Exam 1 Flashcards
fill in the blanks for the photosynthesis reaction H2O + ______+______+_______—>______+ O2
(H2O)+CO2+light+chlorophyl—>C6H12O6+O2
how is absorption spectrum different from action spectrum
absorption spectrum shows the light absorption pattern of pigments such as chlorophyll
how is action spectrum different from absorption spectrum
action is a graph that shows the relative effectiveness of the different wavelengths of light in inducing a particular light requiring process such as photosynthesis
which family of pigments do xanthophylls belong to
carotenoids
what unique role do xanthophylls (besides leaf color have in plants’ life?
they play a photoprotection role
how do xanthophylls accomplish a photoprotective role in plant life?
excess light energy is used to convert xanthophylls from one form to another which helps redirect excess light and protects from photooxidation
how do you tell if a leaf cross section is a C3 or C4 plant?
if C4 mesophyll cells are rounder and vascular bundle is rounder also the vascular bundle has bundle sheath cells surrounding it C3 does not
what does Kranz anatomy refer to
the tightly fitted layer of cells known as the bundle sheath cells that fit around the vascular bundle in C4 plants
What 2 enzymes differ C3 and C4 plants in photosynthesis?
in C3= RuBISCO in C4= PEP Carboxylase
what cells are RuBISCO found in?
stroma of C3 and C4 plants
what cells are PEP Carboxylase found in?
chloroplast of mesophyll cells
what reaction does PEP Carboxylase catalyze?
fixes CO2 into a 4 Carbon compound (hense C4)
what reaction does RuBISCO catalyze?
to fix CO2 into a 3 Carbon compound (C3)
is C3 or C4 plants more efficient at photosynthesis?
C4
what is photorespiration?
light-dependent oxidation of carbohydrates by the Oxygenase activity of RuBISCO
how does photorespiration effect photosynthesis in C3 and C4 plants
photorespiration increases in C3 plants with the rise of temperature, at high temps CO2 diffusion is reduced and RuBISCO can not fix CO2 efficiently so PS is reduced, but PEP Carboxylase can fix CO2 at low availability levels therefore in C4 plants PS is not reduced as much
how can C3 and C4 plants regulate photorespiration to their advantage?
C4 plants can use it to their advantage to take over the landscape during the summer when it becomes too hot for C3 plants to photosynthesize due to photorespiration
do C3 or C4 plants do better in warmer drier conditions?
C4
why do C4 plants do better in warmer drier conditions than C3 based on leaf anatomy
C4 plants have more chloroplasts in bundle sheath that are able to process higher concentrations of CO2 and because bundle sheath is close to vascular bundle sugars are exported quicker
what is the double jepardy of C3 plants
- rate of photorespiration increases in C3 2. stomata close during warm conditions and C3 cannot PS but C4 can due to PEP Carboxylase
define inverted stomata cycle
CAM plants open their stomata and fix CO2 primarily at night
what is the significance of inverted stomata cycle to geography and climate?
CAM plants can do better in warmer drier climates and locations because they can have their stomata closed during the day because CO2 fixation only occurs at night. This allows the plant to conserve enough water to survive in harsh conditions
what is an example of a CAM plant
pineapple
do C3 or C4 have higher CCP?
C3
explain CCP and its relevance to PS efficiency
a lower CCP mean that plants can carry out PS even at lower CO2 concentrations in the air and this means more efficient PS
what is the formula for water use efficiency?
WUE= g dry matter produced/g of water transpired
how does WUE inform a horticulturist about a given plant?
WUE can tell conditions a plant will do best and the conditions it requires ie CAM has high WUE and C3 have low WUE
do shade adapted or sun adapted leaves have lower respiration rates?
shade
what is the impact of lower respiration of shade plants on growth, survival, and leaves in low light environments?
in order for a plant to grow net PS must exceed respiration. shade plants get little light so PS is low therefore in order for growth to occur it is beneficial that respiration is also low.
leaves that are often exposed to full, bright sun have more than one layer of _____
palisade cells
what is the role of multiples layers of palisade cells
they provide internal shading and protect the leaves from too much light
where do C3 get its name
they fix CO2 into 3 carbon compounds
where do C4 get its name
they fix CO2 into 4 carbon compounds
what is the primary plant pigment involved in photosynthesis
chlorophyll
what wavelengths are most useful for photosynthesis?
400-700 nm (red and blue)
the overall process of PS is a two step process involving what sets of reactions
- Light reactions (hill) and 2. dark reaction (calvin cycle)
