Photosynthesis (Quiz 2) Flashcards
Respiration equation
6 O2 + C6H12O6 –> 6 CO2 + 6 H2O + ATP
Photosynthesis equation
6 CO2 + 6 H2O + (light) –> C6H12O6 + 6 O2
Fates of light after energy absorption (4)
fluorescence
conversion to heat
resonance transfer
e- donation
fluorescence =
release of excitation energy as a photon
energy conversion to heat =
energy is converted to heat, usually by accessory pigments
energy conversion to heat happens especially in
carotenoids
(energy conversion to heat) when a molecule…
(especially a pigment) absorbs light energy, an e- can get excited (jumps from ground state to excited state)
when an e- jumps to excited state…
the rest of the energy…
it goes from a higher excited state to a lower excited state (this little bit of energy is lost as heat) (always happens)
the rest of the energy must be released as fluorescence
fluorescence is always
at a lower wavelength than the higher ES
which electrons get excited
the ones in the molecular orbitals
carotenoids & other accessory pigments absorb
“excess light” & convert it to heat
resonance transfer =
excitation energy being transferred from one molecule to another
examples of resonance transfer
chl a gets energy from chl a or chl b molecules, & carotenoids
electron donation =
(last step) redox rxns that lead to light dependent reactions (molecule that donates e- after getting excited)
electron donation via
trap chlorophyll (traps excitation energy & uses it for redox rxns)
Light absorption & physiology can be seen with (2)
absorption spectrum
action spectrum
absorption spectrum shows
the relationship between the proportion of photons absorbed and the wavelength of light
action spectrum shows
the relationship between the physiological activity (rate) and the wavelength of light
(absorption spectrum) chl a peaks
430, 660
early, late
(absorption spectrum) chl b
460, 640
after early, before late
(absorption spectrum) carotenoids
450, 470
both early-ish
wavelength just above 400 =
violet
wavelength around 450
indigo
wavelength just below 500
blue
wavelength just above 500
green
wavelength just above 600
orange
wavelength just below 700
red
wavelength just around 550
yellow
