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 ____