Term
Photosynthesis, the process by which organisms ______ ______ from sunlight and use it to build
______ ______ that are rich in ______ ______. |
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Definition
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Term
The energy used by most living cells comes
ultimately from the Sun and is captured by ______, _____, and _____ through the process of photosynthesis.
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Definition
| Plants, Algae and Bacteria |
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Term
What are the beginning reactants and ending products of photosynthesis? |
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Definition
6 CO2 + 12H2O + Light ---> C6H12O6 + 6H2O + 6O2
carbon diox + Water + Light ---> Glucose + Water +Oxy |
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Term
What is anoxygenic photosynthesis? What organisms use this process? What is oxygenic photosynthesis? What organisms use this process?
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Definition
Anoxygenic Photosynthesis does not produce oxygen and found in four different bacteria groups: purple bacteria, green sulfur bacteria, green non-sulfur bacteria, and heliobacteria
Oxygenic does produce oxygen and is found in cyanobacterian, seven groups of algae and basically all land plants |
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Term
What structures in plants carry out photosynthesis? |
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Definition
| In plants it takes place in the leaves in chloroplasts. |
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Term
What are the three stages of photosynthesis? Which of these are light-‐dependent and which are
light-independent? |
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Definition
- Capturing energy from sunlight
- Using energy to make ATP and to reduce the compound NADP+, and electron carrier to NADPH; and
- Using the ATP and NADPH to power the synthesis of organic molecules from CO2 in the air
The first two are light-dependent and the third in ligh-independent |
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Term
| Draw and label a picture of a chloroplast. Where does each step of photosynthesis take place in this organell? |
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Definition
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Term
| What must be present for carbon fixation reactions to occur? |
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Definition
| As long as ATP and NADPH are available the carbon fixation reactions can occur either in the presence or absence of light |
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Term
How are the reactions for respiration and photosynthesis related? |
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Definition
The equation for photosynthesis is reverse for the respiration reaction equation.
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Term
What similarities are there in mitochondria and chloroplast structure? |
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Definition
| both the complex structure internaly and externaly contribute to it's functions. |
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Term
In respiration electrons are passed from one molecule to another; is this the case in photosynthesis? Why or Why not? |
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Definition
| THe excited electron is not transfered physically---rather, its energy passes from one molecule to another. This passage is similar to the transfer of kinetic energy. |
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Term
Does O2 come from the splitting of CO2 or H2O during photosynthesis? |
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Definition
| Electrons lost during phostosynthesis are replaced by the oxidation of water, producing O2 as a by product. |
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Term
| What structure must be present to absorb light energy to make use of the energy? |
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Definition
| For plants to make energy from sunlight, some biochemical structure must be present in chloroplasts and thylakoids that can absorbe this energy. Molecules that absorbe light energy in the visible range are termed pigments. |
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Term
In pigments, the color we see is the color that is _____, that is, it is _____. |
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Definition
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Term
| What does light wavelength impact? What is an electromagnetic spectrum? |
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Definition
| The wave nature of light produces an electromagnetic spectrum that differentiates light based on its wavelenth |
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Term
| How is the energy of a photon related to the wavelength of light? |
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Definition
| A partical of light termed a photon, acts like a discrete bundle of energy. We use the wave concept of light to understand different colors of light and the partical nature of light to understand the energy transfers that occur during photosynthesis. |
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Term
| What is the photoelectric effect? |
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Definition
| A beam of light is able to remove electrons from certain molecules, creating an electrical current. This phemomenon is called the photoelectic effect. |
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Term
How does wavelength of light impact the strength of the photoelectric effect? |
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Definition
| The stenbth of the photoelectric effect depends on the wavelenth of light; that is, short wave lengths are far more effective than long ones in producing the photoelectric effect because they have more energy. |
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Term
