6.5.2 - Transfer of Biomass & 6.5.3 - Manipulating TOB

• what is the main route by which energy enters an ecosystem?

  photosynthesis (sunlight)
• what is biomass?

  mass of the living material
• why do plants convert sunlight energy during photosynthesis?

  during photosynthesis plants convert sunlight energy into a form that can be used by other organisms.
• what are biomass transfers?

  transfer of biomass from one trophic level to another
• how is energy transferred through living organisms of an ecosystem?

  when organisms eat other organisms
• what do food webs and food chains show?

  food chains and food webs show how energy is transferred through an ecosystem.
• what do food chains show?

  show simple lines of energy transfer
• what do food webs show?

  lots of food chains in an ecosystem and how they overlap
• What happens to the energy locked up in the things that can't be eaten?

  gets recycled back into the ecosystem by decomposers
• what are the pyramids of numbers ?

  what are the disadvantages of pyramids of numbers?

  • represents number of organisms at each trophic level by the width of the bar
  • it doesn't take into account the amount of biomass at each level + inverted pyramids can be generated
• how do you calculate the efficiency of biomass transfer?

  1. draw a pyramid of biomass, where the area of each bar is proportional to the dry mass of all the organisms at that trophic level.
  2. collect samples from each trophic level
  3. put in oven at 80*c so water removed by evaporation
  4. wait till mass stays the same
  5. calorimeter can be used to measure energy stored
• how do you calculate the efficiency of biomass transfer betweeen trofic level ?

  $(biomass at the higher tropic level / biomass at the lower trophic level) *$$100$

  $(biomass of primary consumer / biomass of producer ) *$$100$
• what are some of the reasons that some of the available energy is never taken in by the organisms?

  • plants cant use all the light energy that reaches their leaves
  • some sunlight can't be used because it hits parts of the plant that can't photosynthesise
  • some parts of foods ( roots, bones) aren't eaten by organisms so the energy isn't taken in - they pass to decomposers
  • some parts of the food are indigestible so pass through organisms and come out as waste (faeces ) also passed to decomposers
• define productivity

  the rate production of new biomass by producers
• Gross Primary Productivity (GPP)

  The rate at which an ecosystem absorbs and converts carbon dioxide and other nutrients into glucose through photosynthesis, producing biomass.
• Net Primary Productivity (NPP)

  The rate at which an ecosystem produces new biomass, minus the rate at which biomass is decomposed or lost, resulting in a net accumulation of biomass.
• Respiratory Loss

  Energy expended by organisms through cellular respiration, resulting in the release of heat and the loss of biomass.
• Calculating Net Primary Productivity (NPP)

  NPP = GPP - Respiratory Loss, where GPP is the rate of gross primary production and Respiratory Loss is the energy expended by organisms through respiration.
• What is one human activity that increases the transfer of energy in agriculture?

  Using herbicides to kill weeds
• How do herbicides affect crop productivity?

  They reduce competition for energy, allowing crops to grow faster and larger
• What is the effect of fungicides on agricultural crops?

  They allow crops to use more energy for growth instead of fighting infections
• Why do crops grow larger when fungicides are used?

  Because they allocate more energy to growth rather than fighting infections
• What do insecticides do in agriculture?

  They kill insect pests that damage crops
• How does killing insect pests with insecticides affect crop productivity?

  It reduces biomass loss, allowing crops to grow larger
• What is the role of fertilizers in crop growth?

  They provide essential minerals needed for growth
• How do fertilizers increase energy conversion efficiency in crops?

  By replacing lost minerals, allowing more energy from the ecosystem to be used for growth
• What does intensive livestock rearing involve?

  Controlling the conditions in which livestock live
• How does controlling livestock conditions affect their energy use?

  It allows more energy to be used for growth rather than other activities
• What are the benefits of using herbicides, fungicides, insecticides, and fertilizers in agriculture?

  • Herbicides reduce competition, allowing crops to grow faster and larger.
  • Fungicides allow crops to allocate more energy to growth instead of fighting infections.
  • Insecticides reduce biomass loss, enabling crops to grow larger.
  • Fertilizers provide essential minerals, increasing energy conversion efficiency.
• How does intensive livestock rearing improve energy efficiency?

  • Controls living conditions
  • Maximizes energy use for growth
  • Minimizes energy used for other activities