Lent Flashcards
1
Q
How much of the BMR is used by the CNS and how much by ion transport?
A
CNS= 30-40%
Ion transport= 40-60%
2
Q
What 3 components of food (groups) make up a healthy diet?
A
Sugars/Starch
Fats/Oils
Proteins
3
Q
Why are proteins an inefficient energy storage?
A
1) Lots of E is required to make the peptide bond in the first place, so overall not much energy is being released
2) Also only half of the protein is actually available, a large proportion is essential for body function and can’t be broken down
4
Q
Where is fat stored in humans?
A
Muscle, liver, heart and adipose tissue
5
Q
Describe the structure of adipose tissue
A
White Adipose tissue contains 1 lipid droplet
Brown Adipose tissue contains multiple lipid droplets
6
Q
Why are carbohydrates vital?
A
Brain only uses glucose for energy
Fat is unable to pass blood brain barrier
Fats cannot be converted back into carbs
Carb also required by RBC and parts of the kidney
7
Q
Why is muscle glycogen only for muscle?
A
Unable to transport Glucose-6-phosphate
G-6-phosphotase not present
Unable to form glucose to be transported
8
Q
What types of fuel storage are present in plants?
A
Starch= Amylopectin + Amylose
Can convert triglycerides into carbs
Movement of sucrose around instead of as glucose
9
Q
Where are fats stored in plants?
A
Oleosomes- commonly in seeds
10
Q
What are endosperms?
A
Tissue surrounding seed of an angiosperm
is an energy store, technically a separate organism
Activated by Gibberellins
e.g. coconut water
11
Q
What is the use of Phosphocreatine?
A
Buffer to keep ATP concentration constant
Converted from creatine to phosphocreatine by creatine kinase
12
Q
How can levels of ATP and Pcr be measured?
A
Using NMR spectroscopy and P31
- Only shows relative conc changes
-Only shows molecules with ‘spin’
13
Q
What energy stores are used to stay alive overnight?
A
Glycogen
Then protein
14
Q
What is the order of energy store usage during long starvation?
A
Glycogen
Protein breakdown- then conserved
Fat breakdown- until fully exhausted
Then protein breakdown
Until death
15
Q
Why is protein broken down when glycogen runs out?
A
Protein can be broken down to produce carbs to feed the brain. The body takes a while to switch to ketone bodies which can be produced from fats to feed the brain
16
Q
What are the difference between the muscle of a marathon runner and that of a sprinter?
A
Marathon- aerobic respiration so Type I, high glycogen storage
Sprinter- Anaerobic respiration Type II, many mitochondria, less glycogen storage
17
Q
Why is fat not immediately used as a fuel source?
A
Production of ATP from fat is slow
Requires more O2
Brain requires carbs to stay alive
18
Q
How efficient are we?
A
20%
19
Q
What processes decreases muscle efficiency?
A
Heat loss
Loss in the conversion process in mitochondria
20
Q
Define homeotherms
A
Able to maintain internal temperature
21
Q
Define Poikilotherms
A
Don’t actively regulate internal temperatures
22
Q
Define Ectotherms
A
Dependent on external sources of heat to regulate temperature (fish, reptile, invertebrates)
23
Q
Define Endotherms
A
Control body temperature by metabolic processes (mammals, birds, tuna)
24
Q
Positives and negatives for being an endotherm
A
Can operate at many temperatures
Require extra food to carry out metabolic processes
25
How are fluctuations in temperatures created in humans?
External environment- causing redirection of blood
Hormones- progesterone increases body temp
Circadian rhythms- body colder at night
26
Ways in which heat can be retained?
Redistribution of blood to core
Counter current exchange- warming of cold returning blood so heat contrast when moved to extremities is less (dolphins)
27
Define heat capacity
1kcal raises the temp of 1kg of water by 1 degree celcius
28
What are the 3 processes to increase heat production?
1) Shivering
2) Changes in BMR (futile cycles)
3) Brown adipose tissue
Activation of sympathetic pathway
29
How does changes in BMR increase heat production?
Decreases efficiency of processes, leading to heat production
Controlled by the hypothalamus and thyroid gland
T4 conversion to T3 increases amount of ineffciency
1) Uncoupling proteins- less ATP made (UCP1)
2) Increase Na/K activity- large energy cost
3) Promotion of futile cycles
30
Why are uncoupling proteins present in plants?
For generation of heat
- attract pollinators
- help melt ice (skunk cabbage)
31
What is a dangerous example of uncoupling proteins?
DNP- weight loss drug
Mitochondrial uncoupler bypassing ATP-synthase and diffusing the H+ gradient
Side effects
- Nausea, Headaches, Death, Dehydration
32
What are the 4 ways of losing heat?
Radiation
Conduction
Convection
Evaporation
33
What is heat loss dependent on?
Surface area
Temperature difference
Evaporation rate also dependent on humidity
34
How is heat lost by radiation?
Loss of IR heat
35
How is heat lost by conduction?
Depends on the surface that is in contact
Water is much more conductive than air or fat
Adipose tissue can act as an insulator, but can be bypassed to increase heat loss
36
How is heat lost by convection?
