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Questions and Answers
What are the dominant pigments responsible for absorbing light in plants?
What are the dominant pigments responsible for absorbing light in plants?
Which photosystem is primarily responsible for producing both ATP and NADPH?
Which photosystem is primarily responsible for producing both ATP and NADPH?
What is the primary function of the Calvin cycle in photosynthesis?
What is the primary function of the Calvin cycle in photosynthesis?
Which light wavelengths are primarily absorbed by chlorophyll a?
Which light wavelengths are primarily absorbed by chlorophyll a?
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What molecule is produced as NADP+ is reduced during photosynthesis?
What molecule is produced as NADP+ is reduced during photosynthesis?
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What is the primary byproduct of photosynthesis?
What is the primary byproduct of photosynthesis?
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What process is essential for the production of oxygen during photosynthesis?
What process is essential for the production of oxygen during photosynthesis?
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Which component of chloroplasts is primarily involved in capturing sunlight?
Which component of chloroplasts is primarily involved in capturing sunlight?
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Which of the following substances is a raw material for photosynthesis?
Which of the following substances is a raw material for photosynthesis?
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What type of reaction occurs during photosynthesis?
What type of reaction occurs during photosynthesis?
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Where within the plant does photosynthesis primarily take place?
Where within the plant does photosynthesis primarily take place?
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What is the role of the stoma in plants?
What is the role of the stoma in plants?
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Which statement about Jan Ingenhousz's contribution to photosynthesis is correct?
Which statement about Jan Ingenhousz's contribution to photosynthesis is correct?
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What is the primary reason C3 plants are more efficient in cool and moist conditions?
What is the primary reason C3 plants are more efficient in cool and moist conditions?
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Which enzyme is used by C4 plants to fix CO2?
Which enzyme is used by C4 plants to fix CO2?
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What is a key characteristic of CAM plants regarding stomata behavior?
What is a key characteristic of CAM plants regarding stomata behavior?
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What disadvantage do C3 plants face in hot and dry conditions?
What disadvantage do C3 plants face in hot and dry conditions?
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Which of the following adaptations is specific to C4 plants?
Which of the following adaptations is specific to C4 plants?
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Which statement accurately describes the differences between C4 and CAM plants?
Which statement accurately describes the differences between C4 and CAM plants?
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How do CAM plants manage photosynthesis to ensure water efficiency?
How do CAM plants manage photosynthesis to ensure water efficiency?
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Which of the following is NOT an advantage of C4 plants?
Which of the following is NOT an advantage of C4 plants?
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Where do the light reactions occur within the chloroplast?
Where do the light reactions occur within the chloroplast?
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What energy form is produced in the light reaction?
What energy form is produced in the light reaction?
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What is the fate of water (H2O) during the light reaction?
What is the fate of water (H2O) during the light reaction?
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What is produced in the non-cyclic electron pathway?
What is produced in the non-cyclic electron pathway?
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In the cyclic electron pathway, what happens to the electrons after they move down the electron transport chain?
In the cyclic electron pathway, what happens to the electrons after they move down the electron transport chain?
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What role do H+ ions play in the formation of ATP during the light reactions?
What role do H+ ions play in the formation of ATP during the light reactions?
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What is the initial stage in the non-cyclic electron pathway?
What is the initial stage in the non-cyclic electron pathway?
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Which of the following statements is true about the light-dependent reactions?
Which of the following statements is true about the light-dependent reactions?
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In which part of the chloroplast does the Calvin Cycle occur?
In which part of the chloroplast does the Calvin Cycle occur?
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Which of the following best describes the end result of the first step of the Calvin Cycle?
Which of the following best describes the end result of the first step of the Calvin Cycle?
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What is the role of G3P in the Calvin Cycle?
What is the role of G3P in the Calvin Cycle?
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How many ATP molecules are consumed in the regeneration of RuBP during the Calvin Cycle?
How many ATP molecules are consumed in the regeneration of RuBP during the Calvin Cycle?
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What happens to the concentration of photosynthesis when light intensity is decreased?
What happens to the concentration of photosynthesis when light intensity is decreased?
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What is needed for the second step of the Calvin Cycle, Carbon Dioxide Reduction?
What is needed for the second step of the Calvin Cycle, Carbon Dioxide Reduction?
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Which of the following is NOT true about the Calvin Cycle?
Which of the following is NOT true about the Calvin Cycle?
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What is the total requirement of NADPH for two turns of the Calvin Cycle?
What is the total requirement of NADPH for two turns of the Calvin Cycle?
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Study Notes
Photosynthesis Overview
- Photosynthesis converts inorganic materials into organic materials
- Performed by autotrophs (producers).
