Pre-Midterm Flashcards
1
Q
What is phyisology
A
branch of biology relating to the function of organs and organ systems, and how they work within the biological body to respond to challenges
2
Q
Plant Physiology
A
The study of how different parts of plants function for many aspects of plant life.
3
Q
Translocation in the Phloem
A
Source to sink
4
Q
Chloroplast
A
powerhouse for plant life
5
Q
C4 Photosynthesis
A
A CO2 pump, fast photosynthesis of C4 plants under high light intensity and high temperature
6
Q
Phytohormones
A
regulation of many aspects in all stages of the plant life cycle
7
Q
Water balance
A
important properties of water molecules
How to pull water through the xylem
Water potential
8
Q
Movement of water in plants
A
water moves from soil to root
water gets through the root
water moves up through the xylem
water moves from leaf to air
9
Q
History- the study of plant water relations
A
Malpighi and Grew (1670-1680s)
Observations of plant conducting tissues
They found out plant structures which are similar to animal vasculature
10
Q
Important properties of water
A
water is cohesive
water is an excellent solvent
water can dissociate into ions
water has a high latent heat of vaporization
Water has a high tensile strength
11
Q
Water is cohesive
A
No net charge to a water molecule, however electronegative
12
Q
Electronegative
A
Attract the electrons of the covalent bond
13
Q
Hydrogen bonding and polar structures
A
Good solvents for ionic substances, sugar and proteins
14
Q
Water has a high latent heat of vaporization
A
The heat required to change one mole of liquid at its boiling point under standard atmospheric pressure
44 kJ needed to cause 1 mole water to go from liquid to vapor state
15
Q
Tensile strength
A
Ability to resist a pulling force of molecules before breaking their bonds
16
Q
Cohesion
A
a molecule is attracted to the same molecule
17
Q
Adhesion
A
a molecule is attracted to the other type of substances
18
Q
Surface tension
A
the property of liquid surfaces which allows it to resist an external force, due to the cohesive nature of its molecules
19
Q
How do plants bring water from the roots to the shoots?
A
Capillary action (Capillarity)
20
Q
Water potential in Plants
A
Ability of water molecule to move freely in solution
Measurement of the potential energy in water
21
Q
Water movement
A
high to low water potential
22
Q
Chemical potential
A
Quantitative expression of the free energy associated with a substance
23
Q
Water potential consists of 3 components
A
Solute potential
Pressure potential
Gravity potential
24
Q
The major factors influencing the water potential in plants
A
Concentration
Pressure
Gravity
25
-sign for solute potential
Reduction of the water potential dissolved solutes
26
Pressure potential
effect of hydrostatic potential
27
Turgor pressure
+ hydrostatic pressure within cells (pressure potential >0 MPa)
Supports plants cells and tissues
water limitation lowers turgor pressure
28
Tension
- hydrostatic pressure, frequently develop in xylem
Pressure potential <0 MPa
29
Gravity potential in plants
plant height is generally to short for gravity potential to make a difference with water potential
Unless it is something tall like trees
30
Why is water potential important?
Cell growth, photosynthesis and crop productivity are highly influenced by water potential
31
Scholander pressure chamber
The pressure chamber method for measuring plant water potential
32
How to pull water through the xylem:
Cohesion, adhesion and surface tension
33
Water potential
Ability of water molecule to move freely in solution
34
Important mechanisms for water movement in plants
osmosis "water follows sugar"
Turgor pressure and plasmolysis
35
Solute potential
The solute potential is reduced when solutes are added to an aqeuous system
Water moves from 0 to negative number
36
Osmosis
phenomenon of water flow across a semi-permeable membrane
Sucrose cannot pass through the membrane, water moves across membranes
Important for water movement in plants, water borrows sugar, water follows sugar
37
Equilibrium
Water stop moving across membranes
38
Water potential =0
Pure water
39
Resistance of cell wall to deformation
Rigidity of plant cell wall to prevent the osmotic lysis by hydrostatic pressure (turgor pressure)
40
Plasmolysis
if water is moving out of the cell
41
Cell Inside: Hypotonic
Cell outside: hypertonic
Plasmolyzed
Water is moving outside of the cell
Solute potential outside of cell < solute potential cell inside
42
Cell inside: isotonic
Cell outside: isotonic
Flaccid
Solute potential cell outside is equal to solute potential cell inside
43
Cell inside: hypertonic
Cell outside: hypotonic
Turgid
Water moving into the cell
Solute potential cell outside > solute potential cell inside
44
Turgor pressure (osmotic pressure)
pressure from fluid within the cell pushing against the cell wall
45
How do water molecule move across plasma membrane
water channels
46
How do water molecules go through aquaporins?