Movement of air and water maintaining temperature gradient
37
How is heat lost by evaporation?
Sweating @ sweat glands
Acted on by sudomotor nerves
Sympathetic NS, with cholinergic receptors (muscarinic)
Similar to salivary secretion, undergoes primary and secondary modification
NOTE: it's an active process so does produce heat itself
38
What are behavioural responses to control heat loss/gain?
- Movement into the sun/shade
- Removal/addition of layers
39
What autonomic controls for heat control are present?
Cholinergic= shivering, sweating
Noradrenergic= BAT, piloerection, vasoconstriction
40
What part of the hypothalamus controls the satiety signal?
Ventro- medial nucleus (VMN)
41
What part of the hypothalamus is responsible for hunger centre?
Lateral hypothalamus
42
What area of the hypothalamus is responsible for body temperature control?
Preoptic area
43
What type of mechanism is used to control heat and why is it important?
Feed-forward mechanism
Anticipate future events, to maintain a stable internal temperature, and ensure that overcorrection doesn't occur
Important for homeostasis
44
How can metabolic rate be increased?
Exercise
Digestion
Illness
Pregnancy
Change in temp
45
How does body size effect BMR and SMR?
Body size does increase BMR however doesn't increase SMR. SMR being specific metabolic rate, which is greater in small animals due to the SA:Vol
46
What is allometry?
Study of scaling relationships
47
What is the Bergmann Rule?
Endotherms living in colder environments are larger than their warmer environment counterparts
48
What is Allen's Rule?
Endotherms living in cold environments they have smaller/shorter limbs
49
What is Kleiber's 3/4 rule?
Shows that BMR does not increase in proportion to body mass
Endotherms have a greater BMR compared to poikilotherms
- Not very accurate
50
What are the implications of metabolic scaling?
Biochemistry for smaller life occurs faster
They have faster HR and BR
51
What is the free radical theory of ageing?
- Quicker metabolism quicker ageins
- Due to more production of harmful chemicals
- This can damage cells and DNA, leading to mutations
However: some tortoises and birds live very long despite their size
52
What is the bird anomaly?
Birds have a longer lifespan
e.g. comparison between rodents of similar sizes and bats
Perhaps due to wing evolution, meaning more likely to survive
So reproductively active later in life
Slower life cycle = Live longer
53
What are the main differences between plants and animals?
1) Plants are sessile
2) Individual plant cells have controls
3)Plants are autotrophs
4) Plant cells have cell walls
54
What are the key similarities between plants and animals?
1) Both carry out gas exchange
2) Both are multicellular organisms
3) Both require nutrients
4) Have structural support
55
What are the differences between monocots and dicots?
Monocot- one cotyledon, SAM at soil level, parallel vasculature, fibrous root system
Dicot- two cotyledon, SAM in top of plant, tree-like vein vasculature, form lateral roots
56
What are differences in animal and plant development?
Plant development not restricted to young plants
Fast response
Animal- homeostasis
Plants- guard cell
57
What are the two types of division in plant cells?
Anticlinal (within the layer) (L1 and L2
Periclinal (forms new layer) L3
58
What are the 3 zones in the SAM
1) Central zone- dividing cells
2) Peripheral zone- divide and differentiate
3) Rib zone- provides cells for stem
59
What 3 key hormones regulate growth in plants?
Auxin
Gibberellins
Cytokinins
60
What is apical dominance and how is it achieved?
AM stops control of axillary meristem.
Production of IAA, stops lateral root growth. Use of sucrose by AM means not enough for axillary meristem
61
Where is the root apical meristem located?
In the tip of the root, protected by the root cap
62
What are the zones present in the RAM?
Quiescent zone- for dividing cells
Root cap- mechanical protection, and gravity sensor
63
Where are lateral roots formed, and what controls the growth?
Lateral roots are formed from the perricycle
They are controlled by pulses of auxin which prime the areas for growth, however actual growth is controlled by NRT1.1 channels
64
What is the vascular cambium?
Secondary growth, where phloem and xylem are made depending on their location, within the stem
65
What 2 hormones control the expression of the vessels (phloem and xylem)
Cytokinin
Auxin
66
What does a phytochrome consist of?
Protein and Chromophore
67
Which phytochrome is active Pr or Pfr?
Pfr- when in trans state
68
How does Pfr work?
Moves into the nucleus
Acts as a transcription factor
Some remain in the cytoplasm to control ion concs
69
What two complexes detect blue light?
Cryptochrome
Phototropin
70
What complex detects UV light, specifically the residues?
UVR8, specifically tryptophan residues
71
What can a plant 'hear'?
Buzzing, e.g. buzz pollination by bees
72
What can a plant 'smell'?
Ethylene- causing colour development and ripening
Warning signals released by other plants
73
How are plant defences coordinated between plants?
Jasmonic acid
-to deter herbivores
- warn other plants (HexVic)
74
How can caterpillars overcome plant defences?
