7 Flashcards
Bulk Flow?
The movement of a fluid driven by a pressure gradient.
Positive pressure results in a?
A push
Negative pressure results in a?
Pull
Transpiration?
Gas exchange and water loss occur simultaneously through an open stomata and also pulls water up to the root from the soil.
How do guard cells cause the stomata to close?
They diffuse water and potassium out across its membrane, and H2O escapes through the stomata
How to reduce water loss when stomata is open?
•They are located in the lower side (abaxial) of the leaf.
•protect and hide stomata and the use of trichomes to allow moisture to build up.
•Cuticles: epidermis cells
•CAM and C4 activate CO2 concentrating mechanisms, and Rubisco is more efficient, which means that stomata can be open for less time.
Why is Xylem and Phloem bundled together?
Water transfer between them.
Root pressure?
Ions accumulate in the vasculature, increasing solute potential. It push water inside the root. This can also occur when the stomata is closed.
Guttation?
When water is forced out exclusively due to root pressure at night.
Water and nutrients move along the?
Xylem. Which is a one way flow of sap.
Water diffuses from _____ to _______ water potential?
High, low
What water potential value determines where water flows?
The more negative values.
Negative potential water?
Pulls water.
Positive water potential?
Push water
Solute potential is measured with positive/negative?
Negative
When water gets pulled in the root, how does the pulled water drive water up the plant?
It pushes the water already present in the xylem and water potential is positive.
Hypotonic, hypertonic, isotonic
Turgor pressure?
During a hypotonic plant cell, the cell wall stops the cell from bursting. The pressure is pushing outwards.
Since water flows up the plant, is the water potential of the air higher/lower than in a plant?
Lower
Water potential gradient in a plant?
What affects water potential?
•As humidity increases, water potential increases
•Heat encourages evaporation
How do guard cells cause the stomata to open?
They accumulate a huge quantity of potassium ions, which increases solute potential and decreases water potential. More water enter the guard cell, increasing turgor pressure and causing it to become rigid.
