CH 10 Photosynthesis vocab
Describe a chlorophyll molecule
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Photosynthesis converts light energy to the chemical energy of food
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Photorespiration
A metabolic pathway that consumes oxygen and ATP, releases carbon dioxide, and decreases photosynthetic output. Photorespiration generally occurs on hot, dry, bright days, when stomata close and the O2/CO2 ratio in the leaf increases, favoring the binding of O2 rather than CO2 by rubisco.
Which of the following equations represents photosynthesis? 6CO2 + 6O2 → C6H12O6 + 6H2O 6H2O + 6O2 → C6H12O6 + 6CO2 C6H12O6 + 6O2 → 6CO2 + 6H2O C6H12O6 + 6CO2 → 6O2 + 6H2O 6CO2 + 6H2O → C6H12O6 + 6O2
6CO2 + 6H2O → C6H12O6 + 6O2 Photosynthesis requires carbon dioxide and water for the production of sugar and oxygen.
Reaction-center complex
A complex of proteins associated with a special pair of chlorophyll a molecules and a primary electron acceptor. Located centrally in a photosystem, this complex triggers the light reactions of photosynthesis. Excited by light energy, the pair of chlorophylls donates an electron to the primary electron acceptor, which passes an electron to an electron transport chain.
Light harvesting complex
A complex of proteins associated with pigment molecules (including chlorophyll a, chlorophyll b, and carotenoids) that captures light energy and transfers it to reaction-center pigments in a photosystem.
Thylakoids
A flattened membrane sac inside the chloroplast, used to convert light energy to chemical energy.
Thylakoids
A flattened, membranous sac inside a chloroplast. Thylakoids often exist in stacks called grana that are interconnected; their membranes contain molecular "machinery" used to convert light energy to chemical energy.
Chlorophyll
A green pigment located in membranes within the chloroplasts of plants and algae and in the membranes of certain prokaryotes. Chlorophyll a participates directly in the light reactions, which convert solar energy to chemical energy.
Photosystem I
A light-capturing unit in a chloroplast's thylakoid membrane or in the membrane of some prokaryotes; it has two molecules of P700 chlorophyll a at its reaction center.
Photosystem
A light-capturing unit located in the thylakoid membrane of the chloroplast or in the membrane of some prokaryotes, consisting of a reaction-center complex surrounded by numerous light-harvesting complexes. There are two types of photosystems, I and II; they absorb light best at different wavelengths.
C4 Plants
A plant in which the Calvin cycle is preceded by reactions that incorporate CO2 into a four-carbon compound, the end product of which supplies CO2 for the Calvin cycle.
CAM plants
A plant that uses crassulacean acid metabolism, an adaptation for photosynthesis in arid conditions. In this process, carbon dioxide entering open stomata during the night is converted to organic acids, which release CO2 for the Calvin cycle during the day, when stomata are closed.
C3 plants
A plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a three-carbon compound as the first stable intermediate.
Glyceraldehyde 3-phosphate (G3P)
A three-carbon carbohydrate that is the direct product of the Calvin cycle; it is also an intermediate in glycolysis.
What two molecules are produced by the light reactions and used to power the Calvin cycle? CO2 and O2 C6H12O6 and O2 C6H12O6 and RuBP ATP and NADPH G3P and H2O
ATP and NADPH ATP and NADPH are both products of the light reactions and are used to power the Calvin cycle.
Carotenoids
An accessory pigment, either yellow or orange, in the chloroplasts of plants and in some prokaryotes. By absorbing wavelengths of light that chlorophyll cannot, carotenoids broaden the spectrum of colors that can drive photosynthesis.
What connects the two photosystems in the light reactions? Chlorophyll A thylakoid An electron transport chain A chain of glucose molecules The Calvin cycle
An electron transport chain
PEP carboxylase
An enzyme that adds CO2 to phosphoenolpyruvate (PEP) to form oxaloacetate in mesophyll cells of C4 plants. It acts prior to photosynthesis.
Heterotrophs
An organism that obtains organic food molecules by eating other organisms or substances derived from them.
In which of the following organelles does photosynthesis take place? Chloroplast Mitochondrion Ribosome Central vacuole Nucleus
Chloroplast Chloroplasts use energy from light to transform carbon dioxide and water into sugar and oxygen.
Three molecules of carbon dioxide are added to three molecules of a five-carbon sugar abbreviated RuBP. These molecules are then rearranged to form six molecules called 3-PGA, which have three carbons each.
Describe Carbon Fixation in the Calvin Cycle
In both cases, rubisco is not used to fix carbon initially.
How is photosynthesis similar in C4 plants and CAM plants?
transmitted
If wavelengths are not absorbed they are
Bundle-sheath cells
In C4 plants, a type of photosynthetic cell arranged into tightly packed sheaths around the veins of a leaf.
Primary electron acceptor
In the thylakoid membrane of a chloroplast or in the membrane of some prokaryotes, a specialized molecule that shares the reaction-center complex with a pair of chlorophyll a molecules and that accepts an electron from them.
Photo system II
One of two light-capturing units in a chloroplast's thylakoid membrane or in the membrane of some prokaryotes; it has two molecules of P680 chlorophyll a at its reaction center.
Chlorophyll Photo
Light comes into cell, Light is absorbed by Granum, Light is reflected back.
Linear Electron Flow
Light drives the synthesis of ATP and NADPH by energizing the two photsystems embedded in the thylakoid membranes of chloroplasts. The key to this energy transformation is a flow of electrons through the photosystems and other molecular components built into the thylakoid membrane. This flow occurs during the light reaction of photosynthesis.
NADP
Nicotinamide adenine dinucleotide phosphate, an electron acceptor that, as NADPH, temporarily stores energized electrons produced during the light reactions.
