2.54: Describe the Xylem in Transporting Water and Mineral Ions from the Roots to Other Parts of the Plant

XYLEM: Tube system composed of dead cells (reinforced with Lignin) that transports Water through the plant via transpiration - evaporation of water from the surface of plant)

STRUCTURE OF XYLEM:

                               

Diagram showing Structure of Xylem in Plant

TRANSPIRATION IN XYLEM

x Diagram Showing the Process of Transpiration in Plants

PROCESS: Cohesion: Force of attraction between Water molecules which allow Water to stick together Adhesion: Force of attraction between Water molecules and other polar molecules - e.g Cellulose in plant cell wall Water is transported throughout the plant via Xylem Water is heated into Water vapour by sunlight in Spongy Mesophyll, transpiring out of Stomata which are pores on the underside of leaves Loss of Water via transpiration creates negative pressure, causing transpiration pull of Water molecules up the Xylem to form a continuous transpiration stream As a result, more Water is absorbed by the roots of the plant via osmosis

FUNCTIONS: Constant uptake and transport of Mineral ions in plant (e.g Nitrates as a source of Amino acid to build Protein) Maintaining turgidity of cells for plant growth Provide Water to Photosynthesising cells in for Photosynthesis Evaporative cooling of plant leaves to maintain optimum temperature for optimum enzyme activity