Unit 2: Seeds: the Record-Keepers

Unit 2: Seeds: The Record-Keepers

Lesson 2: Pollination and Hybrid Seeds

Grade Level: Third Grade

Time Required: 45 – 60 minutes

Primary AZ State Standards:

(Cross-reference “Standards Matrix” for full listing)

Science:

S03-S3C1-02: Describe the beneficial and harmful impacts of natural events

and human activities on the environment.

S03-S4C1-01: Describe the function of the following plant structures:

-flowers, attract pollinators and produce seeds for reproduction.

Objective(s):

Students will examine flowers and identify flower parts involved in pollination.

Students will create a hybrid fruit or vegetable.

Students will analyze the environmental and financial impacts that seed company technologies have in our society.

Background Information:

As much as we would like to believe that flowers were created for our enjoyment, the truth is that flowers are actually solely to ensure seed creation. Flowers lure in pollinators with their attractive petals and smells to pollinate and fertilize seeds. Only through the process of pollination will plants produce the fruits and vegetables of which we are so fond.

Flowers have several key parts which students should review for this lesson. (Willow Bend Environmental Center does a program called “Reason for a Flower” which would be a great class for students to have prior to this lesson. The Arboretum at Flagstaff also offers a 4th grade program on “Pollination” that would reinforce these same concepts.) Flowers have both male and female parts. The female parts are contained in the pistil. The parts of the pistil are called the stigma, the sticky top part that catches pollen; the style, a tube that lead down to the ovary; and the ovary, which is where the seed grows safely protected. The male parts are contained in the stamen. The stamen consists of the anther, which is a ball like structure which produces pollen, help up by the filament. Pollination occurs when the pollen is transferred from the male flower parts to the female flower parts. The tiny grain of pollen either flies on the wind or is carried by a pollinator to the sticky stigma, is transferred down the style into the ovary where it fertilizes an egg and becomes a seed.

Heirloom seeds, as discussed in Lesson 1 of this unit, are open-pollinated, which means that pollination occurs naturally in the field. Seeds from heirloom plants can be harvested and replanted year after year, reliably producing offspring that exactly resemble their parent plants.

Hybrid seeds, however, have been artificially cross-pollinated with the goal of producing more durable, resistant, tasty, or attractive plant. People who create hybrids choose different plants to breed together based on qualities of each that they wish to preserve. Unfortunately, because the breeding is unnatural, the next generation of seeds from hybrid plants cannot be relied upon to produce exact copies of their parent plants. As a result, hybrid plants can only be reliably grown from first generation hybrid seeds produced by seed companies.

One seed company in the United States has taken the process of hybrid seed manufacturing step further. They have introduced a terminator gene into seed development that causes subsequent seeds to become sterile, which means the seeds won’t even grow a new plant. The scary thing about this terminator gene is that it can be genetically transferred to other plants through open pollination, by traveling within pollen on the wind, to other non-hybrid plants in the environment. When this happens, then the newly contaminated plant will begin producing sterile seeds. The seed company’s goal is to force farmers and gardeners to buy new seeds from them every year, not save seeds and replant on their own. For more information about this new technology, please see

Pre-lesson Preparation:

Print out Appendix 3J, cut up labels and distribute among plastic easter eggs.

Activity Instructions:

Flower FunctionReview and Exploration

Whole class, individual

5- 20 minutes (can be shortened to a simple 5 minute review if students have recently learned about flower parts and functions)

Gather students as a whole group. Pass around flowers, have students inspect them and answer the question, “What purpose to flowers serve?”
Have students freeze with whatever flower they have in their hand and take them back to their desks.
Explain that everyone is going to look at their flower with the hand lens and describe the parts they see.
As students find the parts of the flower, ask them what they think those parts do.
After some discussion, show Appendix 3J and discuss the parts of the flower.
Discuss open-pollination versus hybrid pollination.

Creating a Hybrid

Partners

20 minutes

Tell students, “So imagine you are a seed company. What kind of new plant would you make if you could? The best inventions are ones that are driven by people’s needs. What kinds of fruits and vegetables do you think people need?”
Explain and model the task with an example hybrid (strawberry/banana).
Students will work in pairs for 10 minutes to design a new fruit or vegetable by mixing qualities of different fruits or vegetables.
Students should name their creation and be ready to “sell” it to the class as if they were the seed company.
Students should also figure out how much they wanted to charge for a package of their seeds.
Put students in pairs.
Distribute blank paper and drawing/coloring tools. Give them 10 minutes to work.
After 10 minutes, have students share creations.
Ask students, “So what would happen to your company if people bought one pack of seeds, planted 10 or 20 plants, and then just collected the seeds from those plants and planted them again?” If the seeds were viable and produced offspring that were identical to the parents, people wouldn’t need the seed companies anymore.

The Impact of Seed Company Technologies - Simulation

Whole class

20 minutes

Tell students, “This next activity is to get you thinking about the challenges that seed companies have and the solutions we need to find together to make sure our ecosystems don’t get hurt.”
Get students back together as a whole group.
Ask the group, “As a seed company, what would you do to make sure that people keep buying seeds from you?”
Tell students the information about terminator genes as explained in the Background section. Before revealing to students how ecologically damaging this technology could be, have them predict how they think it would affect seed companies and how it would affect the environment.
Tell students, “To get a better understanding, we are going to an activity now to help you think about the financial and ecological impacts that seed company technologies may have.”
Explain the activity to students.
The teacher will place Easter eggs all over the room. The Easter eggs are actually “the flowers” that contain the plants’ seeds. The flowers will either have heirloom seeds, hybrid seeds, or seeds that contain the terminator gene. They will also have information that the farmer/gardener needs to know (See Appendix 3K for inserts).
Students will walk over to a place where there is an egg and stay there with the egg.
Students will open up their flowers (eggs) and read their information, and complete any activities that may be required.
Finally, students will share information they learned.
The key to this activity is that any student that opens an egg with a terminator gene will sterilize all heirloom (and hybrid) seeds within a 15 foot radius. You can adjust this distance as needed. Encourage students to actually measure out this distance with a tape measure, string or yard stick.
In closing, ask students:

What affects might these seed company technologies have on gardeners’ and farmers’ bank accounts?

What affects do the technologies have on the seed companies’ bank accounts?

What affects do the seed company technologies have on the environment?

What do you think you, as a gardener, should do?

Resources:

Organic Consumers Association Website.Accessed June 18, 2010 from