a. light trapping adaptations
leaf
large SA: capture max light
thin: light penetrates through
stomata & air spaces: CO2 diffuse in to photosynthesising cells
transparent cuticle & epidermis: light penetrates through
palisade cell
large vacuoles: chloroplasts form single layer at cell periphery – don’t shade each other
more chloroplasts than spongy mesophyll – near top of cell = more exposed to light: capture max light
chloroplast
thylakoid large SA
move within cell: max light absorption (top) / protect pigments from bleaching (bottom)
rotate within cell
pigments in single layer along thylakoid membrane
b. chloroplasts = transducers: convert light photon energy to chemical energy (ATP)
Photosynthetic pigments – absorb photons at great range of wavelengths of light
Chlorophyll – absorb red & blue-violet Carotenoids – absorb blue-violet
chlorophyll a: yellow-green beta-carotene: orange
chlorophyll b: blue-green xanthophylls: yellow
c. light harvesting by antenna complex to reaction centre to emit e -
Absorption spectra of pigment: how much light absorbed at different wavelengths
Action spectra: rate of photosynthesis at different wavelengths
d. Photosystem 1 (P700) & 2 (P680) – thylakoid membrane: absorb light at range of wavelengths
antenna complex – contains pigments & proteins: energy passed through pigments to reaction centre
reaction centre – 2 chlorophyll a: energy from absorbed light boosts electrons to excited state = emit high-energy e -
leaf
large SA: capture max light
thin: light penetrates through
stomata & air spaces: CO2 diffuse in to photosynthesising cells
transparent cuticle & epidermis: light penetrates through
palisade cell
large vacuoles: chloroplasts form single layer at cell periphery – don’t shade each other
more chloroplasts than spongy mesophyll – near top of cell = more exposed to light: capture max light
chloroplast
thylakoid large SA
move within cell: max light absorption (top) / protect pigments from bleaching (bottom)
rotate within cell
pigments in single layer along thylakoid membrane
b. chloroplasts = transducers: convert light photon energy to chemical energy (ATP)
Photosynthetic pigments – absorb photons at great range of wavelengths of light
Chlorophyll – absorb red & blue-violet Carotenoids – absorb blue-violet
chlorophyll a: yellow-green beta-carotene: orange
chlorophyll b: blue-green xanthophylls: yellow
c. light harvesting by antenna complex to reaction centre to emit e -
Absorption spectra of pigment: how much light absorbed at different wavelengths
Action spectra: rate of photosynthesis at different wavelengths
d. Photosystem 1 (P700) & 2 (P680) – thylakoid membrane: absorb light at range of wavelengths
antenna complex – contains pigments & proteins: energy passed through pigments to reaction centre
reaction centre – 2 chlorophyll a: energy from absorbed light boosts electrons to excited state = emit high-energy e -
