Chapter 8: photosynthesis
electrons and H+
NADP reductase transfers two ____ and one _____ to NADP to generate NADPH
how is NADPH formed in PSI
NADP+ reductase adds two electrons and a H+ to NADP+
what molecule is used as an electron carrier during photosynthesis
NADPH
through the process of photsynthesis, photautotrops produce
O2 and organic molecules
absorption spectrum
a ___ ____ is a diagram that depicts the wavelengths of electromagnetic radiation that are absorbed by a pigment
what is a photon
a discrete particle of light
thylakoids
a granum is a stack of ____
what environmental condition favors photorespiration
a hot dry environment
NADPH
a key role of PSI is to produce high-energy electrons that are used to make ______
chlorophyll, carotenoid
a leaf that appears green has more ____ than a leaf that appears yellow. A leaf my appear to be yellow due to ____ pigments
ATP
a major purpose of the electronchemical gradient generated in the light reactions of photosynthesis is to synthesize ____
particle and a wave
a photon of light has properties of both a ___ and a ____
2
according to the Z scheme, how many photoactivation events occur during photosynthesis
CH2O A2 H2O
according to the general equation for photosynthesis, CO2+2h2A+ light energy --> ____+____+___
Qb
after electrons reach ___ they eneter an electron transport chain in the thylakoid membrane
action
an ____ spectrum for photosynthesis shows the rate of photosynthesis plotted as a function of light wavelength
what summarized the events of the first phase of the calvin cycle
atmospheric carbon dioxide is fixed into five carbon sugar
a key difference between noncyclic electron flow and cyclic electron flow is that in cyclic electron flow electrons are ultimately transferred
back to PSI
what type of organisms carry out cellular respiration
both heterotrophs and autotrophs
what organisms are photoautotrophs
green plants cyanobacteria algae
how might electrons in an excited state release energy
heat, light
photorespiration
in hot dry conditions, rubisco can attach O2 to RuBP in a process called _____. Which ultimately produces CO2
reduced oxidized
in the generalized equation for photosynthesis, the transfer of electrons occurs such that CO2 is ____ and H2A is _____
water
in the light reactions, both photosystems absorb and capture light energy in the form of excited electrons; however PSII is able to oxidize _____, which in the production of oxygen
where do the light reactions occur
in the thylakoid membrane
an action spectrum
is a visualization of the rate of photsynthesis plotted as a function of light wavelength
what is the function of chlorophyll during photosynthesis
it absorbs light energy
what is the role of the reaction center in a photosystem
it transfers a high-energy electron to another molecule
what is the source of energy for photoautotrophs
light
how does an electron present in the pigment of the light harvesting complexes become excited
light excites an electron in a pigment found in the light harvesting complexes of the photosystem
electromagnetic
light is considered a form of _____ radiation because it consists of energy in the form of electric and magnetic fields
heterotroph
must consume food to obtain organic molecules
the flow of elecgtrons from PSII and PSI is considered to be
noncyclic electron flow
through the process of photosynthesis photoautotrophs produce
organic molecules O2
through the process of photosynthesis photoautrophs produce
organic molecules O2
during photosynthesis water is
oxidized
what are major chemical products of the light reactions of photosynthesis
oxygen ATP NADPH
a molecule that can absorb light energy is called
pigment
what happens during photosynthesis
plants capture energy from sunlight and use it to synthesize organic molecules
photoautrophs
produce most of the earths organic molecules
autotroph
produces organic molecules from inorganic molecules
chemiosmotic
similar to ATP synthesis in mitochondria ATP synthesis in chloroplasts is achieved by _____ mechanism
cellular respiration
the CO2 that is used during photosynthesis is regenerated by the process of ______
z, light
the ____ diagram (or scheme) describes the energy transitions of electrons as they move through the ___ reactions
sunlight
the energy required for the synthesis of glucose from carbon dioxide ultimately comes from _____
stroma
the fluid-filled region of the chloroplast between the thylakiod membrane and the inner membrane is known as the _____
fixation
the incorporation of carbon from CO2 in the atmosphere into an organic molecule is called carbon ____
in a green plant the majority of photosynthesis takes place in
the leaves
solar chemical
the light reactions convert ____ energy into ___ energy stored in covalent bonds
electrons
the light reactions of photosynthesis require water to supply _____ that are transferred to P680
what part of a photsystem contains dozen of pigment molecules that absorb light photons
the light-harvesting complex
pigment
the light-harvesting complex is composed of several dozen ____ molecule that are anchored to transmembrane proteins
water
the oxidation of ____ results replenishment of electrons lost in PSII when electrons are excited and the formation of oxygen gas
light
the photsynthetic ____ reactions are composed of a series of energy transfers
oxygen and CO2
the reactions of photorespiration consume ____ and produce ___.