Cause stomatal closure
Prevents release of signalling chemicals
Stop plant from controlling water content also
75
What are 2 examples of plants that use smell to attract pollinators?
Skunk cabbage
TItan Arum
76
How do plants tell the time?
Circadian rhythm present in cells
Also effected by environment
77
How does reaction to stress vary between types of plants?
Perennial (many season)- focus on growth
Annual (1 season)- focus on reproduction
78
What is an example of plant acclimation?
Yorkshire fog grass- adapt to reduce arsenic intake
acclimate to arsenic by incorporating it into building molecules
79
What are the 3 main abiotic stresses and their effect on plants?
Temp- denaturation of proteins, change in DNA/RNA
Drought- Plasma membrane contraction
ROS- denaturation of proteins
80
What does PGR stand for?
Plant growth regulators
81
What are the names of the 9 plant signalling chemicals?
Auxin
Cytokinin
Gibberellins
Ethylene
ABA
Jasmonic acid
Salicylic acid
Brassinosteroids
Strigolactone
82
What does auxin do?
Controls growth and plant development
e.g. lateral root formation
83
What does cytokinin do?
Stimulates cytokinesis, or senescence
84
What does Gibberellins do?
Present in chloroplast, controls cell elongation
Upregulated by auxin
Binds to DELLA and breaks it down
85
What does ABA do?
Prevent growth and germination
Found when conditions are bad e.qg. drought
86
What does Ethylene do?
Cause fruit ripening
Is a gas hormone
87
What does strigolactone do?
Allows for symbiosis with fungi
88
What does brassinosteroids do?
Cell growth, development, everything
89
What does jasmonic acid do?
Responds to herbivores
90
What does salicylic acid do?
Responds to pathogens
91
How does the DELLA- Gibberellins signalling work?
Signal transduction by degradation
DELLA usually bound to TF, doesn't allow transcription
Gibberellins binds to DELLA, breaks it apart
TF able to bind and cause transcription
92
How does phosphorelay signalling occur?
Phosphorylation cascade
Usually for hormones ethylene and cytokinin
93
How can signalling occur inside plant cells?
Symplastically- Signalling via plasmodesmata
Via movement of phytochromes and steroid hormones
94
How and why does Ca2+ signalling occur in plants?
Occurs by movement of Ca2+ via plasmodesmata
Occurs in response to wounding, salt stress
95
What type of signalling can lead to systemic acquired acclimation?
ROS communication
96
What is the evidence for long distance communication via nucleic acids?
GFP (green fluorescent protein) used to tag RNA.
Shows movement of RNA all around the plant
97
What is the difference between tropic and nastic movement?
Tropic- in a certain direction
Nastic- in any direction (non-directional)
98
How does gravitropism work in the roots?
Statoliths in statocytes relocate to the bottom
PIN-3 relocate to the bottom
PIN-2 and AUX1 relocate auxin to bottom
Auxin INHIBITS growth of bottom side
99
How does gravitropism work in the shoots?
Statoliths in endodermis relocate
PIN-3 relocate to bottom
Auxin redistributed
Auxin CAUSES growth of bottom side
100
What channel proteins are involved in phototropism?
PHOT1 and 2 temporarily stop auxin transport
PIN-3 resumes movement
101
What is thigmonasty and an example?
Response to touch
e.g. Mimosa Pudica contraction due to changes in turgor pressure
102
What is nyctinasty?
Movement associated to circadian clock
103
How does movement in a venus fly trap occur?
Cl- efflux causing Ca2+ signalling
Causes movement of K+ out
Changing elastic potential
Causing it to snap shut
104
What is circumnutation?
Swinging motion
Both nastic and tropic
e.g. vines growing
105
What are the responses in growth of shoots and roots to changes in environment (water and Pi)?
Shoots continue to grow until roots can't provide more water
Roots grow until shoot can't provide more phosphate
106
What are the effects of light stress?
Too high energy light can cause photobleaching
107
What are the effects of temperature stress?
Too high- denature enzymes, water evaporation, effect membrane fluidity
Too low- ice crystals form (can pierce mem)
108
What are 4 metabolic changes that can occur to maintain protein integrity in plants?
Metabolic
1) Dehydrins- form shield around protein
2) Chaperones- stabilize and repair
3) Desaturase enzymes- increase no of unsaturated to control mem fluidity
4) Anti-freeze- stop ice crystals from growing, by binding to them
109
What are 3 physiological changes that can occur to maintain protein integrity in plants?
1) Abscission- leaf loss
2) Change leaf shape/angle
3) Modify leaf surface (waxy cuticle)
110
What is heliotropism?
Directional response to sunlight (detects blue light)
111
Why is heliotropism important for angiosperms?
Important to attract pollinator
Important for pollen germination
112
How do lateral roots form?
Usually NRT1.1 moves auxin away from the pericycle, so lateral root can't form
When nitrate present, the NRT1.1 begins to transport nitrate instead of auxin
This allows auxin build up
Causing the formation of a lateral root
113
What are trichoblasts?
Root hair cells
Important for increasing SA
114
What are 5 ways plants deal with toxic compounds?
