osmosis, diabetes, urine, urination, thirst, sugar, glucose, observation
Each student should receive two pieces of a high water-content vegetable such as eggplant, squash or beet. The vegetable pieces should be blotted dry with the paper towels and weighed. Honey ( represents sugar ) should be sprinkled onto one of the vegetable slices ( the one without honey is the control sample ). ( Approximately 1/4 of a teaspoon of honey with a slice of zucchini squash which is one inch across works well! ) The students should record what they observe at the beginning (time = 0), and then at five minute intervals for 15–20 minutes. The honey will extract the water from the veg-etable; the water will accumulate on the surface of the vegetable and be readily visible. This demonstrates how the high sugar content of blood in a diabetic extracts water from the body's tissues resulting in frequent urination and dehydration. The vegetable can be toweled off, so that students can further observe the water that was extracted from the vegetable and weighed again. Point out that the sugar has the same drying effect that salt has.
1. High water-content vegetables (1/4 inch thick slices)
3. Paper towels
5. Lab worksheet