during photsynthesis oxygen is produced by
the removal of electron from water in PS2
carbon dioxide
the source of carbon for the carbohydrates synthesized in the calvin cycle is _____ from the atmosphere
oxygen
the splitting of water in photosystem II results in the production of ____ gas
what is the name of the space enclosed by the thylakoids
the thylakoid lumen
photosystems I and II are located in:
the thylakoid membrane
why are leaves green
they reflect green light
what is the purpose of phase 3 of the Calvin cycle
to create a new 5 carbon sugar for the "next" calvin cycle
photautotroph
uses light energy to drive the synthesis of organic molecules from inorganic molecules
the pigments in the antenna complex transfer energy
via resonance energy transfer
electron
when a pigment molecule absorbs a photon of light a ___ is boosted to a higher energy level
excited
when an electron absorbs energy it becomes ____
what is the primary output of the calvin cycle
glyceraldehyde-3 phosphate
what is true about carotenoids
- they may appear yellow, orange, or red -they are found in chloroplasts -they are abundant in flowers and fruits
in C4 plants, the first products of carbon fixation is
-a four-carbon molecule
what are components of both PSI and PSII
-a reaction center -a light harvesting complex
what membranes are found in a chloroplast
-an inner membrane -the thylakoid membrane -an outer membrane
the two stages of photosynthesis
-calvin cycle -light reactions
why is the rate of photosynthesis slow in the green region of the visible light spectrum
-green light is not absorbed by chlorophyll
how does photosynthesis benefit organisms that are not plants
-it produces oxygen that can be used for aerobic respiration -it produces organic molecules that other organisms use as food
what are products of the light reactions
-o2 -ATP -NADPH -oxygen
the energy released as electrons pass from an electron carrier to another in the electron transport chain between photsystem II and photosystem I is used to
-pump H+ -establish an electrochemical gradient
the G3P produced at the end of the second phase of the Calvin cycle is directly used to
-regenerate ribulose bisphospate -make glucose or other carbohydrates
what are examples of redox reactions that occur during photosynthesis
-the transfer of high-energy electrons from a pigment molecule to the primary electron acceptor -the generation of NADPH -the removal of low energy electrons from water
what is the products of the light reactions feed into the calvin cycle
ATP, NADPH
arrange the electron carriers in PS2 in order of decreasing electronegativity
1. Qb 2.Qs 3.Pp 4.P680
rank the electrons that occur in photsystem II in order of potentail energy levels beginning with the highest potential energy
1. an electron excited transfered to a primary electron acceptor 2. an electron transferred to Qa 3. an electron transferred from water to P680 4. an electron waiting to be excited by sunlight
sequence the phases of the Calvin cycle from first to last
1. carbon fixation 2. reduction and carbohydrate production 3. regeneration of ribulose bisphosphate
sequence the process of electron transfer in PSII
1. excited electrons move form P680 2. excited electrons move down a series of electron carriers 3. excited electrons are transferred to Qb 4. excited electrons move out of PSII into PSI
the steps in calvins isotope-labeling experiment in the correct order
1. injection of algae with 14 C-Labeled CO2 2. incubation of cells for various time periods 3. paper chromatography 4. autoradiography
arrange the elctron carriers in photosystem I in order of decreasing potential energy
1. primary electron acceptor 2. ferredoxin (FD) 3. NADP+ reductase 4. NADP+
arrange the following molecules according to the order of electron flow during photosynthesis
1. water 2. P680 3. cytochrome complex 4. plastocyanin 5. P700 6.NADP+
how do CAM plants avoid water loss
CAM plants close their stomata during the day and open them at night
what molecule is reduced in the calvin cycle
CO2
respiration photosynthesis
CO2 and H2O are produced during cellular ____ and consumed during ____
what two chemical reactions are catalyzed by rubiso
RuBP+CO2--> 2 3PG RuBP+O2--> 3PG+ phosphoglycolate
during photosynthesis, CO2 is reduced during the formation of
glucose
CAM stomata
___ plants only uptake CO2 at night because they close their ___ during they day
examples of CAM plants
cactus pineapple
plants appear green because they contain
chlorophyll
prophyrin
chlorophylls a and b are composed of a _____ ring containing a magnesium ion and a phytol tail
thylakoid
chlorophylls a and b are found bound to intergral membrane proteins in the _____ membrane of the chloroplast
what are C4 plants
crabgrass sugarcane corn
oxygen
during replenishment of electrons that have become excited, PSII produces ____ which can be used by plant cells or released to the environment
during resonance energy transfer, what is transferred from one molecule to another
energy
energy
every photon contains a specific amount of ____