1) Chelation- make less active
2) Accumulation - stored in a specific place where doesn't cause damage
3) Ion transport modified- As removal by Yorkshire fog grass
4) Deposition of lignin- harden root, reduce uptake
5) Reduce uptake- change channels etc.
115
What are the main risks and responses to drought?
Risk- dehydration, death, lose turgor pressure
Response- ABA, close stomata, dehydrins
116
What are the main risks and responses to too much water?
Risk- lack of O2, for respiration, death
Response- Ethylene coordination
117
What are aerenchyma and its use?
Aerenchyma- air gaps in plants, caused by the death of cells coordinated by ethylene
Use- reduce nutrient & water requirement, helps plant tolerate stresses
118
What is xerobranching?
Repression of growth of a lateral root due to the lack of water in contact with the root tip. Which is an ABA dependent mechanism
119
What is hydropatterning?
Position of lateral roots on the side with most water, causing lots of branching and brush like look.
120
Which hormones act as positive and negative hydrosignals?
Positive- Auxin
Negative- ABA
121
Why can a combination of stresses be more detrimental? Give an example
The responses to different stresses may oppose each other
e.g. Heat + drought
heat- open stomata to cool plant
drought- close stomata to reduce water loss
Can't do both at the same time
122
How can adaptations to stresses increase food security?
Plants can be modified to be resistant to salt stress or drought which can increase food security.
123
What are the components of a seed?
SAM, RAM
Endosperm
Seed coat
124
How do seeds cope with desiccation during quiescent stage?
Accumulate sugars
LEA (late embryogenesis abundant proteins)
- Slows diffusion and metabolism
125
What hormone controls germination?
Ratio of Gibberellins to ABA
126
What environmental signals effect germination?
Temp
Light
Chemicals
127
What hormone causes cell elongation?
Auxin
128
How does cell expansion in plants occur?
Expansins proteins, loosen the bonds in the cell wall
Turgor pressure increase causes expansion
129
What are the 3 components of a plant cell wall?
Cellulose
Pectin
Hemicellulose
130
What are the steps involved in plant growth in the dark?
Pr present (inactive)
Gibberellins builds up
Binds to DELLA, so TF can bind
Cell elongation occurs out of the shade and into the light
131
How do angiosperms transition to flowering?
Detect long or short day, depending on the plant
Long day- wheat, bread
Short day- rice
132
What does ripening involve?
Stimulation by ethylene
Soften- breakdown of cell wall
Sweetening- accumulation of sugars
Colour &scent- pigments (Anthocyanin- blue, Carotenoids- red)
133
What 2 hormones control abscission?
Ethylene
Auxin
134
Why does senescence/ abscission occur?
Lack of nutrients
Stop infection spreading
Re-distribution of nutrients to younger leaves
135
What are the 3 stages of leaf senescence?
Initiation- receive signal
Degenerative- breakdown
Termination- cell death, abscission
136
What is the role of the waxy cuticle?
Protect
Prevent drying out
137
What is the role of the stomata?
Control gas exchange
Control water and heat loss
138
How are monocot and dicot stomata different?
Monocot- dumbell shaped with subsidiary cells
Dicot- liver/ sausage shaped
139
What are the 3 cues that control stomatal opening and closure?
O2
Water
Light
140
What physiolgoical feature allows the guard cell to open and close the stomata?
Polar stiffening, so that when turgor pressure increases, opens stomata as a hole
Varied thickness of walls
141
How does stomatal opening occur?
Activation of H+ ATPase
Causes hyperpolarisation
Passive uptake of K+ and and Cl-
Production of malate from CO2
Movement of water in
142
How does stomatal closure occur?
Ca2+ signalling
efflux of K+ and Cl-
Reduce activity of H+ ATPase
Depolarisation
Movement of water out
143
How is stomatal opening/closure controlled by light?
Via phototropin
Detects blue light
Binds and activates P-type ATPase
144
How is stomatal opening/ closure controlled by presence of water?
ABA (drought)
Binds to PYR1
Activates MAP kinase- phosphorylation cascade
Release of Ca2+ promotes closure
145
Why does Ca2+ not effect the ion conc and cause water movement directly?
Too small conc to have an effect
146
What is anion trapping?
Way to control water use by controlling location of ABA
ABA acts as a weak acid that is kept in chlorplasts
147
How can pathogens control stomatal opening/closure?
Release of chemicals/ enzymes that effect turgor pressure
Fusicoccin- causes stomatal opening
Caterpillar salivary enzymes cause stomatal closure to stop release of plant warning chemicals
148
How can stomatal development vary?
High light- many stomata
High CO2- few stomata
High water- many stomata
Once fully developed, cannot change
149
What is the photic zone?
Zone in water (~50-100m) where red light can still get to and so photosynthetic plants can live
150
What is Blackman's limiting factor analysis in terms of plants?
Factors such as CO2 and light can become limiting depending on the environment
151
What is the light compensation point?
Where respiration= photosynthesis
Zero net CO2 uptake
152
How are thylakoids and the PSs located in the chloroplasts?
