Chapter 32 Flashcards
Solutes diffuse..
Down their electrochemical gradients
Water and solutes can move through the root’s epidermis and cortex by going…
Through cells, between cells or both
What are aquaporins?
Transport proteins in plant membranes for the passage of water
Passive transport and examples
NO energy required, moves from high to low concentrations. Examples: Diffusion (movement of solutes) and Osmosis (movement of water) across cell membranes
Active transport and examples
Energy IS required to move substances UP gradient. Examples: Transport proteins allow large, or charged molecules to move across the phospholipid membrane.
What does the proton pump do in plants?
Creates an electrochemical gradient by using the energy from ATP to pump H ions across the membrane.
What is cotransport?
The coupling of this H gradient with another solute and using it to transport the other molecule across.
What is the apiplasyic route?
Uptake of water and dissolved minerals through the cortex and into extra cellular spaces between cell walls
What is the symplastic route?
Uptake of water and dissolved minerals in through the plasma membranes
When does root pressure occurs?
Occurs when water diffusing in from the root cortex generates a positive pressure that pushes xylem sap up. This is not enough to push enter to the top of trees.
Transpiration provides the pull (tension) for the ascent of…
Xylem sap by cohesion between water molecules created by hydrogen bonding and adhesion between water molecules and plant cell walls.
Guard cells are stimulated to open by…
1) The presence of light
2) Loss of carbon dioxide
3) Normal circadian rhythms (plant’s internal biological clock)
Guard cells are prompted to close to conserve water. When closed…
Photosynthesis is halted and the plant cannot wake its own food.
Stomata open when guard cells take up water in what process?
> Potassium is actively taken up by guard cells from nearby cells.
This creates an osmotic gradient and water follows.
Uneven cell walls of guard cells cause them to bow when water is taken up.
The bowing of guard cells causes the pore of the stoma to open
When guard cells lose K+ ions, the guard cells become flaccid and the stoma closes
Phloem sap transports sugars known as…
… “translocation” made by photosynthesis and using a pressure flow mechanism.
