Laboratory Investigation # 9
Plant Reproduction and Cell Division
Description of the Lab
This lab allows the students to identify the different phases of mitosis using an
onion root tip. Looking at the root tip also allows the students to see the role of cell
division and cell growth in root growth. Various types of vegetative propagation will be
Outline of Investigation
1. Locations of Mitosis
A – C. Allium (onion) root tip, longitudinal section, prepared slide
2. Stages of Mitosis
A – C. Allium (onion) root tip, longitudinal section, prepared slide
3. Cell Division in Vegetative Propagation
A. Tobacco callus culture and media
Laboratory Materials and Equipment for Student Use
Materials and Equipment
Per
Student
Per Pair of
Students
Per Lab
Group
Per
Room
Bag of Sphagnum moss
1
Plastic wrap
1
Plastic cups
Foam cups
Bag of vermiculite or sand
1
Knife
1
15
Grow mobile with grow lights
1
Fresh live material
Tobacco callus culture & media
2
Navel orange, seedless banana
1
of one
type
Rhizome, bulbs and/or tubers.
1 of
each
Prepared Slides
Allium root tip, ls, prepared slide
1
15
Preparation of laboratory Materials and Reagents
At the beginning of the semester make sure you have the plants needed and that they are
large enough to use for demonstrations of layering and cuttings for vegetative
propagation. You will need enough leaves for each pair in the labs to plant a cutting.
Two weeks prior to the lab
1. Manipulate the medium of one of the tobacco callus cultures so that shoots will
One week prior to the lab
1. Layer the Hibiscus or other tropical shrub
1 day prior to the lab
1. Gather the plant, foam cups, plastic cups, vermiculite, knives needed for cuttings
After the Lab has finished
Other seedless fruits
1
Spider plant (Chlorophytum
Tropical shrub (ex. Hibiscus)
1
Questions for Plant Reproduction and Cell Division
Use the knowledge you acquired in this lab exercise, along with information from your
textbook, to answer the following questions.
1. Indeterminate growth is the growth of a stem and root throughout the lifetime of the
plant. What did your observations of the onion root tip tell you about the cellular basis
for indeterminate growth?
2. Leaves, fruits, and flowers of plants have determinate growth; that is, they grow for
only a short time during the lifetime of the plant. What is the cellular basis of
determinate growth?
Cells stop dividing and the part of the plant stops growing.
3. Describe in sequence, the events that occur during each phase of mitosis.
Prophase: chromosomes condense, nuclear envelope begins to disassemble
4. Based on your knowledge of the cell cycle, explain why in the apical meristem there is
a high proportion of cells in interphase and a much smaller percentage in mitotic phase.
5. What are some practical reasons for propagating plants by tissue culture?
Propagation of seedless varieties of fruits
6. What are the advantages and disadvantages of propagating plants by vegetative
propagation?
Advantages: perpetuate the excellent genotype, making many identical plants to use