Non-appressed (not stacked) contain PSI (smaller), cytochrome b6f complex, ATP synthase
Appressed (stacked) contain PSII (larger)
153
How do electrons travel between photosystems?
Mobile e- carriers (quinones)
154
What damage and repair occurs in the appressed thylakoids?
Damage of D1 proteins, by products of photolysis of water
Move D1 out of appressed stacks
Dismantle and repair and then replace
155
What happens during photobleaching to the thylakoids?
D1 damage > rate of repair
156
What are 2 protection mechanisms from photobleaching?
1) Relocation of PSII to non-appressed so not to much energy is funneled down
2) Dissipation of energy as heat
157
How can leaf morphology show acclimation to varying light intensities?
Shade and Sun leaves in Beech trees
158
What is the morphology of sun leaves?
Thicker
Vertical chloroplasts
More lamellae (non-appressed thylakoids)
159
What is the morphology of shade leaves?
Thin
Horizontal chloroplasts for greater SA
More PSI and PSII in chloroplasts
More stacks (appressed)
More air space to scatter light
160
How does the light response curve differ between sun and shade leaves?
Sun-higher photosynthetic capacity, higher light compensation point
Shade- lower LCP, lower photosynthesis capacity
161
Why can the route of CO2 be slow?
Has to pass liquid and gas phase boundaries
Resistance of stomata
162
How are leaves morphologically adapted to increase rate of CO2 uptake?
Hairs on the leaves cause streamline action
163
How old is RuBisCO?
+3 billion years old
164
Why is RuBisCO so inefficient?
Can't distinguish well between O2 and CO2
165
What does RuBisCO produce in the photorespiration cycle?
Phosphoglycolate which is toxic for Calvin cycle, needs to be removed using ATP
166
What are the potential reasons RuBisCO has not evolved to become more efficient?
Initial evolution in atmosphere with low O2
Changing shape could effect other reactions it's involved in
Specificity v speed
Specificity v stability
167
What are the 2 carbon concentrating mechanisms in plants?
CAM and C4
168
How are CAM and C4 different?
C4- spatially separated
CAM- temporally separated
169
What is the C4 pathway?
Oxaloacetate(C4) is made by PEPC, instead of using RuBisCO
Then transported (as malate) from mesophyll to bundle sheath to Calvin Cycle
170
How are CAM and C4 different?
C4- spatially separated
CAM- temporally separated
171
Describe the Kranz Anatomy of C4 plants
Larger bundle sheath around vascular bundle
Chloroplasts pressed up against the cell membrane
Greater density of chloroplasts
172
What are the 4 advantages of suppressing photorespiration by adapting the C4 mechanism?
1) Energetic, less ATP needed to remove phosphoglycolate
2) Lower CO2 compensation point
3) Greater yield with C4 than C3
4) Less water use, as stomata don't have to stay open for as long= more efficient use
173
When did the C4 pathway evolve?
Around 20million years ago
Shows convergent evolution
174
What does CAM stand for?
Crassulacean Acid Metabolism
175
What is the CAM mechanism?
Temporally separate CO2 fixation and C4 decarboxylation
PEPC present to make C4 compound
176
What are the 4 phases of CAM?
I- @night, PEPC active, CO2 fixed
II- Early morning, burst of CO2 fixing
III- Day, stomata close, RuBisCO function
IV- Late day, open stomata, normal C3 photosynthesis
177
How is PEPC controlled?
By phosphorylation by a kinase, becomes active
Under circadian control
178
What are anatomical features of CAM plants?
Large cells
Large vacuoles (malic acid store)
Thicker leaves
Small air spaces
179
What are ecological advantages of CAM plants?
Can live in areas with low CO2
E.g. aquatic environments where rate of diffusion is x1000 slower
180
Are C4 and CAM compatible? Is there an exception?
Not compatible due to different anatomy
PEPC in either are active at different times
C4- PEPC active during the day and vice versa
Exception- Portulaca Oleracea, has different isoforms of the proteins
181
What ideas are present to increase food security?
1) Using different freqs of light (different pigments)
2) Improving efficiency of RuBisCO
3) Introduce C4 into C3 plants
4) Engineering stomata, to be more water efficient
182
What are source and sink tissues? Give examples.
Source- provide energy e.g. leaves, potatoes
Sink- use energy e.g. fruit, roots, seeds
183
What is the structure of the phloem?
Companion Cell
Sieve tube element
Symplastic connections
Phloem Parenchyma Transfer Cell (PPTC)- increase SA
184
By which model does mass flow occur in plants?
Pressure- flow model
High to low conc
Down pressure gradient
185
What is phloem loading?
Apoplastic loading
Using sucrose transporters on membrane
Use hexose transporters and ATPase
186
What is phloem unloading and what may it require?
Symplastic unloading
May require active unloading (ATP), as it may be moved into a store where sugar is still sucrose and not turned into starch
187
What are 3 main pieces of evidence for sucrose movement?
1) Radio labelled carbon, detect movement
2) Aphids- target phloem which contains sucrose
3) Mutation of sucrose transporter effected growth
188
What compounds does sap flow contain?
