key definitions

• biodiversity 


  variety of living organisms in an ecosystem
• pyramid of biomass

  shows the mass of the creatures at each level of a food chain in an ecosystem if u put them all together

  how much energy is at each stage of a food chain
• to calc the efficiency of the energy transfer between each trophic level

  efficiency =(energy transferred to next level / energy available at previous level) x 100

  can do this for biomass too just switch the energy for biomass
• sustainability 


  meeting the needs for us present day but making sure it doesnt affect the future gen's to meet their needs - links to food security