WATER

MOLECULAR MOVEMENT A liquid in which a substance dissolves Solvent Water

MOLECULAR MOVEMENT Nature adores balance Wind Wicking Hot air moving toward cold air Wicking Water moving from wet to dry

MOLECULAR MOVEMENT Movement of molecules from region on higher concentration to a region of lower concentration Diffusion Moving from high to low Along the diffusion gradient Moving from low to high Against the diffusion gradient

MOLECULAR MOVEMENT Molecules equally distributed in space Equilibrium

Fig. 9.2b

Fig. 9.2c

MOLECULAR MOVEMENT Membranes that allow molecules to pass through Permeable, or semipermeable Plant membranes are semipermeable

MOLECULAR MOVEMENT Natural Movement of substance from one side of a membrane of higher concentration to the other side of lower concentration Osmosis Water enters cells via osmosis

MOLECULAR MOVEMENT The pressure that would be required to stop osmosis Osmotic potential The pressure that develops on the inside of the cell wall Pressure potential osmotic potential + pressure potential Water potential The ability or a solution to draw water toward it The more solutes, the higher the water potential

MOLECULAR MOVEMENT Pure water Water with more dissolved salts Higher water potential Water with more dissolved salts Lower water potential

Solute potential is another name for osmotic potential

osmosis Isotonic Water potential same inside and outside of cell No water movement

osmosis Hypotonic Water potential lower inside cell More solutes inside cell Water moves into cell

osmosis Hypertonic Water potential lower outside cell More solutes outside cell Saline water Water moves out of cell

MOLECULAR MOVEMENT Two adjacent cells One with higher water potential moves water to the one with lower water potential Water in soil has higher water potential than water inside root cells Water moves from soil into root cell

MOLECULAR MOVEMENT Salt-contaminated water has lower water potential than root cells Water moves out of roots plasmolysis

MOLECULAR MOVEMENT The attraction of water inside roots Osmosis Imbibition Water attracted to Charged particles inside roots This is not osmosis Seeds swell with great force Lentils breaking box (seed coat)

MOLECULAR MOVEMENT Roots expend energy to pump water inside plant Active transport Water at tips of leaves in morning Guttation through hydathodes Night time No transpiration Active transport saturates plant until pushing out tip

TRANSPIRATION More than 90% of water evaporated through stomata Corn plant transpires 4 gallons a week

TRANSPIRATION Water moves through xylem by attractive forces Cohesion Water molecules attracted to each other Train As water molecule evaporates out stomata, pulls the train through the roots

Fig. 9.10

Water molecules Cohesion Adhesion Water molecules attraction to each other Adhesion Water molecules attraction to surfaces

transpiration Openings on bottom of leaf Stomata

transpiration Guard cells open and close stomata Controls turgor pressure with potassium ions Absorb K Guard cells swell with water and open stomata Departure of k Guard cells shrink and close stomata

Translocation Sugar (food) produced in leaves High concentration of sugar solution Source cell Sugar (food) solution moves to lower concentration cells Sink cells Roots Storage cells