The first part of this investigation, students examine slides of mitosis in an onion root tip and count the number of cells in each phase of the cell cycle. An equation is then used to estimate the percentage of time the cell spends in each phase and students create a bar graph to display results. A CER (claim, evidence, reasoning) chart is required for analysis to answer the question: “How much time is spent in each phase of the cell cycle?”
Part two of the investigation presents a more challenging activity where students explore how the mitotic index is used in cancer studies. It is based on a study from the Journal of Veterinary Pathology which examined the mitotic index of different grades of tumors in dogs with mast cell cancer. This section requires an analysis of sample data and analyzing graphs and charts.
Time Required: 50-60 minutes
Grade Level: 11-12
Part 1 Only: 9-12
HS-LS1-4 Use a model to illustrate the role of cellular division (mitosis) and differentiation in producing and maintaining complex organisms.