Mitosis practical

• What is the purpose of preparing a stained squash of cells?

  To work out the mitotic index
• What are the main components of the mitosis root tip squash practical?

  • Equipment needed
  • Method of preparation
  • Risk assessment
  • Calculation of mitotic index
  • Typical exam questions
• What is one piece of equipment used in the experiment?

  Hydrochloric acid
• Why is hydrochloric acid used in the experiment?

  To soften the root tissues
• What color is the acetic orcein stain?

  Dark reddy purple
• What is the function of the mounted needle in the experiment?

  To prevent air bubbles under the cover slip
• What part of the onion or garlic is used for the experiment?

  The last five millimeters of the root tip
• Why is the last five millimeters of the root tip used?

  It is the region where cells divide
• What should you do after cutting the root tip?

  Add it to hydrochloric acid and heat
• What temperature should the water bath be set to?

  60 degrees Celsius
• What is done after rinsing the root tip in distilled water?

  Transfer it to a microscope slide
• Why is filter paper used during the experiment?

  To absorb excess water or stain
• What is the purpose of squashing the root tip?

  To create a thin layer for viewing
• What happens if you press too hard while squashing?

  You may break the glass cover slip
• What is a hazard associated with using a scalpel?

  You could cut yourself
• How can you prevent cutting yourself with a scalpel?

  Cut away from yourself on a tile
• What is a risk associated with hydrochloric acid?

  It can be an irritant
• How can you protect yourself from hydrochloric acid?

  Wear goggles to protect your eyes
• What should you do if hydrochloric acid gets on your hands?

  Wash your hands immediately
• What stage of mitosis is shown in the observed cell?

  Anaphase
• Why might you only see a few cells in mitosis?

  Most cells are in interphase
• How is the mitotic index calculated?

  Cells in mitosis divided by total cells
• What is the formula for calculating the mitotic index?

  $\text{Mitotic Index} =$$\frac{\text{Number of cells in mitosis}}{\text{Total number of cells}} \times 100$
• What should you do to ensure an accurate count of cells for the mitotic index?

  Examine multiple fields of view
• Why is it important to have a representative sample when counting cells?

  To ensure accurate mitotic index calculation
• What are the typical exam questions related to the mitosis root tip squash practical?

  1. Why use the first five millimeters of root tip?
  2. Why press down gently?
  3. Why use a stain?
• Why do we use only the first five millimeters from the root tip?

  It contains cells undergoing mitosis
• Why do we press down gently during the squash step?

  To avoid breaking the cover slip
• Why do we use a stain in the experiment?

  To make chromosomes visible under the microscope
• What is the significance of examining multiple fields of view?

  To obtain a representative sample
• How can you improve the accuracy of your mitotic index calculation?

  Count cells in multiple fields of view