23.3 Recycling in ecosystems

• What is meant by 'nitrogen fixation'?

  When nitrogen gas is converted to nitrogen containing compounds
• Give examples of two types of bacteria that are involved in nitrogen fixation

  Azotobacter and Rhizobiu
• Explain why Rhizobium bacteria can be described as mutualistic

  Rhizobium live in root nodules in peas and beans and they get carbohydrates from the plant, the plant gets amino acids from the bacteria
• What is meant by ammonification?

  Production of ammonia from organic compounds e.g. urea, proteins and nucleic acids
• Describe the process of nitrification

  Ammonium ions --> nitrite ions --> nitrate ions
• Give the role of nitrosomonas bacteria in the nitrogen cycle

  Ammonium ions --> nitrite ions
• Give the role of nitrobacter bacteria in the nitrogen cycle

  Nitrite ions --> nitrate ions
• What is denitrification and how does it occur?

  When soil nitrates are converted to nitrogen gas. Occurs when soil becomes waterlogged, short of oxygen and carried out by anaerobic bacteria - means that less nitrogen compounds are available to plants.
• List 3 processes that return carbon dioxide to the atmosphere

  Respiration, decomposition and combustion
• name a process that removes carbon dioxide from the atmosphere

  Photosynthesis
• Give reasons for the levels of carbon dioxide increasing over the past 100 years

  Combustion of fossil fuels, deforestation
• Define the term global warming

  The increase in average temperature over the last century
• Give 3 consequences of global warming

  Changes in temperature, precipitation, failure of crops, timings of the seasons may change, melting ice caps, flooding of low-lying land, increasing extreme weather, alter niches available - loss of species we don't know
• Give reasons for the levels of methane increasing

  Increased extraction of fossil fuels, increased decaying waste in landfill, more cattle producing methane, frozen stores are thawing