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52 Cards in this Set
- Front
- Back
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What is photosynthesis? |
The process by which carbon compounds are synthesized using light energy. |
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What are the two inorganic raw materials required for photosynthesis? |
Carbon Dioxide Water |
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What are the products of photosynthesis? |
Glucose Oxygen |
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What are the conditions for photosynthesis to occur? |
Presence of light Presence of chlorophyll |
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What substance is responsible for absorbing light energy? |
Chlorophyll |
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The chloroplast is the organelle in which photosynthesis takes place. Describe the structure of a chloroplast. (5) |
Double membrane. Inner fluid called stroma. 70s ribosomes. Small inner membranes called thylakoids. Thylakoids are piled in stacks called grana. |
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What are the adaptations of the structures of chloroplasts? |
Double memebranes - separate photosynthetic reactions from other reactions in the cytoplasm. Thylakoids membranes - contain chlorophyll, which is used to absorb light to form ATP in the process of phosphorylation. Stroma - contains enzymes necessary for the light independent reactions in the Calvin cycle 70s ribosomes and circular DNA- synthesize and code for the enzymes in the stroma respectively. |
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Describe the arrangement of chlorophyll pigments/molecules in each thylakoids membrane. |
Chlorophyll molecules are arranged in groups called photosystems. There are 2 photosystems: photosystem 1 and photosystem 2. PS1 has a higher energy level than PS2. In each photosystem (group of chlorophyll molecules) there is a special chlorophyll molecule in the center, which makes up the reaction center. |
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What are the two stages of photosynthesis? |
Light dependent reaction Light independent reaction |
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Where does the light dependent reaction of photosynthesis take place? |
Thylakoid membranes. |
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Where does the light independent reaction of photosynthesis take place? |
Stroma |
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What is the role of PS1 in the light dependent reactions? |
PS1 absorbs light, electrons get excited. A pair of electrons is emitted from the reaction center. Electrons are passed along a series of electron acceptors. The electrons are added to NADP, and form reduced NADP. PS1 is unstable due to the loss of electrons…. |
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What is the role of PS2 in the light dependent reactions of photosynthesis? |
PS2 absorbs light, the electrons get excited a pair of electrons is lost from the reaction center. Chemiosmosis, similar to that in cell respiration occurs: The electrons are passed along a series of electron carriers, and lose energy as they go. The last carrier adds the electron to PS1. PS1 becomes stable again. The energy lost by the electrons are used to pump protons from the stroma to the thylakoid space. High concentration of protons in the thylakoid space creates strong conc gradient. Protons diffuse back into the stroma through ATP synthase. ATP synthase uses the energy lost by protons during this diffusion to synthesize ATP from ADP and Pi. These protons are added to the reduced NADP formed from PS1. PS2 remains unstable, as it has lost electrons.
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Describe photolysis, and the role of its products. |
Energy from light is used to split water molecules into protons (H+), electrons (H-), and oxygen (O2). The protons are used to form the conc gradient in chemiosmosis. The electrons are given to PS2 to stabilize it. Oxygen is a direct by-product of photosynthesis. |
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Describe how ATP is formed during the light dependent reactions. |
PS2 absorbed energy. Excited electrons are emitted. Electrons are passed along electron carriers and lose energy in the process. Protons from photolysis are pumped from the stroma to the thylakoid space using the energy lost by the electrons. Due to the conc gradient, proton Ms diffuse back into the stroma through ATP synthase. Energy lost by the protons during diffusion is used by ATP synthase to form ATP from ADP and Pi. |
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Where do the light independent reactions take place? |
Stroma of the chloroplast. |
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What is the name given to the series of reactions in the light independent reactions of photosynthesis. |
Calvin’s cycle |
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Describe the Calvin’s cycle |
Carbon dioxide and RUBP (5 carbon compound) combine with the help of enzyme RUBISCO. This is carboxylation. 6 carbon compound immediately breaks down through carboxylation to form two three carbon compounds called Glycerate-3-phosphate, the first stable product of photosynthesis. The glycerate-3-phosphate is reduced to triose phosphate using reduced NADP. This requires ATP and reduced NADP from the light dependent reactions. Some triose phosphate is used to directly form glucose, amino acids, and fatty acids. The remaining (most) triose phosphate are used to regenerate RUBP to continue the cycle (in the presence of ATP). |
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What was the reason for Calvin’s experiment? |
Calvin’s experiment was conducted to find the order in which photosynthetic products are formed during the light independent reactions of photosynthesis. |
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What was the name of Calvin’s experiment? |
The lollipop experiment |
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What was the first stage of Calvin’s experiment? (4steps) |