Amino acids
Signalling chemicals
Sugars
Growth Regulators
189
How can the phloem and transport of nutrients be protected?
By blocking the phloem, stop leakage of nutrients
1) P-type plastids- blocks sieve plates, dislodge from cell wall
2) Forisomes- Spindle shape, conformationally changed by Ca2+ signalling, becomes crystalline
3) Callose- permanent blocker
190
What are tracheids and what are they present in?
Thin spindly structure to move water
Present in angiosperms and gymnosperms
191
What are the 4 key properties of water?
Hydrogen bonding
Cohesion- stick to each other
Tensile strength
Adhesion- stick to cell wall
192
What is Darcy's law for water movement?
Flow water= pressure gradient/ resistance
193
What is Poiseuille's Law?
Resistance = (8xlengthxviscosity)/(pix radius ^4)
194
What does Poiseuille's Law mean?
Resistance is effected massively by the radius of the vessel
Also by the viscosity of the fluid and length of the vessel
195
What evidence is there for water stress in relation to plant height?
Leaves of very tall trees, usually at the top they are smaller
196
What can lead to hydraulic failure in plants?
Creation of an embolism
Air bubble gets trapped
Stops normal water flow
197
How has the anatomical structure of the xylem evolved to be less affected by embolisms?
Structure of the xylem is more complex
Less neighboring vessels, reduces chance of embolism spreading
198
How do plants adjust to osmotic stress?
Create compatible solutes
e.g. Proline
which are neutrally charged
199
How do plants cope with salinity?
Production of Proline
Protects hydration shell of protein from attack by Na+ and Cl-
200
How does ABA signal drought and salinity?
Promotes a transcription factor
TF activates Dehydration Responsive Element-binding (DREB)
201
How many essential minerals are required by plants?
16
202
What does the critical concentration of mineral means?
Minimum conc at which yield reaches 100%, however above that could become toxic
203
What are the 3 main properties of soil?
Heterogeneous (air and water)
Acidic (5.5-6.5)
Contains charged particles
204
What are the uses and properties of nitrate?
Amino acid and nucleotide
Prone to leaching as it is negatively charged
205
What are the use and properties of phosphate?
DNA and RNA backbone, ATP
Extremely immobile
206
What are the 4 components of the radial root?
Root epidermis- ion uptake
Cortex- storage
Steele- vasculature
Casparian Strip- diffusion barrier
207
How is apoplastic and symplatic movement different?
Apoplastic- between cell wall and membrane, stops at Casparian strip
Symplastic- through plasmodesmata
208
How does potassium uptake occur?
Via AKT1 and KAT1
AKT1- high affinity when low conc
209
How does nitrate uptake occur?
NRT1.1 (CHL1), NRT2
NRT1.1 is dual affinity
210
How does phosphate uptake occur?
PHT1 transporters
211
How do K+ transporters and nitrate transporters show biphasic kinetics?
K+ =2 transporter AKT1 and KAT1, which respond to varying concs
Nitrate= NRT1.1, dual affinity transporter
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What are symbioses and when do they form?
Mutually beneficial interactions
Form in nutrient deficient situations (e.g. formation of a depletion zone)
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What is a depletion zone?
Zone around the roots, which form due rapid uptake of nutrients which has not been replenished due to slow diffusion rate
214
What are ectomycorrhiza and endomycorrhiza?
Ecto- extracellular colonisation by fungi, form a Hartig net
Endo- intracellular colonisation by fungi, form arbuscular structure
215
What are hyphae?
Branching filaments from fungi
216
How do hyphae help plants uptake phosphate?
H+/Pi symporter
Pi then turned into a polymer
Transported to vacuoles
Then converted back into Pi
- also release enzymes that break down organic matter to make phosphate and nutrients more accesible
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What are obligate mycotrophs?
Plants that are unable to photosynthesise
So rely on fungi symbiotic relationship with neighboring plants for nutrients
Arbuscular mycorrhizal fungi able to connect to more than one plant
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In what organism is nitrogenase present?
prokaryotes
219
What are the type of free-living nitrogen fixing bacteria?
Cyanobacteria- 3 cell walls to stop diffusion of O2, and no PSII
When die, releases N into soil
220
What are the 2 types of symbiotic nitrogen fixers?
Rhizobia (rod-shape) and Frankia (filamentous)
Rhizobia- commonly form relationships with legumes
221
How is the symbiotic relationship between Rhizobia and a plant formed?
Rhizobia releases lipo-chitooligosaccharides
Stimulates pericycle division
Rhizobia binds to root hair cell
Forms infection thread
Bacteria moves towards nodule primodia
Bacteria released into nodule
Grows in nodule tissue, protected by symbiosome membrane
Form protrusion
Fixes N2
222
What are the 4 solutions to reduce inactivation of nitrogenase by oxygen?
1) Reduced gas permeability
2) Leghemoglobin- High affinity to O2, transports O2
3) Cytochrome oxidase- higher affinity to O2, transfer O2 from leghemoglobin
4) Produce lots of nitrogenase
223
What is biofilm?
