FBS 31_Plant-Water Relations

Water constitutes what percentage of the mass of the plant?

80-95%

Unique characteristic of water which makes it an excellent solvent

Polarity of the molecule H2O

Unique characteristic of water which makes capable of moving through plant tissues by capillary action

Viscosity

Unique characteristic of water which makes it capable of cooling plant tissues

Thermal properties

What do you call a plant cell that is swollen and firm due to high water content

Turgid

What part of the root in plants absorb water

Root hair

Where in the root tip does root hair grow?

Region of maturation

Well-watered plants keep their shape because of the internal pressure of water in the cells that is called?

Turgor pressure

What is the movement of atoms or molecules from an area of high concentration to an area of low concentration.

Diffusion

This energy is the power of a moving body to accomplish work

Kinetic energy

A hypothetical term describing the  potential ability of a gas, liquid or solid to diffuse from an area of its greatest concentration to an area of lesser concentration.

Diffusion pressure

The direction of diffusion of a substance is determined entirely by the difference in diffusion pressure of the substance and is completely independent of the diffusion pressure of surrounding substances.

Independent diffusion

Factor affecting rate of diffusion where the rate at which a substance (gas) will diffuse increases with increase in what?

Temperature

Factor affecting rate of diffusion that includes Graham’s Law

Density of diffusing molecules

What is being described?

“As density is increased, rate of diffusion is decreased.”

Graham’s Law

Factor affecting rate of diffusion where the more concentrated the medium is, the slower is diffusion.

Medium in which diffusion occurs

Factor affecting rate of diffusion where if there is a large difference in concentration between two areas (the steeper) then the faster the rate of diffusion

Diffusion pressure gradient

Factor affecting rate of diffusion that has to do with size.

Size of diffusing molecule

Factor affecting rate of diffusion that has to do with solubility

Solubility of diffusing molecule

Type of diffusion where the movement of water passes through a semi-permeable membrane

Osmosis

What does DPD stand for?

Diffusion pressure deficit

The pressure needed to prevent the passage of water into an aqueous solution

Osmotic pressure

The pressure needed to prevent the leakage of water from a cell

Turgor pressure

What is the process whereby the water from the cytoplasm of cells is removed causing the cytoplasm to shrink?

Plasmolysis

What do you call the solution where plasmolysis occurs?

Hypertonic solution

What do you call the solution where more water enters the cell, increasing turgidity?

Hypotonic solution

What do you call the solution where the amount of water transported into the cell is equal to the amount of water transported out?

Isotonic solution

What is the formula for Osmotic Pressure?

OP=\frac{22.4MT}{273}

What does M mean in the formula for Osmotic Pressure?

concentration of external solution at incipient plasmolysis

What does T mean in the formula for Osmotic Pressure?

absolute temperature

Importance of imbibition where it initiates seed ____

Germination

Importance of imbibition where it is adhering water to the walls of ____ elements

Xylem

Importance of imbibition where it helps ___ to retain water

Fruits

Importance of imbibition where it plays a major role in young and actively growing ___

Tissues

A DP gradient must exist between the imbibant and the substance imbibed

A certain affinity must exist between components of the imbibant and the imbibed substance

Conditions for imbibition to occur

A DP gradient must exist between the imbibant and the substance imbibed. This means that DP of the water in dry plant materials capable of imbibition is practically ___

Zero

Imbibition of water by dry plants is due to the hydrophyllic colloidal substances as proteins and polypeptides – namely, ____ and ____

Starch, Cellulose

Analogous to Osmotic pressure (OP) in the sense that it represents the potential maximum pressure developed by the imbibant if submerged in pure water.

Imbibition pressure

DPD = IP if imbibant is placed in an ____ condition

Unconfined

Factor affecting rate and extent of imbibition where an increase in this, increases the rate of imbibition

Temperature

Factor affecting rate and extent of imbibition where addition of solute to pure water lowers diffusion pressure of water

OP of substance to be imbibed affects amount and rate of water diffusion

Volume of whole system decreases after imbibition because water molecules are adsorbed tightly and as such are packed closer together. As a result, some KE is lost as heat, therefore an increase in temperature after imbibition.

