The Transport Of Water And Ions Into And Across The Root Flashcards
What do you root hair cells have that facility at the uptake of water
Large surface area
Why does the water enter the root
By osmosis
Water in the soil has all higher water potential than the root hair cells due to the sugars and other compounds present in the cells
What is the uptake of water aided by
The presence of a thin exchange surface
What is the exchange surface
Cell-surface membrane and the cell wall is permeable
How many root hairs does a typical root have
Thousands
How does the water move once in the root hair cell
Across the cells of the cortex and into the xylem in the stele
What tow pathways can watermove through root
Apopolasr
Symplast
Apopplast pathway
Involves water moving along the cellulose microfibrils of the cell walls
What aids apoplast pathway
This is facilitated by the Parlow arrangement of the microfibrils and the Celulose wall. Allows water to pass easily between the different layers rather than through them. The mesh like arrangement of the walls further aids movement
What helps pull the column of water along
The cohesive properties of the water aided by hydrogen bonding help all the water come along as the water most through the wall
Why will most water go apopplast
Limited resistance to water movement
Symplast way
Water moving by osmosis from one cell to the next across the cortex
What happens for symplast way to be possible
The movement of water across the road creates a water potential gradient necessary
E.g. as a root hair cell text and water is water potential becomes less negative and is higher than the adjacent sell. Water moves from the root hair cells into the cortex cells by osmosis and so on across the cells of the cortex
How does the water move form cell to cell in symplast
Through the plasmodesmata Thant links the cells of the cortex together
How can ions entire root hair cells
By facilities diffusion
Or active transport
Depnds on conc grad for the ion concearned
