Students will compare and contrast methods of selective plant breeding, describe the scientific process of creating a genetically modified plant, compare genetically modified soybean seeds to conventional soybean seeds, describe the impact weeds have on plant growth, and understand how a genetically modified seed can help farmers manage weeds.
Preparation Note:While not required, it is highly recommended (for a greater "wow" factor) that you plant and grow conventional and GM soybean seeds to the stage of first or second true leaves (about three weeks) and conduct the Leaf Test Lab as outlined in Activity 4. Many students have never grown a plant let alone conducted a test to determine if it contains a protein signifying that it has been genetically engineered. For this lesson to flow in your classroom, it is suggested that you plant the soybean seeds as you complete Activity 1 and then circle back to Activity 4 when the soybean plants have true leaves to complete the lesson. Planting instructions are found in Activity 4. If time does not allow you to grow the seeds, the GM Soybean Seed lab (in Activity 4) will also demonstrate the same concept, but with less "wow." Safety Note: Let students know that they will be working with soybeans and if they have a soybean allergy please take precautions.
genetically modified organism (GMO): an organism whose genome has been altered by adding one or more genes
transgenic: an organism that contains genetic material (DNA) from an unrelated organism
farming: the activity or business of growing crops and raising livestock
protoplast: a plant, bacterial, or fungal cell that had its cell wall completely or partially removed using either mechanical or enzymatic means
particle gun bombardment: a method by which foreign substances such as DNA are introduced into living cells and tissues via high-velocity microprojectiles
Agrobacterium tumefaciens: a rod-shaped, gram-negative soil bacterium which can be used to introduce new genes into a plant cell
Roundup herbicide: systemic herbicide and crop desiccant containing Glyphosate used to kill weeds especially annual broadleaf weeds and grasses
genetically engineered (GE): an organism or crop whose characteristics have been deliberately modified by manipulating its genetic material
genetically modified (GM): an organism or crop containing genetic material that has been artificially altered so as to produce a desired characteristic
cross breeding: the intentional breeding of a plant or animal with another breed, species, or variety
mutagenesis: a process by which genetic information of an organism is changed, resulting in a mutation which can occur spontaneously or as a result of intentional exposure to mutagens
polyploidy: cells and organisms containing more than two paired (homologous) sets of chromosomes
protoplast fusion: a type of genetic modification in plants when two distinct species are fused together to form a new hybrid; also known as "somatic fusion"
transgenesis: the process of introducing an exogenous gene, called a transgene, to a living organism
phenotype: the set of observable characteristics of an organism resulting from the interaction of its genotype with the environment
genotype: the genetic constitution of an individual organism
herbicide: a substance that is toxic to plants and is used to kill unwanted vegetation
transformation: the introduction of exogenous genes into plant cells, tissues, or organs
tolerant: ability of a plant or animal to endure
glyphosate: a synthetic compound (herbicide) commonly used to kill weeds (unwanted plants)
Did you know? (Ag Facts)
Farmers began cross breeding plants in the 1700s to perpetuate ideal plant characteristics.1
Herbicide- and insect-resistant crops began introduction and adoption in 1996.2
There is no substantiated evidence of a difference in risk to human health between current commercially available genetically modified (GM) crops and conventionally bred crops.3
Weeds damage cultivated crops by reducing crop yield; competing for water, nutrients and light; reducing the quality of the harvested crop; and by harboring harmful insects, pests, and disease pathogens.9
The use of herbicides to control weeds allows farmers to practice conservation tillage (reduced- or no-till farming) which decreases erosion, runoff, and the escape of greenhouse gasses from the soil when it is tilled.16
Background Agricultural Connections
Interest Approach – Engagement
At the beginning of class, open the What is the Difference? Kahoot survey. Complete the four-question survey with students, allowing them to use personal devices to answer the survey questions.
If students do not have access to devices for the Kahoot survey, use the optional attached PowerPoint to complete the survey.
Following the survey, discuss with students that each difference (illustrated in the 4 pictures) is due to a genetic change. Using our knowledge of science, plant breeders have learned many ways to change and improve the genetic traits of plants. For example, drought tolerant corn (question 1) was developed using cross-breeding. Strawberries (question 2) are larger due to a plant breeding method called polyploidy which increases the number of chromosomes in the plant's genome, and corn plants (question 3) can become genetically resistant to pests like European Corn Borer after acquiring a gene that produces a protein that kills the pest.
