photosynthesis

• Photosynthesis


  The process by which green plants, algae, and some bacteria use sunlight to convert carbon dioxide and water into glucose and oxygen
• Photosynthesis


  1. Occurs in the chloroplasts of plant cells, primarily in the leaves

  2. Involves two main stages: the light-dependent reactions and the Calvin cycle (light-independent reactions)
• Raw Materials


  • Water (H₂O)
  • Carbon Dioxide (CO₂)
• Products


  • Glucose (C₆H₁₂O₆)
  • Oxygen (O₂)
• Conditions


  • Sunlight
  • Chlorophyll
  • Enzymes
• Word Equation for Photosynthesis

  Carbon dioxide + Water + Light energy → Glucose + Oxygen
• Light-Dependent Reactions


  1. Location: Thylakoid membranes of the chloroplasts

  2. Process: Chlorophyll absorbs light energy, which splits water molecules into oxygen, protons, and electrons. This generates ATP and NADPH, which are used in the next stage
• Calvin Cycle (Light-Independent Reactions)

  1. Location: Stroma of the chloroplasts

  2. Process: Uses ATP and NADPH from the light-dependent reactions to convert carbon dioxide into glucose through a series of enzyme-driven steps
• Location of Photosynthesis


  Chloroplasts within the leaves of plants
• Fate of Products


  • Glucose: Used immediately for energy or stored as starch in the plant
  • Oxygen: Released into the atmosphere through the stomata
• Storage of Glucose


  Glucose produced in photosynthesis is often stored as starch in different parts of the plant, such as roots, stems, and leaves
• Variegated Leaves


  "Variegated" refers to leaves that have both green and non-green (often white or yellow) areas. Only the green areas contain chlorophyll and can perform photosynthesis
• Starch Test

  1. Boil the leaf to kill it

  2. Soak the leaf in alcohol to remove chlorophyll

  3. Rinse the leaf in hot water to soften it

  4. Add iodine solution. A blue-black color indicates the presence of starch
• Leaf Cross-Section


  • Cuticle
  • Epidermis
  • Palisade Cell
  • Spongy Mesophyll Cell
  • Air Space
  • Chloroplasts
  • Guard Cell
  • Xylem
  • Phloem
• How Structures Aid Photosynthesis

  • Cuticle and Epidermis: Protect against water loss and injury
  • Palisade Cells: Packed with chloroplasts to maximize light absorption
  • Spongy Mesophyll: Facilitates gas exchange
  • Air Spaces: Enhance the movement of gases
  • Guard Cells: Control gas exchange and water loss by opening/closing stomata
  • Xylem and Phloem: Transport water and nutrients efficiently
• Energy from the Sun


  • Captured by plants through photosynthesis, producing glucose
  • Converted by your body into ATP through cellular respiration
  • Provides the energy your muscles need to contract and move, enabling you to dance