L2 primary production (processes) and photosynthesis

oxidation is the X of electrons

loss

reduction is the X of electrons

gain

reactions including both an oxidation and reduction are called..

redox reactions

product of photosynthesis

glucose C6H12O6 (and o2)

product of respiration

ATP (and (6)co2 and (6)h2o)

average solar electromagnetic energy reaching and absorbed by earth is..

160 W/m²

other sources of energy (irrelevant) the earth gets

tidal energy, cosmic rays, geothermal energy

why is sunlight the main energy source for all of earths biosphere

as solar radadiation as an energy source surpasses any others by 5 orders of magnitude (more of it)

how much of this solar radiation the earth receives is converted into chemical energy via photosynthesis?

0.1%

autotrophs meaning

organisms which obtain their energy via converting simpe inorganic compounds to organic (photosynthesis and chemosynthesis)

photoautotrophs def

(obtain energy by) use light as energy source (convert inor to org)

chemoautotrophs def

(obtain energy by) use various chemicals as source of energy (inorg to org)

heterotrophs def

organisms which obtain their energy from consuming/ breaking down organic matter

mixotrophs def

can be autotrophic and heterotrophic eg some dinoflagellates eg dinophysis

prefix ‘litho’ meaning

inorganic

what is anoxygenic/ anaerobic photosynthesis

photosyn without the production of o2, meaning water isnt used as the electron donor. here the photosynthesisers get electrons from other reduced substances

in anoxygenic photosyn, what other reduce(able) substances do organisms get electrons from

h2 (dihydrogen), s (sulfur), alcohols, acids

what organisms use anoxygenic photosynthesis

purple sulfur bacteria, green sulfur bacteria, purple non-sulfur bacteria and heliobacteria

why are chemoautotrophs important

1. as they provide organic, chemical energy, often in places where there isnt any/ wouldnt be any without them eg deep sea vents, deep below earths surface.

2. to the global nitrogen cycle

why is autotrophic carbon fixation important

as it provides organic carbon used by all life on earth

whats is photosynthesis the conversion of (what to what)

light energy to chemcial energy AND simple molecules into complex molecules

what is respiration the conversion of

complex molecules into simple molecules

the two components of the photosynthesis reaction

the light, and light independant reaction

simply, what happens in the light reaction

the photolysis of water (oxidation of water (as water loses electrons)), and oxygen becomes a waste product

equation for the light reaction

2H2O + light → O2 + 4H+ (protons) + 4e

what are hydrogen ions essentially

protons

essentially/ simply what happens in the light indepedant reaction

CO2 is fixed into organic molecules (carbs/ glucose) using ATP and NADPH.

equation for light independant reaction

CO2 + 2H+ + 2e → CH2O (glucose)

where does photosynthesis occur (in eukaryotic cells)

light reaction occurs in the thylakoid membrane, light independent reaction occurs in the chloroplasts stroma

what is the electron donor in photosynthesis?

water/ H2O

what is the electron acceptor in photosynthesis?

NADP+ (forms NADPH after accepting electron)

products of the light reaction

ATP, NADPH (and irrelevant O2)

what happens to NADPH in the light independant reaction

oxidised (so loses an electron) to regenerate NADP+ and the electrons and protons from these conversions are used to convert CO2 into glucose

4 phases of the light independant reaction

carboxylation, reduction, regeneration and product synthesis

what happens in the first stage of the LIR - carboxylation?

the enzyme rubisco is used to catalyse the fixation of CO2 into a 6 carbon molecule by adding it to a 5 carbon molecule (RuBP). This 6c mol is unstable so quickly converts into 2, 3c mols

what happens in the 2nd stage of the LIR - reduction?

the 2, 3c mols are reduced (gain an electron) using energy from ATP and NADPH to form a sugar intermediate mol

what happens in the 3rd stage of the LIR - regeneration?

the sugar intermediate mols produced in reduction stage, regenerate RuBP (the 5c mol) so the cycle can continue

what happens in the 4th stage of the LIR - product synthesis?

the remaining sugar intermediate mols from reduction stage are synthesized to form a 6c sugar eg glucose, sucrose etc. these sugars can then be converted into fats, amino acids etc

products of the LIR

sugar eg glucose, ADP and NADP+

how many photons are needed for the LIR

8 photons