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Questions and Answers
What is the net output of the Calvin cycle after 6 terms of the cycle have occurred?
What is the net output of the Calvin cycle after 6 terms of the cycle have occurred?
Which of the following molecules is required in the regeneration of RuBP during the Calvin cycle?
Which of the following molecules is required in the regeneration of RuBP during the Calvin cycle?
How many moles of ATP are used for every 6 mol of CO2 in the Calvin cycle?
How many moles of ATP are used for every 6 mol of CO2 in the Calvin cycle?
In the process of photosynthesis, what is the primary acceptor molecule needed to initiate the Calvin cycle?
In the process of photosynthesis, what is the primary acceptor molecule needed to initiate the Calvin cycle?
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Which molecule is primarily produced directly from the Calvin cycle for the synthesis process?
Which molecule is primarily produced directly from the Calvin cycle for the synthesis process?
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What is a characteristic feature of the CY cycle?
What is a characteristic feature of the CY cycle?
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What is the main function of the Calvin cycle in photosynthesis?
What is the main function of the Calvin cycle in photosynthesis?
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Where does the Calvin cycle occur in eukaryotic photosynthetic organisms?
Where does the Calvin cycle occur in eukaryotic photosynthetic organisms?
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Who were the scientists awarded the Nobel Prize for their elucidation of the Calvin cycle?
Who were the scientists awarded the Nobel Prize for their elucidation of the Calvin cycle?
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How many molecules of carbon dioxide are required for the net synthesis of one molecule of G3P in the Calvin cycle?
How many molecules of carbon dioxide are required for the net synthesis of one molecule of G3P in the Calvin cycle?
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What is the role of RuBisCO in the Calvin cycle?
What is the role of RuBisCO in the Calvin cycle?
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Which of the following indicates a product formed during the reduction phase of the Calvin cycle?
Which of the following indicates a product formed during the reduction phase of the Calvin cycle?
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How many molecules of ATP are used in the reduction phase of the Calvin cycle?
How many molecules of ATP are used in the reduction phase of the Calvin cycle?
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What is produced as a direct result of the carboxylation phase of the Calvin cycle?
What is produced as a direct result of the carboxylation phase of the Calvin cycle?
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What is the primary function of the regeneration phase in the Calvin cycle?
What is the primary function of the regeneration phase in the Calvin cycle?
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What is the primary role of the enzyme RuBisCo in the carboxylation phase of photosynthesis?
What is the primary role of the enzyme RuBisCo in the carboxylation phase of photosynthesis?
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How many molecules of 3-phosphoglycerate are produced from one molecule of CO2 during the carboxylation phase?
How many molecules of 3-phosphoglycerate are produced from one molecule of CO2 during the carboxylation phase?
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Which of the following statements about RuBisCo is true?
Which of the following statements about RuBisCo is true?
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What are the products of the reduction phase involving 6 molecules of 3-PGA?
What are the products of the reduction phase involving 6 molecules of 3-PGA?
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During the reduction phase, which of the following is NOT a reagent used?
During the reduction phase, which of the following is NOT a reagent used?
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What is the first product fixed by the C4 cycle?
What is the first product fixed by the C4 cycle?
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Which two types of cells are characteristic of C4 plants?
Which two types of cells are characteristic of C4 plants?
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In what year was the malic enzyme type of the C4 cycle discovered?
In what year was the malic enzyme type of the C4 cycle discovered?
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What percentage of species do C4 plants represent in relation to angiosperms?
What percentage of species do C4 plants represent in relation to angiosperms?
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What distinguishes C4 plants from other angiosperms?
What distinguishes C4 plants from other angiosperms?
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What is the primary function of the enzyme PEP carboxylase in the process of photosynthesis?
What is the primary function of the enzyme PEP carboxylase in the process of photosynthesis?
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Which product is formed as a result of the decarboxylation process in the bundle sheath cell?
Which product is formed as a result of the decarboxylation process in the bundle sheath cell?
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What is the role of the bundle sheath cell in the photosynthesis process described?
What is the role of the bundle sheath cell in the photosynthesis process described?
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Which of the following statements accurately describes the initial step of the photosynthetic process detailed?
Which of the following statements accurately describes the initial step of the photosynthetic process detailed?
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What are the outcomes of the reduction process mentioned in the photosynthesis cycle?
What are the outcomes of the reduction process mentioned in the photosynthesis cycle?
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Which statements about the dark reactions are true?
Which statements about the dark reactions are true?
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Which of the following cycles is specifically associated with C4 plants?
Which of the following cycles is specifically associated with C4 plants?
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What is the primary dependency for the dark reactions in photosynthesis?
What is the primary dependency for the dark reactions in photosynthesis?
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In which part of the chloroplast do dark reactions primarily take place?
In which part of the chloroplast do dark reactions primarily take place?
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Which of the following statements correctly describes a characteristic of dark reactions?
