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PHYSIO LEC > Module 2 > Flashcards

Module 2 Flashcards

1
Q

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

A

water

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2
Q

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

A

70—95%

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3
Q

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

A

water

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4
Q

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

A

water

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5
Q

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

A

water

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6
Q

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

A

positive; “turgor”

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7
Q

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

A

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

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8
Q

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

A

transpiration

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9
Q
  • 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
A

transpiration

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10
Q

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

A

aquaporins

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11
Q

are proteins embedded in cell membrane that regulate flow of water

A

aquaporins

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12
Q

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

A

aquaporins

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

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13
Q

water potential is the combined effects of

A
  1. solute concentration
  2. physical pressure (cell wall)
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14
Q

water potential symbol

A

Ψ (Psi)

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15
Q

water potential is measured in ______

A

megapascals (MPa)

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16
Q

1 MPa = __ atm

A

10 atmospheres of pressure

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17
Q

Formula of water potential

A

Ψw = Ψs + Ψp + Ψg

where,

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

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18
Q

plants can use the _____ energy in water to perform work

A

potential energy

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19
Q

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

A

regains

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20
Q

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

A

less

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21
Q

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

A
  • 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
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22
Q

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

A

stomatal conductance

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23
Q
  • effect of dissolved solutes on water potential
A

solute potential

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24
Q

reduce free energy of water

A

solutes

25
Q

is the hydrostatic pressure of the solution

A

pressure potential

26
Q

______ pressure raises the water potential while _____ pressure decreases it

A

positive,
negative

27
Q

Positive pressure – _____ and;
negative pressure - _____

A

turgor
tension

28
Q

potential that is generally negligible

A

gravity potential

29
Q

gravity potential is overcome by

A

transpiration pull

30
Q

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

A

water potential

31
Q

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

A

water potential

32
Q

immediate contact of root and soil is necessary for

A

water uptake

33
Q
  • 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
A

hydraulic lift

34
Q

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

A

apical part of root that includes the root hair zone

35
Q

are most active in water absorption process.

A

root hairs

36
Q
  • water moves across the plasma membranes, with a short visit to the cell wall space.
A

transmembrane pathway

37
Q

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

A

symplast

38
Q

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

A
  • Apoplastic pathway
  • Symplastic pathway, and
  • Transmembrane transport.
39
Q

At the endodermis, the apoplast pathway is blocked by the

A

Casparian strip

40
Q

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

A

Casparian strip

41
Q

Factors affecting water absorption (5)

A
  • Available soil water
  • Concentration of soil solution
  • Soil temperature
  • Soil aeration
  • Transpiration, etc.
42
Q

Factors affecting rate of transpiration (7)

A
  • Humidity of air
  • Temperature
  • Wind velocity
  • Light
  • Atmospheric pressure
  • Carbon dioxide concentration
  • Root : Shoot ratio
43
Q

Significance of TRANSPIRATION (3)

A
  • It helps in ascent of sap.
  • It helps in the absorption of water and minerals.
  • It has cooling effect
44
Q

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

A

cohesion-tension theory

45
Q
  • 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.
A

cohesion-tension theory

46
Q

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

A

STEPHEN HALES

47
Q

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.”

A

STEPHEN HALES

48
Q

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

A

Freezing Injury

49
Q

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

A

browning, blackening, wilting or curling leaves and stems

50
Q

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

A

chilling injury

51
Q

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

A

chilling-sensitive,

52
Q

Coping Mechanism of Plants During Cold (4)

A

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

53
Q

So how do plants survive winter?

A

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

54
Q

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.

A

Create anti-freeze

55
Q

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.

A

Move water deeper

56
Q

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

A

Enter dormancy

57
Q

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.

A

Drop their leaves.

58
Q

“The Earth is what we all have in common.”

A

Wendell Berry

PHYSIO LEC (12 decks)

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