Test 2 (Chapter 32) Flashcards
1
Q
Uptake and Transport
A
- Water/solutes move through epidermis & cortex; into water-conducting xylem in vascular cylinder
- Must pass through plasma membrane of root cells
2
Q
Casparian strip
A
- continuous waxy barrier stops water and solutes from entering the xylem through the cell walls, instead forcing them to cross a plasma membrane into an endodermal cell. Ion selection occurs at this membrane instead of in the epidermis. Once the selected solutes and water are in the endodermal cell, they can be discharged into the xylem
3
Q
Cohesion-Tension Theory
A
- explains the process of water flow upwards (against the force of gravity) through the xylem of plants
- water in xylem is pulled upward by air’s drying power, which creates tension, transpiration puts negative pressure (pulls) on continuous columns of water that fill the narrow conductive tubes of xylem, this pressure pulls on the entire column of water that fills the xylem tube
4
Q
Cohesion-Tension Theory
A
- explains the process of water flow upwards (against the force of gravity) through the xylem of plants
- water in xylem is pulled upward by air’s drying power, which creates tension, transpiration puts negative pressure (pulls) on continuous columns of water that fill the narrow conductive tubes of xylem, this pressure pulls on the entire column of water that fills the xylem tube
5
Q
Transpiration Control
A
Stomata - adjust transpiration rates
- Pair of guard cells flank stoma; control opening by changing shape
- Helps balance photosynthesis requirement (CO2 & O2) with water conservation
- Cues for opening; light, low CO2 levels, & internal timing (biological clock
6
Q
Pressure Flow Theory
A
- Active transport loads sugar from photosynthetic cell into phloem tube.
- High concentration of solute draws H2O into tube by osmosis. Water flow raises water pressure
- Sugar leaves phloem, lowering solute concentration at sink.
- Water follows by osmosis, lowering water pressure
