Download Lesson Plan - Colorado FFA

Colorado Agriscience Curriculum
Section:
Plant Reproduction
Unit 4:
Plant Reproduction
Lesson Number 2:
Sexual Reproduction in Plants
Colorado Agricultural Education Standards:
AS 11/12.4 The student will demonstrate an understanding of physiological processes in
agriculturally important plants
HRT 11/12.2 The learner will understand and describe the anatomy of horticulture plants.
Colorado Science Standards:
SCI 1.1
Asking questions and stating hypotheses, using prior scientific knowledge to help
guide their development
SCI 3.1
Students know and understand the characteristics of living things, the diversity of
life, and how living things interact with each other and with the environment.
SCI 3.3.5
Using examples to explain the relationship of structure and function in organisms.
SCI 3.3.6
Describing the pattern and process of reproduction and development in several
organisms.
SCI 3.o
Describing how DNA serves as the vehicle for genetic continuity and the source
of genetic diversity upon which natural selection can act.
Student Learning Objectives (Enablers)
As a result of this lesson, the student will …
Objective 1: Explain sexual reproduction of plants and it importance to plant survival.
Objective 2: Explain how pollination occurs and describe the different types of
pollination.
Objective 3: Explain fertilization in flowering plants.
Time: Instruction time for this lesson: 55 minutes.
Tools, Equipment, and Supplies
Power Point or Colored Overheads
Complete Flowers
Dissection Kit
Introduction to Plant and Soils Science and Technology Text (page 57)
Crayons or Colored Pencils
Key Terms.
Chromosomes
Deoxyribonucleic acid (DNA)
Double Fertilization
Fruit
Haploid
Scarification
Sexual Reproduction
Cotyledons
Diploid
Embryo
Genes
Hybrid
Zygote
Cross-Pollination
Disseminate
Endosperm
Germination
Pollination
Self-Pollination
Interest Approach
Acquire perfect or complete flowers from a floral shop (They will usually give you flowers that
are about to be discarded). Work with the class in a dissection to show the students the various
parts of a flower. Dissect the flower and demonstrate to students how the pollen gets from the
anther to the stigma and then grows the pollen tube and travels down through the style to
fertilize the egg. Students should be able to see how thee various parts of the flower interact for
pollination and fertilization to occur.
Summary of Content and Teaching Strategies
Objective 1. Explain sexual reproduction of plants and it importance to plant survival.
Slide 2: Sexual Reproduction in flowering plants involves flowers, fruits, and seeds. In sexual
reproduction, sperm carried in the pollen from the male part of a flower fuses with the egg in the
female part of the flower. Both the sperm and the egg contribute genetic material to the new life
within the seed.
What advantage does sexual reproduction provide to the plant? For survival, a plant species
must live to reproduce in its environment. However, the earth and the environment have been
changing since the beginning of time. Plants adapted to conditions thousands of years ago may
not be able to survive in today’s conditions. Sexual reproduction gives the plant species the
means to change with a changing environment. Every time sexual reproduction occurs there is a
recombining of genetic material. Some genetic changes are beneficial. Plants receiving genes
that enable them to adapt to a changed environment are more likely to survive to pass genes onto
their offspring. Thus, species evolve in order to survive.
Objective 2. Explain how pollination occurs and describe the different types of
pollination.
Slides 3-4
Slide 3: Flowering plants have evolved with a number of methods to accomplish pollination.
Pollination is the transfer of pollen from the male to the female part of a plant. Colorful, scented
flowers attract birds, insects, bats, and other animals. These creatures unknowingly pick up
pollen from the anthers and, when they visit another flower, deposit the pollen on the stigma.
Pollinators are rewarded by the plant with food. They feed on nectar, which is a sugary, energy
rich food made in the flower or the pollen itself, which is a food rich in protein.
Other plants rely on the wind to transfer pollen to the stigma. The force of the wind physically
moves pollen from on flower to another. Since there is no need to attract pollinators, these plants
do not produce colorful flowers with large petals, scents, or nectar. Plants that depend on wind
for pollination actually rely on luck for the pollen of a plant species to blow onto the stigma of
the same species. Plants that depend on wind for pollination produce a great abundance of
pollen to improve the odds that pollination will occur. Ragweed, many trees, and grasses are
wind-pollinated plants. Hay fever suffers are well aware of when they are producing pollen.
When the pollen of a plant pollinates a flower on the same plant, it is called self-pollination.
Some plants have this ability; others do not. When the pollen of plant pollinates the flower of
another plant, it is said to be cross-pollination. Cross-pollination is required for most varieties of
apple trees. Also, it is important to understand that plants must be closely related for crosspollination to occur. For example, an oak tree cannot pollinate a soybean plant.