Explain that these are just 4 examples of desirable traits found in plants. There are many more that range from resistance to disease or herbicides to characteristics of fruit like color or sweetness.
Activity 1: Crops vs. Weeds Simulation
Ask students to brainstorm and list ways that farming could be considered a gamble. Students may list factors in agricultural production that are outside of the farmer’s control such as the weather, weed or insect infestation, and market prices. In addition, farmers make dozens of decisions each day that determine the success or failure of their crop. Unlike the weather, these factors are in their control. Examples include choosing which type of seed to plant, seed source, fertilizer type and application, equipment, herbicides, insecticides, and fungicides.
Point out that some farmers choose a seed that helps control the weeds that would grow in their field.
Explain to students that they are going to do a simulation illustrating why farmers need to control the weed growth in their fields. Each of them will represent a plant. Some will be a planted crop and others will be weeds. Distinguish between a desired plant and a weed by explaining that weeds are plants that are not desired in a specific growing area. For example, corn growing in a soybean field would be considered a weed.
It's critical for students to understand that weeds in a field of crops are not just undesirable for aesthetic reasons. Weeds reduce overall crop yield and use limited natural resources such as water and nutrients found in the soil.
Choose an open area to represent a field where your students (plants) are growing. A vacant hallway, outdoor space, or any other large space works well. Explain to students that plants have roots and cannot move to a new location. Throughout the simulation students cannot move their feet, but they can move their arms.
Complete Round 1:
Before class, prepare sample green and red cards in a 3:1 ratio to account for the number of students in your class. These cards will help divide your class by assigning 75 percent to be crop plants and 25 percent to be weeds (green=planted crop, red=weed).
Explain that you (the teacher) will play the role of “Mother Nature.” Choose three students from your class to represent the resources of rain, sunlight, and fertilizer. Give each student the poker chips representing their resource (blue=water, red=sunlight, black=fertilizer).
Pass out the green and red cards at random to the remaining members of your class. Line up the students with green cards in rows to simulate a field of planted crop. Students should be far enough apart that they cannot touch when arms are extended. Students with red cards will then “plant” themselves anywhere in the field at random.
Instruct the three students representing resources to sprinkle their “chips” around the feet of the students representing crops and weeds. They should do so after your prompt. For example, “Water, you may make it rain a lot.” [wait a couple of seconds for students to drop blue chips on the floor]. “Okay, the rainstorm is over.” [water stops tossing blue chips.] Continue similar prompts for sunlight and fertilizer. Students (crops and weeds) will scramble to pick up as many poker chips as they can without moving their feet (roots).
Note that the three students representing resources may move around as they please during the simulation. For example, one section of the field may receive a lot of sun but no water.
At the end of the round, students who have exactly three of each color may stay standing and go to “harvest.” Students who did not collect three of each chip should sit down to represent the plant dying due to a lack of resources.
Note that too much rain, fertilizer, or sun can damage plants.
Round 2: Repeat steps outlined above, except begin with 50 percent of the students representing weeds and 50 percent representing planted crops.
Round 3: Repeat steps outlined above, except begin with 75 percent weeds and 25 percent planted crops.
Conclude the activity with questions such as:
What resources/elements do plants need to survive? (Sunlight, water, and soil nutrients)
Why are weeds a problem for farmers? (Water and soil nutrients such as nitrogen, potassium, and phosphorus are in limited supply. If they are consumed to grow weeds instead of food crops, it limits our ability to produce food in an efficient and effective manner.) Display the images of soybeans with and without weed control to illustrate.
How can farmers control weed growth in their fields?
Activity 2: Methods of Crop Modification
Pass out one copy of the Crop Modification Interactive Notebook Pages. Instruct students to cut out the pieces of the layered tabs.
As students are cutting out their layered tabs, draw on their prior knowledge and review basic concepts of inheritance and genetics. Students should be able to distinguish the difference between phenotype and genotype, understand basic principles of genetic inheritance from parent to offspring, and recognize the difference between dominant and recessive genes.
After reviewing the vocabulary and principles above, explain to the class that there are numerous methods plant scientists can use to improve plants.
