E in ecosystems/nutrient cycles

• What is the process by which producers convert light energy into chemical energy?

  Photosynthesis
• How is energy transferred from producers to primary consumers?

  Through consumption of biomass
• What percentage of energy is typically passed to the next trophic level?

  Around 40%
• What are the ways energy is lost at each trophic level?

  • Not all light energy is absorbed
  • Not all parts of organisms are eaten
  • Incomplete digestion of consumed organisms
• What fraction of the energy passed to the next trophic level is converted into biomass?

  10%
• Why do food chains rarely exceed four or five trophic levels?

  Insufficient energy remains for higher levels
• What is the official method for measuring energy transfers between trophic levels?

  1. Sample a specific area
  2. Dehydrate organisms in an oven
  3. Weigh to find dry mass
  4. Calculate biomass difference
• What is net productivity in an ecosystem?

  Energy available to the next trophic level
• What is the formula for calculating net productivity?

  Net Productivity = Gross Productivity - Respiration
• What does Gross Primary Productivity (GPP) refer to?

  All energy consumed by plants
• How can we calculate the efficiency of energy transfer?

  Net productivity divided by total energy
• What do food chains illustrate in an ecosystem?

  • Feeding relationships between organisms
  • Flow of energy from one organism to another
  • Starts with energy from the Sun
• What are organisms that produce biomass called?

  Producers
• Who are primary consumers in a food chain?

  Organisms that feed on producers
• What is the role of secondary consumers in a food chain?

  They eat primary consumers
• What do food webs represent in an ecosystem?

  Interconnected food chains
• What happens to populations in a food web if one organism's population changes (interdepedence) ?

  It affects all interconnected organisms
• What role do decomposers play in ecosystems?

  • Break down dead material
  • Recycle nutrients back into the soil
  • Enable chemical elements to be reused
• How do farmers increase energy transfer efficiency?

  • Use insecticides to kill pests
  • Apply herbicides to eliminate weeds
  • Restrict animal movement
• What is saprotrophic nutrition?

  External digestion of dead organic matter
• What are the long, thin strands of fungi called?

  Hyphae
• What is the relationship between fungi and plant roots called?

  Mycorrhizae
• What form of nitrogen can plants absorb?

  Nitrate- depend on nitrogen-fixing bacteria
• What do nitrogen-fixing bacteria do in nitrogen fixation? and how is this a symbiotic relationship w plants?

  Convert nitrogen into nitrate

  • plants get nitrates while bacteria get organic compounds e.g glucose
• What is the Haber process used for?

  To convert nitrogen into ammonia
• What is nitrification by nitrifying bacteria?

  Conversion of ammonium ions into nitrates
• What do plants do with absorbed nitrates?

  Use the N into AA for building proteins- which is then broken down as urea and removed in urine
• What is ammonification?

  Decomposition of dead matter into ammonia by sapriobionts
• What do denitrifying bacteria convert nitrates into when there is a lack of oxygen?

  Nitrogen gas
• Under what conditions do denitrifying bacteria typically operate?

  Anaerobic conditions
• What is the role of phosphates in organisms?

  • Essential for phospholipids
  • Necessary for nucleic acids
  • Required for ATP production
• How are phosphates released into the soil?

  Through erosion of rocks in the form of phosphate ions
• How do plants utilize phosphate ions absorbed through roots?

  To synthesize nucleic acids and membranes
• What is guano?

  Phosphate-rich waste from sea birds that makes an effective fertiliser
• Why do farmers use fertilizers?

  • Replace lost nutrients in soil
  • Enhance crop growth and yield
  • Prevent nutrient depletion
• What is leaching in the context of fertilizers?

  Washing away of soluble nutrients
• What is algal bloom?

  Rapid increase in algal growth
• How does algal bloom affect aquatic plants?

  Blocks sunlight, preventing photosynthesis
• What happens to oxygen levels during algal bloom decomposition?

  Oxygen levels decrease significantly
• How do natural fertilizers differ from artificial fertilizers?

  • Natural fertilizers release nutrients slowly
  • Artificial fertilizers release nutrients quickly
  • Natural fertilizers are organic, artificial are synthetic