Lecture 26: Photosynthesis and Environment Flashcards
what factors affect the rate of photosynthesis
light intensity
CO2 concentration
temperature
differences between sun and shade leaf
sun - high photosynthesis rate, thick leaves, high stomata density, long palisade cells, and low chlorophyll/soluble protein ratio
shade - low photosynthesis rate, thin leaves, short palisade cells, high chlorophyll/soluble protein ratio
PAR (Photosynthetically Active Radiation)
light intensity
the rate of net photosynthesis is saturated at higher light intensities
at the light saturation point, photosynthetic reaction rate is determined by light-independent reactions
at low light intensities, the relationship between net photosynthesis and light intensity is linear. why?
at low light intensities, light is limited for photosynthesis, so it is used efficiently
at low light intensities, there is a negative value of net photosynthesis. Why?
plants have mitochondria and respire, consuming O2 and producing CO2, CO2 production is greater than CO2 consumption
quantum yield
moles CO2 fixed per moles photons
what factors influence quantum yield
light absorbance
balance in excitation energy between PS1 and PS2
temperature
what determines the efficiency of photochemistry
quantum yield
dynamic photoinhibition
under moderate excess light that is short-term and reversible. The maximum photosynthetic rate remains unchanged
chronic photoinhibition
under excess light that is long term and reversible. It causes photodamage and photosynthetic rate is decreased
photodamage
mechanism associated with damage and replacement of D1 protein in PS2
points of resistance to the CO2 diffusion from outside the leaf to the chloroplasts
boundary layer resistance
stomatal resistance
intercellular air space resistance
mesophyll resistance
what type of plant is expected to benefit from elevated levels of CO2
C3
carbon-assimilation of C3 plants _________ with increasing CO2 concentration
increases
