Year 11 1. Discuss in detail how water and inorganic nutrients flow through xylem from the roots to the leaves? Water moves from root to leaves via xylem by Transpiration pull & Root Pressure Transpiration Pull The loss of water from the stomata creates a tension/vacuum (pulling force) which is relayed downward along a chain of water molecule from leaf end to root end by cohesion. Cohesion: hydrogen bond that take place between water molecule and another water molecule. Adhesion force holds the water column temporary again gravity. Water temporary attach to wall of xylem because they are both polar. Root Pressure Root pressure is caused by the uptake of mineral nutrient ions into the root xylem. Without transpiration to carry the ions up the stem, they accumulate in the root xylem and lower the water potential. Water then diffuses from the soil into the root xylem due to osmosis. Root pressure is caused by this accumulation of water in the xylem pushing on the rigid cells. Root pressure provides a force, which pushes water up the stem, but it is not enough to account for the movement of water to leaves at the top of the tallest trees. The maximum root pressure measured in some plants can raise water only to about 7 meters, and the tallest trees are over 100 meters tall. In 2 sentences “Explain how water travels through plants using the words: [Osmosis, root pressure, cohesion theory of water and transpiration pull.] “ __________________________________________________________________________________________ __________________________________________________________________________________________ __________________________________________________________________________________________ Draw what you understand from Transpiration pull & Root Pressure