- A complex chemical reaction
- Involves water and carbon dioxide
- Light is required for the reaction
- Oxygen and high-energy carbohydrates are produced
History of Photosynthesis
- Jan van Helmont (1643): Plants gain most of their mass from water
- Joseph Priestley (1771): Plants release oxygen
- Jan Ingenhousz (1779): Plants need sunlight to produce oxygen
- Julius Robert Mayer (1845): Plants convert light energy to chemical energy
- Frederick Frost Blackman (1905): Photosynthesis comprises two reactions
- Cornelius B. Van Neil (1930): Oxygen given off during photosynthesis comes from water
- Melvin Calvin (1948): Traced the path of carbon (CO2) in forming glucose; the Calvin cycle; also known as the Dark Reaction
- Rudolph Marcus (1992): Won Nobel Prize for describing electron transfer in electron transport chain
Photosynthetic Organisms
- Examples include prayer plants, kelp, and nostoc (producers) – plants and algae
Photosynthesis Equation
- 6 H₂O + 6 CO₂ + (light) → 6 O₂ + C₆H₁₂O₆
Photosynthesis Redox Reaction
- Reduction: Addition of electrons
- Oxidation: Loss of electrons
Location of Photosynthesis
- Takes place in the mesophyll tissues of leaves and stems
- Chloroplasts are the organelles where photosynthesis occurs
Chloroplast Structure
- Chloroplasts have a double membrane
- Stroma is fluid in the chloroplast
- Thylakoid membranes are flattened sacs inside the stroma
- Chlorophyll is contained within the chloroplasts
- Grana are stacks of thylakoid membranes
Pigments
- Pigments are light-absorbing molecules
- Chlorophyll a and b are the dominant pigments, appearing green
- Chlorophyll absorbs violet, blue and red light best
- Chlorophyll mostly reflects green light
- Carotenoids (yellow and orange) absorb violet-blue-green light
Photosystems
- Consist of pigment complexes and electron acceptors
- "Antenna" for gathering light
- Photosystem I (PSI) discovered first
- P700
- Produce ATP and NADPH
- Photosystem II (PSII)
- P680
- Produce ATP
Quick Review Questions (Light Reactions)
- Where does photosynthesis occur within a plant?
- What is the specific name of the plant tissue where photosynthesis occurs?
- What is contained within the thylakoid membrane?
- What are grana?
- What is the location of the stroma?
Electromagnetic Spectrum
- Visible light is a part of the electromagnetic spectrum that we can see
- Plants absorb different wavelengths of light
Two Reactions of Photosynthesis
- Light Reaction (Light-Dependent Phase)
- Converts solar energy into ATP and NADPH
- Calvin Cycle (Light-Independent Phase / Dark Reaction)
- Produces glucose using CO₂ and energy.
Light Reaction Details
- Takes place in the thylakoid membranes
- Requires light
- Converts solar energy into chemical energy (ATP and NADPH is formed)
- Uses two photosystems (PSI & PSII) and two electron pathways (cyclic and noncyclic)
Noncyclic Electron Pathway
- Uses both photosystems
- Radiant/Solar energy is absorbed by PSI and PSII
- Water is split into O2, H+ and electrons
- Electrons move down the electron transport chain
- Electrons move to NADP+ and create NADPH
- H+ ions form a gradient which flow through ATP synthase and produce ATP
- ATP and NADPH are sent to the Calvin Cycle
Cyclic Electron Pathway
- Starts with PSI
- Absorbs solar energy
- Electrons move down the ETC
- Energy is captured and stored as a H+ gradient
- H+ flow down ATP synthase
- ATP is created
- Electrons return to PSI
Quick Review Questions (Electron Pathways)
- Which part of the electromagnetic spectrum can we see?
- Which wavelength of light is absorbed by the plant?
- Which wavelength of light is reflected by the plant?
- How is chlorophyll a different from chlorophyll b?
- What is the wavelength of light absorbed by photosystem I?
Calvin Cycle Details
- Takes place in the stroma
- Light is not required
- Uses ATP and NADPH from the light cycle to make glucose
- Three steps
- CO₂ fixation
- CO₂ reduction
- Regeneration of RuBP (ribulose bisphosphate), which begins the cycle again.
Types of Photosynthesis
- C3 Plants: Most common, but less efficient in hot or dry conditions.
- C4 Plants: More efficient in hot or dry conditions due to special internal cellular structure, preventing photorespiration.
- CAM Plants: Open their stomata at night in order to conserve water for the hot conditions, and release CO2 during the day
Factors Affecting Photosynthesis
- Light Intensity
- Temperature (0°C – 35°C)
- Water availability
Quick Review Questions (Calvin Cycle)
- Where does the Calvin cycle occur in the chloroplast?
- What are the three major steps in the Calvin cycle?
- What is the end result of step 1?
- What is the end result of step 2?
- What are the end results of step 3?
- What factors affect photosynthesis?
G3P Uses
- G3P can be converted into other organic molecules (glucose, starch, sucrose, cellulose, fatty acids, amino acids)
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Description
Explore the fundamental process of photosynthesis and its historical development through key figures. Learn how autotrophs convert inorganic materials into organic matter and the significance of light, oxygen, and chemical reactions involved. Discover the contributions of scientists like Jan van Helmont and Melvin Calvin to our understanding of photosynthesis.
