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PLANT PHYSIOLOGY > 8a > Flashcards

8a Flashcards

1
Q

What is the most abundant molecule in plants?

A

Water

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2
Q

9 properties of water

A

Polar molecule, hydrogen bonding, hydration shells, liquid over a large range of temperatures, thermal conductivity, high heat of vaporization, solvent properties, biochemical reactions, transparency

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3
Q

Waters physiological roles?

A

Uptake to maintain turgor, nutrient carrier

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4
Q

Water cohesion: strong mutual attraction between water molecules is due to?

A

Hydrogen bonding

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5
Q

Water cohesion: what does it do to waters surface tension?

A

Gives high surface tension

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6
Q

Water cohesion: what is waters tensile strength?

A

Unusually high tensile strength (max tension that an uninterrupted column can withstand)

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7
Q

Water adhesion: what is water attracted to?

A

Solid surfaces

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8
Q

Water adhesion: what does this allow for?

A

Allows capillary rise in small- diameter columns

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9
Q

What is diffusion? How do particles move?

A

Simplest way of movement through a solution or across a membrane

Particles move from high concentration to low concentration

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10
Q

What is diffusion of water called?

A

Osmosis

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11
Q

What does water cross during osmosis?

A

A selectively permeable membrane

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12
Q

What is osmotic potential? Positive or negative?

A

The change in free energy or chemical potential of water produced by solutes

Negative

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13
Q

What is water potential?

A

The sum of osmotic potential and wall pressure - potential energy of water

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14
Q

What is water potential affected by?

A

Affected by how much is dissolved

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15
Q

What is osmotic pressure?

A

The pressure needed to stop water movement

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16
Q

What is osmotic pressure the difference of?

A

The difference in chemical potential of the two solutions

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17
Q

Water potential is designated as?

A

ψ psi (sigh)

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18
Q

Osmotic potential is designated as?

A

ψ pi

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19
Q

Pressure potential is designated as?

A

ψ p

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20
Q

Matric potential is designated as?

A

ψ m

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21
Q

Osmotic potential is the effect that…

A

Solutes have on water potential

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22
Q

What is pure water’s potential

A

0

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23
Q

What does solute addition do to potential?

