Module 1 Flashcards
Properties of water that allows it to fulfill specific roles in plants
- Universal solvent
- Hydrolysis
- Transparency (for photosynthesis)
- Turgor pressure
- Thermal properties
9 Physical and chemical properties of water
- Polar
- High specific heat
- High heat of fusion
- High thermal conductivity
- High heat of vaporization
- High dielectric constant
- Liquid at physiological temp.
- Cohesion
- Adhesion
Why does ice float?
The density of water is highest at 4 Celsius. Density of water decreases upon crystallization.
Differentiate the “cohesion” and “adhesion” properties of water.
Cohesion - between the water molecules
Adhesion - attraction to surfaces
Relate the statement to a specific property of water.
Water resists temperature changes.
High specific heat
Relate the statement to a specific property of water.
Water resists freezing
High heat of fusion
Relate the statement to a specific property of water.
Allows water to transfer heat away from the site of heat generation.
High thermal conductivity
Relate the statement to a specific property of water.
Allows water to form hydrogen bonds.
Polar
Relate the statement to a specific property of water.
Leaves transpire because of this property
High heat of vaporization
Relate the statement to a specific property of water.
Contributes to tensile strength and surface tension
Cohesion
Positive hydrostatic pressure is useful in plants for? How about negative pressure?
Turgor pressure.
Long-distance water transport
Differentiate diffusion and bulk flow.
Diffusion - driven by difference in concentration of water
Bulk flow - driven by difference in pressure
In water movement, net movement stops when ___________ is achieved.
Dynamic equilibrium
Diffusion of water across plant membrane is facilitated through the ____________.
Membrane bilayer
___________ facilitate bulk flow of water to the plant cells
Aquaporins
T or F. ATP is not needed when water moves through the aquaporins.
True
5 Factors influencing the rate of diffusion
- Concentration Gradient
- Molecular Speed
- Temperature
- Pressure
- Solute effect on the chemical potential of the solvent
Molecular movement is directly proportional to _____________.
Temperature
Molecular movement is inversely proportional to _____________.
Molecular weight
Heavier particles move more slowly.
T or F. The solute effect on the chemical potential of the solvent states that the charge or particle size affects the free energy of a solvent.
FALSE.
NUMBER OF SOLUTE PARTICLES, NOT THE CHARGE OR PARTICLE SIZE, decreases the free energy of a solvent.
Relationship of mole fraction and free energy.
Higher mole fraction, higher free energy.
The concentration gradient is the principal driving force of water movement. This is governed by which law.
Fick’s first law
This is a special case of diffusion involving water movement across a selectively permeable membrane.
Osmosis
The membrane encasing the vacuole is the _________.
Tonoplast
What is the chemical potential of pure water?
Zero
T or F. Addition of solutes decreases the mole fraction of water. Lower mole fraction, lower chemical potential.
True
T or F. Plants control the movement of water indirectly by moving ions to alter the chemical potential since water moves actively. This means that for two sides of a membrane with different chemical potentials, water will move actively from the higher chemical potential to the lower chemical potential.
FALSE.
water moves actively –> water moves PASSIVELY
What is active transport?
Movement AGAINST the gradient.
The manipulation of ion transport to control water movement is an example of _____________.
Osmotic adjustment
What are the three components of water potential in the thermodynamics of water movement?
Pressure potential
Solute/Osmotic potential
Matric potential
Which component of the water potential is usually excluded as it is near negligible?
Matric potential.
Matric potential is SOMETIMES included when ___________________ is accounted for
Adsorption of water to solid surfaces
What is seed imbibition?
Uptake of water by a seed
Organelle contributing the most in a plant cell’s water potential.
Vacuole
Turgor pressure during incipient plasmolysis
Zero
Aquaporins mediate transport of water and __________
neutral solutes e.g. glycerol
T or F. Unlike plant stomates, aquaporins remain open throughout.
FALSE. Aquaporins are GATED channels that selectively open and close.
T or F. The rate of diffusion remains constant at increasing difference of concentration between two areas.
False. Greater difference in concentration between two areas –> Faster rate of diffusion
T or F. The lower the water potential, the higher the accumulation of abscisic acid.
True. Abscisic acid induces stomatal closing. Lack of water makes plants close their stomata to decrease transpiration rate.
Describe the state of plant cells in different situations.
- Isotonic solution
- Hypertonic solution
- Hypotonic solution
- Turgor pressure is zero
- Filled with water
- Excessive loss of water
- Flaccid
- Plasmolyzed
- Turgid
- Flaccid
- Turgid
- Plasmolyzed
Plant cells under incipient plasmolysis are in which state?
Flaccid
