Exam Study Guide 10/3/16 3:57 PM

How does air affect evaporation?

Notes

Transpiration

• root – shoot transport

o translocate water and nutrients from root to shoot

o phloem vessels

• shoot - root

o translocation photosynthates from shoot to root

o in xylem vessels

• water always flows towards low water potential/high solute potential • soil properties influence water availability

o porosity, water retention, aeration

o sand – large particles, large pore space, low water retention, high  aeration

o clay – small particles, low porosity, high water retention, low  

What is transported through symplast?

aeration

o silt – in between size

o loam – mixture of sand, slit and clay

o field capacity

▪ soil after drainage

???? low for sand

???? high for clay

o permanent wilting point

▪ soil capacity so low plants cannot take up water

▪ permanent wilting percentage  

???? soil water content at this point  

▪ available water = field capacity – permanent wilting %

???? high in loam soils, low in sand

o transpiration  

▪ uptake in root symplast

What is transpiration explain?

???? passes through membrane  

???? solute-driven osmosis  

▪ export into root xylem apoplast

???? passes a membrane

???? pressure driven osmosis

▪ bulk flow to shoot We also discuss several other topics like How much input, y, is produced for any given amount of factor inputs?

???? no membrane

???? bulk flow (not osmosis)

▪ uptake in shoot symplast

???? passes membrane

???? solute-driven osmosis

▪ evaporation into air

???? passes a membrane

???? pressure-driven osmosis

• driving forces of water movement

o short distance – osmosis

▪ into cells: solute driven

▪ out of cells: pressure driven

o long distance – bulk flow

▪ suction created by leaf evap

▪ cohesion/adhesion of water

▪ root pressure

• cavitation

o high temperature conditions, air bubble is created, hindering  transpiration If you want to learn more check out What are the different types of chemical reactions and chemical bonds?
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• acclimation

o metabolic changes morphological changes

• adaptation

o genetic

10/3/16 3:57 PM

10/3/16 3:57 PM