plant physiology lec unit 2

65問 • 1年前

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Thermal properties of water

high specific heat, high latent heat of vaporization, high latent heat of fusion

The ampunt of heat energy needed to change the temperature to specific amount. Water can absorb a lot of heat energy before it gets hot. Help the plant resist temperature fluctuations

high specific heat

The energy needed to transform water from liquid phase to gas phase. This enables the plant to cool themselves by evaporating water from the leaf surfaces

high latent heat of vaporization

The energy needed to convert water from solid to liquid. High energy must be released by water to freeze. Water resist freezing

high latent heat of fusion

Physical properties pf water

cohesion, adhesion, surface tension, high tensile strength

Hydrogen bonds between water molecule make liquid water delf-sticky. The hydrogen from one water to molecule are sttracted tp the oxygen of other water molecule. Water bead up on a surface

cohesion

The attraction of water molecules to non-water hydrophilic substances. This property of water gives it the ability to climb the wall of any container it is in

adhesion

A measure of how difficult it is to break the surface of a liquid. An energy required to increase the surface area of a liquid. Generates the physical force that pull water through the plants vascular system

surface tension

Maximum force that a continuous column of water can withstand before breaking. Can withstand high stress while being stretched

high tensile strength

All pf the above forces give rise to a phenomenon called?

capillarity

Water transport occurs in three levels

cellular, lateral transport, whole plant

Mechanism of water movement

bulk and diffusion

Mass movement of molecules in response to pressure gradient. The molecules move from high to low pressure. Functions in long-distance transport. Occurs usually along the vertical axis of the plant

bulk

The net random movement of individual molecules driven by random thermal motion. Movement of molecules is from an area of high concentration to an area of low concentration, until molecules reach a dynamic equilibrium. Occurs rapidly over dhort distance

diffusion

Factors affecting rate of diffusion

concentration gradient, molecular speed, temperature, pressure

Rate diffusipn is directly proportional to the concentration gradient

concentration gradient

Directly proportional to temperature and indirectly proportional to molecular weight

molecular speed

Increase the rate pf molecular movent

temperature

Increase the speed of molecules

pressure

Specialized case of diffusion. Diffusion across a selectively permeable membrane. Movement is driven by the sum of a concentration gradient and pressure gradient

osmosis

Transport proteins in the cell membrane that allow the passage pf water. It does not affect water potential.

aquaporin

They facilitate the transport of water and small neutral solutes pr gases

aquaporin and water transport

Water flows upward in tress, from the soil to the leaves. It causes the water to move downward unless it is opposed by an equal and opposite force

gravity

Water moves from regions of higher to lower pressure

pressure

Water moved by diffusion from regions of higher to lower water concentration. Solutes added to pure water dilute the water concentration

concentration

Potential energy of water per unit volume relative to pure water. A measure of free energy of water used to move water from one place to another. Determines the direction of water movement

water potential

Aldo called ad osmotic potential, it reduces psi by consuming the potential energy available in water. Additipn of solute make the psi negative

solute potential

The hydrostatic pressure produce by a splution in a space divided by a differentially permeable membrane. Due to the difference in the concentrations of solute

pressure potential

How to measure solute potential

solute potential=iCRT

Plays sn important role in the retention and availability of water

soil

The amount pf water a certain soil can hold

soil water- holding capacity

Soil water- capacity at its maximum

field capacity

Soil has a high water potential. As the soil dries, the water potential?

decreases

Water evaporates first from the center, and as the soil dries, the water id replaced by?

air

The measure of ease at which moves through the soil.

soil hydraulic conductivity

As the water potential in soil decreases, the soil hydraulic conductivity will?

decreases

Which one has higher hydraulic conductivity sandy or clay soil?

clay soil

Soil water moves by bull flow.

water balance of the plant

When water in the soil near the roots is depleted, the pressure potential will?

go down

Increase the absorptive area of the roots

root hairs

Movement of water in the roots

apoplastic pathway, transmembrane, symplastic pathway

Movement of water in the cell until the endodermis

apoplastic pathway

Passage of water across the plasma membrane

transmembrane

Movement of water from one cell to snother via the plasmodesmata

symplastic pathway

Have a thick lignified walls, preventing its collapse during water transport due to water tension and pressure

tracheary elements

The lost of water from s plant in the form Of water vapor

transpiration

As the water evaporates or converts from liquid to a gas at the leaf cell and atmostphere interference, energy is released

evaporative colling

When the plant is transpiring, its stomata are open, allowing gas exchange between the atmosphere and the leaf

carbon dioxide entry

Water loss at the leaf area lowers the water potential in the leaf, driving movement of water, along with the nutrients, from the soil and the roots

nutrient and water uptake

Types of transpiration

cuticular transpiration, lenticular transpiration, stomatal transpiration

Loss of water through the epidermis whoch is usually covered with a cuticle. In some temperature plants, about 5-10% of the water loss from Plants maybe lost from this pathway

cuticular transpiration

Loss of water through numerous pores in the puter layer of a woody plant stem, called lenticels.

lenticular transpiration

Loss of water through stomata which can sccpunt ss much as 90% of the water loss from the plants

stomatal transpiration

Transpiration id driven by the difference in vapor pressure

water vapor concentration

It is the amount of water vapor in the air compared to the ampunt of of water vapor that air cpuld hold at a given temperature

relative humidity

High relative humidity

air is moist

Influences the magnitude of the driving force for water movement out of a plant

temperature

Affects the transpiration by removing the boundary layer of leaves

wind

Increases the movement of water from The leaf surface when it reduces the boundary layer

wind speed

When light is low the transpiration is?

low

Water potential st which plant cells lose their turgor pressure. This causes wilting in plant. Water potential of soil is lower or equal to the water potential in the roots

permanent wilting point

The parameters help plants control rates of transpiration by serving as forms of resistance to water movement out of the plant

diffusional resistance

Control the opening and closing of the stomata

guard cells

It is a thin layer of still air hugging the surface of the leaf. This layer pf air is not moving

boundary layer resistance

Allows the gas exchange where water vapor leaves the plant, and carbon dioxide enters

stomata

histology unit 1

ユーザ名非公開 · 49問 · 1年前

histology unit 1