Post Midterm Flashcards
1
Q
Plant Primary Macronutrients
A
Nitrogen (N)
Phosphorus (P)
Potassium (K)
2
Q
Plant Secondary Macronutrients
A
Magnesium (Mg)
Sulfur (S)
Calcium (Ca)
3
Q
Plant Micronutrients
A
Boron (B)
Chlorine (Cl)
Manganese (Mn)
Iron (Fe)
Nickel (Ni)
Copper (Cu)
Zinc (Zn)
Molybdenum (Mo)
4
Q
Micronutrients
A
Normally found in small amounts
5
Q
Concentrations of macronutrients range from
A
1000-450,000 ppm
6
Q
Iron (Fe)- general info
A
Biologically relevant form in plants- Fe+2, Fe +3
Concentration in plant: Deficiency- <20, Normal- 20-1000, Toxicity- >2000
7
Q
Copper (Cu)- General info
A
Biologically relevant form in plants- Cu+, Cu +2
Concentration in plant (ppm): Deficiency- <10, Normal- 10-25, Toxicity- >25
8
Q
Zinc (Zn)- General info
A
Biologically relevant form in plants- Zn+2
Concentration in plant: Deficiency- <10, Normal- 10-120, Toxicity- >120
9
Q
Manganese (Mn)- general info
A
Biologically relevant form in plants- Mn+2, Mn+3, Mn+4
Concentration in plant: Deficiency- <90, Normal- 90-200, Toxicity- >200
10
Q
Molybdenum (Mo)- General info
A
Biologically relevant form in plants- Mo+4, Mo+6 (in moco or FeMoco)
Concentration in plant: Deficiency- <0.1, Normal- 0.1-90, Toxicity- >90
11
Q
Boron -General info
A
Biologically relevant form in plants- B(OH)3
Concentration in plant: Deficiency- <10, Normal- 10-80, Toxicity- >80
12
Q
Chloride- general info
A
Biologically relevant form in plants- Cl-
Concentration in plant: Deficiency- >100, Normal- 100-800, Toxicity- <800
13
Q
Nickel (Ni)- General info
A
Biologically relevant form in plants- Ni+2
Concentration in plant: Deficiency- >0.05, Normal- 0.05- 10, Toxicity- <10
14
Q
Micronutrients- general info
A
narrow optimal concentration range
most are immobile in plants
15
Q
Micronutrients necessary for chlorophyll production
A
Iron (Fe) and Manganese (Mn)
Deficiency: poorly mobile elements causes interveinal chlorosis (yellowing)
16
Q
Iron (Fe)
A
Abundant, important and largely insoluble
Fe largely oxidized and insoluble
17
Q
Interveinal chlorosis
A
Yellowing
the characteristic symptom of iron deficiency
18
Q
Strategies to improve nitrogen-use efficiency and decrease N pollution
A
Altering flux into amino acid pools or breeding strategies can enhance nitrogen use efficiency
19
Q
Iron cells can be found in
A
Heme
Fe plays central role in electron transport (oxidation/reduction) processes
20
Q
What is Chelation
A
The formation of bonds between two or more separate binding sites within a ligand and a single central atom
complex compounds consisting of A central metal atom attached to a ligand in a cyclic or ring structure “clamp”
21
Q
DTPA chelates
A
Iron (Fe+3)
22
Q
Organic acid (Citrate) binds to
A
Fe
Fe solubilization in soil
to maintain an accessible pool of Fe
23
Q
Plant root exudate and microbial exudate
A
Increasing Pi availability
24
Q
Rhizosphere
A
soil area around the plant root
25
yellow- stripe1 mutant
was identified from maize
A lack of chlorophyll
In the 1950s and 1960s, this phenotype is caused by iron deficiency
The transporter (YS) was cloned in 2001
26
Siderophores:
small metal-binding molecules
generated from bacteria
27
Phytosiderophores
generated from plants
28
Silicone
is beneficial to plants, especially under stress conditions
29
Iron uptake
Strategy I- dicots
Strategy II- monocots
30
Transport systems that operate across membranes
Symporter
Anitporter
Channels
H+ pump
ABC transporter
31
Flux (J) crossing biological membrane
Diffusion
32
Diffusion
Movement of individual molecules of a substance through a from an area of higher concentration to an area of lower concentration
33
Chemical potential
