Module 2 Flashcards by Ateeya Cali

is important to the physiology of plants because of its crucial role in all physiological processes and because of the large quantities that are required

water

How well did you know this?

Not at all

Perfectly

Water typically comprises ________ mass of nonwoody tissues such as leaves and roots

70—95%

How well did you know this?

Not at all

Perfectly

At the cellular level, _______ is the major medium for transporting metabolites through the cell

water

How well did you know this?

Not at all

Perfectly

readily dissolves large quantities of ions and polar organic metabolites like sugars, amino acids, and proteins that are critical to metabolism and life

water

How well did you know this?

Not at all

Perfectly

is the medium that transport the raw materials (carbohydrates and nutrients) as well as the phytohormones that are required for growth and development from one plant organ to another

water

How well did you know this?

Not at all

Perfectly

Living cells must maintain a ________ water pressure, or “________” to grow and function properly.

positive; “turgor”

How well did you know this?

Not at all

Perfectly

Plant cells are mostly water; __ -__%
seeds: __ -__%
cabbage: __ -__%
sapwood: __ -__%

80 -95%
10-15%
95%
30-35%

How well did you know this?

Not at all

Perfectly

plant loose large quantities of water in _______, the evaporation from the interior of leaves through the stomata

transpiration

How well did you know this?

Not at all

Perfectly

100% water exchange in one hour
water loss through leaf surface
helps heat dissipation by leaves
half of the heat by sunlight is dissipated by this
latent heat of vaporation

transpiration

How well did you know this?

Not at all

Perfectly

water passes easily through biological membranes, particularly through _____ - low resistance pores

aquaporins

How well did you know this?

Not at all

Perfectly

are proteins embedded in cell membrane that regulate flow of water

aquaporins

How well did you know this?

Not at all

Perfectly

the opening and closing stomatal pores are based on short distance intercellular transport through?

aquaporins

(Aquaporins aid in this process by facilitating the movement of water into and out of the guard cells)

How well did you know this?

Not at all

Perfectly

water potential is the combined effects of

solute concentration
physical pressure (cell wall)

How well did you know this?

Not at all

Perfectly

water potential symbol

Ψ (Psi)

How well did you know this?

Not at all

Perfectly

water potential is measured in ______

megapascals (MPa)

How well did you know this?

Not at all

Perfectly

1 MPa = __ atm

10 atmospheres of pressure

How well did you know this?

Not at all

Perfectly

Formula of water potential

Ψw = Ψs + Ψp + Ψg

where,

Ψw = water potential
Ψs = solute potential
Ψp = pressure potential
Ψg = gravitational potential

How well did you know this?

Not at all

Perfectly

plants can use the _____ energy in water to perform work

potential energy

How well did you know this?

Not at all

Perfectly

plants ______(loses/regains) turgor pressure when cell pushes against wall due to uptake of water

regains

How well did you know this?

Not at all

Perfectly

plants in desert climates have _____ (more/less) water potential than well-water plants

less

How well did you know this?

Not at all

Perfectly

as the water potential decreases (dehydration), what physiological changes happens? (7)

increase in abscisic acid accumulation
increase in solute accumulation
decrease in photosynthesis
decrease in stomatal conductance
decrease in protein synthesis
decrease in wall synthesis
decrease in cell expansion

How well did you know this?

Not at all

Perfectly

it is the measure of the rate of passage of CO2 entering or water vapors exiting through stomata

stomatal conductance

How well did you know this?

Not at all

Perfectly

effect of dissolved solutes on water potential

solute potential

How well did you know this?

Not at all

Perfectly

reduce free energy of water

solutes

is the hydrostatic pressure of the solution

pressure potential

______ pressure raises the water potential while _____ pressure decreases it

positive, negative

Positive pressure – _____ and; negative pressure - _____

turgor tension

potential that is generally negligible

gravity potential

gravity potential is overcome by

transpiration pull

Cell growth, photosynthesis, and crop productivity are all strongly influenced by ________ and its components

water potential

Like the body temperature of humans, _________ is a good overall indicator of plant health.

water potential

immediate contact of root and soil is necessary for

water uptake

- deep-rooted plants pull water upward - is the passive movement of water from roots into soil layers with lower water potential, while other parts of the root system in moister soil layers, usually at depth, are absorbing water - moves out into drier, shallow soils - allows survival of shallow-rooted plants during drought, or in arid environments

hydraulic lift

what part of the root absorb water and nutrients from the soil?

apical part of root that includes the root hair zone

are most active in water absorption process.

root hairs

- water moves across the plasma membranes, with a short visit to the cell wall space.

transmembrane pathway

water flows between cells through the plasmodesmata without crossing the plasma membrane.

symplast

For the movement of water roots of the plants 3 pathways are known i.e.

* Apoplastic pathway * Symplastic pathway, and * Transmembrane transport.

At the endodermis, the apoplast pathway is blocked by the

Casparian strip

breaks the continuity of the apoplast pathway, hence water movement across the endodermis occurs through the symplast.

Casparian strip

Factors affecting water absorption (5)

* Available soil water * Concentration of soil solution * Soil temperature * Soil aeration * Transpiration, etc.

Factors affecting rate of transpiration (7)

* Humidity of air * Temperature * Wind velocity * Light * Atmospheric pressure * Carbon dioxide concentration * Root : Shoot ratio

Significance of TRANSPIRATION (3)

* It helps in ascent of sap. * It helps in the absorption of water and minerals. * It has cooling effect

According to the _______________, transpiration is the main driver of water movement in the xylem.

cohesion-tension theory

- It creates negative pressure (tension) equivalent to -2 MPa at the leaf surface. - Water from the roots is ultimately pulled up by this tension. - Negative water potential draws water from the soil into the root hairs, then into the root xylem.

cohesion-tension theory

was the first to suggest that water flow in plants is governed by the C-T mechanism

STEPHEN HALES

states "for without perspiration the [water] must stagnate, notwithstanding the sap-vessels are so curiously adapted by their exceeding fineness, to raise [water] to great heights, in a reciprocal proportion to their very minute diameters."

STEPHEN HALES

If water freezes in a plant cell, the sharp ice crystals can cut cell membranes, resulting in fluids leaking from the cell, leading to cell and plant death

Freezing Injury

Freezing injury symptoms include tissue ______, _____, ______ or _________ of leaves and stems.

browning, blackening, wilting or curling leaves and stems

can occur at temperatures from 32 to 55 F (0 to 10 C).

chilling injury

Plants from tropical origins are often _________, while most temperate zone species are not.

chilling-sensitive,

Coping Mechanism of Plants During Cold (4)

*Create anti-freeze. *Move water deeper. *Enter dormancy. *Drop their leaves.

So how do plants survive winter?

As the days shorten and temperatures change, hormones are triggered in plants that signal changes.

Some plants increase the amount of sugar, salt or other compounds mixed in the water of their cells. This lowers the freezing point, requiring much colder than normal temperatures to cause their cells to freeze.

Create anti-freeze

Some plant move water/sugar/sap into the roots and/or into the spaces between cells, where it is less likely to freeze or cause damage if it does freeze.

Move water deeper

Some plants reduce or nearly stop growing. This helps plants conserve energy and food, as well as reduces the amount of water they need

Enter dormancy

By dropping their leaves, plants reduce the surface area that is exposed to the cold, drying air, saving water in the plant. In addition, dropped leaves break down and return nutrients to the soil. When the leaves return in the summer, the increased surface area helps move water up from the roots into the leaves.

Drop their leaves.

"The Earth is what we all have in common."

Wendell Berry