vocab

photolysis - part of the light-dependent reactions where water is split

  • the energy in photons is used to split the water

  • produces electrons, oxygen & hydrogen ions

light-dependent reactions - initial stages of photosynthesis that occur in thylakoid membranes of chloroplast

  • photolysis

  • electron transport chain

  • chemiosmosis

  • produces ATP & reduced NADP & oxygen (through photolysis)

light-independent reactions - 2nd stage of photosynthesis

  • occur in stroma of chloroplasts

carbon fixation - the conversion of inorganic carbon (CO2 from atmosphere) to organic carbon

electromagnetic spectrum (EM) - the range of frequencies of electromagnetic radiation

Absorption spectrum - a type of graph that shows the wavelengths of light that’re absorbed by each pigment

Action spectrum - a graphical representation that shows the effectiveness of different wavelengths of light in driving a specific process, such as photosynthesis

photosystems - large protein complexes that’re found in the thylakoid membranes of chloroplasts

  • they’re involved in the light-dependent reactions

  • contain pigments (chlorophyll & accessory pigments) that capture light energy & begin the electron transport chain

reaction centre - a specific protein-complex within the photosystem that light energy to chemical energy

  • has specialised chlorophyll molecules that donate electrons directly to the Electron Transport Chain

photoactivation - activation of chlorophyll & other pigments, which triggers biochemical changes

photophosphorylation - the process of generating ATP using light energy

  • occurs during light-dependent reaction, where light energy is used to phosphorylate ADP into ATP

  • can be cyclic or non-cyclic

cyclic photophosphorylation - light energy excites electrons from photosystem I

  • the electrons move through ETC

  • promote pumping of hydrogen ions, creating electrochemical gradient

  • generates enough energy to phosphorylate ADP into ATP

  • electrons return to photosystem I after moving along ETC, replacing the electrons that’re lost

non-cyclic photophosphorylation - light energy excites electrons in photosystem II

  • electrons move through ETC

  • promote pumping of hydrogen ions, creating electrochemical gradient

  • generates enough energy to phosphorylate ADP into ATP

  • electrons enter PSI

    • re-energised with light energy, passed to ferredoxin & used to reduce NADP

NADP - the electron carrier for photosynthesis