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40 Cards in this Set

  • Front
  • Back
The photosystem is in the thylakoid membrane of the chloroplasts and consists of several _______ surrounding a ________ and associated proteins
Antenna system

Reaction center
When the chlorophyll molecule at the reaction center absorbs energy from the adjacent chlorophyll in the antenna centers, it becomes excited. When it falls back to ground or unexcited state, the reaction center converts the absorbed light energy into ________ energy
Chemical
There are two types of reaction centers ________ and __________
Photosystem I and Photosystem II
Photosystem I has P___ chlorophyll at its reaction center

Photosystem II has p___ chlorophyll at its reaction center
P700

P680
These photosystems work together to produce an ______ effect, where photosynthesis increases when cells are exposed to both red and far-red light
Enhancement
After energy absorbed by the antenna system reaches the reaction center of photosystem II the chlorophyll P___ at the reaction center is _______ when it donates high-energy electrons to the electron acceptor _______
P680

Oxidized

Pheophytin
The pheophytin molecule has been
reduced
Electrons are passed from the reduced pheophytin to an ___________
Electron transport chain
The ETC includes _________ which is a molecule that is able to carry electrons from the pheophytin across the thylakoid membrane to more electronegative molecules in the chain including a _________ complex
Plastoquinone (PQ)

Cytochrome complex
The released potential energy allows protons to be pumped across the thylakoid membrane building up the concentration of protons on one side of the membrane and creating a _________
Proton-motive force
_________ results when the flow of protons go through ATP synthase due to the proton-motive force ans causes a change in its shape driving the phosphorylation of ADP to ATP
Chemiosmosis
This capture of light energy by photosystem II to produce ATP (storing energy in the bonds of ATP) is called
photophosphorylation
Photosystem II _____ water to replace electrons used during the light reactions
oxidizes
Photosystem II "splits" water to replace lost electrons and in the process produces oxygen. This process is called
Oxygenic photosynthesis
Photosystem I produces _____, an electron carrier
NADPH
When excited electrons leave the chlorophyll molecule in the reaction center of photosystem I, they are transferred to a series of electron acceptors in an ETC. They move down the ETC until they reach______
Ferredoxin
In an enzyme-catalyzed reaction, the reduced form of ferredoxin reacts with NADP+ to produce
NADPH
_______ produces a proton gradient that drives the synthesis of ATP

_______ yields reducing power in the form of NADPH
Photosystem II

Photosystem I
At the end of photosystem II's ETC, the electron is passed to a protein called ________, which carries the electron back across the thylakoid membrane and donates it to photosystem I, thus linking the two photosystems
Plastocyanin (PC)
Electrons from PC replace electrons from the P______ pair of chlorophyll molecules in the photosystem I reaction center
P700
These electrons enter an ETC, then are eventually passed to _______ and used to reduce _______ to ______
Ferredoxin

NADP+
NADPH
The Z scheme explains the _____ effect
Enhancement
At times, photosystem I transfers electrons to photosystem II's electron transport chain to increase ATP production, instead of using them to reduce NADP+. This _________ coexists with the Z scheme and produces additional ATP
Cyclic Photophosphorylation
ATP and NADPH are produced by the photosystems I and II in the presence of light. The energy in these molecules is used next in the carbon-fixation reaction to "fix" CO2 into a reduced form and convert it to carbohydrates. These reaction produce sugar/carbohydrates from carbon dioxide in the __________ and are light-independent
Calvin cycle
The Calvin cycle has three phases, each of which is catalyzed by a specific enzymes
Fixation: CO2 reacts with __________ producing two _________ molecules. Rubisco catalyzes this reaction
Ribulose biphosphate (RuBP)

3-phosphoglycerate
(the attachment of CO2 to an organic compound is called carbon fixation)
The Calvin cycle has three phases, each of which is catalyzed by a specific enzymes
Reduction: the 3-phosphoglycerate molecules are phosphorylated by ATP and reduced by NADPH to produce
glyceraldehyde 3-phosphate (G3P)
Regeneration: The remaining ____ is used in reactions that regenerate _____
G3P

RuBP
The Calvin Cycle occurs in the chloroplasts
Stroma
The CO2-fixing enzyme is called ___________. It catalyzes the first reaction in the Calvin Cycle
Ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco)
Rubisco is found in all photosynthetic organisms that use the Calvin cycle to fix carbon, and is thought to be the most
abundant enzyme on Earth
Oxygen and carbon dioxide compete at the enzymes active sites, which slows the rate of CO@ reduction. When O2 and RuBP react in rubisco's active site, one of the products undergoes a process called
photorespiration
Photorespiration "undoes" photosynthesis because it consumes energy and releases ______ CO2
fixed
______ are leaf structures where gas exchanges occur, They consist of two _______ that change shape to open or close
Stomata

Guard cells
The ___ pathway, which occurs mostly in plants from hot, dry habitats limits the damaging effects of photorespiration by ______ carbon fixation and the Calvin cycle
C4

Spatially separating
In _________ plants, carbon fixation and the Calvin cycle are separated in time.
Crassulacean Acid Metabolism (CAM)
In C4 plants, which perform _______, carbon fixation and the Calvin cycle occur in separate types of cells
C4 photosynthesis
This occurs in a three-step process

PEP carboxylase fixes to CO2 in ______

The four-carbon organic acids move to _________

The four carbon organic acids release a CO2 molecule, which _____ uses to form three-phosphoglycerate (3PG), thus initiating the Calvin cycle
Mesophyll cells

Bundle-sheath cells

Rubisco
In ____ plants, the reactions catalyzed by PEP carboxylase and rubsico are separated in space

In ____ plants, the reactions are separated in time
C4

CAM
G3P molecules produced by the Calvin cycle are often used to make glucose and fructose, which can be combined to form
Sucrose
In rapidly photosynthesizing cells where sucrose is abundant, glucose is temporarily stored in the chloroplast as
Starch