Cotton and Cabbage

Nadja Wehmeyer(1), Kirstin Bittel(2), and Rachel Hughes(3)

1. BioTECH Project, MCB Dept., University of Arizona
2. Mansfeld Middle School, Tucson, AZ.
3. Southwest Environmental Health Sciences Center, University of Arizona

Time: Approximately 2 days and small portions of several days thereafter.
Preparation Time: Gathering pots, plastic cups, netting, soil, seeds, ordering insects, and materials for inquiry.
Materials: B\Bt-cotton and regular cotton seeds
Pots (specific type to order from SOLO cup…)
See-through plastic cups, 4 and 16oz
Cabbage Looper Moths (obtained from the USDA- not needed until week 3)
RoundUp (not needed until week 3)
Planting diagram
Experimental design sheet

Important Considerations!
1. Do not let the Bt-cotton go to seed. Typically it is difficult to get it to this point.
2. Do NOT release Cabbage Looper Moths as caterpillars or moths, dispose of them by freezing them

Students have been introduced in “Just what are you Eating?” to genetically engineered food (GEF) and the controversy surrounding GEF. During this exercise students are introduced to a specific genetically engineered organism. Students will plant a variety of cotton seeds including Bt cotton and will then create experiments using the Cabbage Looper Moth and RoundUp herbicide to determine which plant is genetically engineered and what trait has been added. Throughout the exercise students are asked to observe both the lifecycle of the moth and the cotton. The exercise covers several weeks. Days 1-2 of the exercise includes planting the cotton and designing the experiment. Also on days 1-2, students identify possible uses for GEO. Subsequent days during the cotton’s germination and growth require only a small amount of time for maintenance purposes. At approximately 3 weeks students will assess which plants are Bt Cotton and how effective the engineering of this plant is. This exercise will vary in length and depth depending on the individual teacher and the class. It is advisable that teachers plant some seeds in advance. This activity is based in part on the products on BioTECH’s Biology Bootcamp, specifically the work of Andrew Lettes and Mike Smith.

Students will be able to:
Days 1-2

1. Note how given traits could be achieved by selective breeding and by transgenesis.
2. Identify different uses of GEO (to create possible vaccines, to express relevant pesticides or herbicides and as way to produce food colorations).
3. Recognize that the use of letters (Bt) before an organism’s name means that the organism has had a gene inserted into its genetic makeup that originates from another organism (the Bacillus thuringiensis bacterium). This gene produces a protein toxic to many insects, and previously extracts of the bacteria had been applied to achieve the same goal.
4. identify multiple ways that seeds can disperse

Day 14 and onward:

1. Describe the lifecycle of the cotton plant and Cabbage Looper Moth using pictures and words.
2. Determine the effectiveness of a genetically engineered plant against a pest insect and an herbicide; describe the specificity of the change.
3. Collect and analyze data
4. Design an inquiry using their understanding of Bt cotton and the Cabbage Looper Moth.

National Science Education Standards
Content Area C - Life Science
The Cell
Cells store and use information to guide their functions. The genetic information stored in DNA is used to direct the synthesis of the thousands of proteins that each cell requires.

The Molecular Basis of Heredity
In all organisms, the instructions for specifying the characteristics of the organism are carried in DNA, a large polymer formed from subunits of four kinds (A, G, C, and T). The chemical and structural properties of DNA explain how the genetic information which underlies heredity is both encoded in genes (as a string of molecular "letters") and replicated (by a templating mechanism). Each DNA molecule in a cell forms a single chromosome.

Content Area A - Science as Inquiry

Teacher Background
As has been covered in the previous lesson in the teacher background, genetic modifications of agriculturally important organisms have been conducted since the advent of agricultural practices. In this lesson, students get to have hands-on experience with a genetically engineered organism, Bt-cotton.
Bt (Bacillus thuringensis) is a soil bacterium. B. thuringensis makes a toxin that, when ingested by insects, affects the digestive tract to decrease their ability to obtain nutrients from their food. Insects die either by starvation or by septicemia. Until recently, extracts or slurries of this bacteria were prepared to spray on crops (called a foliar treatment). These had a limited time period in which they were active, as they had to be in the right place and time to be munched on by the insects and they do degrade in the environment.
Scientists more recently (mid 1980’s) found a way to incorporate the gene for the toxin into the genome of the plants affected by these insects. This way, the plant makes the toxin and insects that feed on the plant leaves (where the toxin is expressed) will ingest it and have the same effect as if they had ingested the bacteria. Incorporating the gene is done using either a vector (a plasmid of Agrobacterrium tumefaciens that scientists put the desired gene into and will incorporate it into the genome of the plant.) or by shooting tiny metal balls covered with the desired gene into plant cells which will then incorporate these segments into the genome.
For more information, use the sites below.

