photosynthesis and biomineralisation Flashcards
Light Dependent reaction
Produces Oxygen.
NADPH and ATP for the CC
light independent reaction
G3P, build more complex molecules.
C3, C4 and CAM plants
C3 use only the CC, 95% plants photorespire
C4 plants, minimise photorespiration, 1% plants, light and dark reactions.
CAM plants, areas of low light, two systems separated by time
Seagrass what?
Around 90mya.
Only flowering plant
Mono/mixed meadows.
Shallow/shelters, soft env.
Threatened, affected by temp, salinity, waves, currents, light and substrate.
ecological engineers:
-Absorb nutrients, slow water increase clarity, decrease erosion. Nutrient pump in low nutrient areas.
Rhizome anchors and transfers nutrients.
high light needs, 10% surface light. Specialized C fixation, photosynthesis ;limited by low carbon dioxide
Seagrass Carbon Acquisition adaptation
salinity 33+, pH~8.2, Bicarbonate 2mol/m3
Primary C source is bicarbonate, acidification is reducing it.
Carbonic anhydrase interconverts carbon dioxide and bicarbonate.
Blue carbon >10% ocean C store, unreliable burial rates, hard to determine rates, lateral C transport. Fluxes of methane and NO. Vulnerable to climate change
macroalgae what?
Protection and nursery for species.
Drives inshore food webs.
Food source, fertiliser and counteract erosion, sequester over a billion tons C/year.
Photo inhibition to prevent too many oxygen radicals.
Chloroplast rearranged, cryptochrome in brown algae.
low light 0.001% to 1.2% surface light
Nutrient uptake fast growth in eutrophic, slow in oligotrophic.
Surge uptake of N when conditions are good.
Currently saturated w/ organic C sources
Climate change on macro algae and seagrass
Macroalgae can use bicarbonate efficiently, saturated seagrass less efficient, inorganic carbon limited, low and slow carbon dioxide macro algae have advantage on C uptake.
Future climate change
Depend on temperature and salinity tolerances.
Series bilatudinal migration due to changes.
Local populations affected by humans, urbanisation and eutrophication.
Biomineralisation and evolution
Mineral crystal deposited in matrix of living organisms
Evolved when energetic cost was less than making an equivalent structure.
750mya, sponges may form calcite.
Use form of Calcium carbonate which is most stable at the time.
Roles:
Protective shells, endoskeleton, exoskeleton.
Organomineralisation
Bio induced, metabolism mineral formation.
Composition of mineral shells
Phosphates: hydroxyapatite, primary component of bone, teeth and fish scales.
Silicates: Silification. Diatoms and radiolaria form frustules from hydrated amorphous silica.
Fe: Magnetite/geothite, teeth and radula.
Pyrite and gregite: Gastropods close to vents reinforce carbonate shell.
Carbonates: Calcite, coccos forams. Aragonite in corals.
Marine calcification
Fixation of calcium carbonate.
When saturation is >1, organisms can extract Ca and carbonate from seawater to form solid crystals.
<1 favours dissolution.
Mollusc calcification
95-99% carbonate.
Proteins direct crystal dynamics.
Nacre, mother of pearl. Strong, resilient inner cell layer.
Hexagonal platelets of aragonite in lamina defend soft tissues against pathogens.
Crustacean calcification
Hard outer shell, 20-50% carbonate rest is chitin fibre network.
Molt to grow, can reabsorb minerals from old shell to new shell.
Echinoderm calcification
Intracellular calcification.
Large vesicles from fusing cell membranes, in vesicles calcified crystals form.
Carbonate exposed to environment when cell membranes are degraded, endoskeleton enclosed by epidermis.