Brainstorm examples of genetic traits that could be desirable in plants. Examples include:
Resistance to plant disease
Resistance to pests
Nutrition content of edible plant parts (fruits, vegetables, or grains)
Flavor or texture
Size or color of flowers or leaves (for ornamental plants)
Instruct students to work individually or in groups to match the three layered tabs that represent: 1) crop modification technique, 2) its description, and 3) an example of each of the six different modification methods.
After students have had a chance to match these to the best of their ability, review each method. Discuss each plant modification method, applying what students already know about genetic traits, DNA, and inheritance.
Have each student place the layered tabs inside their interactive notebook OR on a blank sheet of paper (if you don’t use interactive notebooks), matching the correct modification method, description, and example.
As a class, discuss the benefits and potential drawbacks of each plant modification method. Instruct students to keep notes about each method as you go about your discussion (see example pictured below). Share the Comparing Methods of Genetic Modification in Plants Table.
Ask students the following questions to gather their thoughts and existing perceptions:
Which method is best?
Which method is least desirable?
Which method do you think would be most efficient in creating plant varieties to produce a healthy and abundant food supply?
Summarize with students that our scientific knowledge of genetics and inheritance has allowed us to improve and change crops to be healthier (more resistance to disease and pests), to utilize natural resources (such as water and soil nutrients) more efficiently, and to improve the overall quality and taste of our food. Review the benefits and drawbacks of each method, helping students understand that each method has limitations and applications for different circumstances.
Three Dimensional Learning Proficiency:Science and Engineering Practices Students engage practices of science and engineering as they formulate questions that can be answered through investigation and formulate a problem that can be solved through design.
It is critical for students to understand that no single modification method can be used successfully to reach the goals of ALL farmers and consumers. Each method has benefits and drawbacks unique to every plant. For example polyploidy is a benefit in the seedless watermelon, but it could be a drawback in another plant if it increases the size of the fruit and causes it to become watery in flavor.
Activity 3: How Are GMOs Created?
Write the following terms on the board: transgenic, genetically modified (GM), genetically engineered (GE), and genetically modified organism (GMO). These words are often used synonymously.
There are many words associated with genetically modified organisms. Clarify the definitions of each term and acronym for better understanding.
Ask students to share what these words and acronyms mean to them. Do they know what they mean? Do they have a positive or negative association to the words? Explain that this activity will focus on the science of the GMO and the steps used to create a genetically modified plant.
Pass out the How to Create a GMO Interactive Notebook Page. Instruct students to cut out the diagrams and place them in their notebook or on a blank sheet of paper (if you don’t use interactive notebooks) using tape or glue.
Beginning with the number one at the top of the diagram, go through each step of the process (left to right, top to bottom).
After you have explained each step of the process, introduce students to an example of a transgenic crop, Roundup Ready® Soybeans.
Give each student one copy of the handout Creating the Roundup Ready® Soybean. Instruct students to read the handout and create their own diagram representing the steps taken in the creation of the Roundup Ready® soybean by adding words and illustrations.
Activity 4: How Do You Know it's a GMO?
This final activity allows students a hands-on opportunity to see and handle the seeds and/or plants of both conventional soybeans and genetically modified soybeans. You may choose to complete just one, or both of the lab activities below. If time is short, choose the GM Soybean Seed Test. If you have additional time and resources to grow the soybeans, continue to the GM Soybean Leaf Test allowing students the unique opportunity to not only compare the seed, but the germination and growth of conventional and GM soybean plants.
GM Soybean Seed Test Lab
*This lab can be completed as a classroom demonstration or by placing students in small groups. For a classroom demonstration, you will need one GM Soybean Seed kit per class. To allow students to perform the test in groups, provide one kit per group.
Using the seeds in the GM Soybean Seed Kit, allow students to observe and compare the seeds. Let them know they are the same type of seeds pictured in question #4 of the Kahoot they completed at the beginning of the lesson. Ask students to examine the seeds and look for observable differences in size, shape, and color. Little or no difference will be found in the seeds.
Note: As students observe the seeds, be sure the two varieties are kept separate. Place seeds in ziploc bags for observation to help avoid cross contaminating the seeds during observation.
Explain to the class that although the two seeds look the same, there is a difference between them, and you are going to do an experiment to discover it.
Complete the following lab test for the class to see:
Label the reaction vials for identification of the seed that will be tested by labeling one vial "A" and the other vial "B".
