Plants In A Changing Atmopshere Flashcards
What are the 3 things plants respond to
Elevated co2
The impact of ozone depletion and increaed Uv-B
Air pollutants
What is the perturbed carbon cycle
Humans can release the locked carbon from carbon bearing rocks, shales and gases
What does more co2 entering the atmosphere than coming out else to
Increaed co2 concentrations
What drives the agricultural demands
Large populations suffering from hunger
What is the predicted growth rate of population
The rate is increasing but slowing down
What2 ways can increaed co2 affect plants
Directly and indirectly
What has happened to photosynthesis form the mid 20th century to the mid 21st century
Increased co2 concentration gradient
Increaed co2 uptake
Increased co2 concentration in leaf
Increaed rate of photosynteheis as more co2 in air spaces
What is a c3 plant
Co2 being fixed in plant as sugars containing 3 carbons
How do most plants fix co2
Using ribulose bisphosphate carboxylase-oxygenase (RUBISCO)
Why is rubisco most abundant protein on globe
Bc it’s in all plants
What are the two properties of rubisco
Carboxylase or oxygenase
What happens during photosynthesis in rubisco
Carboxylase to phosphotlyceetate to sugars (used in Calvin cycle to fix carbon as sugar) good for plant
What happens during photo respiration in rubisco
Oxygenase to phosphoglycolate to co2 it uses oxygen and takes fixed carbon to spit it co2 in other side
What is photorespiration classed as
An energetically wasteful process
Why is photorespiration not a useful process
Uses lots of energy and ATP as it does so not useful. Affects co2 gradient within leaf as it increases co2 in leaf.
What are the results of photorespiration
Increased co2 concentration in leaf
Decreased co2 concentration gradient
Decrease co2 uptake
Decreased rate of photosynthesis
What happens if there’s an increase in co2 concatenation in the Calvin cycle
Increase carboxylase activity - increases photosynthesis
Inhibits oxygenase activity - reduces photorespiration
Increased carbon fixed as C3 sugars
In C3 plants how does elevated atmospheric co2 concentration increase photosynthesis
By increasing the gradient for co2 and by increasing the efficiency of rubisco (decreasing photorespiration)
How does C4 plants photosynthesis
It is initially fixed as acid. These are then transported into bundle sheath cells and broke down into c3 acid and co2. In breaking them down the co2 allows the rubisco in the sheath cell to always be in a high co2 environment. Rubisco then fixes carbon dioxide in the Calvin cycle.. co2 has different effect therefore.
What happens in the mesophyll of a c4 plant during photosynthesis
Co2 fixed by PEP carboxylase as C4 acids (Malate/aspartate6
What happens in the bundle sheath of a c4 plant during photosynthesis
C4 acid broken down to co2 and fixed by rubisco
In C4 plants what does high co2 do
Surpressed rubisco oxygenase activity
In C4 plants how does elevated atmospheric co2 concentration increase photosynteheis
By increasing the gradient for co2 uptake
Why does increasing the co2 gradient in C4 plants have no effect in rubisco
They already have highco2 environment in the bundle shealth even under ambient atmospheric conditions
Example of C4 plant
Sugar cane
What does increasing co2 concentration result in C4 plants compared to c3 plants
Smaller increase in rate of photosynthesis
How does increaed co2 indirectly effect photosynteheis
Increasing temperatures lead to increasing photosynteheis
Temperature related increase in photosynthesis are far greater in C4 plants than C3
Why does increaed temp mean higher increase in C4 plants than C3 ones
Increase in oxygen means wasteful photorespiration but for C4 it’s always suppressed so no change
What happens to the rubisco cycle if we increase temperature
Increase oxygenase activity wnd increases photorespiration
Relatively small increase in carboxylase activity
Increased loss of fixed carbon
What effects does high temperature have on C4 plants
Minimal
What effect can increase in photorespiration with temperature have
A marked effect on crop photosynthesis and productivity
In which plant is the direct effect of infrwsed co2 on photosynteheis greater
C3
In which plant is indirect effect of increased co2 in photosynteheis via higher temperature greater
C4
What does overall effect on c3 and C4 species depend on
Region and climate : tempetehee and drought
What is the effect of increaed co2 in stomata
Results in stomata closure: No increase in photosynwthsis Decrease water loss via transpiration Decreased water loss while maintains photosynteheis Increased water use efficiency
What is WUE measured by
Yield per unit of crop water used
What is a way to measure stomata aperture
Thermal imaging. Take a field or a Forest and put a ring of gas releasing tubes and you make within the ring elevated co2 concentration to look at physiology or stomata apeture.
What does stomata closure in thermal imaging mean
The plant got hot as the pink is higher temperature and darker ones on outside are lower temps. Plants are warmer meaning less water is escaping through stomata
What does stomata closure show
Elevated co2 affects transpiration as well
How does elevated co2 increase water efficiency
You use more water more efficiently and you need less water to produce the crop making it more important in being drought resistant
What is the water use efficiency typically under elevated co2
20-25% higher
What can plants grown at elevated co2 have
An increased ability to cope with drought
What is the triangle for direct effects of elevated co2
Can effect temperature which has effects on drought. Interplay between all three.