Stroma
The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water.
Photosynthesis
The conversion of light energy to chemical energy that is stored in glucose or other organic compounds; occurs in plants, algae, and certain prokaryotes.
Light Reactions
The first of two major stages in photosynthesis (preceding the Calvin cycle). These reactions, which occur on the thylakoid membranes of the chloroplast or on membranes of certain prokaryotes, convert solar energy to the chemical energy of ATP and NADPH, releasing oxygen in the process.
Carbon Fixation
The initial incorporation of carbon from CO2 into an organic compound by an autotrophic organism (a plant, another photosynthetic organism, or a chemoautotrophic prokaryote).
ATP and NADPH
The light reactions of photosynthesis supply the Calvin cycle with
thylakoids; stroma Within the chloroplast, the light reactions take place in the flattened sacs called thylakoids and the Calvin cycle takes place in the thick fluid called the stroma.
The light reactions take place in the _________ and the Calvin cycle takes place in the _________. stroma; thylakoids thylakoids; stroma inner membrane; outer membrane chloroplasts; mitochondria mitochondria; chloroplasts
Photophosphorylation
The process of generating ATP from ADP and phosphate by means of chemiosmosis, using a proton-motive force generated across the thylakoid membrane of the chloroplast or the membrane of certain prokaryotes during the light reactions of photosynthesis.
Calvin cycle
The second of two major stages in photosynthesis (following the light reactions), involving fixation of atmospheric CO2 and reduction of the fixed carbon into carbohydrate.
removal of electrons from chlorophyll molecules
Which process is most directly driven by light energy? creation of a pH gradient by pumping protons across the thylakoid membrane removal of electrons from chlorophyll molecules reduction of NADP+ molecules ATP synthesis carbon fixation in the stroma
Carbon Fixation Energy Consumption and Redox Release of G3P; Regeneration of RuBP
What are the three phases of The Calvin cycle?
Chlorophyll is the green pigment within chloroplasts that makes plants green
What is chlorophyll and why is it necessary?
H2O Electrons are stripped from water in the light reactions of photosynthesis. Light provides the energy to excite electrons.
What provides electrons for the light reactions? CO2 The Calvin cycle H2O Light O2
Carbon dioxide (CO2) Carbon dioxide provides the carbon atoms that are incorporated into sugars in photosynthesis. Carbon dioxide initially combines with RuBP, and RuBP is regenerated to continue the Calvin cycle.
What provides the carbon atoms that are incorporated into sugar molecules in the Calvin cycle? Sucrose (C12H22O11) RuBP Carbon dioxide (CO2) Glucose (C6H12O6) G3P (C3H6O3)
NADPH NADPH is an electron carrier that picks up electrons in the light reactions and releases them in the Calvin cycle. An electron transport chain conveys electrons from one photosystem to the other within the light reactions.
What transports electrons from the light reactions to the Calvin cycle? NADH NADPH An electron transport chain FADH2 Chlorophyll
The Calvin cycle is a complex series of chemical reactions carried out in the stroma.
Where does the Calvin cycle take place?
release of oxygen
Which of the following does not occur during the Calvin cycle? release of oxygen regeneration of the CO2 acceptor oxidation of NADPH consumption of ATP carbon fixation
H2O → NADPH → Calvin cycle
Which of the following sequences correctly represents the flow of electrons during photosynthesis? NADPH → chlorophyll → Calvin cycle H2O → NADPH → Calvin cycle NADPH → O2 → CO2 NADPH → electron transport chain → O2 H2O → photosystem I → photosystem II
Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic.
Which of the following statements is a correct distinction between autotrophs and heterotrophs? Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic. Only heterotrophs require oxygen. Cellular respiration is unique to heterotrophs. Only heterotrophs have mitochondria. Only heterotrophs require chemical compounds from the environment.
Absorption Spectrum
a graph plotting a pigment's light absorption versus wavelength
Photons
a particle representing a quantum of light or other electromagnetic radiation. A photon carries energy proportional to the radiation frequency but has zero rest mass.
Chloroplasts
absorbs sunlight and uses it to drive the synthesis of organic compounds from carbon dioxide and water.
chlorophyll b
accessory pigment that broadens the spectrum used for photosynthesis
Visible Light
between 360-750 nm in wavelength on the em spectrum. Visible to the human eye
visible lightsu
consists of wavelengths that produce colors that we can see
photon
discrete particle which light consists of
wavelength
distance between the crests of waves, determines the type of electromagnetic energy
higher
does a shorter wavelength have higher energy or lower energy?
stomata
little pores or openings in the leaves that allow CO2 to come in and O2, water evaporates through these
chlorophyll a
main photosynthetic pigment
spectrometer
measures a pigments ability to absorb various wavelengths. It sends light through pigments and measures the fraction of light transmitted at each wavelength
6 CO2 + 12 H2O + Light energy → C6H12O6 + 6 O2 + 6 H2O
photosynthesis equation
Stomata
pores on the leaf where O2 exits and CO2 enters
Autotrophic
produce their organic molecules from CO2 and other raw material from the environment.
Autotrophs
produce their own organic molecules from CO2
Action Spectrum
profiles the relative effectivenes of differenet wavelengths of radiation in driving the process.
Mesophyll
specialized for photosynthesis. In C3 and CAM plants, mesophyll cells are located between the upper and lower epidermis; in C4 plants, they are located between the bundle-sheath cells and the epidermis.
pigments
substances that absorb visible light and different wavelengths
Spectrophotometer
the ability of pigment to absorb different wavelengths of light that can be measured with an instrument
electromagnetic spectrum
the entire range of electromagnetic energy
light dependent and light independent
what are the two stages of photosynthesis
photophosphorylation
what is oxidative phosphorylation in cellular respiration similar to