A

Decreases potential

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24
Q

Osmotic potential is related to the number to of…

A

Particles in solution

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25
What is pressure potential?
Pressure in excess of ambient atmospheric pressure
26
What effect does pressure have on water potential
Stretching or compression
27
Pressure potential units
MPa or bars
28
What is pure waters potential at 1 atmosphere?
Zero
29
Pressure potential is positive or negative?
Can be both
30
What is matric potential
Water adhesion to cell walls, membranes, soil particles
31
matric potential is positive or negative
Always negative
32
matric potential is important for _________, and ignored for __________ _______
Soils, living cells
33
Water moves to:
Moves to where water potential is more negative Moves from high water potential to lower water potential
34
When does water move?
Whenever there is a difference in potential
35
What happens when the water potentials of two regions are equal?
Regions are in equilibrium, no net movement of water
36
Water potentials must always be considered in:
Pairs or groups
37
Water flows in the direction of
lowest water potential
38
how does a cell decrease its water potential?
Cell must lose water or gain solutes
39
Water potential usually only varies from...
1-2 Mpa - otherwise can be fatal
40
Cel volume is small and changes do to
Pressure potential
41
What happens if a plant cell is placed in A solution of pure water?
- Water moves into cell - protoplast expands, plasma membrane puts pressure on the cell wall - Will take in water until the pressure opposes further water uptake
42
What is incipient plasmolysis?
Protoplasm exerts no pressure on the wall but does not pull away either
43
What is plasmolysis?
Plasma membrane pulls away from the cell wall
44
What happens if the plant cell is moved from water to a solution of -3 Mpa?
- incipient plasmolysis - water potential now equal to osmotic potential only - if plant isn't at equilibrium at point of incipient plasmolysis it becomes plasmolyzed - water potential inside continues to get more negative until it reaches outside potential
45
Most plants can't survive lower than _____MPa
- 2
46
Lower than _____MPa stops leaf growth
- 1
47
Water will move from a region of __________ to a region of __________. A) low water concentration; high water concentration B) low solute concentration; high solute concentration C) low water potential; high water potential D) low pressure; high pressure
B) low solute concentration; high solute concentration
48
In plasmolysis: A) entire cell becomes turgid B) cell wall shrivels into center of the cytoplasm C) plasma membrane pulls away from the cell wall D) plasma membrane is pushed against the cell wall
C) plasma membrane pulls away from the cell wall
49
Turgor pressure results most directly from: a) solutes moving out of a cell by osmosis B) solutes moving into a cell by osmosis C) water moving into a cell by osmosis D) water moving out of a cell by osmosis
C) water moving into a cell by osmosis
50
A plant cell with a water potential of -1 Mpa is placed in a sucrose solution with a water potential of -4 Mpa A) Will there be a net movement of water into the cell or solution? B) Will the turgor of the plant cell increase or decrease?
A) into solution B) decrease
51
Using water potential terminology explain: A) why wilted lettuce can be recovered by placing it in cold water B) why cut strawberries soften when you put sugar on them
A) plasmolyzed to turgid. Water goes into cell by osmosis B) sugar draws the water out of the strawberry cells- cells become plazmolyzed
52
Intercellular transport: who do plant cells communicate with?
Neighboring cells
53
Intercellular transport: connected by _____________ - also called ____________ extensions
Plasmodesmata, cytoplasmic
54
Intercellular transport: what is a continuous protoplast called?
Symplast
55
Intercellular transport out of the membrane into intercellular space its called?
Apoplast (varies between tissues)
56
Molecules either travel through the ________ or through the __________ to other cells
Symplast, apoplast
57
What is transpiration?
Loss of water from the plant in the form of water Vapor
58
Transpiration: majority of water loss is through what? What may contribute?
Leaves, lenticels
59
Transpiration: water Vapor diffuses to the atmosphere through what?
Stomata
60
Transpiration: where dues gas exchange take place?
In the substomatal space
61
Transpiration: name the 5 forces involved.
Diffusion, osmosis, capillary forces, pressure, gravity
62
Guard cells: pore opening and closing is based on…
Short distance intercellular transport
63
Guard cells: when stomata are closed, guard cells are:
Shrunken and have little internal pressure
64
Guard cells: opening of stomata is a result of turgor pressure caused by:
High solute concentration in guard cells
65
What is water transport controlled by?
Guard cells
66
Bulk flow is powered by water loss through
Transpiration
67
Stomata exchanges which 2 gases?
Co2 and H2O
68
Transpiration is advantageous under which conditions?
Moist conditions
69
Transpiration is lethal under which conditions?
Dry conditions
70
Stomata control mechanisms: healthy turgid plants are controlled by?
Light
71
Stomata control mechanisms: which light absorbed by the photo receptor?
Blue
72
Stomata control mechanisms: triggers stomatal opening or closing?
Opening
73
Stomata control mechanisms: in morning, uptake of K+ by guard cells is driven by a
Proton gradient
74
Stomata control mechanisms: proton gradient accompanied by uptake of ___ and accumulation of ___________.
Cl- and malate
75
Stomata control mechanisms: in afternoon, ______ is the dominant osmoticum
Sucrose
76
Stomata control mechanisms: stomatal closing is associated with a decrease in ________ ________ in guard cells
Sucrose content
77
Stomata control mechanisms: water stressed plants are controlled by?
ABA
78
Stomata control mechanisms: ABA synthesis in roots is increased or decreased?
Increased
79
Stomata control mechanisms: ABA is released to ______ and transported to _______
Xylem, leaves
80
Stomata control mechanisms: guard cells lose ___, _______, and _____
Cl-, malate, K+
81
Stoma closing: rapid movement of ___, ______, and ____ out of the guard cells results in a higher water potential Of the _______ and a lower water potential in the __________
Cl-, malate, K+ Cytosol, cell wall
82
Stoma closing: water moves down the water potential gradient and ______ the cell which reduces ________ and the stoma closes
Leaves, turgor
83
Stoma opening: for stoma to open, guard cells transport ___ and ____ back into the cell using an ______________ gradient generated by a _______ pump
Potassium and chloride Electrochemical Proton
84
Environment and transpiration: increased CO2 causes stomata to close or open?
Close
85
Environment and transpiration: evaporation increased with increased ___________
Temperature
86
Stomata close when temperature exceeds
30 - 35°C
87
4 environmental factors of transpiration
CO2 concentration, temperature, humidity, air currents

PLANT PHYSIOLOGY (2 decks)

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