Expression of an aquaporin in an Xenopus oocyte accelerates water uptake
47
Thermodynamic gradients
First response to solute potential gradient
Intermediate response to solute potential gradient
Late response to solute potential gradient
Equilibrium situation
48
First response to solute potential gradient
Water diffuses from pore orifice
water pulled thru channel by cohesion
49
Intermediate response to solute potential gradient
Water diffuses from pore orifice
Water pulled thru channel by cohesion
Pressure potential increases in cytoplasm
50
Late response to solute potential gradient
water diffuses from pore orifice
Water pulled thru channel by cohesion
Pressure potential increases in cytoplasm
51
Equilibrium situation
Pressure potential increased to balance solute potential
Equilibrium between cells
No NET flux of water across channel
52
Tetrameric arrangement (tetramer)
each monomer forms a water channel
53
Phosphorylation and pH
Modify aquaporin channel activity
54
How to stop osmosis
You need hydrostatic pressure
55
Diffusion
water movement during transpiration
56
Transpiration
Evaporation of water mainly through the stomata of leaves
57
Movement of water in plants (steps)
1. Osmosis
2. Bulf flow
3. Bulk flow
4. Diffusion
58
Diffusion rate is affected by
Area, distance and gradient
59
Surface tension
Enhancement of intermolecular attractive forces at the surface
60
Water movement through the leaf
1) Stomata open
2)Water vapor Diffueses from internal air space, down it concentration gradient, into the air
3) Net loss of water vapor causes air-water- interface to recede towards outer microfibrils
3)Establishment of water gradient begins when the air-water-interface touches outer microfibrils
4)H-Bonding/Cohesion transmits tension at surface to bulk water
5) Time dependent buildup of surface tension
6) Water is pulled towards air-water-interface
61
Analysis of pathway water flow
Apoplasmic (Apoplastic) pathway
Symplasmic (Symplastic) pathway
Transcellular pathway
62
Apoplasmic (Apoplastic) pathway
Never goes into the plant cell
Water moves through the intercellular spaces (e.g. cell walls) with no entry into cells
No resistance
63
Symplasmic (symplastic) pathway
First moves into cell through PM
Water moves through the cells via plasmodesmata
Some resistance
64
Transcellular pathway
Water moves across the plasma membrane
Passes through all of the membranes (vacuole membrane)
65
Plasmodesmata
microchannel connecting between plant cells through the cell wall, small channel that allows movement through cell walls to other cells
66
Tracheids
Primitive water-conducting elements
Present in gymnosperms and angiosperms
Cell size species dependent (is small)
Long, thin cells with tapered ends
Walls reinforced with lignin (support)
67
Gymnosperm
naked seed
68
Angiosperm
seed is covered
69
Pit pair
two pits occurring opposite one another in the walls of adjacent tracheid or vessel elements
70
Vessels
Advanced water-conducting elements
Present only in the angiosperms
One vessel-
71
Pits
effective combination of primary anf secondary walls
72
Caviation
a condition where in an air bubble moves into a vessel or tracheids
73
Embolism
the blocking of a xylem vessel or tracheid by an air bubble or cavity (xylem blocked)
74
Embolisms spread
from conduit to conduit; a pathway connecting the embolized vessels is shown in yellow
75
Embolized xylem vessel
No longer hold water
decrease xylem hydraulic conductance
76
Tensile strength
ability to resist a pulling force of molecules before breaking their bonds
77
Cohesion theory
the tensile strength of water is high enough to allow water to be pulled through the Treachiary elements
78
Xylem is vulnerable to
Cavitation (embolism)
79
Embolized xylem vessel;
no longer hold water
decrease xylem hydraulic conductance
80
Soil particle size affects
water movement
water retention
81
Large pore space
Gravitational pull
(sandy soil)
82
Small pore space
Capillary action
Clayey soil
83
Saturated soil
All pores are full of water
Gravitational water is lost
84
After drainage in soil
Field capacity
available water for plant growth
85
After drying in soil
Wilting point no more water available to plants
86
The type of soil particle affects
