Transport in Plants

• the cells on the surface of plant roots grow into hairs which stick out into the soil
• each branch of a root will be covered in millions of these microscopic root hairs
• root hair cells give plants a large surface area for absorbing water and mineral ions from the soil
• the concentration of mineral ions is usually higher in the root hair cells than in the soil around them, so mineral ions are absorbed by active transport
• phloem tubes are made out of columns of elongated living cells with small pores in the end walls to allow stuff to flow through
• phloem tubes transport food substances (mainly sucrose) made in the leaves to the rest of the plant for immediate use (in growing regions) or for storage
• the process of phloem tubes transporting food is called translocation and it requires energy from respiration. the transport goes in both directions
• xylem tubes are made of dead cells joined end to end with no end walls between them and a hole down the middle (basically one long tube)
• xylem tubes are strengthened with a material called lignin
• xylem tubes carry water and mineral ions from the roots to the stem and leaves
• the movement of water from the roots, through the xylem and out of the leaves in called the transpiration stream