Break the seed by placing one Roundup Ready® soybean seed between two small weigh boats and tapping it with a hammer. The seed should break into two to three pieces to allow enough surface area to be exposed for extraction. Do not crush the seed. Crushing can cause issues recovering all the pieces for extraction and may cause cross contamination of the testing area. Repeat this step with the conventional soybean, using separate weigh boats to avoid cross-contamination.
Remove the top weigh boats and place the seed pieces into the correct reaction vial. If the seed is stuck to the boat, use tweezers to gently release it. Do not touch the seeds with your hands (clean tweezers with 50-70% ethanol to prevent cross contamination).
It's important to understand that GM seeds are perfectly safe to touch. The only reason you shouldn't in this experiment is to avoid altering the test results by cross contaminating the seed samples or contaminating the experiment with human microbiome.
Use pipette to fill reaction vial with 1% PBS buffer or distilled water (approximately 0.5 mL). Using the pipette as a pestle and the reaction vial as a mortar, stir the seed pieces and distilled water together for 20-30 seconds. Be sure to stir with separate pipettes to avoid cross-contamination.
Let the vial with the seed/distilled water mixture stand for three to five minutes.
Place one QuickStix test strip inside each reaction vial, with the arrow pointing down.
Allow the test to incubate in the reaction vial at room temp for five minutes. While the test incubates, explain how the lateral flow test strip works using the information found in the Background Agricultural Connections section of the lesson. Conclude with students that the test will show a “positive” line if an additional protein is found in one or both of the soybeans. Both test strips should have a "control" line indicating that the test is functioning.
Note: You may see positive results in less than five minutes, however the full incubation time will allow for the negative control to fully develop.
Interpreting Results: If the sample contains CP4 EPSPS protein, a second line will develop between the control line and the tape with the arrow on it. If the sample does not contain the CP4 EPSPS protein, a second line will NOT be present on the test strip.
Ask students, “Is there a difference between these two varieties of soybean?” Guide a class discussion for students to conclude that these two varieties of soybean are fundamentally the same. They are both soybeans. However, one variety has a protein that the other does not which gives the plant resistance to the herbicide glyphosate.
Ask students, "How did this seed obtain the unique protein?" (transgenesis)
GM Soybean Leaf Test Lab
*This lab can be completed as a classroom demonstration or by placing students in small lab groups. For a classroom demonstration, you will need one GM Soybean Leaf Kit per class. To allow students to perform the test in groups, provide one kit per group.
Gather the Roundup Ready®soybean seeds, conventional soybean seeds, and planting supplies outlined in the Materials section of the lesson. Plant the seeds using the following steps:
Fill tray with soil media, level soil throughout the tray, and saturate with water.
Use a pencil to press a hole into the moist soil 1/2 inch deep.
Drop a soybean seed into each hole and sprinkle soil on top of all seeds.
Note, you can label and separate the Roundup Ready® seeds from the conventional soybean seeds, or you could mix the seeds up and plant them randomly without labeling to see if students can distinguish one plant variety from the other.
Place seed tray in a location that receives at least eight hours of bright light per day and maintains warm temperatures of 75-85.° For best results, add water to the bottom tray.
Check plants daily for watering and growth. Water trays only if soil is dry. Avoid over watering, but be sure to keep plants from wilting.
Students should make regular observations of the germination and growth of the plants. Have students record their observations in their interactive notebook or on a worksheet with column headings such as Date, Temperature, Plant Growth, and Observations.
Allow the seedlings to grow for 2-3 weeks or until true leaves appear. (The first two leaf-like structures that emerge from the soil are cotyledons, not true leaves.)
Once students have adequately observed the plants and compared them, complete the following lab to test the leaves of the soybean plants for the CP4 EPSPS protein:
Label the microfuge tubes for identification of the plant (leaf) that will be tested by labeling one microfuge "A" and the other microfuge "B."
Obtain 1 leaf from a conventional soybean plant and 1 leaf from a Roundup Ready® soybean plant. Use a true leaf, not a cotyledon (see diagram in Materials section).
Take a leaf punch using the microfuge tube by placing the leaf between the cap and body of the tube. Close the lid of the tube and tear away extra leaf from around the outside of the closed tube. Allow the leaf punch to fall into the tube.
Use the micropestle to push the leaf punch into the bottom of the tube.
