Chapter 8 Flashcards
photosynthesis
converts solar power into chemical energy
autotrophs
get energy from nonliving sources
autotrophs are ____?
producers
producers
make organic molecules from CO2 and other inorganic molecules
heterotrophs
obtain energy from other organims
heterotrophs depend directly or indirectly on photoautotrophs for?
food and O2
chloroplasts of eukaryotes likely evolved from?
photosynthetic bacteria
_____ enters and _____ exits through stomata.
CO2, O2
Chloroplasts are mainly found in?
mesophyll cells
mesophyll
interior tissue of leaf
thylakoid
suspended in stroma and composed of sacs
the color of leaves come from?
chlorophyll
Chloroplasts split H2O into _______ and ______, incorporating the electrons of _____ into _____ molecules and releasing _____.
hydrogen, oxygen, hydrogen, sugar, O2
Photosynthesis does what to electron flow compared to cellular respiration?
reveres the direction
photosynthesis is a ____ process, in which ___ is oxidized, _____ is reduced.
redox, H2O, CO2
Photosynthesis is a ______ reaction.
endergonic
2 steps of photosynthesis
light reactions, photosynthesis
The electron acceptor NADP+ is reduced to?
NADPH
Photophosphorylation
ATP is generated by adding a phosphate group to ADP
The Calvin cycle produces?
sugar from CO2 with help from NADPH and ATP
Carbon Fixation
CO2 is incorporated into organic molecule
Wavelength
distance between crests of electromagnetic waves
Electromagnetic spectrum
entire range of wavelengths
Visible light consists of waves lengths ____ to ______
380nm, 750nm
photosynthesis is powered by ____
visible light
photons
light behaves as discrete particles
Pigments
absorb visible light
waves that are not absorbed are?
reflected or transmitted
spectrophotometer
measures a pigments ability to absorb different wavelengths
absorption spectrum
plots a pigment’s light absorption vs wavelength
chlorophyll a absorbs?
violet-blue and red
What is the main photosynthetic pigment?
chlorophyll a
carotenoids
absorb excessive light that would damage chlorophyll
when pigments absorb light, an electron is elevated from?
ground state to excited state
fluorescence
electrons fall down, releasing photons
photo system
reaction-center complex surrounded by light harvesting complexes
light harvesting complexes
transfer the energy of photons to reaction center
light harvesting complexes are composed of?
pigment molecules bound to proteins
reaction center complex
association of proteins holding a pair of chlorophyll a and a primary electron acceptor.
First steps of light reactions
chlorophyll a transfers an excited electron to the primary electron acceptor.
What occurs in the reaction center is a?
redox reaction
Photosystem II is best at absorbing what wavelength?
680nm
P680
the reaction center of chlorophyll a of PSll
Photosystem l is best at absorbing what wavelength?
700 nm
P700
the reaction center of chlorophyll a of PSl.
how are P680 and P700 different?
associated with different proteins.
Linear electron flow
flow of electrons through photosystems.
what is produced in linear electron flow?
ATP and NADPH
Electrons are passed down an ________ from PSll to PS1 releasing ____ to form ______.
electrons transport chain, energy, a protein gradient across the thylakoid membrane.
chloroplast and mitochondria generate _ by the same mechanisms.
ATP
The light reactions of photosynthesis generate _____ and increase the _____ of electrons by moving them from _____.
ATP, potential energy, H2O to NADPH
The Calvin cycle is ____?
anabolic
Calvin Cycle
uses energy from ATP and reducing power of NADPH to build sugar.
Carbon enters the cycle as ___ and leaves as ___
CO2, Glyceraldahyde 3-phosphate (G3P)
For the net synthesis of 1 G3P, the cycle must?
take place 3 times, fixing 3 molecules of CO2.
3 phases of the Calvin Cycle
-Carbon Fixation
-Reduction
-REgeneration of the CO2 acceptor
Phase 1
carbon fixation forms 6 carbon molecule by combining CO2 and RuBP
ribulose biphosphate (RuBP)
5 carbon sugar
RuBP oxygenase/carboxylase catalyzes?
Phase 1
Phase 2
phosphorylation of 3-phosphoglycerate to 1,3-biphosphoglycerate which is then reduced to G3P.
____ ATP and ______ NADH are required to produce _____ but only ____ exits the cycle for use by the cell.
6, 6, 6 G3P, 1
Phase 3
Rearrangement of the 5 remaining G3P molecules to regenerate CO2 acceptor RuBP.
Since the move to land 475 million years ago, plants have been?
adapting to the problem of dehydration.
On hot dry days, plants close stomata, which reduces?
evaporative water loss and prevents gas exchange.
When stomata are closed, CO2?
levels are reduced and O2 accumulates
C3 plants
initial fixation of CO2 (via rubisco), forms 3-phosphoglycerate
Photorespiration
rubisco fixes O2 instead of CO2 releasing CO2 without producing O2, ATP, or sugar
Photorespiration may provide some ____ that builds up when the ____.
protection against light damage, Calvin cycle slows
C4 plants
CO2 is fixed in mesophyll cells and Calvin cycle runs in bundle-sheath cells.
CAM plants
Open stomata at night and incorporate CO2 into organic acid
C4 and CAM plants are similar because?
both incorporate CO2 into organic intermediates before Calvin cycle
In C4 plants, carbon fixation and Calvin cycle occur in?
different cells
In CAM plants, carbon fixation and Calvin cycle occur at?
different times of the day