The human circulatory system delivers fluid to cells in a meshed web of capillaries. Plant cells, however, have sturdy cell walls and grow in an orderly pattern that permits cells to turn into chains of hollow tubes (called xylem) when the cells die and become hollow within the walls.

The celery stalk in the picture below has been split part way up the middle so the two ends can be placed separately in beakers containing water colored with food dye. Click on the celery stalk to see what happens as water moves into the celery from the beakers. Then answer the questions in your Lecture-Lab Manual.