| What is the role of chloroplasts regarding the photoelectric effect? |
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Definition
| In photosynthesis, chloroplasts are acting as photoelectric devices: they absorbe sunlight and transfer the excited electrons to a carrier. |
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Term
| What is a molecule’s absorption spectrum? |
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Definition
| A specific atom can absorb only certain photons of light---namely, those that correspond to the atom's available energy levels. As a result, each molecule has a characteristic absorption spectrum, the range and efficiency of photons it is capable of absorbing. |
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Term
| What types of pigments are used in green plant photosynthesis? |
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Definition
| Chlorophyll a and chlorophyll b preferentially absorbe violet-blue and red light. |
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Term
What are the two chlorophylls in plants? What light do they absorb? Reflect? How are they different from each Other? |
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Definition
| Chlorophyll a and b. Chlorophyll a is the main photosynthetic pigment in plants and cyanobacteria and the only pigment that can act directly to convert light energy to chemical energy. Chlorophyll b, acting as an accessory pigment, or secondary light-absorbing pigment, complements and adds to the light absorption of chlorophyll a. |
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Term
Is light absorbed by independent pigment molecules or clusters of chlorophyll molecules? What data supports this Finding? |
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Definition
| Light is absorbed, not by independent pirment moluecules, but rather by clusters of chlorophyll and accessory piment molecules. expiriement proving this pg. 154 |
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Term
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Definition
| In all cholorplasts and in all but one photosynthetic prokaryotes, light is captured by a photosystem. Each photosystem is a network of chlorophyll a molecules, accessory pigments, and associated proteins held together within a protein matrix on the surface of a photosynthetic membrane. |
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Term
| What is a reaction center chlorophyll? |
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Definition
| is a transmembrane protein pigment complex. |
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Term
| What is an antenna complex? |
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Definition
| also called light-harvesting complex, which accurately describes its role. |
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Term
How are these threecomponents related? What gets passed between each? How does this transfer energy? |
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Definition
| the light-harvesting complex captures photons from sunlight and channels them to the reaction center chlorophylls. More explanation pg. 155 |
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Term
Where do the light-dependent reactions of photosynthesis occur? How does this differ in prokaryotes and eukaryotes ? |
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Definition
| these reactions take place on the membrane. In photosynthetic bacteria, the plasma membrane itself is the photosynthetic membrane. In many bacteria, the plasma membrane folds in on itself repeatedly to produce and increased surface area. In plants and algea, photosynthesis is carried out by chloroplasts which are thought to be evolutionary desendents of photosynthetic bacteria. |
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Term
| What are the four stages of Thylakoid reaction? |
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Definition
- Primary photoevent. A photon of light it captured by a pigment. This primary photoevent excites an electron within the pigment.
- Charge seperation. This excitation energy is transfered to the reaction center, which transfers an energetic electron to an acceptor molecule, initiating electron transport.
- Electron Transport. The excited electrons are shuttled along a series of electron carrier molecules embedded within the photosynthetic membrane.
Several of them react by transfering protons across the membrane, generating a proton gradient. Eventually the electrons are used to reduce a final acceptor, NADPH.
- Chemiosmosis. The protons that accumulate on one side on the membrane now flow back across the membrance through ATP synthase where chemiosmotic synthesis of ATP takes place, just as it does in aerobic respiration.
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Term
Are these part of the light-‐dependent or light-‐independent reactions? Why? |
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Definition
| These four stages make up the light-dependent reactions mentioned earlier. Steps 1-3 represent the stage of capturing energy from light; step 4 is the stage of producing ATP. |
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Term
| What is cyclic photophosphorylation? Why is it named as such? How many photosystemsystems are involved? |
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Definition
| In bacteria a single photosystem is used that generates ATP via electron transport. This process then returns the electrons to the reaction center. For this reason it is called the cyclic photophosphorylsation. |
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Term
How many photosystems are linked in chloroplasts? What are they called? How do they differ? What electron carriers connect these photosystems? |
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Definition
Chloroplasts have two connects photosystems. Photosystem I and II.This overcomes the limitations of cyclic photophosphorylation by providing an alternative source of electrons from the oxidation of water.
