Computer with Internet access
Research materials on viruses
Research materials on local weeds in your area
1. Review with your students what they know about viruses. Be sure they understand that viruses occur in plants, as well as animals. (You might cite the tobacco mosaic virus, which kills tobacco plants.)
2. Tell your students that they are going to work on a project in which they will suggest a useful purpose for a virus, but first they need to know more about how viruses work.
3. Have students use print research materials and the Internet to add to their knowledge about viruses. (See Vocabulary and Links.) Students should understand the following before they continue with the activity:
- A virus is an infectious organism that reproduces within the cells of an infected host.
- A virus is not alive until it enters the cells of a living plant or animal.
- A virus contains genetic information wrapped in a protein coat.
- A virus that mutates ensures its own survival by making itself unrecognizable to immune systems and vaccines.
4. Divide your class into groups. Ask group members to imagine that they are part of a team of scientists assigned to stop a local weed epidemic by genetically engineering a virus that will target a local pest plant, or weed.
5. Discuss with the class how such a way of using a virus, while useful in some ways, could create dangers to the environment. Challenge students to suggest ways of safeguarding against such dangers.
7. Instruct groups to perform the following tasks to complete their assignment:
- Make a sketch of the target weed.
- Make a sketch of how the virus will look.
- Make a series of sketches showing the stages in the virus's life cycle and the end result of its infection.
- Describe safeguards you would take to keep the virus localized, make sure it isn't harmful to animals or nontarget plants, and ensure that it doesn't persist in the environment once the weeds are gone.
- Make a display of your invention and post it in the classroom.
ADAPTATIONS: Have students work in groups to research viruses that have been used to control weed epidemics. Each group can write a report describing the outcome of such a program and the safeguards that were employed.