Soil interactions with water
87
Other factors of soil interaction with water
Organic matter, microbes, salinity, etc
88
Root architecture
Length of roots, branching, angle
89
Root architecture is affected by
water flow into roots
90
Shallow root systems
Effective at catching limited rainfall, things like winter wheat
91
Hydrotropism
root growth in response to water deficit
92
Gravity dominates the root growth in
Water sufficient environment
93
The root can exhibit hydrotropic growth
growth towards water
94
Osmosis
water uptake from soil to the roots
95
Root pressure
Positive pressure that forms in the root as the roots uptake water from the soil by osmosis
96
Apoplasmic pathways
movement through cell walls, except when crossing endodermis
97
Symplasmic pathway
Movement through cytoplasm and plasmodesmata
98
Transcellular pathway
water crosses plasma membrane and parallel with movement through plasmodesmata
99
Epidermis
Production of root hairs which project into the soil increasing surface for water and nutrient uptake
100
Casparian strip forces
water to cross a plasma membrane
101
Casparian strip is made of
lignin
102
Suberin
Cell wall- associated biopolymer found in endodermis
103
Role of suberized endodermis in the roots
decreasing the water permeability
xylem tensions extending further into the root system
104
Water movement through the plant like a
tug of war
105
Radial and axial conductance
importance of water flow through roots
106
Radial conductance
From soil to stele
107
Radial conductance is affected by
Anatomy, morphology, cell wall permeability, activity of water channels, etc.
108
Axial conductance
through the xylem
109
Axial conductance is affected by;
Number, diameter and structure of the xylem conduits, formation of embolisms etc
110
Root pressure and guttation
positive pressure is generated by osmosis in the roots
111
High value of pressure means
high value of tension and a high degree of water stress
112
Air-water-interface in mesophyll being pushed back to original position
water re-enters cut element
113
Plant response to water stress depends upon
imposed conditions
genetic background
physiological status
114
tomato plant subjected to rapidly drying soil
hydropassive response
115
plant response to water stress varies
with extent of water deficit, rate of dehydration and by genotype
116
The plant responds to water deficit after
a critical soil water potential is reached
117
Rate of water deficit and genotype affect
plant response and survival
118
Osmotic adjustment
a lowering of solute potential due to net solute accumulation in response to drought-stress
119
Osmotic adjustment for turgor regulation
maintains water absorption and cell turgor in drought conditions
sustain higher photosynthetic rate and expansion growth under drought
120
Elastic adjustment of cell wall
the relationship between cell volume and turgor
121
softening
increased cell wall elasticity
delaying the loss of turgor
122
plant responses to water deficit affect many processes
photosynthesis goes down
stomatal aperture goes down
shoot meristem and leaf growth decreases
root growth increases
solute accumulation increases
water uptake decreases
123
plants have to balance
their growth and survival responses
124
Modes of energy exchange
Conduction
convention
latent heat transfer
radiative exchange
125
Conduction
individual molecules transfer kinetic energy from one to another, but... they do not move far in the process
126
Convection
individual molecules gain kinetic energy from one regions and themselves transfer it to another region
transport of energy by a volume of fluid (here air)
127
Latent heat transfer
latent heat of vaporization
water has a very high latent heat of vaporization
128
radiative exchange
all matter acts as a near perfect black body
129
high temp
short wavelength, strong emissivity energy
130
low temp
long wavelength, weak emissivity energy
131
leaf temperature
energy input= energy output
132
energy input
short wavelength- radiation from sun (6.28 x 10^4 Joule)
long wavelength- reradiation from soil (3.35)
long wavelength- reradiation from air (1.26)
133
conduction
direct transfer of heat energy from one body (leaf) to another (surrounding atmosphere: boundary layer)