PI has an absorbtion peak of 700 nm, so its reaction center pigment is called P700. PII has an absorbtion peak of 680nm, so its reaction center pigment is P680. This photosystem can generate an oxidation potential high enough to oxidize water. |
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Term
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Definition
| this diagram illustrates the two electron-energizing steps, one catalyzed by each photosystem. more on pg 157 |
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Term
| How do light reaction generate NADPH and ATP? |
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Definition
| Photosystem II acts first. High-energy electrons generated by photosystem !! are used to synthesize ATP and are then passed to photosystem I to drive the production of NADPH. For every pair of electrons obtained from a molecule of water, one molecule of NADPH and slightly more than one molecule of ATP are produced. |
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Term
| What is a carbohydrate? How does the cell build carbohydrates? |
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Definition
Carbohydrates contain many C--H bonds are are highly reduced compared with CO2. To build carbohydrates cells use energy and a source of electrons produced by the light dependent reactions of thylakoids: Energy and Reaction Potential.
Energy:
ATP (provided by cyclic and non cyclic photophosphorylation) drives the endergonic reactions.
Reaction Potential. NADPH (provided by photosystem I) provides a source of protons and the energetic electrons needed to bind them to carbon atoms. Much of the light energy captured in photosynthesis ends up invested in the energy-rich C--H bonds |
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Term
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Definition
| Reactions that form a cycle of enzyme-catalyzed steps much like the krebs cycle of respiration. Unlike the Krebs cycle however, carbon fixation is geared toward producing new compounds so the nature of the cycles is quite different. |
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Term
| What is the Calvin Cycle? Where does it occur? What are the energy sources? |
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Definition
| The cycle of reactions that allow the carbon fixation is called the Calvin Cycle, also called C3 photosynthesis because of the three carbon atoms contained in the first intermediate of the cycle. pg. 161 for more info |
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Term
Without going into details on enzyme names, what are the three phas
es of the Calvin cycle and what is the purpose and
product of each? |
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Definition
- Carbon Fixation
- Reduction
- Regeneration
The carbon fixation reaction generates two molecules of the 3-carbon acid PGA; PGA is then reduced to G3P by reactions that are essentially a reverse of part of glycolysis; finally the PGA is used to regenerate RuBP. Three turns around the cycle incorperat enough carbon to produce a new molecule of G3P, and six turn incorporate enough carbon to synthesize one glucose molecule. |
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Term
| What does the enzyme rubisca do? |
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Definition
| Ribulous Bisphosphate carbon/oxygenase (abbreviated to Rubisca) carries out the carbon fixation reaction. Pg. 161 for more info. |
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Term
| What are the net imputs and outputs of the Calvin cycle? |
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Definition
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Term
| Is glucose a direct output? Why or Why not? |
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Definition
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Term
| How does the Calvin Cycle compare with glycolysis? |
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Definition
Reactions are reversed similar to glycolysis. pg. 162
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Term
| What is the energy cycle relatioshit between photosynthesis and respiration? |
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Definition
| The energy-capturing metabolism of the chloroplasts studied in this chapter and the mitochondria studied in chapter 7 are intimatley related. Photosynthesis uses the products of respiration as starting substrates, and respiration uses the products of photosynthysis as starting substrates. The production of glucosen from G3P even uses part of the ancient glycolic pathway, run in reverse. Also, the principlal proteins involved in electron transport of ATP productions in plants are evolutionarily related to those in mitochondria. |
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Term
| 1.) The light dependent reactions of photosynthesis are responsible for the production of... |
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Definition
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Term
| 2.) What region of a chloroplast is associated with the capture of light energy? |
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Definition
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Term
| 3.) The colors of light that are most effective for photosynthesis are... |
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Definition
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Term
| 4.) During noncyclic photosynthesis, photosystem I functions to ___, and photosynthesis II functions to ___. |
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Definition
| Reduce NADP+; Oxidize H2O |
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Term
| 5.) How is a reaction center pigment in a photosystem different from a pigment in the atena complex? |
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Definition
