Transport in plants
Transport mechanisms
– Passive transport
– Active transport
•Osmotic active transport
•Non osmotic active transport
Plant transport…
• What substances move throughout a
plant?
– Where
– Where
– Where
– Where
– Where
does water go?
does sugar go?
to inorganic nutrients (minerals) go?
do gasses go? (ie. O2/CO2)
do secundary organic molecules go?
Fig. 39.8
Water movement
• Where does water move within a plant?
• How does water move at the cellular
level?
– Remember osmosis?
– What is water potential?
• Balancing osmosis
Water movement
• What is solute potential (ψS)?
– Is ψS positive or negative?
• What is pressure potential (ψP)?
– Is ψP positive or negative?
• What is WATER POTENTIAL (ψ)?
– ψS + ψP
– Pure water has no water potential
• Ψwater = 0
Water transport in roots
• How does water enter roots?
– Remember root hairs
– What is the apoplastic route?
– What is the symplastic route?
– What is the casparian strip?
• Remember subarin?
– How does mineral transport help?
Fig. 39.9
(Symplastic)
(Apoplastic)
Water transport in shoots
• How does water
move up the
plant?
– What is root
pressure?
– What is guttation?
– When does this
occur?
More water transport in shoots
• What is transpiration?
– Where is most water lost from plants?
• Remember stomata?
– How does transpiration affect water potential
in xylem?
• What happens to ψS?
• What happens to ψp?
• Remember…XYLEM SUCKS!!!
Fig. 39.10
Controlling transpiration
• How do stomata open?
– The inner tube story…
– How are guard cell walls specialized?
– What happens when guard cells expand?
– How do guard cells expand
• Where salt goes, water follows!
• Remember abscisic acid?
Sugar movement in plants
• Where are sugars produced?
– What is the source?
• Where do sugars go?
– What is the sink?
– Where are sugars needed?
– How do they get there?
• Remember phloem
Fig. 39.17a
Sugar movement in phloem
• How do sugars get into phloem?
– What is the concentration gradient for sucrose
entering sieve tubes?
– Where does energy for transport come from?
• Remember respiration
Fig. 39.17b
Back to the sugar…
• What are the biologically relevant forms of
energy?
– Light energy
– Electrical energy
– Chemical
– Concentration gradients
Plant productivity
720 billion tonnes of global carbon every year
• 10% is sugar
• 0.0001% is CO2
• Where does the sugar come from
More productivity
• Where does energy for photosynthesis
come from?
– The power of light…
– Where is the trick
• Remember pigments
• Where do the raw materials come from?
– Remember CO2, H2O
Photosynthesis (C3)
• What is the overall scheme
– Gathering energy
– Converting light  usable energy
• Photophosphorylation
• Making ATP, stored electrons
– Using stored energy to  sugar
• Calvin cycle
• Biochemical baby steps
• Built on THREE CARBON intermediates