Once the pollen lands on the stigma, it grows a thin pollen tube down the style to the ovary. The
cell within the grain of pollen divides to form two sperm nuclei. These travel down the pollen
tube to the embryo sac that holds the egg.
Slide 4: Display the diagram on slide four. Utilize a Go-With-The-Flow E-Moment to capture
the anatomy of pollination into the student’s notes.
Objective 3. Explain fertilization in flowering plants.
Slides 5 – 9
Slide 5: Fertilization in flowering plants is unlike fertilization in any other living organism.
This is because both sperm nuclei in the pollen grain are involved in fertilization. Flowering
plants actually have a double fertilization. One fertilization occurs when one sperm fuses with
the egg. The resulting cell is called a zygote. In this process, the sperm carries genetic material
from the male part of the flower. The egg contains genetic material from the female part of the
flower. The resulting seed contains a combination of genetic material received from the male
and female parts of a flower. The other fertilization has the second sperm nuclei fusing with two
nuclei in the embryo sac. It develops into the endosperm. The ovule of the flower becomes the
seed.
Slide 6: The offspring of genetically different parents is said to be a hybrid. People have greatly
improved agricultural crops and animals through hundreds of years of hybridization. The first
farmers saved seed from their best plants for planting the following year. Over many generations
of saving the best seed and discarding the less valuable seed, crops changed. In many cases, you
would find it difficult to recognize the distant ancestors of today’s crops and animals. For
example, ancient corn looked more like a grass than today’s hybrids. The advantage of
hybridizing is the best traits of each parent may be expressed in the offspring. Those traits might
be expressed as more vigorous growth, insect and disease resistance, or uniformity.
Slides 7 – 8: An understanding of genetics is necessary when hybridizing plants. Genetic
information is stored in every cell of a plant or animal in long molecular chains made of
deoxyribonucleic acid or DNA. Segments of the DNA, called genes, code for life processes and
the appearance of a plant. For instance, genes in a petunia plant may code for a red flower.
Genes in that petunia plant also tell it when to flower and haw many petals to make. An
individual plant may have 100,000 genes informing it what to do and how to look.
The genes are arranged in a set of chromosomes. Normal cells contain a double set of
chromosomes and are said to be diploid. Reproductive cells, sperm and egg, have a single set of
chromosomes and are said to be haploid. When fertilization occurs, both the sperm and the egg
contribute a single set of chromosomes. Each cell of the resulting seed ends up with a normal
double set. In this way, traits from each of the parent plants may be passed on to the offspring.
Slide 9: Use a Go-With-The-Flow E-Moment to get the diagram of fertilization into the student’s
notes.
Review/Summary.
All of you did a great job today. We covered a lot of information about sexual reproduction in
plants and began to take a look at plant genetics. Let’s take a few minutes to look back at what
we have learned today. Without looking back in your notes what was sexual reproduction in
plants? Very good, sexual reproduction involves flowers, fruit, and seed. It involves the union
of sperm or pollen with the ovum or egg. Sexual reproduction is what enables plants to evolve to
continue to survive in a changing environment.
What is pollination? Great, pollination is simple the transfer of pollen from the anthers of one
flower to the stigma of another flower. There are two types of pollination, self-pollination and
cross-pollination. Self-pollination is the result from the pollen on one plant landing on the
stigma of the same plant. Cross-pollination is when pollen from the anther of one plant
pollinates the stigma of a different plant.
Finally, we learned about fertilization. Fertilization is necessary in flowering plants for a seed to
develop. Double fertilization is unique to plants; no other organism utilizes this process. The
first fertilization occurs when a sperm unites with the ovum creating a zygote. The second
fertilization occurs when the second sperm unites with the zygote in the embryo sac creating the
endosperm. Hybrids result from cross-pollination and results in hybrid vigor or the passing on of
the best traits from each parent. Genetic information is stored in every cell of the plant in DNA.
Segments of DNA, called genes, establish a code for how the plant looks and functions. Those
genes are arranged into chromosomes. Most chromosomes appear as diploid which is a pair or
set of chromosomes. Sex cells are haploid, which is to say they contain one chromosome and
when fertilization occurs the two single chromosomes are united to form a complete set that is
once again a diploid.
Utilize a Crayon E-Moment to highlight the most important information in their notes.
Application
Extended classroom activity:
Using fast plants duplicate Mendel’s genetic experiment.
FFA activity:
Using LifeKnowledge HS 60 show how through natural selection, the positives traits of plants
are selected, just as individuals select positive relationships to help them grow as a person.
SAE activity:
Invite a local seed dealer to come visit with the class and describe his career and what it entails.