Where is good ozone
Stratosphere
Where is bad ozone
Troposphere
Where is the upper part of the atmosphere
20km upwards
What is reducifon of ozone proportionate to
Useage of CFCs
Can ozone have localised effects
Yes w.g spring ozone depletion in Manchester
For each 1% decrease in stratospheric ozone what happens to uv-b radiation reaching the biosphere
There is a 2% increase
What is the wavelength of visible light
400-700nm
What is the name of visible light
Photosynthetically Active Radiation (PAR)
What is the wavelength of ultraviolet radiation
200-400nm
What percentage of environment UV is uv-b
5%
Why does uv-b has protential to be absorbed by biomolecules and causes significant damage
Short wavelength so highly energetic
Which uv light is affected by stratospheric ozone detention
Uv-b
In humans what can uv-b lead to
Skin damage and ultimately cancers. Unable to repair dna damage
Why does skin cancer develop
Damage caused by uv-b to dna that can not be repaired
What can the absorption of uv-b in nuclei acids lead to
Cancer in high prevalence incidences
What 4 things is uv-b radiation strongly absorbed by
Nucleic acids
Amino acids
Proteins
Plant hormones
Examples of nucleic acids
DNA
RNA
Examples of amino acids
Phenylalanine
Tyrosine
Examples of proteins
photosynthetic ones
Examples of plant hormones
IAA
GIbberellins might be influences so growth is reduced despite lack of change in photosynteheis
How does uv-b damage affect plants
DNA damage does occur but it is repaired very quickly
Not much evidence that uv-b induced dna damage in plants is an issue in terms of ozone depletion
How long does it take for plants to repair after exposure to uv-b
6 hours
How does uv-b affect photosynthesis
Nothing dramatic in field. However reduced leaf area but not reduced photosynthesis
Why do we have to be careful doing experiments on increased uv-b and photosynthesis
Quite often light level in field is less
What may happen to plant growth due to increased uv-b
Reduce it with potential impacts of crops and natural ecosystems. Has ability to change ecosystem composition.
Not caused by damage to photosynthesis however.
Why are changes in growth due to ozone dpwelerion likely to be small
Due to the implementation of the Montreal protocol (on substances that deplete the ozone layer)
How does changes in uv-b raidqiron alrer the plant
Changes in primary metabolism, growth and morphology.
What can we assume when we look at ecosystems rather than looking at individuals in isolation
We can expect to see different species responding differently to uv-b effects, changes in competitive ability in species and changes in composition of ecosystems
How do plants acclimate to increaed uv-b
Accumulating uv absorbing pigments. This accumulation involves increased synthetic of phenolic compounds. These compounds are vital for defence against pests and disease.
How is uv-b making plants more tolerant to uv-b and pedts and pathogens and decomposers
accumulation of uv absorbing pigments involves increased synthetic of phenolic compounds. These compounds are vital for defence against pests and disease.
What does understanding the impacts of ozone depletion on ecosystems require
An understand of the responses of a wide range of organisms, processes and interactions
What is uv-bs direct effect in decompose fungi (aspergillosis)
When it’s ambient it’s a diffuse colony of fungus and when it’s elevated it’s even more diffused. Sees marker impact on growth
What is the responses to fungi isolated from birch litter after 2 months under ambient or elevated uv-b at a sub-Arctic field site
In ambient one takes up about 50% but in elevated there’s a significant increase and significant loss and some new species
Example of uv-b reducing plant disease
Leaf blotch disease in wheat.
Increased uv-b before inoculation had no effect.
Increaed uv-b after inoculation significantly reduced the infection. Doesn’t matter what happens before the fungus encounters plant.
When does solar uv-b reducing herbivory occur
Within the ambient range not just when uv-b is underwear due to ozone depletion
What does normal variations in uv-b do to ecosystems
Some parts of the community are exposed to ambient level while some is exposed to less due to natural shading of canopy
Where are the effects of uv-b likely to be most pronounced
In high latitude ecosystems
What is a pollutant
A chemical that is in the wrong place and the wrong concentration at the wrong time with the potential to cause damage
What is an air pollutant
Chemicals that are emitted into the atmosphere which adversely affect physical and bipggical systems
What are the two kinds of air pollutants
Particulate air pollutants
Gaseous pollutants
What are primary pollutants
Chemicals that are emitted directly into the atmosphere
Examples of primary pollutants
Nitrogen monoxide
Sulphur dioxide
What are secondary pollutants
Chemicals that are formed by the reactions in the atsmlpehte between primary pollutants and other agents
Examples of secondary pollutants
Nitrogen dioxide
Ozone
How does nitrogen monoxide turn to nitrogen dioxide
Complex reactions in photochemical smog
What is the general term of nitrogen’s in atmosphere
NOx
What are the natural origins of gaseous pollutants
Volcanoes
Swamps
What do volcanoes emitted
Sulphur dioxide so smells
What do swamps emit
Methane and hydrogen sulphide
What are anthropogenic sources of gasesous pollutants
Domestic sources
Industrial sources
What did a report in America say about domestic sources of pollutants
If you cooked a Sunday roast you are raising particulate concentration in your house for an hour higher than the sixth most polluted city in the world
Power and heat 74.9%
What is the main cause of sulphur dioxide in the atmosphere
What is the main cause of oxides of nitrogen in atmosphere
Power and heat 53.2% and transport 41.7%
Why is diesel not good
Produces less co2 but more nox
Historically how did some poor countries real with pollutants
Dilute and dispersal - big chimney into atmosphere . This can move things globally
How do air pollutants get deposited back
Dpeendns on if they encounter water and go into solution - wet deposition.
