AP Lab 3

Completing the Research Notebook for AP Biology Lab #3.....Mitosis and Meiosis


Resource: Lab Three, Mitosis and Meiosis

Page 29 in the AP Biology Lab Manual


1. Develop your title in the form of a question after you have completed the pre-lab.


2. Objectives (see page 29 of the AP Biology Lab Manual)


3. Pre-lab Questions

a. Explain how to use a compound light microscope (A light, or optical, microscope contains

lenses (10X) in an eyepiece and objectives (10X or 40X). An electric bulb usually provides the light

which must go through the transparent specimen. A total magnification is obtained by multiplying

the 10X eyepiece magnification by the magnification of the objective lens being used. A diaphragm

can be used to control the intensity of light in order for the observer to see the parts of the specimen

more distinctly. Microscopes should be carried, used, and stored with extreme care as the

instruments and lenses are expensive.

b. Describe chromosome structure (include DNA, genes, and centromere, duplicated

chromosome, sister chromatics, homologous chromosomes in your answer)

c. How is the genetic code transmitted from parent to offspring?

d. Briefly describe the life cycle of a typical animal, plant, and fungus.

Use the background info and the Campbell text.

e. Explain the functions of each of the regions of a root.

f. What is a fish blastula and why is it used for “mitosis” studies?

g. What is meant by “reduction division” (use the terms diploid and haploid in your answer)?

When does this occur during meiosis?

h. Explain figure 3.14 (Meiosis with No Crossing Over), page 42.

h. Relate “frequency of crossover” to “distance between genes” . What is meant by a “Map

unit” (see page 43 of AP Biology Lab Manual).


Part 4: Methods

a. Exercise 3A-1 Mitosis

Longitudinal sections of onion root tips will be observed. The meristematic region will

be located and the stages of mitosis will be reviewed and observed. The stages of mitosis will be

observed in slides of a fish blastula to review mitosis. The following diagrams will be drawn in 3 X 3

cm boxes FOR EITHER THE ONION ROOT OR THE FISH BLASTULA as the stages are found:

interphase, prophase, metaphase, anaphase, telophase, cytokinesis (plant or animal)

b. Exercise 3A 2 Relative Lengths of Mitotic Stages.

The meristematic region of an onion root tip will be used to estimate the relative

length of time that a cell spends in the various stages of mitosis. The total cells will be counted in

three different fields for each phase and an estimated time in the phase will be calculated.

c. Exercise 3B -1 Meiosis A simulation of the process of meiosis will be done using strands

of yellow and red beads connected to magnetic centromeres.

d. Exercise 3B-2 Crossing over during Meiosis in Sordaria

The life cycle of the fungus Sordaria will be reviewed. Microscope slides of Sordaria

asci or flashcards of asci will be used to gather data which evidences crossing over. “Map units” will

be calculated which will be relative measures of the distance of the gene for spore color to the



Part 5: Data

Exercise 3A.1 will be neat drawings.

Exercise 3A.2 Table 3.1

Exercise 3B.2 Table 3.3



Part 6: Questions and answers

Exercise 3A.1 page 33

Exercise 3A.2 page 34 (do question 3 in the graph section)

Exercise 3B.1 page 39

Exercise 3B.2 page 44


Part 7: Graphs

Page 34, Question 3 (pie chart of the onion root tip cycle)


Part 8: Theme Correlation: How can organisms in a species maintain their species chromosome

number (continuity)? How can organisms in a species show such a variety of phenotypes from

generation to generation (change)?


Part 9: Conclusion Topics

1. Discuss, using data, the relative time a cell spends in each phase of mitosis.

2. Discuss the significant events in each phase of meiosis.

3. Discuss significant differences in mitosis and meiosis.

4. Discuss how “map units” are used with respect to crossing over. Explain how data was used to

calculate “map units” and what this means.