Related Websites

Link to GEO related information
http://pewagbiotech.org/resources/factsheets/display.php3?FactsheetID=2 - 2003 state of genetically engineered crops in the US, emphasis on soy, cotton and corn.
http://www.sciencedaily.com/releases/2000/09/000904092612.htm - describes the impact of genetically engineered herbicide tolerant crops on bird populations
http://www.biotechknowledge.monsanto.com/biotech/bbasics.nsf/faq.html - OpenPage - Monsanto site that gives genetic engineering information

Cabbage Looper Moths and cotton biology
http://creatures.ifas.ufl.edu/veg/leaf/cabbage_looper.htm – cabbage looper biology and lifecycle
http://www.mhhe.com/biosci/pae/botany/botany_map/articles/article_30.html - info on cotton biology

Bacillus thuringiensis - it should be clear that Bt and transgenic use of Bt toxins are different things
http://www.ext.colostate.edu/pubs/insect/05556.html - overview of Bt- very reader friendly.
http://ace.orst.edu/info/npic/factsheets/BTgen.pdf - overview of Bt, more scientific w/ LD50 values and references
http://www.umass.edu/umext/ipm/ipm_projects/landscape/bt.pdf - short synopsis of Bt for foliar application

GEO’s in the classroom
http://biotech.biology.arizona.edu/labs/bt_cottonSG.html - describes a PCR activity using Bt-cotton, begins with an ok commentary on the differences between selective breeding (artificial selection) and transgenesis
http://www.uga.edu/discover/educators/activities/act6.pdf - was an inspiration for this exercise, you can find more great exercises at: http://www.uga.edu/discover/educators - compares Bt and non-Bt corn with European Corn Borers (ECB’s)
http://www.angelfire.com/az3/a_lettes/2002/btcotton/plant.html - shows a class sample of cotton plants before and after the attack of the Cabbage Looper Moth!



Initial question on the board: “How does genetic engineering of organisms differ from modifying their genes with selective breeding?”

Day 1
1. During the last class period students were asked to review their evening meal to see what the prevalence of GEO’s are on their diet. Engage students by connecting to yesterday’s class and homework. Ask them: “Yesterday we discussed the prevalence of GEO in our diet, what did you notice in your dinner last night? Any GEO’s?” Discuss what might have been in their dinner and ask why those particular plants might have been engineered. Set up a chart with changes that might be desirable.
(If students seem interested in how this is done, you might use the following to demonstrate transgenesis: http://www.pbs.org/wgbh/harvest/engineer/, they will get a chance to do this again later in the semester in “Chocolate Flavored Cherries”)

2. Introduce the seeds to the students, “I actually have some GEO seeds here along with some wild type seeds. They are color coded so I can tell the difference. I am, however, not going to tell you the difference! I’m also not going to tell you what changes have been made, but I am going to expect you to determine which is the genetically engineered plant and provide evidence in support of that.”

3. Tell the students that you will narrow the types of possible changes to three. 1) The plant contains a gene that makes it not susceptible to the herbicide RoundUp. 2) The plant contains a gene that is a natural insecticide. 3) The plant contains a gene that accelerates the plant’s lifecycle.

4. On the board, list each of the changes and have students describe how each might be accomplished by selective breeding. Then remind them that, in this case, the traits have been added through genetic engineering. On the board take down their ideas about where these traits could have been taken from (1-tough weeds, perhaps, 2-something that kills insects, either another plant, bacteria, virus, 3- a fast growing plant). Ask students if it is possible to selectively breed anything (green polka-dot corn, for example)? Is it possible to genetically engineer anything?

5. Provide students with information about how to plant the seeds. As a hint tell them that they should design their planting pots using the solo cups with the netting across; consult the planting diagram.

6. In their groups students should identify the variables involved and controls needed in testing these plants for specific engineered genes. Students should write out their experimental design, figuring out how many seeds and pots they will need. Before receiving soil, seeds and plants, students should get approval on their design. See design sheet.

7. Students plant seeds. Remind students that they are responsible for taking care of the plants and watering them. Students should make DAILY observations and measurements over the next three weeks until the next stage of the lab.

Day 20 after seed planting
8. Introduce the tools to test the plants with- RoundUp and Cabbage Looper Moth egg masses. Students may already have come to a decision about the third option- a more robust plant- as they should be measuring the plants daily.

9. Prior to today, students have been looking at some of the issues associated with the use of pesticides and herbicides. This is a good time to remind them about what they have learned while handling the RoundUp. Spraying the plants should be done in a well-ventilated area.10. Students apply treatment and observe for the next few days. What happens? They should record what happens in their science notebooks.

Day 24 from seed planting

11. Students use the information sheets to support their explanations as they write their lab report.

This is a long project, so make sure to make time to talk with students about how this experiment fits in with the rest of the lessons in this unit. They are using an organism that has been changed through our knowledge of how genetics works and the improving of technology to allow us to manipulate genes. Ask them to consider what this means to them. Throughout the semester they are increasing their knowledge, and ultimately realizing different ramifications to these technological advances. Be sure to bring this all up again in “Golden Rice or Frankenfood”.

Students will be asked to complete a lab report at the end, using information sheets/data sheets they have kept over the previous 3.5 weeks. Some of the questions asked in class on the first two days could also be take-home questions to answer as a family. Students’ explanations of their results may be evaluated.

Embedded Assessment

There are opportunities for group participation throughout this lesson. Evaluate group dynamics, follow-through and organization. Also, as this lesson spans a long period of time, there is ample opportunity to have students reflect on their evolving ideas about transgenic crops.


PULSE is a project of the Community Outreach and Education Program of the Southwest Environmental Health Sciences Center and is funded by:

NIH/NCRR award #16260-01A1
The Community Outreach and Education Program is part of the Southwest Environmental Health Sciences Center: an NIEHS Award


Supported by NIEHS grant # ES06694

1996-2007, The University of Arizona
Last update: November 10, 2009
  Page Content: Rachel Hughes
Web Master: Travis Biazo