134
If plants are under drought stress conditions
stop transpiration by closing stomata, LE approaches zero, leaf temperature begines to rise, eventually a new thermal equilibrium will be established at each leaf surface
135
Spines
functioning as reflectors and reradiators
136
Essential element
an element that is needed for completion of life cycle
molecular constituent, without which the plant cannot perform the physiological function necessary to allow development to proceed to maturation
137
Most fertilizers contain
nitrogen, phosphorus and potassium
138
Environmental and health problems by using excess amounts of fertilizers
nitrogen fixation is energy demanding
phosphate and potash mining is destructive
eutrophication
nitrous oxide is a major greenhouse gas
139
Primary macronutrients
nitrogen
phophorus
potassium
140
Secondary macronutrients
magnesium
sulfur
calcium
141
Micronutrients
boron
chlorine
sodium
manganese
iron
nickel
copper
zinc
molybdenum
142
Boron nutrient deficient conditions
discoloration of leaf buds. breaking and dropping of buds
143
Calcium nutrient deficient conditions
plant dark green, tender leaves pale. drying starts from the tips. Eventually leaf bunds die
144
Sulphur nutrient deficient conditions
Leaves light green, veins pale green no spots.
145
Iron nutrient deficient condition
leaves pale, no spots, major veins green
146
Manganese nutrient deficient conditions
leaves pale in color, veins and venules dark green and reticulated
147
Copper nutrient deficient conditions
pale pink between the veins, wilt and drop
148
Zinc nutrient deficient conditions
Leaves pale, narrow and short. veins dark green. dark spots on leaves and edges
149
Molybdenum nutrient deficient conditions
leaves light green/lemon yellow/orange. spots on whole leaf except veins. sticky secretions from under the leaf
150
magnesium nutrient deficient conditions
paleness from leaf edges. no spots. edges have cup shaped folds. Leaves die and drop in extreme deficiency
151
potassium nutrient deficient conditions
small spots on the tips, edges of pale leaves. spots turns rusty. folds at tips
152
Phosphorus nutrient deficient conditions
plant short and dark green. In extreme deficiencies turn brown or black. Bronze color under the leaf
153
nitrogen nutrient deficient condition
stunted growth. extremely pale color. Upright leaves with light green/yellowish. Appear burnt in extreme deficiency
154
Very mobile
N,P,K,Mg
Deficiency symptoms appear first in older leaves and quickly spread throughout the plant
155
Moderately mobile
S, Cu, Fe, Mn, Mo, Zn,
Deficiency symptoms are normally seen over the entire plant, but the growth rate and rate of nutrient availability can make a considerable difference on the locations at which the symptoms develop
156
Immobile
B, Ca
Calcium is very immobile
157
pH
important to nutrient availability, soil microbes and root growth
158
Bacteria are prevalant in
alkaline (pH>7)
159
Fungi are prevalent in
acidic (pH<7)
160
Root growth
5.5
161
Nutrient uptake
Cation exchange capacity (CEC)
cations dissolved in soil water bind to negatively charged soil particles
162
CEC
degree to which a soil can absorb and exchange ions
plants can free up positively charged nutrients to secrete H+ to exchange with bound cations
163
Higher CEC
more potential for minerals in the soil
164
Hoagland nutrient solution
highest possible nutrient concentrations without producing toxicity symptoms
165
Roots hairs
extensions of root epidermal cells
increasing surface area for absorption
166
Carnivorous plants
can obtain nutrients by digesting trapped animals
167
Vascular plants assimilate mineral nutrients mostly
via roots
168
root developmental responses
cluster roots
169
biochemical responses roots
root exudates
170
Nitrogen
the most abundant mineral element in a plant
the most abundant element in the earth's atmosphere
the 4th most abundant element in a plant after C, H, and O
part of carbon compounds: amino acids, nucleic acids, chlorophyll, etc
171
If plants are under N-deficient conditions
it progresses
plant stunting
yellowing: lack of chlorophyll
older tissue affected first: N is mobile in plants
172
Why is nitrogen an essential element?
