Energy and Ecosystems

• What are the two types of factors that control the distribution and abundance of organisms in a habitat?

  Biotic and abiotic factors
• What is the role of a species in its habitat called?

  Niche
• What is the source of all energy in ecosystems?

  The Sun
• What are organisms that can produce their own food called?

  Autotrophs
• What percentage of chemical food energy is passed on between organisms in the food chain?

  10%
• What are the main ways energy is lost in a food chain?

  Uneaten parts, decay, excretion, exothermic reactions
• How is the efficiency of energy transfer between trophic levels calculated?

  Percentage efficiency = (energy transferred / energy received) x 100
• How is biomass typically measured?

  Mass of carbon or dry mass of tissue per given area per given time
• Why is dry mass used instead of wet mass to measure biomass?

  Wet mass can vary too much
• How is the chemical energy stored in dry biomass estimated?

  Using calorimetry in a bomb calorimeter
• What is Net Primary Productivity (NPP)?

  The rate at which energy is transferred into new plant biomass after respiratory losses
• What is Gross Primary Productivity (GPP)?

  The rate at which energy is incorporated into organic molecules in plants through photosynthesis
• How is Net Primary Productivity (NPP) calculated?

  NPP = GPP - R
• What is the net production of consumers (N) calculated by?

  N = I - (F + R)
• What does 'I' represent in the net production of consumers formula?

  Chemical energy store in ingested food
• What does 'F' represent in the net production of consumers formula?

  Chemical energy lost in faeces and urine
• What does 'R' represent in the net production of consumers formula?

  Respiratory losses to the environment
• What are the key differences between GPP and NPP?

  • GPP: Total energy incorporated into organic molecules through photosynthesis
  • NPP: Energy stored in plant biomass after respiratory losses (NPP = GPP - R)
• What are the main processes involved in energy transfer in ecosystems?

  • Photosynthesis by autotrophs
  • Energy transfer through food chains
  • Energy losses through uneaten parts, decay, excretion, and respiration
  • Calculation of energy efficiency between trophic levels
• How is energy flow measured in an ecosystem?

  • Measuring biomass (dry mass or carbon mass)
  • Using calorimetry to estimate chemical energy in biomass
  • Calculating GPP and NPP
  • Measuring energy transfer efficiency between trophic levels
• What are the implications of energy loss in food chains?

  • Only 10% of energy is transferred between trophic levels
  • Limits the length of food chains
  • Affects the biomass and population sizes at higher trophic levels
• What is the role of decomposers in energy flow?

  • Break down dead material and waste
  • Release nutrients back into the ecosystem
  • Contribute to energy loss through decay processes
• How would you calculate the energy available to the next trophic level?

  • Measure the energy stored in the biomass of the current trophic level
  • Subtract energy lost through uneaten parts, decay, excretion, and respiration
  • The remaining energy is available to the next trophic level
• What factors influence the efficiency of energy transfer in ecosystems?

  • Type of organisms involved
  • Environmental conditions (e.g., temperature, light)
  • Availability of resources
  • Predation and competition
• What is the significance of the Sun in ecosystems?

  • Primary source of energy for all ecosystems
  • Drives photosynthesis in autotrophs
  • Basis for energy flow through food chains
• How would you measure the energy content of a plant sample?

  • Dry the sample to remove water
  • Burn the sample in a bomb calorimeter
  • Measure the temperature change in surrounding water
  • Calculate energy content using the temperature change and known mass
• What are the ecological implications of high vs. low NPP?

  • High NPP: Supports larger populations and more complex food webs
  • Low NPP: Limits the number of trophic levels and population sizes
  • Affects biodiversity and ecosystem stability
• What is the relationship between GPP, NPP, and R?

  • GPP: Total energy from photosynthesis
  • R: Energy lost through respiration
  • NPP: Energy remaining after respiration (NPP = GPP - R)
• How would you calculate the net production of a consumer?

  • N = I - (F + R)
  • I: Energy in ingested food
  • F: Energy lost in faeces and urine
  • R: Energy lost through respiration
• What are the ecological consequences of energy loss in ecosystems?

  • Limits the number of trophic levels
  • Affects the biomass and population sizes at higher levels
  • Influences the structure and function of ecosystems
• What is the role of autotrophs in energy flow?

  • Convert solar energy into chemical energy through photosynthesis
  • Serve as the primary producers in ecosystems
  • Basis for energy flow through food chains
• How would you determine the energy efficiency between two trophic levels?

  • Measure the energy stored in the biomass of both levels
  • Calculate the percentage efficiency using: (Energy at higher level / Energy at lower level) x 100
• What are the factors that affect NPP in an ecosystem?

  • Availability of sunlight
  • Temperature and climate conditions
  • Availability of water and nutrients
  • Presence of herbivores and decomposers
• What is the significance of respiratory losses in energy flow?

  • Represents energy lost as heat during metabolic processes
  • Reduces the amount of energy available for growth and reproduction
  • Affects the net production of organisms
• How would you calculate the energy lost through respiration in a consumer?

  • Measure the total energy ingested (I)
  • Subtract the energy lost in faeces and urine (F)
  • Subtract the net production (N)
  • R = I - (F + N)
• What are the ecological implications of energy flow in ecosystems?

  • Determines the structure and function of ecosystems
  • Influences biodiversity and population dynamics
  • Affects the stability and resilience of ecosystems
• What is the role of heterotrophs in energy flow?

  • Cannot produce their own food
  • Rely on consuming other organisms for energy
  • Include herbivores, carnivores, and decomposers
• How would you measure the energy content of a consumer's diet?

  • Collect and dry the food samples
  • Burn the samples in a bomb calorimeter
  • Measure the temperature change in surrounding water
  • Calculate energy content using the temperature change and known mass
• What are the factors that influence the efficiency of energy transfer between trophic levels?

  • Type of organisms involved
  • Environmental conditions (e.g., temperature, light)
  • Availability of resources
  • Predation and competition
• What is the significance of energy loss in faeces and urine?

  • Represents energy that is not assimilated by the consumer
  • Contributes to the overall energy loss in the food chain
  • Affects the net production of consumers