Transport in plants Transport mechanisms Passive transport Active

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 does water go? – Where does sugar go? – Where to inorganic nutrients (minerals) go? – Where do gasses go? (ie. O 2/CO 2) – Where 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. 17 a

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. 17 b

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 CO 2 • 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 CO 2, H 2 O

Photosynthesis (C 3) • 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