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Questions and Answers
What is the primary role of green plants in the ecosystem?
Which process do green plants use to convert light energy into chemical energy?
What substance was used by Bassham in his studies to label carbon dioxide?
What significant recognition did Melvin Calvin receive for his research in photosynthesis?
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How do all living forms on Earth ultimately depend on sunlight?
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What is the primary role of photosynthesis in relation to food on earth?
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Which of the following is essential for photosynthesis to occur?
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What is released into the atmosphere as a byproduct of photosynthesis?
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What does the experiment involving starch formation in variegated leaves demonstrate?
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What happens to the CO2 in the experiment where one half of a leaf is enclosed in KOH-soaked cotton?
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What indicates the primary regions of light that promote oxygen evolution in photosynthesis?
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What does the empirical equation for photosynthesis primarily represent?
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Who demonstrated that photosynthesis is a light-dependent reaction involving hydrogen from an oxidizable compound?
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In green plants, which compound serves as the hydrogen donor in photosynthesis?
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What do purple and green sulfur bacteria produce as an oxidation product during photosynthesis?
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What is the main function of ATP and NADPH in the biosynthetic phase of photosynthesis?
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Which of the following statements about the biosynthetic phase of photosynthesis is true?
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What was the first product formed when CO2 is fixed according to Melvin Calvin's research?
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Which process continues even after light is no longer available, as identified in photosynthesis?
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What is the significance of the Calvin cycle in photosynthesis?
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What is the primary function of RuBP carboxylase in the Calvin cycle?
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Which stage of the Calvin cycle involves the formation of two molecules of 3-PGA?
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During which stage of the Calvin cycle is ATP and NADPH used?
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What molecule is regenerated at the end of the Calvin cycle to continue the process?
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Which of the following statements is true about the Calvin cycle?
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What is the end product of the reduction stage in the Calvin cycle?
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What is the significance of CO2 fixation in the Calvin cycle?
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Which process does RuBisCO also catalyze that may affect the Calvin cycle's efficiency?
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Study Notes
Photosynthesis in Higher Plants
- All animals rely on plants for food, green plants produce their own food through photosynthesis: the process of using light energy to create organic compounds.
- Green plants are autotrophs and other organisms relying on them for food are heterotrophs.
- Photosynthesis is the primary source of food on Earth and is responsible for releasing oxygen into the atmosphere.
- Sunlight provides the energy for life on Earth and its use by plants in photosynthesis is crucial.
- Chlorophyll, light, and CO2 are required for photosynthesis.
- Experiments using variegated leaves (partially green) showed photosynthesis occurred primarily in the green areas in presence of light.
- Experiments using leaves partially enclosed in test tubes containing KOH (absorbing CO2) revealed that CO2 is essential for photosynthesis
- Experiments illuminating green algae with different colors of light showed higher O2 evolution in blue and red light regions, coinciding with Chlorophyll a and b absorption spectrum.
- By the mid-19th century, scientists understood that plants use light to synthesize carbohydrates from CO2 and H2O.
- Cornelius van Niel's research on purple and green bacteria showed that photosynthesis is a light-dependent process involving hydrogen from a compound reducing carbon dioxide to carbohydrates.
- In green plants, H2O is the hydrogen donor, and it is oxidized to release O2.
- Other organisms don't release O2 during photosynthesis, using H2S as a hydrogen donor instead, which is oxidized to sulfur or sulfate depending on the organism.
- Melvin Calvin's research using radioactive 14C in algal photosynthesis uncovered that the first CO2 fixation product was a 3-carbon organic acid.
- The Calvin cycle, named after its discoverer, outlines the complete biosynthetic pathway
- The first product identified in CO2 fixation was 3-phosphoglyceric acid (PGA), a three-carbon molecule.
- The Calvin cycle occurs in all photosynthetic plants, regardless of their C3 or C4 pathways.
- The Calvin cycle has three stages: carboxylation, reduction, and regeneration.
- Carboxylation is the fixation of CO2 into a stable organic intermediate, catalyzed by RuBP carboxylase.
- RuBP carboxylase also has an oxygenation activity, making it more accurately called RuBP carboxylase-oxygenase or RuBisCO.
The Calvin Cycle
- Carboxylation involves CO2 combining with RuBP (ribulose-1,5-bisphosphate) to form two molecules of 3-PGA.
- Reduction involves the use of ATP and NADPH from light reactions to convert 3-PGA into carbohydrate (triose phosphate).
- The regeneration phase involves the synthesis of RuBP from triose phosphate to continue the Calvin cycle.
- The products of the Calvin cycle are sucrose and starch.
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Description
This quiz explores the intricate process of photosynthesis in higher plants. Learn how green plants utilize sunlight, chlorophyll, and carbon dioxide to produce food and release oxygen, making them vital to life on Earth. Test your knowledge on the experiments that demonstrate these key concepts.
