must link reason to a correct change in a gas carbon dioxide has decreased due to: accept idea of to indicate a decrease ‘used’ plants / micro organisms / bacteria / vegetation / trees • photosynthesis • ignore respiration up’ in (sedimentary) rocks / carbonates / fossil fuels • ‘locked dissolved in oceans • ignore volcanoes oxygen has increased due to: accept idea of out / produced’ ‘given plants / bacteria / micro organisms / vegetation / trees • photosynthesis • ignore respiration nitrogen increased due to: accept idea of out / produced’ ammonia reacted with oxygen • bacteria / micro organisms • ignore (increase in) use of fossil fuels / deforestation 2 (b) (because methane’s) boiling point is greater than the average / surface temperature or Titan’s (average / surface) temperature is below methane’s boiling point ignore references to nitrogen or water 1 any methane that evaporates will condense accept for evaporates
must link reason to a correct change in a gas carbon dioxide has decreased due to: accept idea of ‘used’ to indicate a decrease • plants / micro organisms / bacteria / vegetation / trees • photosynthesis ignore respiration • ‘locked up’ in (sedimentary) rocks / carbonates / fossil fuels • dissolved in oceans ignore volcanoes oxygen has increased due to: accept idea of ‘given out / produced’ • plants / bacteria / micro organisms / vegetation / trees • photosynthesis ignore respiration nitrogen increased due to: accept idea of out / produced’ • ammonia reacted with oxygen • bacteria / micro organisms ignore (increase in) use of fossil fuels / deforestation 2 (b) (because methane’s) boiling point is greater than the average / surface temperature or Titan’s (average / surface) temperature is below methane’s boiling point ignore references to nitrogen or water 1 any methane that evaporates will condense accept for evaporates
organic_chemistry_mark_scheme_2.docx