A classic demonstration of how transport works in a vascular plant is to place a stick of celery in a glass of water that has food coloring added to it. Cut a slice across the stem of a stalk of celery. Put several ounces of water in a glass and add a few drops of red or blue food coloring. Insert the cut end of the celery into the glass of colored water. Every few hours make observations to see if the colored water is being drawn up the stalk through its vascular system.
Oil spills can occur both in the ocean and on land, even though many safeguards are in place. Conduct a science project to see if water that has been polluted with oil is taken up by a tomato plant’s transport system and deposited in the plant’s leaves and fruit. Locate three small tomato plants of about equal size that have not yet grown any tomatoes. Label one plant as the “control” plant. Label another plant as “water plus food coloring,” and the third plant as “water plus oil.” Place the plants in a sunny area and give each an equal amount of water as needed. However, when watering the plant labeled “water plus food coloring,” add a few drops of blue food coloring. When watering the plant labeled “water plus oil,” add a significant amount of motor oil, such as 30 or 40 SAE weight, to the water. You can use empty plastic gallon milk jugs to pre-mix your food coloring and oil mixtures. Let the plants grow, and maintain proper sunlight and moisture. To do this project indoors, you use tomato plants that don’t grow too big, such as cherry tomatoes.
When the plants begin to bear fruit, cut open tomatoes from each plant. Observe if the food coloring is evident in the plant that was fed blue dye. Observe the smell and taste of a tomato from the plant fed oil-mixed water. Similarly, examine the leaves of the plants and compare them by color to the control plant’s leaves.
Too much oil mixed into the water that is fed a tomato plant may kill the plant. Conduct a science project to determine how much oil pollution a tomato plant can withstand and still produce usable fruit. This would require planting a number of tomato plants and feeding each a water and oil mixture of varying ratios, such as 10 percent oil, 25 percent oil, 50 percent oil, and so on.