8.1 Overview of Photosynthesis

• Only photosynthetic organisms such as plants, algae, and cyanobacteria can convert radiant (solar) energy into the chemical energy of carbohydrates.
• Photosynthesis is extremely important because almost all living organisms are dependent on photosynthesis for a supply of nutrient molecules.
• Photosynthesis takes place in chloroplasts, organelles that have two parts: membranous thylakoids are surrounded by a fluid-filled stroma.
• Photosynthesis has two sets of reactions: the light reactions during which solar energy is captured and the Calvin cycle during which carbohydrate is synthesized.

1. What is the ultimate source of energy for nearly all organisms on the earth?
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2. What do plants use to capture the energy from sunlight?
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3. Light energy is transformed into what form of energy during the light reactions in chloroplasts?
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4. What happens to the chemical energy in ATP and NADPH during the Calvin cycle?
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Essential Study Partner
    Energy Flow
    Fossil Fuels
    Chloroplast

Labeling Exercise
Chloroplast Structure (48.0K)
Leaf Anatomy (30.0K)

Art Quiz
    Leaf – Levels of Organization (2)

General Biology Weblinks
    Photosynthesis

8.2 Solar Energy Capture

• During the light reactions, solar energy is used to synthesize ATP and NADPH molecules

1. What are photosystems and how are they related to chlorophyll?
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2. How do the products of the cyclic electron pathway differ from those of the noncyclic electron pathway?
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Essential Study Partner
    Light and Pigments
    Light Dependent

Labeling Exercise
Electromagnetic Spectrum (20.0K)

Art Quizzes
    Light and Photosynthesis
    Photosystem Antenna Complex
    Photosystems I and II
    Photosynthetic Electron Transport Chain
    Chemiosmosis in a Chloroplast

Animation Quiz
    Photosynthesis Light reactions

8.3 Carbohydrate Synthesis

• During the Calvin cycle, carbohydrate is synthesized from carbon dioxide using the energy of ATP and NADH2

1. Is glucose the only compound that plants form from PGAL?
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Essential Study Partner
    Light Independent

Art Quiz
    Calvin Cycle

Animation Quiz
    Photosynthesis Calvin cycle

8.4 Other Types of Photosynthesis

• Plants use either C₃, C₄, or CAM photosynthesis, named for the manner in which CO₂ is fixed.

1. Why do different plants have variations in their pathways of photosynthesis?
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Art Quiz
    Comparison of C₃ and C₄ Plant Leaves

8.5 Photosynthesis Versus Cellular Respiration

• Photosynthesis captures energy in chemical bonds that is then released for biology work during cellular respiration.

1. Plants carry out photosynthesis to capture energy but do they release stored energy in the same manner as do animals?
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Art Quiz
    Chloroplasts, Mitochondria, and the Energy Cycle