Unit 3

• All organisms need a source of energy and a source of carbon to make sugars and amino acids.
• Heterotrophs obtain energy from

  Other organisms
• Autotrophs obtain energy from

  Nonliving sources
• Photoautotrophs depend on photosynthesis for energy and carbon compounds
• Photosynthesis uses solar energy to convert carbon dioxide into sugar
• Photosynthesis is needed for

  Cotton, wood, fruits, vegetables, animal food, wool
• Fossil fuels formed millions of years ago from dead plants and animals
• Chemoautotrophs obtain energy by

  oxidizing inorganic substances. Use this energy to form sugars from CO2
• Chemoautotrophs are

  All bacteria + are found in extreme environments
• Bacteria will

  Act as producers in the food chain where plants don't exist
• Light is


  Vibrating electric and magnetic fields
• Vibrations are

  waves of light
• Length of light waves determine the light's color and energy
• Shorter waves

  More energy
• Longer waves


  Less energy
• Visible light is


  A particular range of wavelengths
• Visible light ranges cause

  Reversible changes in molecules
• When visible light hits our eyes, a chemical message is sent to our brains. This allows us to see
• In a photoautotroph

  Its cells can capture the energy of visible light and use it.
• Energy from the sun travels to the Earth in the form of light
• Sunlight is

  A mixture of different wavelengths
• Wavelengths are

  Visible to our eyes, and make up the visible spectrum
• Plants gather the sun's energy with light absorbing molecules called, pigments.
• Chlorophyll is the 


  MOST important pigment in plants
• Chlorophyll will absorb blue-violet and red lights best
• Chlorophyll reflects green light, which is why leaves are green
• Pigments are

  Light absorbing molecules
• Chloroplasts are

  structures in plant cells that contain the pigments involved in photosynthesis
• Chloroplast is the site of photosynthesis
• Chloroplast's pigment is chlorophyll
• Chloroplast's plant cell is mesophyll
• Chloroplast's gas exchange is stomata
• Chloroplast has a double membrane
• Chloroplast contains

  Thylakoids, grana, and stroma
• Thylakoids are

  Membranes that form sacs, in which photosynthetic pigments are embedded (Found in a chloroplast)
• In bacterial cells, the thylakoids are found floating in the cytoplasm
• Grana is

  The stacks of thylakoids that are formed
• Stroma is

  The fluid filled space inside the chloroplast, surrounding the thylakoids
• Enzymes

  • Found in the stroma
  • Catalyze the formation of sugar from CO2 and water
  • Uses light energy (captured by thylakoids) to perform this catalyzation
• Stroma contains the chloroplast's DNA and RNA