Case Study: Tougher Plants 1. The major stresses agricultural plants face include heat in the summer, frost in winter, and salt from irrigation. 2. In figure 2, the wild type is represented by the normal tomato plant. L1 is the mutated form of the wild type. 3. Glycine betaine makes the leaves, flowers, and fruits resistant to severe or lethal frost-damage in cold-exposed plants through osmotic regulation. 4. X-axis measures how long it last after the cold treatment. 5. Y-axis measures the percentage of ions that leak after cold treatment. 6. WT stands for wild type, the “natural” or common version of the gene. 7. L1 and L5 are both transgenic versions of the plant. That is, these versions had a gene modification. 8. D. Whether electrons will transfer from photosystem 2 9. One Trend: After three days of cold treatment, the percentage of ion leakage begins to stabilize over all three types of plants: L1, L5, and wildtype.
This "clicker case" follows two recent college graduates as they look for scientific answers to explain why the plants on their new tomato farm are not doing well. Working with their agricultural extension agent, they explore the scientific literature and learn how cold, heat, and salt can stress plants. They also learn that plants genetically engineered to produce glycine betaine, a modified amino acid, can withstand the environmental conditions that stress many agricultural plants. In their explorations, the fledgling farmers read graphs from the primary literature and review photosynthetic processes from their introductory biology course. The case consists of a PowerPoint presentation with embedded multiple-choice questions that students answer using clickers. Developed for a first-year class in biology, it could be used in any lower-level college biology class or potentially an advanced biology class in high school. The case is also accompanied by an optional PowerPoint presentation (see "Supplemental Materials" tab above).