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What is photosynthesis?
Photosynthesis is the process by which plants prepare organic food from carbon dioxide and water using sunlight and chlorophyll.
Which of the following are requirements for photosynthesis? (Select all that apply)
Autotrophs are important because they form the base of food chains.
True
What are photoautotrophs?
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Where does photosynthesis occur in plant cells?
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What role do stomata play in photosynthesis?
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What is the primary site of photosynthesis?
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In which part of the chloroplast do light-dependent reactions occur?
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What are the products of light-dependent reactions?
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What is the Calvin cycle?
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Temperature has no effect on the rate of photosynthesis.
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Which of the following adaptations aid in photosynthesis? (Select all that apply)
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Study Notes
Photosynthesis
- Photosynthesis is the process plants use to create organic food (carbohydrates) from carbon dioxide and water.
- This process requires sunlight and chlorophyll.
- The product is glucose, which is stored as starch and serves as the source of internal energy for the plant.
Photosynthesis Equation
- Carbon dioxide + Water → Glucose + Oxygen
- CO2 + H2O → C6H12O6 + O2
Requirements for Photosynthesis
- Sunlight
- Chlorophyll (photosynthetic pigment)
- Carbon dioxide (CO2)
- Water (H2O)
Importance of Autotrophs
- They form the base of food chains, supporting herbivores and carnivores.
- Photosynthesis stores solar energy in carbohydrates, which heterotrophs break down to produce ATP, the energy needed for life.
Photosynthetic and Chemosynthetic Organisms – Photoautotrophs
- Organisms that synthesize their food (organic compounds) via photosynthesis, including plants, algae, phytoplankton, kelp, and cyanobacteria.
Leaf Structures
- Photosynthesis occurs in chloroplasts within the leaf cells.
- Stomata allow CO2 and O2 to enter and exit the leaf.
Water movement in the leaf
- Water moves from the xylem into the leaf tissues.
- Gases like CO2 and O2 move in and out through stomata, regulated by the guard cells.
Chloroplasts
- Site of photosynthesis.
- Thylakoid: Coin structures where light-independent reactions occur.
- Stroma: Aqueous fluid space where the Calvin Cycle occurs.
- Granum: Stacks of Thylakoids
Stages of Photosynthesis
1. Light-Dependent Reactions
- Location: Thylakoid membrane
- Need: Light
- Process: Uses light to split water molecules into hydrogen and oxygen.
- Creates: O2, ATP, and NADPH
2. Light-Independent Reactions (Calvin Cycle)
- Location: Stroma
- Process: Uses ATP (chemical energy) and NADPH (reducing energy: gain of electrons) to convert carbon dioxide into glucose (carbon fixation).
- Creates: Glucose
- Rubisco enzymes catalyze the reaction between CO2 and RuBP, which forms a six-carbon compound. This compound is immediately converted into two three-carbon compounds. This process is called "carbon fixation" because CO2 is "fixed" from an inorganic form into organic molecules.
Factors Affecting Photosynthesis
- Light Intensity: More light speeds up the splitting of water molecules.
- Temperature: Affects the Calvin Cycle, with higher temperatures increasing the rate of carbon fixation.
Adaptation of Leaves for Photosynthesis
- Broad, flat shape: Maximizes light and CO2 absorption.
- Thin structure: Facilitates diffusion of gases.
- Large air spaces: Ease of CO2 diffusion.
- Stomata: Located mainly on the lower leaf surface for gas exchange.
- Chloroplast distribution: More in the upper cells (palisade) for efficient light capture.
- Veins: Ensure water supply to photosynthesizing cells.
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Description
This quiz covers the fundamental aspects of photosynthesis, including its process, equation, and requirements. It also highlights the significance of autotrophs in food chains and the role of photoautotrophs in energy production. Test your understanding of how plants convert sunlight into energy!