The sum of the concentration, electrical and hydrostatic potentials (under standard conditions)
34
Facilitated diffusion
involved in the movement of specific molecule (e.g. ions)
Needs specific channels or carrier proteins
needs no ATP energy for its transport
35
Facilitated diffusion of "i"
"i" interacts with a "molecule" in the membrane to permit its passive diffusion down its chemical potential gradient
36
Limited numbers of membrane transporters
membrane proteins are saturated at the high concentration
37
Glucose Permease
glucose transporter
38
Plastid glucose transporter
(pGluT; Glucose permease)
located in chloroplast inner envelope
39
Facilitated Diffusion of Charged Species in biological systems
Diffusion force drives in one direction, while electrostatic force drives in the opposite direction
40
Nernst potential
Electric field balances the concentration gradient in Activity of "i"
41
Active transport includes
ATPase, symporter and antiporter
42
Nitrogen that roots take up
They take up NO3- (Nitrate) or NH4+ (ammonium)
43
Phosphate transporters
PHT1 for phosphate (Pi) uptake and transport
44
H+-pumping ATPase:
Primary active transport system
45
Pumping protons out of the cell
Production of electric pH gradients
46
Proton (H+) electrochemical gradient
Driving processes of other transporters
47
Guard cells
Model systems for the study of membrane transport
opening and closing
48
Development of the plant vascular system
Coordination with the demands on the organism
49
Phloem and xylem
conducting elements in plants
50
Xylem
Root to shoot translocation
51
Phloem
Source to sink translocation
52
Source tissue
Exporting plant tissues or organs that produces photosynthate (e.g. sugars)- mature and photosynthetically active leave
53
Sink tissue
Non-photosynthetic developing organ or an organ that does not produce enough photosynthate
54
Leaf maturation
From leaf tip to the base
55
If plants 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
56
Sieve tube
the functional units for long distance translocation of plant materials
stacked sieve elements
57
Sieve plate
a perforated wall between the sieve elements
58
Mature sieve elements contain
1. Structural phloem specific proteins (P-proteins)
2. Endoplasmic reticulum (ER)
3. Mitochondria
4. Sieve element plastids
59
Mature sieve elements DO NOT contain
1. Nucleus
2. Vacuole
3. Golgi bodies
4. Chloroplast (at the shoot)
60
P-proteins and Callose
protection mechanism in phloem
61
P protein
Sealing off damaged sieve elements by plugging up the sieve plate pores
quick plant response (short term solution)
62
Callose
B-(1,3)-glucan
seal off damaged sieve elements
long-term solution
63
Heterotrophic shoot
Assimilate "sink"
64
Autotrophic leaf
Assimilate source
65
Heterotrophic root
Assimilate "sink"
66
Sucrose loading into minor leaves
1) Symplasmic sucrose loading model
2) Apoplasmic sucrose loading model
67
Symplasmic sucrose loading model
sucrose moves through the plasmodesmata from the mesophyll cells to the phloem
68
Can all sugar forms move through the phloem?
"nonreducing sugars (less reactive) can be transported via the phloem"
Generally not reducing sugars
69
Glucose, Mannose and Fructose (reducing sugars) contain reducing groups (aldehyde and ketone group)
Chemically too reactive to be translocated through the phloem
70
Sucrose
the most common form of sugar
translocated through the phloem
71
Aphids feed directly from
phloem
72
What is being loaded/translocated through phloem?
water
photosynthate (raffinose group-sucrose):Sugars
Specific amino acids
Ions
Metabolites
Hormones (Auxin, gibberellic acid, etc.)
