Investigating Mitosis

• What is the purpose of preparing a root tip cell squash?

  To observe the stages of mitosis
• Why should safety goggles and gloves be worn during the procedure?

  To protect against harmful stains and acids
• What is the first step in preparing a root tip for observation?

  Add 1 M hydrochloric acid to a boiling tube
• At what temperature should the water bath be set for the root tip preparation?

  60 °C
• Why is it important to cut the root tip from the growing end?

  Because mitosis occurs at the growing tip
• How long should the root tip be incubated in hydrochloric acid?

  About 5 minutes
• What should be done after removing the root tip from the acid?

  Rinse it well with cold water
• What is the purpose of adding a stain to the root tip cells?

  To make chromosomes easier to see
• What should be done to the root tip before adding the stain?

  Spread the cells out thinly
• Why should the cover slip not be smeared sideways?

  To avoid damaging the chromosomes
• What can be observed under an optical microscope after preparation?

  Stages of mitosis in root tip cells
• What should be included when drawing cells undergoing mitosis?

  Relative sizes and magnification used
• What does the mitotic index represent?

  The proportion of cells undergoing mitosis
• How can the mitotic index be calculated?

  Visible chromosomes / total cells observed
• What does a high mitotic index indicate in a tissue sample?

  Rapid growth or potential cancerous growth
• How can the mitotic index be expressed as a percentage?

  Multiply by 100
• What tools are used to calculate the size of cells under a microscope?

  Eyepiece graticule and stage micrometer
• What is the function of the eyepiece graticule?

  To measure size without units
• How do you determine the value of divisions on the eyepiece graticule?

  Using the stage micrometer at a specific magnification
• What should be done before measuring the size of cells?

  Align the eyepiece graticule with the stage micrometer
• What is the purpose of the stage micrometer?

  To provide an accurate scale for measurements
• How do you measure the size of cells after aligning the eyepiece graticule?

  Replace the micrometer with the tissue slide