S oil nutrients must come in contact with roots for the plant to absorb them. One way that nutrients contact roots is through nutrient flow in the soil water solution. Transpiration of water from the plant creates a gradient that drives water movement in the soil towards the roots. This is a very simple mechanism for nutrient uptake, but not all nutrients can be taken up this easily. Much of the water transport within the plant occurs in the xylem .
Water escapes the plant through stomates , openings in the upper or lower surfaces of the leaves.
Specialized cells, called guard cells , are located on the perimeter of the somates and serve to regulate the size of the opening. This allows the plant to control the amount of water loss. CO 2 is one of the main building blocks for production of materials during photosynthesis . The plant is functioning best when there is ample soil moisture available for transpiration, which allows adequate plant cooling and maximum uptake of nutrients and CO 2 . The following demonstration uses celery stalk to display water movement through plants.