Final - Chapter 8 Flashcards
General photosynthesis equation
CO2 + H2O + light –> C6H12O6 + O2 + H2O
What reactant is reduced in photosynthesis?
CO2
What is a phototroph?
Green plants, algae, and cyanobacteria that use light as a source of energy (type of autotroph)
Chloroplasts carry out
photosynthesis
Where does the majority of photosynthesis occur?
The mesophyll
What is the function of the stomata?
Allow CO2 and O2 to exit the leaf
The stroma is
the fluid-filled region between the thylakoid membrane and inner membrane
What are the two stages of photosynthesis?
1) light reactions and 2) calvin cycle
Light reactions occur in
the thylakoid membrane
The products of light reactions include
ATP, NADPH, and O2
The calvin cycle occurs in
the stroma
The calvin cycle uses
ATP and NADPH
The calvin cycle incorporates
CO2 into a carbohydrate
Photosynthesis is affected by
light intensity, temperature, and water availability
In general, shorter light wavelengths have
more energy
Leaves are green because
they absorb red and violet and reflect green
What happens when pigments absorb light energy?
The electrons are boosted to a higher energy level
When electrons jump to an unstable excited state,
they release energy as heat or light
Plants are able to transfer the ___ to another molecule where it is ___.
electron, stable
Absorption spectra show
the wavelengths that are absorbed by different pigments
Action spectra show
the rate of photosynthesis by a whole plant at specific wavelengths
PS1 was discovered
first
In both PSI and PSII, ___ excited the ___
light, pigment molecules
The primary role of PSI is to make
NADPH - electrons move through the ETC to make NADPH from NADP+ and H+
PSI only makes ATP via
cyclic photophosphorylation
PSII is which step in photosynthesis?
The first step
___ is oxidized in PSII
water, makes O2
When the excited electrons travel to PSI, a _____ is formed
H+ electrochemical gradient which is used to make ATP via ATP synthase
What are the three ways that an H+ gradient can be made?
1) oxidation of H2O in the thylakoid lumen, 2) ETC in the thylakoid membrane, and 3) the synthesis of NADPH in the stroma
Homologous genes are
derived from a common ancestral gene
ETCs of mitrochondria and chloroplasts use
homologous genes
How does PSII capture light energy? (prevents electrons from being transferred to more stable molecule)
1) the excited electrons transfer energy within the antenna complex of PSII, 2) the excited energy is transferred to P680, and 3) P680 transfers the excited electron to Pp which is stable
What are the three phases of the Calvin cycle?
1) carbon fixation, 2) reduction and carbohydrate production, and 3) regeneration of RuBP-
In the calvin cycle, what occurs during carbon fixation?
CO2 is incorporated in to RuBP via the enzyme rubisco
In the calvin cycle, what occurs during the reduction and carbohydrate production step?
NADPH is oxidized and electrons reduce the carbon in CO2
In the calvin cycle, what is needed for the regeneration of RuBP-?
ATP
Why would a plant use photorespiration?
Makes photosynthesis less efficient
How does photorespiration work?
Rubisco incorporates O2 into RuBP instead of CO2
How does photorespiration benefit plants?
Protects plants from oxidative damage, minimizes water loss, and prevents the calvin cycle from occurring when O2 levels are high and CO2 is low
Photorespiration mostly occurs in
C3 plants
In C4 plants, the ___ carries out light reactions and generates ___
mesophyll, O2
In C4 plants, ___ is incorporated into phosphenolpyruvate to make ___
CO2, oxaloacetate
In C4 plants, oxaloacetate is transferred to
bundle-sheath cells
In C4 plants, the CO2 is removed from oxaloacetate and the calvin cycle
operates in bundle-sheath cells
C4 plants change the
location of the calvin cycle changes - occurs in bundle-sheath cells
CAM plants change the
timing of the calvin cycle
In CAM plants, what changes during the day?
The stomata are closed and light reactions make ATP and NADPH
In CAM plants, what occurs during the night?
The stomata open and the uptake of CO2 occurs which incorporates it into oxaloacetate