Dry deposition - once deposited go into solution in water coming into intercellular air spaces on surface cells.
How does dry deposition of so2 effect photosynthesis
Disruption of H+ gradient across thylakoids membranes.
Activity of pH-sensitive Calvin cycle enzymes (RUBISCO - ph optima of 9)
What are the 2 sets of reactions to be aware of photosynthesis
Light reactions and dark reactions
What are light reactions
We have electron transport leading to photophospherer relations, produces ATP
What is dark reCtions
Carbon benson where where we fix carbon into sugar. Have h optima and alkaline ph of 9.
What happens if the gaseous airpollutants go into photosynthesis
Make everything acidic and move it away from the optima for rubisco, less activity, less co2 fixed and less sugars produced. Reducing availability of carbon for plants
What percentage does so2 inhibit growth in plants
7.5-25%
What percentage does NOx inhibit growth
Up t 55%
What does inhibiting of growth depend on
Concentration
Exposure
Particular plant
Genotype of plant
Why does gaseous pollutants affect plants
The stomata is open for co2 which let’s other gases in. Under high light the stomata is open more causing more pollution to be allowed in than low light conditions.
What is protongradient under normal gradient dissipated by
ATP synthase (light reactions) generating ATP energy through photo phosperal relations
How does the disruption of H+ gradient across thylakoids membrane work
Acidic gases put more protons into stomata do when election transport tries to generate proton gradient the gradient no longer exists bc it generates high protons in thylakoids space and high concentrations of protons in stomata. Therefore no rpton gradient to dissipate. Reduces ATP production and energy. Disruption of gradient prevents ATP synthase activity. Light reactions disrupted a
Why does acidic gases mean high concentration of protons in the stomata
Bc oh acidic is negative log hydrogen ion concentration. More hydrogen means more acidity
How does acid rain affect souls
Increased acidity so hardest to survive
Loss of fertilise as nutrients leached out
How does acid rain effect plants
Weathering of waterproof cuticle. Reduced growth Leaching of cations from the leaves Seed germination, early seeding growth. Flowering/seed formation
What is the relationship between soil acidity and nutrients
As soil acidity increases and nutrient flow does there’s an increase in loss of nutrients.
High nutrient flow and low soil acidity has high plant uptake of nutrients.
What can wet deposition affect
Pine ‘burning’ Castor bean Grape Wheat Radish
What are symptoms of ozone a product of
Oxidative damage
What are the symptoms, least to worse, of ozone
Water soaked appearance - damage to membranes.
Chlorotic flecking.
Stipple of dead or pigmented cells.
Growth suppression, early abscission - Loss of organs through loss of leaves. Damage to biomolecielsz
How does ozone oxidatively damage biomolecules
Membrane lipids - outside of cell damages.
Proteins - inside.
DNA - nucleic acid.
Scientific name for water soaked appeared
Chlorosis
Examples of ozone damage in crops
Potato Tomato Broad bean Wheat Oat Pine
What is global warming
An average increase in the earths twmperaturw that in turn causes changes in climate
What are greenhouse effect
Trapping of infrared radiation, produced when solar radiation is absorbed and then partially re-emitted by the atmosphere
What is a greenhouse gas
Any gas that absorbs infrared radiation in the atmosphere
What is climate change
Changes in climate resulting from global warming
What is short radiation reradiated as
Longradiation
What happens if you increase greenhouse gases
The greater retention of heat and greater warming
What would the temperature of the world be without greenhouse effect
-18*C
What percentage of global warming does co2 contribute
77%
What percentage of global warming does n2o contribute
8%
What percentage of global warming does o3 contribute
8%
What is the warming potential of co2, n2o and 03 respectively
1:310:2000
What is the concentration in ppb of co2
379 x103
What is the concentration in ppb of N20
313
What is the concentration in ppb of o3
20
What is the warming potential of CFCs and their concentration in atmosphere
10 thousands, 1-2%
What are some widespread impacts of climate change
UK floods Australian coral reefs Wildfires in Europe El Niño in Indonesia Antarctica melts Coastal flooding in bangladesh