| The reaction center pigment loses and electron when it absorbes light energy |
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Term
| 6.) the ATP and NADPH from the light reactions are used... |
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Definition
| During the reactions of the Calvin Cycle to produce glucose |
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Term
| 7.) The carbon fixation reaction converts... |
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Definition
| Inorganic carbon into an organic acid |
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Term
| 1.) The overall flow of electrons in light reactions are from... |
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Definition
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Term
| 2.) Where in the chloroplast would you find the highest concentration of protons? |
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Definition
| In the lumen of the Tykaloid |
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Term
| 3.) How does the reaction center of photosystem I regain an electron during non cyclic photosynthesis? |
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Definition
| The electron is donated form photosystem II |
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Term
| 4.) If the Calvin Cycle runs through six turns... |
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Definition
| Enough carbon will be fixed to make one glucose, but they will not all be in the same molecule |
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Term
| 5.) What are similarities between structure and function of mitochondria and chloroplasts? |
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Definition
They both create internal proton gradients by electron transport and they both have an outer membrane and an inner membrane system.
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Term
| Carbon Fixation by the C4 pathway produces... |
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Definition
| an organic acid, but a 4-carbon one not a 3-carbon. |
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Term
| 7.) If the thylakoid membrane became leaky to ions, what would you predict to be the result on the light reactions? |
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Definition
| It would stop ATP production |
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Term
| 8.) The overall process of photosynthesis... |
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Definition
| results in the reduction of CO2 and the oxidation of H2O |
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Term
| Diagram the relationship between the reactants and products of photosynthesis and respiration |
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Definition
| Figure 8.19 diagrams this relationship. The oxygen produced by photosynthesis is used is used as a final electron acceptor for electron transport in respiration. The CO2 that results from the oxidation of glucose (or fatty acids) is incorperated into organic compunds via the Calvin Cycle. Respiration also produces water, while photo synthesis consumes water. |
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Term
| Do plant cells need mitochondria? Explain. |
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Definition
| Yes, plants use their chloroplasts to convert light energy into chemical energy. During light reactions ATP and NADPH are created, but these molecules are consumed during the calvin cycle and are not available for the cell's general use. The G3P produced by the Calvin cycle stores the chemical energy from the light reactions with in its chemical bonds. Ultimately, this energy is stored in glucose and retrieved by the cell through the process of glycolisis and cellular respiration. |
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Term
| How does the Calvin Cycle compare with glycolisis? |
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Definition
| A portin of the Calvin cycle is the reverse of glycolisis (the reduction of 3-phosphoglycerate to glyceraldehyde-3-phosphate). |
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Term
| 8.5) If the thylakoid were leaky to protons would ATP still be produced? Would NADPH? |
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Definition
| Without a proton gradient, synthesis of ATP by chemiosmosis would be impossible. However, NADPH could still be synthesized because electron transport would still occur as long as photons were still being absorbed to begin the process |
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Term
| 8.4) Why were photosystems an unexpected finding? |
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Definition
| Before the discovery of photosynthesis, we assumed that each chlorophyll molecule absorbed photons resulting in excited electrons. |
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Term
| 8.3) What is the difference between an action spectrum and an absorption spectrum? |
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Definition
| The action spectrum of photosynthesis refers to the most effect wavelengths. The absorption spectrum for an individual pigment shows how much light is absorbed at different wave lenghts. |
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Term
| 8.1) How is the structure of the chloroplast similar to the mitochondria? |
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Definition
| Both chloroplats and mitochondria have an outer membrane and an inner membrane. The inner membrane in both forms an elaborate structure. These inner membrane systems have electron transport chains that move protons across the membrane to allow for the synthesis of ATP by chesiomosis. They also both have a soluable compartment in which a variety of enzymes carry out reactions. |
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