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Principles of Agricultural Science – Plant
1
Principles of Agricultural Science – Plant
Pollination and Fertilization
Unit 7 – Sexual Reproduction
Lesson 7.2 Pollination and Fertilization
2
If We Have Pollen…
pollination can occur.
Pollination is the transfer of pollen from the
anther to the stigma of a flower.
3
Types of Pollination
Some plants use different methods to
achieve pollination:
 Self-pollination: Transfer of pollen from
the anther to the stigmas of the same
flower or to flowers on the same plant.
 Cross Pollination: Transfer of pollen
between two plants that are not of identical
genetic material.
4
Mechanisms Used for Pollen
Transfer




Animals
Insects
Water
Wind
5
Attracting Pollinators
The flower uses important features to attract
animals and especially insects to help the
pollination process:
 Bright petal colors
 Fragrance
 Nectar
6
Fertilization
Fertilization is the union of pollen with the ovule to
produce seeds.
Once pollen grains are transferred to the stigma:
1. Pollen grains move through the pollen tube to
the ovule.
2. A pollen gamete unites with the egg cell
gamete in the ovule.
3. Ovary swells and forms the fruit.
7
A Microscopic View: The Birth of
Pollen and Egg Cells
Pollen and egg cells must undergo the
process of Meiosis to become haploid.
Meiosis is a type of cell division that
reduces the number of chromosomes in
new cells by half.
8
Start With a Sex Cell
• Male and female productive organs
produce sex cells also called germ cells
• The nucleus contains chromosomes,
which carry genes.
Chromosome
Nucleus
Chromatid
9
Meiosis I
Diploid cells, which are cells with two sets of each
chromosome.
Diploid
Sex Cell
Matching chromosomes separate
Haploid
Cells
10
Meiosis II
Cells divide again to produce haploid gametes.
This process
happens for
both pollen
and egg cells.
Four gametes are produced
11
From Gametes Back to a Diploid
I
Pollen Gametes
I
I
I
I
Egg Gametes
I
I
I
Fertilization
This new
cell is called
a zygote.
II
12
The Development of a Zygote
Cells undergo rapid mitosis
as the zygote grows.
Parent Cell
Replication
Cell Division
You will learn more about mitosis in a
later activity.
Daughter
Cells
13
The Next Step
Following fertilization, division of the zygote
will continue the cell replication process.
This process is called mitosis.
14
Mitosis
Mitosis is the division of cells to produce
daughter cells that contain a full set of
chromosomes.
15
Phases to Mitosis
•
•
•
•
•
Interphase
Prophase
Metaphase
Anaphase
Telophase
Mitosis phases will be explored further in Activity
7.2.2 A Closer Look at Mitosis.
16
References
Herren, R. V., & Donahue, R. L. (2000). Delmar’s
agriscience dictionary with searchable CD-ROM. Albany,
NY: Delmar.
Parker, R. (2004). Introduction to plant science (Rev. ed.).
Clifton Park, NY: Delmar.
Schooley, J. (1997). Introduction to botany. Albany, NY:
Delmar Publishers.
Toogood, A. R. (Ed.). (1999). American Horticultural
Society plant propagation: The fully illustrated plant-byplant manual of practical techniques. New York, NY:
Dorling Kindersley.
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