Proteins (role in signaling and SE maintenance)
RNA
(Information superhighway)
73
Chlorophyll
Reflection of green wave length (plants are green)
74
Endergonic (energy in) reaction
potential energy of substrate < product
75
Exergonic (energy out) reaction
Potential energy of substrate>product
76
Pyrenoid
carbon-fixing reactions take place
77
two types of photosynthesis
oxygenic photosyntehsis
anoxygenix photosynthesis
78
Oxygenic photosynthesis
Removal of electrons from H2O->release of O2
Reduction of CO2 to carbohydrate (3 carbon sugar)
Plants, algae and certain types of bacteria (cyanobacteria)
79
Anoxygenic Photosynthesis
Do Not extract electrons from water:
80
Plastids and chloroplasts
Essential organelles for most plant cells
81
Etioplast
dark grown photosynthetic tissue
no chlorophyll
Developed plastid from the proplastid when plants are grown in dark
82
Proplastid
undifferentiated
colorless
seeds, embryonic, meristems and reproductive tissues
83
Chromoplast
red and yellow pigment (carotenoids)
Flower (petal), fruit
84
Identity and abundance of plastids are controlled by
developmental and environmental cues
85
Light induces conversion from
Etioplast to chloroplast
86
Grana stacks in the thylakoids
Speciality of land plants
87
Chloroplast movement is
crucial for the plants living under a canopy
88
Chlorophylls
the essential pigments that harvest the light energy and transduce it into chemical energy
all chlorophyll-based photosynthesis systems use chlorophyll a
are amphipathic molecules
89
Chlorophyll b
land plants, green algae and cyanobacteria
90
Carotenoids
all chlorophyll-based photosynthesis systems
91
Phycoerthrin
non-green algae
92
Phycocyanin
cyanobacteria
93
Protoporphyrin IX
a precursor of Mg-containing chlorophyll and Fe-containing heme
94
Light absorption is affected by
chemical structure of chlorophylls
noncovalent interaction of chlorophylls with proteins in photosynthetic membranes
95
Functions of Carotenoids are
Accessory pigments
Protecting photosynthesizing organisms from destructive photooxidation (anti-oxidant)
Structural role in assembly of light harvesting complex
96
Accessory pigments
Phycobilins
97
Phycobilins
Named with the reason of their resemblance to bile pigments
They are: Linear tetrapyrroles, water soluble, accessory pigment with no associated metal
98
Linear tetrapyrroles
derived from same biosynthetic pathway as chlorophyll and heme
99
Amyloplast
lack pigments
lack elaborate inner membranes
Function: starch storage
Statoliths
100
Statoliths
starch-filled amyloplasts function in gravity sensing
101
Major factors to sustain plant life
Water, air and light
102
Water
Solvent for enzymatic activity and formation of biological membrane
103
Air
Basic elements (C,O,N)
104
Light
Thermonuclear fusion generates ultimate form of energy in sun
105
Photosynthetically available (Active) radiation
The portion of light that can be captured and used by photoautotrophs for photosynthesis
106
Spectrum
the graph of absorbance versus wavelength
107
The energy of the light particle (photon)
Light frequency
108
Photosynthetic action spectrum
Magnitude of biological response to light (wavelength)
Rate of photosynthesis
A single wavelength of light shines on a plant
109
Absorption spectrum
The amount of absorbed light by a molecules (pigment)
Functional wavelength of light in photosynthesis
110
Comparison of action and absorption spectra
Effectiveness of energy transfer between pigments
111
Why do pigments capture the light?
Get energy from the light
112
Photoexcitation outcomes
1. Heat
2. Fluorescence
3. Energy transfer
4. Photochemistry
113
Heat (photoexcitation outcome)
Thermal dissipation
Chlorophylls return to ground state
114
Thermal Dissipation
Converting excitation energy to heat
115
Fluorescence (photoexcitation outcome)
Immediate reemission of energy as a long wavelength
116
Energy transfer (photoexcitation outcomes)
Excited pigment molecules (e.g. chlorophyll) transfers it energy to another molecule
117
Photochemistry (photoexcitation outcome)
Energy of the excited state triggers a chemical reaction and becomes an e- donor
linkage of the excited e- donor to a proper e- acceptor
Transduction of chemical energy
118
Ground state
Electrons occupy the lowest energy level before a photon of light strikes chlorophyll
119
Excited state
Electrons gain energy when a photon hits chlorophyll
120
Energy transfer during photosynthesis
Pure physical phenomenon
no chemical changes
Resonance energy transfer
121
Resonance energy transfer
energy is transferred from pigment to pigment by resonance until it reaches the reaction center pigment
122
Light harvesting complex (LHC, antenna complex)
Pigments molecules bounded to proteins
123
