Plants.

Plants.

• ROOT– root tip– root hairs

Roots • Roots anchor plant in soil, absorb

minerals & water, & store food– fibrous roots (1)

• mat of thin roots that spread out– tap roots (2)

• 1 large vertical root • also produces many small lateral,

or branch roots – root hairs (3)

• increase absorptive surface area

2

1

3

• ROOT– root tip– root hairs

• STEM– nodes

• internodes– buds

• terminal or apical buds• axillary buds• flower buds & flowers

• ROOT– root tip– root hairs

• STEM– nodes

• internodes– buds

• terminal or apical buds• axillary buds• flower buds & flowers

• LEAVES– mesophyll tissue– veins (vascular bundles)

Leaves• Function of leaves

– photosynthesis• energy production• CHO production

– gas exchange– transpiration simple vs. compound

Nutritional needs– plants need…

• sun as an energy source• inorganic compounds

as raw materials– water (H2O)– CO2

– minerals

Macronutrients• Plants require these nutrients in

relatively large amounts– C, O, H, N, P, K, Ca, Mg, S

Micronutrients• Plants require in very small amounts

– Cl, Fe, Mn, Bo, Zi, Ni, Mb– primarily cofactors for enzyme function

Transport in plants• H2O & minerals

– transport in xylem – transpiration

• evaporation, adhesion & cohesion

• Sugars– transport in phloem– bulk flow

• Calvin cycle in leaves loads sucrose into phloem

• Gas exchange– photosynthesis

• CO2 in; O2 out• stomates

– respiration• O2 in; CO2 out• roots exchange gases within air spaces in soil

Water & mineral absorption

• Water absorption from soil– osmosis – aquaporins

• Mineral absorption– active transport– proton pumps

• active transport of H+

H2O

root hair

aquaporin

proton pumps

Mineral absorption

• Proton pumps– active transport of H+ ions out of cell

• chemiosmosis• H+ gradient

– creates membranepotential• difference in charge• drives cation uptake

– creates gradient• cotransport of other

solutes against theirgradient

Water flow through root

• Porous cell wall– water can flow through cell wall route & not

enter cells – plant needs to force water into cells

Casparian strip

Transport of sugars in phloem• Loading of sucrose into phloem

– proton pumps• cotransport of sucrose into cells down proton

gradient