Plant Physiology II

Question	Answer
Ψ =	Ψ s+ Ψ p+ Ψ g
Ψ g	Gravitational potential Gravy causes water to move downward Difference btw. neighbouring cells is negligible Generally omitted when considering water transport at the cellular level
Solute motential	always negative
Ψ p	Effect of pressure on water potential positive = turgid cell negative = xylem Ψ p=Ompa (atmospheric pressure)
Ψ s=	iCRT i= ionisation constant so NaCl =2, glucose = 1 C=conc. R=0.0831 T=temperature in K
Bar to mPa	2.4 bar= 0.24 mPa
Dissolved sugar into water	Ψ p=0mPa [0.1] solute Ψ s=-0.244mPa Ψ = Ψ s+ Ψ p Ψ = -0.244+0 Ψcell=-0.244 mPa
Plasmolysed Turgid Flaccid	Ψcell>Ψs Ψcell<Ψs Ψcell=Ψs
Soil-plant-air continuum	H2O absorbed through roots H2O travels through plant H2O evaporates through leaves
Boundary layer in transpiration	Layer of unstirred air next to leaf surface H2O(g) must diffuse through this Thickness of layer determined by wind speed and leaf size
What air conditions makes the leaf thicker?	In still air layer is thicker
Cavitation	When an embolism appears in H2O column negative pressure gets too great water column snaps air cavity formed Water flow stops
Overcoming this	Vessels and tracheids are connected by pits so can bypass embolisms
Which system of vessels are more vulnerable to cavitation?	Vessels Tradeoff btw. flow rate and risk of cavitations
Tracheary elements in gymnosperms	Most only tracheids, not vessels
Cavitation repair	Positive root pressure from guttation

Resource summary

	Created by J yadonknow over 6 years ago