Reaction center:
Special pair of chlorophyll a
electron acceptor
124
Photosytem
Reaction center surrounded by several LHCs
125
Energy funnel
from antenna system to the reaction center
126
Cyanobacteria and red algae
peripheral antenna systems
127
Plants and green algae
membrane-embedded light harvesting complexes (LHC)
128
Oxygen evolving organisms have two photosytems
Photosystem I and II (PSI and PSII)
129
Emerson enhancement effect
Two photosystems must operate to drive photosynthesis most effectively
130
PSI and PSII are linked by
An electron transport chain
131
Z-scheme
Cooperation of PSII and PSI in the transfer of electrons from water to NADP+
132
Visible spectrum
(400 to 700 nm)
Main light to hit a leaf
133
P700 is a very strong reductant
strong enough to donate electrons to NADP+
134
P680+ is a very strong oxidant
strong enough to pull electrons from H2O
135
The photosystems are embedded in
thylakoid membranes
136
Plastoquinone (PQ)
small molecule and mobile electron carrier
137
Cytochrome b6f (Cyt b6f)
Multiprotein membrane embedded complex
138
Plastocyanin (PC)
small protein and mobile electron carrier
139
Linear electron transport
PSII----> Cyt b6f----> PSI
140
Electron transfer in PSII
(1) Light converts reaction center chlorophyll (P680) to excited form P680*
(2) Electron leaves P680*, forming P680+
(3) The electron is transferred to Pheophytin (Pheo), forming Pheo-
(4) Pheo- passes the electron to QA to produce QA-
(5) QA- passes the electron to QB to produce QB-
141
Ferredoxin
is a soluble electron carrier to transfer electrons to NADP+
142
ATP synthase
multi-subunit rotary machine
movement of protons from inside the lumen to the stroma across the thylakoid membrane
synthesis of ATP from ADP and Pi
143
Photosynthesis
not a single reaction
photochemical reaction, electron transfer, biochemical reaction
144
In the thylakoid membranes
the capture of light energy as ATP and reducing power, NADPH
(light reaction)
145
In the chloroplast stroma
The transfer of energy and reducing power from ATP and NADPH to CO2
(Carbon-fixing reaction)
146
Cyclic electron transport
flow of electron from PSI to Cyt b6f
147
Linear electron transport
Flow of electrons from H2O to NADPH
148
Water-water cycle
another form of electron transport
Product: ATP (no NADPH)
early time period after the transition from dark to light
149
Pathways of electron transport
Linear electron transport
cyclic electron transport
water-water cycle
150
Excess excitation energy can lead to
photo-oxidative damage
151
Reactive oxygen species (ROS)
oxidative damage
reduced growth and yield losses
152
Excess light energy is dissipated via
Non-photochemical quenching (NPQ)
153
Non-photochemical quenching (NPQ)
1. Energy dependent quenching (qE): the xanthophyll cycle
2. State transition (qT): Conformational changes in LHCII
3. Photoinhibition (qI): Light-induced reduction in quantum yield as a consequence of damage
154
Energy- dependent quenching (qE)
Dominant form of NPQ
1. Lumen acidification activates Violaxanthin De-epoxidase (VDE)
2. Zeaxanthin leads to light energy dissipation by rearrangement of LHCII and reaction center II (RCII): decrease of energy transfer to RCII
3. The structural changes result in dissipation of light energy as heat
155
Linear and cyclic electron transport in chloroplast
regulatory mechanism for control over stromal ATP/NADPH ratio
Maintenance of metabolic activities in plants
156
Zeaxanthin and lutein
also have roles as antioxidants and in photoprotection to protect human eyes from phototoxic damage by accumulating in the macula
157
State transition (qT):
Regulating the redox state of plastoquinone (PQ) pool
158
LHCII phosphorylation
preventing the energy transfer to PSII
159
Photoinhibition (qI)
Photodamage to PSII
160
D1 protein
the key subunit of photosystem II (PSII)(Encoded by PsbA gene)
Multicomponent pigment- protein complex of oxygenic photosynthetic organisms
of PSII is susceptible to photodamage: photosynthesis is inhibited
161
Herbicide
Strategies to target photosytems
162
DCMU
a herbicide
blocking electron transport through PSII
163
Paraquat
a herbicide
preventing reduction of NADP+ by accepting electrons in PSI
164
Hexadecameric form of rubisco in plants
8 large subunits and 8 small subunits (L8S8)
Plants and most cyanobacteria (Form I)
Rubisco is found in a variety of forms (Form II, III and IV) in some bacteria, dinoflagellate algae and archaea
165
The catalytic efficiency of Rubisco
very low
166
Regulation of rubisco activity
the transcription, assembly and inhibition of rubisco
167
CO2 fixation needs
3 ATP +2 NADPH
168
Photorespiration is a multi-organellar process
Chloroplast, peroxisome and mitochondrion
169
Peroxisome (called microbody)