DO NOT grind the leaf tissue yet! Over extraction can cause chlorophyll to collect in the test band line of the strip and make it difficult to interpret the results.
Throughout the lab, use separate tools (micropestle, stir stick, and pipette) for each sample. Cross contamination of the leaf samples will void the test results.
Use pipette to add ~0.5mL of 1% PBS solution or distilled water into each microfuge tube containing leaf tissue.
Macerate the leaf (smash up/grind) using the micro pestle until the leaf is broken into pieces. This doesn’t take much. Once you see some green color in the water the sample has been extracted.
Use the stir stick to mix for 30 seconds. You may also close the lid and shake for 30 seconds.
Place 1 QuickStrip test strip in each reaction vial with the arrow pointing down.
Allow test strip to incubate at room temp for 5 min.
Note: You may see positive results earlier than 5 min, however full incubation time will allow for the negative control to fully develop.
A single control line should develop on both tests to indicate a successful test. If it does not, dispose of the strip and retest a new sample with a new strip.
If the sample contains CP4 EPSPS protein, a second (positive) line will develop.
If the sample does not contain the CP4 EPSPS protein, a second line will NOT be present on the test strip.
Summarize results with students. Discuss the similarities and differences of the soybean varieties.
*Note: Formulations of Roundup® available to home owners for lawn and garden use typically have additional ingredients that will kill both the conventional and the Roundup Ready® soybean plant. Spraying the plants with Roundup® as a class demonstration is discouraged and will not be successful if the correct, glyphosate-only spray is not used.
Three Dimensional Learning Proficiency:Science and Engineering Practices Students engage practices of science and engineering as they formulate questions that can be answered through investigation and formulate a problem that can be solved through design.
Discuss the crop modification methods. Ask the following questions:
Which method uses an enzyme to literally change the genetic code (it has the ability to literally edit a genetic sequence like a typewriter)? (genome editing- CRISPR)
Which method increases the number of chromosomes? (polyploidy)
Which method promotes genetic mutations in hopes of randomly generating a new and desired gene? (mutagenesis)
Which method transfers a desired gene from one species to another? (transgenesis)
Which method takes place without scientific intervention and involves specifically cross pollinating two plants with the purpose of improving each generation of plants? (cross breeding)
Which method uses biotechnology to fuse the cells of two different species? (protoplast fusion)
Provide students with a scenario. Explain that they operate a farm with several hundred acres of crops. In groups or pairs have students discuss what type of weed control method they will use. Ask students to think, pair, share advantages and disadvantages of using GM seed to manage weeds.
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Ask students to find two YouTube videos or a website about GMOs. Using their knowledge of the science of a GMO, determine if the video or website is scientifically accurate.
This lesson focuses on the science of a genetically modified seed and its benefit to a farmer to control weeds. While the science is clear, social, environmental, and economic arguments contribute to GMOs being a topic of controversy. See the Evaluating Perspectives About GMOs lesson to address and evaluate multiple perspectives.
Assign students to visit the GMO Answers website. Assign students to ask a question by typing it into the "search" box on the website. After students read the Q&A forum, assign them to summarize what they learned as part of a "bell work" assignment or an "exit ticket" at the end of class.
Watch the video clip How are GMOs Created? to summarize and further illustrate the process of creating a GMO.
To demystify the science concerning molecular biology and genetics consider conducting "hands-on" experiments with PCR tools. The technique is used by scientists in agriculture, medicine, and criminal justice (to name a few). MiniPCR provides inexpensive hardware, software, and classroom tested curriculum resources for a deep dive into DNA. Other PCR machine options maybe found with a Google search.
For a lesson comparing the use of organic and conventional farming (GMO vs non-GMO) see FARMLAND: GMOs and Organic Agriculture. This lesson plan utilizes the documentary by James Moll titled Farmland which highlights the joys and challenges of three conventional farmers and one organic farmer.
Watch The Journey to Harvest (3:01 mins) and learn about the 20-year journey of the Arctic Apple®. As a class discuss how arctic apples could decrease food waste and other consumer benefits such as convenient packaging and nutrition. Visit the Arctic Apple® website for more information.
With permission, portions of this lesson were adapted by the National Center for Agricultural Literacy from the original lesson packet, Crop Biotechnology: Growing and Testing Roundup Ready Soybeanprovided by Monsanto.