photosynthesis

• Plants are called autotrophs because they are self-feeders and produce their own food without consuming other organisms
• Photosynthesis is the process by which plants convert energy from the sun to manufacture glucose
• Most photosynthesis occurs in the leaves, which are the main organs of photosynthesis
• Leaf anatomy:

  • Upper and Lower Epidermis:
  • Outer layer of leaf cells containing the cuticle, guard cells, and responsible for limiting water loss during transpiration
  • Stomata:
  • Epidermal pores where substances pass through, contract to regulate water and gas exchange
• Mesophyll:

  • Middle photosynthetic layer between upper and lower epidermis
  • Palisade mesophyll: composed of columnar structures with spaces between cells
  • Spongy mesophyll: irregularly-formed cells containing vascular tissues and chloroplasts
• Vascular bundle:

  • Consists of vascular tissues holding xylem and phloem
  • Xylem transports water and minerals, phloem transports sugars and other food
• Pigments in plants capture the sun's energy for photosynthesis

  • Chlorophyll:
  • Greenish pigment in the thylakoid membrane of chloroplasts, absorbs blue and red light, reflects green light
  • Carotenoids:
  • Orange, red, yellow pigments attached to cell membranes, act as antioxidants
  • Anthocyanins:
  • Flavonoid pigments providing color to plant tissues
  • Flavonoids:
  • Yellow-colored pigments with antioxidant properties
• Light is provided to plants using artificial light sources in controlled environments like greenhouses

  • Tailoring the light spectrum can optimize plant growth, improve crop yield, and control developmental processes
• Light Reactions (Light Dependent):

  • Occur in thylakoid membranes of chloroplasts
  • Triggered by light absorption by chlorophyll-a, chlorophyll-b, and carotenoids
  • Products: ATP, NADPH, and oxygen
  • Purpose: Capture and convert light energy into chemical energy to power the Calvin Cycle
• Light-Independent Reactions (Calvin Cycle):

  • Take place in the stomata of chloroplasts
  • Utilize carbon dioxide, ATP, and NADPH to produce glucose and other organic molecules
  • Purpose: Synthesize organic compounds through carbon fixation and reduction reactions, converting atmospheric CO2 into usable forms
• Carotenoids are pigments that come in the form of orange, red, and yellow colors
• Carotenoids are insoluble in water
• Carotenoids are attached to the membranes of cell bodies
• Carotenoids are antioxidants
• Carotenoids promote good eyesight in humans
• Anthocyanins are a type of flavonoid pigments found naturally in all the tissues of the higher group of plants
• Anthocyanins provide color to the stem, leaves, roots, fruits, and flowers
• The color of anthocyanins varies based on pH, appearing red, blue, purple, and other dark colors
• Flavonoids are a type of yellow-colored pigments
• Abundantly found in lemons, grapefruit, oranges, and in some ark and yellow-colored flowers
• Largely found in the plastids and cytoplasm of the plant cell
• Flavonoids are chemicals with antioxidant properties
• Flavonoids help in lowering cholesterol levels
• Light-dependent- is triggered by light absorption by chlorophyll and other pigments
• Pigments involved in light absorption include Chlorophyll-a, Chlorophyll-b, and Carotenoids
• Chlorophyll a is the dominant green pigment that plays a central role in capturing light energy for photosynthesis
• Chlorophyll b: A secondary green pigment that assists chlorophyll-a in light absorptionand expands the range of light that can be utilized
• Carotenoids: Include pigments like beta-carotene, which impart orange and yellowcolors to plants. They broaden the spectrum of light absorption and providephotoprotection.
• Light Dependent - Products: Generate ATP, NADPH and oxygen as byproduct
• Light Dependent - Purpose: Capture and convert light energy into chemical energy (ATP andNADPH) to power the Calvin Cycle
• Light-Independent Reactions (Calvin Cycle) - Dependency: Do not directly require light but depend on theproducts of light reactions (ATP and NADPH)
• Light-Independent Reactions (Calvin Cycle)• Location: Take place in the stomata of chloroplasts.
• Light-Independent Reactions (Calvin Cycle) - Inputs: Utilize carbon dioxide, ATP, and NADPH to produce glucoseand other organic molecules
• Light-Independent Reactions (Calvin Cycle) - Purpose: Synthesize organic compounds through carbon fixation andreduction reactions, converting atmospheric CO2 into usable forms