1) Single membrane organelle with diameter of 0.5-1.5 mm
2) no inner membrane
3) No DNA or ribosomes in peroxisome
4) Inside a dense matrix: Urate oxidase crystalline core
5) Glyoxysome: Peroxisome in seeds
6)Peroxisomes tether to chloroplast
170
Kranz anatomy in C4 plants
Bundle sheath cells form a ring around the vascular tissue, and mesophyll cells form a ring around bundle sheath cells
171
Mesophyll cells
Chloroplast with grana
172
Bundle sheath cells
Starch-rich chloroplast without grana
173
Transporters and plasmodesmata
transport function of metabolites between bundle sheath and mesophyll cells
174
Economically important C4 species in agriculture
monocot plants
Corn
Sugar cane
and sorghum
175
In hot and dry weather
Stomata closed: preventing water evaporation and CO2 uptake
The concentration of CO2 is low
HCO3- is generated from CO2 by Carbonic anhydrase
Phosphoenolpyruvate carboxylase fixes HCO3-
176
Crassulacean acid metabolism (CAM)
Carbon fixation at night
177
CAM plants
Cactus and succulents
178
CAM plants are economically important in agriculture
Vanilla orchid
Orchid plant
Agave grown for tequila
Pineapple
Aloe vera
179
PEP carboxylase fixes HCO3-
at night
180
Limiting factors for the rate of photosynthesis
Light intensity
CO2 concentration
Temperature
181
Light intensity
decrease of photosynthesis rate in low light intensity
No effect on the rate of photosynthesis above the optimum conditions
182
CO2 concentration
Decrease of photosynthesis rate in low CO2 concentration
No effect on the rate of photosynthesis above the optimum condition
183
Temperature
lower photosynthesis rate above or below the optimum temperature
184
Chloroplast movement
is crucial for the plants living under a canopy
185
Shade leaf
can capture and use radiation in Far-red and infra-red regions of the light spectrum
186
How to monitor light reactions
O2 production and CO2 consumption
187
Saturation of Rubisco activity for carboxylation=
excess light
188
Photosynthetic CO2 assimilation=
amount of CO2 generated by respiration
189
PAR (photosynthetically active radiation)=
light intensity
190
The light response curve and a quantum efficiency
Light reaction of photosynthesis (quantum yield
191
Quantum
amount of energy in each photon
192
At low light intesities, the relationship between net photosynthesis and light intensity is
linear
193
At low light intensities, there is
a negative value of net photosynthesis
and light is limited for photosynthesis
194
At the light saturation point, photosynthetic reaction rate is determined by
light- independent reactions (carbon fixation)
195
In the dark
CO2 production is greater than CO2 consumption
196
What factors influence quantum yield?
Light absorbance
Balance in excitation energy between PSI and PSII
Temperature
197
Quantum yield determines the
efficiency of photochemistry
198
Dynamic photoinhibition
under moderate excess light
Short-term reversible and regulatory process
maximum photosynthetic rate remains unchanged
199
Chronic photoinhibition
under high excess light
long-term reversible process
Photodamage
photosynthetic rate decrease
200
Photodamage
mechanism associated with damage and replacement of D1 protein in PSII
201
Transport of CO2 from the atmosphere into the chloroplast
Diffusion
202
Diffusion path of CO2 into the chloroplast
Gaseous phase
203
The liquid phase of chloroplasts, stroma
CO2 solubilization and Carbon fixation
204
In air of high relative humidity
the diffusion gradient of water vapor for driving water loss is about 50 times larger than the gradient of CO2 uptake
205
A decrease in stomatal resistance through the opening of stomata facilitates higher CO2 uptake
but unavoidably accompanied by substantial water loss
206
C4 plants use CO2 concentration mechanism
Carbon-fixation in C4 plants saturates at lower-than ambient CO2 levels
207
Carbon assimilation of C3 plants increases
with increasing CO2 concentration
208
C3 plants are expected to benefit more than C4 or CAM plants
from elevated CO2
209
Plants grown in high CO2 environment contain
more total non-structural carbohydrates (e.g. starch, sucrose)
210
Elevated CO2 reduces
overall mineral concentrations, such as contents of N (protein) and other macro and micro nutrients essential for human health
211
Free air CO2 enrichment (FACE) studies
to test the plant response to elevated CO2 concentration
212
Plants can be exposed to elevated CO2 by
pumping CO2 gas into the field
213
Drought
Stomata closed- decrease of CO2 uptake- lowering Ci- decrease of carbon assimilation
214
Heat results
in deactivating rubisco
215
High CO2 environment
can enhance plant growth and flowering as well as senescence
216
Water-use efficiency
can be affected by elevated CO2 levels