Which of the following statements correctly describes a characteristic of dark reactions?
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What is the primary outcome of the light-dependent reactions in photosynthesis?
What is the primary outcome of the light-dependent reactions in photosynthesis?
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Which statement correctly describes the light-independent phase of photosynthesis?
Which statement correctly describes the light-independent phase of photosynthesis?
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Which of the following correctly identifies where the light-dependent and light-independent reactions occur?
Which of the following correctly identifies where the light-dependent and light-independent reactions occur?
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Which of the following substances is released during the light-dependent reactions?
Which of the following substances is released during the light-dependent reactions?
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What is the function of ATP and NADPH produced during the light-dependent reactions?
What is the function of ATP and NADPH produced during the light-dependent reactions?
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What is the primary function of Photosystem II in the light reactions of photosynthesis?
What is the primary function of Photosystem II in the light reactions of photosynthesis?
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Which of the following factors is NOT a common method to increase the efficiency of photosynthesis?
Which of the following factors is NOT a common method to increase the efficiency of photosynthesis?
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In which phase of photosynthesis do electrons from water contribute to the synthesis of NADPH?
In which phase of photosynthesis do electrons from water contribute to the synthesis of NADPH?
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What is the ultimate carbohydrate product of the dark reactions in photosynthesis?
What is the ultimate carbohydrate product of the dark reactions in photosynthesis?
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Which of the following statements is true regarding the arrangement of photosystems in the chloroplast?
Which of the following statements is true regarding the arrangement of photosystems in the chloroplast?
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Study Notes
Carbon Fixation and the Calvin Cycle
- Carbon fixation occurs through the Calvin cycle (C3 cycle) in all oxygenic photosynthetic organisms.
- Takes place in the stroma of chloroplasts in eukaryotes and in cytosol in prokaryotes.
- Elucidated by Melvin Calvin and Andy Benson, awarded the Nobel Prize in 1963.
- The primary product from the cycle is glyceraldehyde-3-phosphate (G3P), a 3-carbon sugar, requiring 3 molecules of CO2 for its net synthesis.
Phases of the Calvin Cycle
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Carboxylation:
- RuBP combines with CO2 to produce a 6-carbon intermediate that splits into two molecules of 3-phosphoglycerate (3-PGA).
- Catalyzed by RuBisCO, the most abundant and slowest enzyme, found in chloroplasts.
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Reduction:
- 3-PGA is reduced to G3P using ATP and NADPH.
-
Regeneration of RuBP:
- G3P is further processed to regenerate RuBP, facilitating continuous cycling.
- Requires 6 carbon atoms from CO2, resulting in the synthesis of glucose and consuming 18 ATP and 12 NADPH.
C4 Cycle Characteristics
- First product formed is oxaloacetate (OAA), distinct from C3 cycle.
- Involves two types of chloroplast-containing cells: Mesophyll and Bundle Sheath cells.
- Discovered by Hatch and Slack in 1966.
- Representatively found in approximately 15% of angiosperm species.
Photosynthesis Overview
-
Comprises two main phases: light-dependent and light-independent (dark reactions).
-
Light-dependent reactions:
- Requires light, splits water, and releases oxygen.
- Produces ATP and NADPH for use in the Calvin cycle.
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Light-independent reactions:
- Occur in the stroma of chloroplasts, utilizing ATP and NADPH to convert CO2 into glucose.
Efficiency of Photosynthesis
- Efficiency can be enhanced by increasing availability of light, CO2, and water, as well as improving the processes of the light reactions and the Calvin cycle.
- Photosystems I and II are critical for light reactions and are optimized for light absorption in chloroplasts.
Key Enzymes and Compounds
- RuBisCO: Most abundant protein on Earth, vital for carboxylation in the Calvin cycle.
- PEP Carboxylase: Important in the C4 cycle, catalyzing carboxylation with HCO3 as substrate.
Key Reactions and Equations
- Calvin Cycle equation: GRUBP + 6 CO2 + 18 ATP + 12 NADPH2 → GRUBP + C6H12O6 + 18 ADP + 18 Pi + 12 NADP + 8 H2O.
- Light-independent reactions also termed dark reactions, differ from light-dependent as they do not require direct light.
Summary of Photosynthesis in Plants
- Photosynthesis occurs in chloroplasts, utilizing light energy to convert CO2 into carbohydrates, releasing oxygen as a byproduct.
- Enzymatic activity is temperature and pH-sensitive, with RuBisCO showing optimal activity at around pH 8.
- The overall process involves a cyclical pattern to ensure continuous sugar production for plant growth and energy.
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Description
Test your knowledge on the Calvin Cycle and carbon fixation processes in photosynthesis. This quiz covers the phases of the Calvin Cycle, including carboxylation, reduction, and regeneration of RuBP. Learn about the discoveries of Melvin Calvin and the role of RuBisCO in these essential biological processes.
