2mm off the tip and place onto a microscope slide
  6. Add a drop of a suitable stain (eg. warm, acetic orcein, which stains chromosomes a deep purple)
  7. The stained root tip is gently squashed on a glass slide using a blunt instrument (eg. the handle of a mounting needle or a cover slip using your fist to gently apply pressure in a rolling motion)
  8. View the slide under the microscope
  9. Cells undergoing mitosis (similar to those in the images below) can be seen and drawn
  10. Annotations can then be added to these drawings to show the different stages of mitosis


  • You should be able to observe cells in different stages of mitosis from the stained meristem 

Micrograph showing a cell undergoing prophase (P)

Micrograph of cells from a meristem showing cells in prophase (P)

Micrograph showing cells undergoing metaphase (M) and anaphase (A)

Micrograph of cells undergoing metaphase (M) and anaphase (A)

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Author: Alistair

Alistair graduated from Oxford University with a degree in Biological Sciences. He has taught GCSE/IGCSE Biology, as well as Biology and Environmental Systems & Societies for the International Baccalaureate Diploma Programme. While teaching in Oxford, Alistair completed his MA Education as Head of Department for Environmental Systems & Societies. Alistair has continued to pursue his interests in ecology and environmental science, recently gaining an MSc in Wildlife Biology & Conservation with Edinburgh Napier University.