Radioactive labeling - A radioactive isotope of Carbon (carbon-14) was added to chlorella (photosynthetic algae) in the form of hydrogen carbonate ions. - The chlorella was contained in the lollipop tube, and was exposed to light to allow photosynthesis to occur. - During photosynthesis using the radioactive carbon, samples of the algae were taken at regular intervals, and immediately exposed to alcohol. - This alcohol killed the algae, leaving the photosynthetic products in the quantity and ratio as it was at the time of sampling. |
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What was the second stage of Calvin’s experiment? |
2 way paper chromatography - A sample of the photosynthetic algae was placed in the corner of a chromatography paper and inserted into a solvent. - The sample was further separated along a perpendicular axis using a second solvent, separated the compounds in another direction. |
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What was the third stage of Calvin’s experiment? |
Autoradiography - An X-ray film of the same size as the chromatography paper is placed over the paper and kept in the dark for several weeks. - the radioactive carbon-14 in the photosynthetic products releases dark spots on the X-ray film. |
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What was the fourth stage of Calvin’s experiment? |
The algae sample obtained after a few seconds of photosynthesis contained mostly radioactive RUBP. The algae sample obtained after about 15 seconds contained mostly Glycerate-3-phosphate. The algae samples obtained after a longer time contain mostly triode phosphate. |
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What was the order of products discovered by Calvin’s lollipop experiment. |
RUBP -> Glycerate-3-phosphate -> Triose phosphate |
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State the four stages of Calvin’s experiment. |
Radioactive labeling 2-way paper chromatography Autoradiography Analysis |
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What is the role and reaction of photolysis. |
Role: Provide protons are chemiosmosis with PS2, and provide electrons to stabilize unstable PS2 Reaction: 2H2O —> 4(H+) + 4(H-) + O2 |
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What is the range of wavelengths of visible light? |
400 to 700nm |
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What is the range of wavelengths of visible light? |
400 to 700nm |
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What region of visible light has the shortest wavelength? |
Blue-violet region of 400nm |
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What part of visible light has the longest wavelength? |
Red region of 700nm |
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What is the range of wavelengths of visible light? |
400 to 700nm |
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What region of visible light has the shortest wavelength? |
Blue-violet region of 400nm |
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What part of visible light has the longest wavelength? |
Red region of 700nm |
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What substance is responsible for absorbing light energy? |
Chlorophyll |
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What is the range of wavelengths of visible light? |
400 to 700nm |
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What region of visible light has the shortest wavelength? |
Blue-violet region of 400nm |
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What part of visible light has the longest wavelength? |
Red region of 700nm |
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What substance is responsible for absorbing light energy? |
Chlorophyll |
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What is the absorption spectrum? |
The absorption spectrum is a graph that shows the wavelengths of light absorbed by photosynthetic pigments such as chlorophyll. |
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What is the range of wavelengths of visible light? |
400 to 700nm |
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What region of visible light has the shortest wavelength? |
Blue-violet region of 400nm to 500nm |
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What part of visible light has the longest wavelength? |
Red region of 650nm to 700nm |
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What substance is responsible for absorbing light energy? |
Chlorophyll |
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What is the absorption spectrum? |
The absorption spectrum is a graph that shows the wavelengths of light absorbed by photosynthetic pigments such as chlorophyll. |
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What are the two main types of chlorophyll? |
Chlorophyll A Chlorophyll B |
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What general trend does the absorption spectrum show? |
Two peaks for both chlorophyll types. Higher peak in the blue violet region. Slightly smaller peak in the red region. Very little light absorbed in the green region. |
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What is the action spectrum? |
The action spectrum is a graph that shows what percentage of absorbed light is used in photosynthesis. |
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What general trend does the action spectrum show? |
Two peaks. Higher peaks in the blue violet region. Slightly lower peak in the red region. Lower, but significant percentage of green light being used. |
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What is the correlation between the absorption spectrum and action spectrum? |
There is a positive correlation between the absorption spectrum and the action spectrum. This means that chlorophyll absorbs more of the wavelengths that are more useful for photosynthesis. |
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How are thylakoid membranes adapted? |
Thylakoid membranes are thin, so that a proton gradient builds up quickly in the thylakoid space. Thylakoid membranes contain chlorophyll, which is used for photosynthesis. |
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How are thylakoid membranes adapted? |
Thylakoid membranes are thin, so that a proton gradient builds up quickly in the thylakoid space. Thylakoid membranes contain chlorophyll, which is used for photosynthesis. |