Thin layer of microoganisms bounf to each other, forming a thin layer of cells
Formed through "quorom sensing"
224
How can bacteria acquire nutrients?
Diffusion
Active transport (chemotaxis)
Endocytosis
Secretion
Symbiotic relationships
225
What are siderophores?
Small high affinity Fe- chelating molecules
Released out to bind to iron
Then taken up by organism (fungi/bacteria) through specific transporters
226
What does Gram positive and Gram negative mean?
Gram positive- retain purple dye, 50 layers of peptidoglyca, permeable to <1000Da
Gram negative- doesn't retain purple dye, 3-5 layers of peptidoglycan, permeable to <700Da, has a second membrane PERIPLASM
227
What determines the shape of a bacteria?
The peptidoglycan cell wall
Evidence- lysozyme, cleaves backbone and shape is not retained
228
How does bacterial growth occur?
Expansion of cell by increasing hydrostatic pressure
Autolysis of outer layers
Biosynthesis of new layers inside
Penicillin inhibits this biosynthesis
229
What is quorom sensing?
Production and response to chemicals
Coordinate behaviour in a biofilm
Density dependent
230
What is an example of electrical signalling within a bacterial biofilm?
Signalling of presence of glutamic acid
K+ signalling, released from YugO
Wave of depolarisation outwards
Stops uptake of glutamate
= even distribution of glutamate
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What are examples of unicellular fungi?
Yeast
232
How are hyphae connected? What can block these pores?
via septa (like plasmodesmata)
Blocked by Woronin bodies
Or material from parenthosome
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How do hyphae grow?
Directional apical growth
Via exocytosis of vesicles containing nutrients
Travel there via actin filaments
234
What is the spitzenkorper?
Where vesicles densely pack
235
What ion stimulates exocytosis and what proteins aid this?
Ca2+
SNARE proteins control where vesicle exocytoses
236
What is catabolite repression?
Control of reactions to stop inefficient ones
237
How does the movement of H+ lead to nutrients acquisition at the tip of a hypha?
H+ pumped out of P-type ATPase in mid
Moves around and H+ back in the tip, where it's still growing
Leads to symport or antiport of nutrients along with the H+
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What channels are present to transport glucose and what are their relative affinities?
HXT transporters
HXT2, 4= low conc so high affinity
HXT1= high conc so low affinity
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Why does senescence occur in fungi?
To redistribute nutrients
Controlled cell death
240
How do fungi show metabolic flexibility?
1) Scavenge for nutrients
2) Switch between oxidative and fermentation, depending on O2 availability
3) Mycorrhizal associations- relation with plants, for nutrients
4) Utilize diverse carbon sources- sugars, lipids, aromatic compounds
241
What is the phyllosphere?
Leaf niche environment
242
What is amenalism?
One species causes harm to the other, with the other not causing harm or having benefit
e.g. ethanol secreted by yeast to stop bacterial growth
243
What are the 2 main types of plant pathogens?
Biotroph- living host, e.g. virus
Necrotroph- kill/ use dead tissue
244
What is an example of a fungal biotroph?
Haustorium
Forms arbuscular like hyphae
245
What is an example of a hemitroph?
Oomycete (P.infestans)
Initially biotroph then necrotroph
Deadly because the spores produced have flagella
246
How do viruses move around in plants and how was this discovered?
Move around symplastically via plasmodesmata
Discovered by infecting plant with GFP expressing virus
247
How can pathogens spread?
Most likely- vector
rain, mechanical wounding
248
How do pathogens enter plants?
Natural entry/ Forced entry
through stomata
wounds
249
What is an example of fungus that comes in via stomata?
Bean rust fungus
Detect 0.5microm stomata ridge, so thigmotrophic
Form appressorium, keeps stomata open
Grow infection in
Pathogenicity determinant is the mechanosensitive cation channel, with the touch sense, wouldn't be pathogenic
250
What is an example of a fungus which uses forced entry?
Rice blast fungus
Forms appressorium
Secretes hydrophobins (PathogenicityD)to stick to leaf
Glycerol accumulates, pressure increases in penetration hypha
Concentrated in one area, leads to puncture
251
What is the method to identify the pathogenic trait/phenotype in plants?
Koch's Postulates
Isolate microbe
Reinfect healthy plant
See if symptoms similar
Re- Isolate microbe and repeat
252
What physical barriers are present in plants?
Waxy cuticle
Cell wall
Preexisting anti-microbal chemicals
253
What is a virulent, non-virulent and avirulent pathogen?
Non-virulent- doesn't get past basal resistance (detect by PAMP)
Virulent- Proceeds past defence
Avirulent- stopped by hypersensitive response
254
What occurs in the PAMP response to non-virulent pathogen?
PAMP= pathogen associated molecular patterns
Lead to production of ROS
Then PTI (PAMP triggered immunity)
Production of anti-microbial chemicals (phytoalexins)
Lead to viral RNA silencing
255
Why are effector R proteins released and when?
