bio. plants summary

• Photosynthesis

  Carbon dioxide + water -> glucose + oxygen
• Photosynthesis

  • Requires energy and chlorophyll
  • Energy is transferred by light and becomes stored in glucose
• Getting water


  1. Roots absorb water from soil

  2. Water flows up xylem vessels to leaf
• Roots


  • Branched and spread out to absorb water from large volume of soil
  • Have root hair cells with large surface area to absorb water quickly
• Mineral salts

  Dissolved in water, keep plants healthy (e.g. nitrates for proteins)
• Water


  • Stops plants wilting by filling up cells
  • Keeps leaves cool
• Getting carbon dioxide


  1. Air containing carbon dioxide diffuses into leaves through stomata

  2. Leaves are thin so carbon dioxide reaches cells quickly
• Increasing carbon dioxide around a plant can speed up photosynthesis
• Leaves


  • Wide to have large surface area to trap light
  • Arranged to not shade each other
• Palisade cells


  • Where most photosynthesis happens
  • Packed with chloroplasts containing chlorophyll
• Increasing light can speed up photosynthesis
• Aerobic respiration


  Glucose + oxygen carbon dioxide + water
• All living cells need energy and respire
• Photosynthesis can only happen when there is light
• Uses of glucose


  • Respiration to release energy
  • Making energy stores (e.g. starch)
  • Making new materials for growth (e.g. cellulose, lipids, proteins)
• Nitrates are needed to make proteins
• New substances made by a plant are carried around the plant in phloem vessels
• Modern farming methods that cause environmental problems

  • Clearing land of hedges and trees
  • Using pesticides
  • Using fertilisers
  • Planting single crop varieties
• Selective breeding


  Choosing organisms with desired characteristics and breeding from them
• Cross-breeding


  Breeding two different varieties to produce offspring with characteristics from both