Honors Biology ___________________
Date ___________
Mrs. Nelson & Dr. Sengupta
Mitosis Lab (Onion root tip)
Aim:
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Roots consist of various tissues. The Ground tissue makes up the majority of the root. The Vascular tissue
makes up transport vessels such as Xylem (water transport) and Phloem (sugar transport). Dermal tissue
forms the outer protective waxy covering. The Root cap has a protective role. The Apical meristem is the
part that contains the most cells undergoing mitosis. The Zone of elongation is the region where growth
occurs. The Zone of maturation is where the root hairs develop and also where cells differentiate into
Xylem, Phloem and other tissues.
Pre-Lab Questions:
1. Which tenet of cell theory applies to the process of cell division?
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2. What is another name for division of the cell’s nucleus?
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3. List any three ways in which mitosis is useful.
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Procedure:
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Place a prepared slide of onion root tip under the microscope. Start with the 4X objective. Locate
the region of active growth and then use the 40X objective to study individual cells.
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Find a cell that clearly demonstrates one of the stages and then draw the cell in the space
provided, starting with the non-dividing cell in Interphase. In each drawing the defining features
of that stage should be clearly labeled.
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Once you are done, observe at least 100 cells in your field and determine what stage of mitosis
they are in and put the data in Table 1.
Observations:
Table 1: Number of cells in different stages of cell cycle.
Stage
Number of Cells
Percentage of Cells
Interphase
Prophase
Metaphase
Anaphase
Telophase
Here you will also include your sketches.
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Post-Lab Questions:
1. How is cell division in plant cells different from cell division in animal cells?
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2. Based upon the data that you collected in Table 1, which of the five stages that you studied is the
longest? Why?
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3. Use your knowledge of Mitosis to speculate as to what would happen if:
a. The nuclear membrane did not breakdown in prophase.
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b. The spindles did not properly attach to the centromeres.
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c. The sister chromatids did not separate in anaphase.
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d. Cytokinesis did not take place after the nuclear division.
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