Against Avirulent, which have gotten past PTI
Lead to hypersensitive response (programmed cell death to stop spread)
E.g. reaction to TMV
256
How can biotrophs effect photosynthesis?
Shade or cover a leaf due to their growth
TMV inhibits PSII, causing chlorosis = necrosis
257
How do necrotrophs effect photosynthesis?
Bacteria- Tabtoxin inhibits glutamine synthetase so stops synthesis, leading to build up of ammonium ions and disruption
Fungi- T-toxin creates pores (URF13) in membrane, uncouples H+ gradient and normal functioning of mitochondria
258
What are 2 examples of pathogens changing metabolic pathways?
Shikimic- Use precursors of glycolysis and pentose to make more lignin and also makesk antigunal enzymes worse
Phenylpropanoid- provide C for salicylic acid pathway
259
What are consequences of water stress?
Wilting
Death
Inhibited cell growth
Inhibited stomatal opening
260
Effects on xylem water movement due to pathogens?
Increased pathogens, increase viscosity
Growth of neighbouring cells could lea to embolisms
261
How can pathogens effect the resistance related in water movement?
P.infestans,Fusicoccin cause stomata to open- changin R stomata
Rice blast- effects R cuticle
262
How does Fusicoccin cause stomatal opening?
Binds to 14-3-3 proteins
Activates P-type ATPase
Influx of K+
Movement of water
Stomatal opening
263
What are the benefits of Cucumber mosaic virus (CMV)?
Lead to drought resistance
Less stomatal opening
Biofilms can protect from desiccation
264
Briefly explain how plants might signal and respond to salt stress
- have receptors to detect changes in conc of Na+ and Cl-
- ABA signalling to the plant to cause
- compatible solute (proline and mannitol)
- bladder cells in halophytes
- Hormones, antioxidants to combat ROS
- Detect high concs of Na+ and Cl-
265
Summarise the ways plants can increase their acquisition of nitrogen
1) Form symbiosis with nitrogen fixing bacteria, for example legumes with Rhizobia
2) Root hair cells, protrusions to increase SA for more nitrogen uptake
3) Mycorrhizal symbiosis- increase SA for nutrient uptake due to large network of hyphae
4) Control gene expression for nitrogen transporters in the roots, increase their expression to increase nitrogen uptake
266
Write brief notes on the similarities and differences between the interactions of plants with fungal biotrophs and with mycorrhizal fungi
Sim
- both establish relationships with the plant
- both involve the exchange of nutrients
- in both, the fungi benefits
Diff
- biotroph doesn't have a positive effect on the plant like mycorrhizal which is symbiotic
- Biotrophs could be pathogenic and so cause damage to plant
- plant have defences against biotroph but not mycorrhizal
267
Compare otoliths and plant statoliths in how they detect gravity
Otoliths found in ear canal, statoliths found in statocytes in roots in plants
Both relocate to the bottom, due to gravity
Otoliths - made of calcium carbonate, statoliths made of starch
Otoliths trigger AP by inertia of movement, Statoliths by sedimentation
268
Describe the anatomical pathways taken from atmospheric air to (a) a pulmonary capillary and (b) a chloroplast in a leaf mesophyll cell
a) mouth, nose, trachea, bronchi, bronchioles, alveoli
gas exchange, into capillaries
b) in stomata, diffuse into the mesophyll cells, have to move through the cytsol to get
into chloroplasts
Have to move through the double membrane and used for photosynthesis
269
How is energy storage and usage in plants different to that in human?
Store
-Plants store as starch, triglycerides
-Animals store as glycogen and fat
Use
-Plants can convert triglycerides to carbs (sucrose), animals cannot convert fats to carbs
-Plants use sucrose for energy, animals use glucose
-Both use energy in the form of ATP
- animals use energy for movement and growth, plants can't move so invest it in growth
Source
- animals heterotrophic, acquire energy from food
- plants autotrophic, acquire energy from photosynthesis (self made)
270
Outline the process of sweating
Acted on by sudomotor nerves
Secretion of sweat from sweat glands
Similar composition to saliva secretion
- Dermcidin- antibiotic present
- Bradykinin- local vasodilator to increase heat loss/rate
271
How do plants and animals thermoregulate?
Decrease temp: Radiation, Convection, Conduction, Evaporation
Plants similar except don't really radiate
- Evaporation of water leads to heat loss
- Convection of air helps will cooling
- When plant or animal in contact with water, likely to lose heat faster
Increase temp:
Plants- changes in leaf orientation e.g. sunflower following sun
Animals- metabolism, behavioural changes
272
Compare and contrast calcium signalling in plants and animals
Similarities
- acts as secondary messenger in both
- posses Ca channels to regulate flux
- have Ca binding proteins that react to Ca e.g. CD- protein kinases
Differences
- animal signalling is more complex
- animals release Ca from SR plants from vacuoles
- plant Ca signalling regulated by cell wall, animals not/ greater flexibility
273
What does Ca signalling in plants lead to?
- triggered by ABA can lead to stomatal closing
- response to wounding
- cell death
- growth (activation of enzymes in photosynthesis)