Volume and energy changes

Term in volume and energy changes that is the binding of molecules or particles to a surface

Adsorption

Term in volume and energy changes that is the filling of pores in a solid

Absorption

Term in volume and energy changes that is the release of an adsorbed substance from a surface

Desorption

Process whereby water is lost in the form of vapor through the leaves

Transpiration

Only __% water vapor is utilized. Most of it is lost in the form of vapor through transpiration.

5

Type of transpiration occurring in the stomata of the leaves

Stomatal

Type of transpiration that is the loss of water from the cuticle of the leaves, fruits and stem

Cuticular

The term used when water, not water vapor, is released from the plant

Guttation

Type of transpiration that is the loss of water through a pore-like structure found in the branches or stem; slow

Lenticular

Method of measuring transpiration that involves loss of weight of plant from one period of time to another surface of soil covered so as to eliminate water loss due to evaporation.

Gravimetric method

Method of measuring transpiration where bubble is introduced in the capillary. The measurement is how far will the bubble travel per minute. Assumption: amount of water loss is the same as the amount of water absorbed.

Potometer method

Specially prepared filter paper coated with cobalt-chloride is used, placed and pressed over a transpiring leaf blade, when not saturated it is colored blue, when saturated colored pink – time it takes to change color is compared to a given table to give the rate of water loss.

Cobalt-chloride method

Plant is enclosed in a box, CaCl2 is used, oven-dried first then weighed, placed inside U- tube, blow in air into box for plant to transpire. The pump will aid CaCl2 to absorb the water transpired.

Box method

What is the method of transpiration being represented in this equation?

Box method

Movement of stomata is dependent upon the turgidity of the ____

guard cells

What does E in physiology mean?

Transpiration

What does G in physiology mean?

Stomatal conductants

When guard cells are swollen the stoma is?

Turgid

When guard cells are shrunken the stoma is?

Flaccid

C3 and C4 Plants have their stomata opening in what time?

Day

Crassulacean acid metabolism (CAM) plants have their stomata opening in what time?

Night

Factor affecting stomatal movement where stomates open in light and close in dark; some will not open when exposed to far red or UV while some will open

Light

Subtopic of factor affecting stomatal movement where under light condition, chloroplasts of the guard cell photosynthesize resulting in an increase of osmotically active substances

Photosynthesis

Subtopic of factor affecting stomatal movement where illumination of the guard cells increases its pH; at high pH opening of the stomates is favored and at low is closing.

A high pH is accompanied by a decrease in starch and an increase of the reducing sugars which are osmotically active resulting in an increase of turgor.

pH

Factor affecting stomatal movement where the greater the degree of water deficit, the sooner the stomates close

Water

Factor affecting stomatal movement where as air temperature increases, stomates open

Air temperature

Factor affecting rate of transpiration that involves, root-shoot ratio, leaf area, leaf structure, and leaf orientation.

Plant factors

Transpiration ____ with increased root-shoot ratio

increases

Greater leaf area, greater amount of water ___

loss

Factor affecting rate of transpiration that has to do with the plant’s surroundings

Environmental factors

Subtopic of factor affecting stomatal movement that causes opening of stomates

Light

Subtopic of factor affecting stomatal movement where increased relative humidity of air decreases rate of transpiration because vapor pressure between the leaves and the atmosphere is not very steep.

Humidity of air

The ratio of the actual vapor pressure to the vapor pressure of atmosphere when saturated at the same temperature.

Relative humidity

Subtopic of factor affecting stomatal movement where where all other factors constant – increase in temperature within a certain physiological range almost increases the rate of transpiration.

Temperature

disperses vapor accumulating or concentrating inthevicinityoftheleafas a result of transpiration and thus may increase transpiration at the immediate onset of application