Resources - Water and Radiation Flashcards
Resource
Anything consumed by an organism, being food, habitats, mating…
Autotrophs
One that produces new biomass from inorganic resources using either light energy or energy from reduced molecules in the envrionment.
Radiation as a resource…
Converted to organic material by CO2 reduction with solar energy assimilation
Heterotrophs
Organisms feeding on material generated by other organisms, using other organic compounds as carbon sources for energy.
Chemoautotrophs
Derive energy from convesion of inorganic ocmpounds like hydrogen sulphide, sulfur, ferrous iron or ammonia to reduce CO2.
Incident solar radiation variability…
Can be direct, diffused or reflected.
Waste of solar energy as a resource…
Reflection from plants as heat or latent heat of evaporation
Solar conversion efficiency…
80% reaches the chlorplasts with only a small amount converted into organic material.
Photosyntheticall Active Radiation
Light of wavelengths between 400-700 in the portion of the light spectrum utilised by plants
What describes available radiation to plants?
PAR
What are the effects of excess radiation to plants?
Contribution to production of damaging intermediates in photoinhibition
Photoinhibition
The decrease in photochemical efficiency experience in response to intense illumination due to radiation damages.
What is full solar radiation assimilation limited by?
Morphology and Physiology, optimal at only one intensity whilst suboptimal at others
Temporal variations of incident solar radiation…
Diurnally and annually
Adaptations of Sun Leaves…
Dense chloroplast packing
Smaller, thicker CP with more cells per unit area
Denser Veins
Greater Dry weight
Adaptations of shade leaves…
Increased CP concentration with decreased investment in other features to maximise light without depleting resoruces under shade.
Example of solar limitations…
Competition with neighbouring leaves, diurnal and seasonal changes
How may leaf morphologyh determine assimilation efficiency?
Angling to maximise surface area, superimposition in a multi-layered canopy
How can net photosynthesis be measured?
CO2 uptake as the two are roughly proportional
Light Compensation Point
Where rate of photosynthesis matches rate of cellular respiration
Photosynthetic Capacity
Measure of maximum rate at which leaves are able to fix carbon during photosynthesis at optimal temperatures, saturated incident radiation and relative humidity.
How is increased plant height a trade off?
Increases compensation point due to more structural tissue, thus more light requried to balance respiratory needs
Which plants have highest PC?
The ones rarely ever limited in nutrients, being colonisers of newly available habitats.
How is water linked to photosynthesis?
Solar radiation is dependent on CO2 concentrations?
Stomata
Cell structures in the epidermis of tree leaves and needles involved in the exchange of CO2 and H2O between plants and the atmosphere.
Trade off of open stomata…
Conserve water at expense of PS or maximise PS at risk of dehydration
How many plants adapt to stomatal water loss?
Remaining dormant as seeds with low water whilst highly photosynthetic plants when abundant
Shedding of leaves in times of drought.
DIrunally stomatal changes…
Remain water tight except in conditions where water is readily available…
Water uptake in plants…
Primarily through the roots with mycorrhizal associaitons.
Soil pores filling…
Pores between soil particles uptake water that enters by precpitation acting as a reservoire
Permanent Wilting Point
The point where no water available to the plant
How does water capacity depend on soil structure?
Capillary action can hold water if pores are wide, so sandy soils drain away against gravity
Why does water extraction for roots require force?
Surface tension holds water there
How does water resistance in absorption change over time?
The first water drained has weakest capillary forces, thus later narrower pathways have increased resistance.