Forms linkage between amino acids via peptide bond- complex proteins
fundamental to chemical structure of DNA and RNA
173
Assimilation
incorporation of inoragnic nutrients into organic substances (amino acids, nucleic acids, etc.
174
N assimilation
GS/GOGAT assimilates inorganic nitrogen into organic molecules
175
Strategies to improve nitrogen- use efficiency and decrease N pollution
Co-cropping or growing in rotation with legumes enriches soil N content
legumes can acquire N from the atmosphere via special soil bacteria (rhizobia) which are housed in nodules on their roots
Altering flux into amino acid pools or breeding strategies can enhance nitrogen use efficiency
176
Nitrogen cycle
nitrification, denitrification, nitrogen fixation
177
roots take up
NO3-(nitrate)
or NH4+(Ammonium)
178
Nitrogen metabolism
uptake, assimilation and remobilization
179
Phosphorus
the 1st or 2nd most commonly limiting nutrient for plant growth
The 5th most abundant element in a plant
the 11th most abundant element in the earth's crust
180
If plants are under Pi-deficient conditions
stunted in plant growth
abnormal dark green color
older tissue affected first: P is mobile in plants
Reddish purple color: accumulation of anthocyanin pigments
181
Phosphorus in soil
immobile, insoluble complexes
182
Arbuscular mycorrhizal (AM) fungi
Facilitator for Pi uptake in most plants
183
Plant root exudate and microbial exudate
increasing Pi availability
184
Phosphate transporters
PHT1 for phosphate (Pi) uptake and transport
185
PHO1
Phosphate (Pi) exporter
moves Pi into xylem: Pi transport to the shoot
186
Phosphorus cycle
phosphorus (P) is assimilated and used as phosphate (Pi)
187
Potassium and soidum
the twins but different
both have a single electron in the outer shell: monovalent cations
both are very abundant elements
potassium is an essential nutrient
sodium is toxic
188
if platns are under K-deficient conditions
substantial growth reduction
yellowing appears on the oldest leaves: K is mobile in plants
brown necrotic lesions develop within the yellow parts and eventually spread to cover the entire leaf blade
189
Potash
potassium fertilizers are mined from underground reserves
provides K+ for fertilizers
190
K+ deficiency
rare but plant growth is usually stimulated by additional K+ supply
191
Potassium is an essential plant nutrient
functions as a counterion for negatively charged molcules, including DNA and proteins: providing stability of dynamic structure for DNA and proteins
Cofactor in some enzymatic reactions
main cation in vacuoles
K+ generates turgor to provide structure: cell expansion, plant growth and plant movement such as regulation of stomatal apertures
192
Homeostasis
ability of an organism to maintain an internal stability in response to environmental changes
important to the survival of plants
allowing consistency needed to function properly
193
Why is calcium an essential element
forms a constituent of middle lamella of cell wall: binds neighboring daughter cells together
required at external surface of plasma membrane and tonoplast for membrane integrity
acts as a second messenger in signal transduction
194
Why is magnesium an essential element
Mg transporters cloned but mechanisms still being elucidated
MG2+ required for: enzyme activities, energy transduction, chlorophyll structure
195
K+ mobilization
critical for K+ homeostasis
196
Potassium uptake by
high and low affinity transporters
