Food Chain

• What is the main focus of today's video?

  Energy passing through an ecosystem
• What does a food chain illustrate?

  What gets eaten by what in an ecosystem
• What is a food chain a simplified version of?

  A food web
• What is the starting point of all food chains?

  A producer
• What type of organism is a producer?

  Photosynthetic organism
• What does "photosynthetic" mean?

  Produces glucose using sunlight
• What example of a producer is used in the video?

  Grass
• What do we call the biological molecules produced by plants?

  Biomass
• Who are the primary consumers in a food chain?

  Organisms that eat producers
• Which example of a primary consumer is used in the video?

  Mice
• What is the role of secondary consumers?

  They feed on primary consumers
• What type of animal is given as an example of a secondary consumer?

  Owl
• What does the term "tertiary consumer" refer to?

  The third level of consumers
• What happens to energy as it moves up the food chain?

  Most of it gets lost
• If there are 1,000 joules of energy in grass, how much energy is passed to mice?

  Approximately 100 joules
• How much energy might be passed on to the owl from the mice?

  Approximately 20 joules
• What do the arrows in a food chain represent?

  The flow of energy up the chain
• What is a predator-prey cycle?

  Population variations of predators and prey
• How do the populations of field mice and owls vary over time?

  They cycle up and down together
• What happens to the predator population in relation to the prey population?

  It lags behind the prey population
• What does it mean when we say the populations are "out of phase"?

  Predator population peaks after prey population
• What occurs at the beginning of the predator-prey cycle?

  Low owl population, increasing mouse population
• Why does the owl population start to increase after the mouse population increases?

  There is more food available for owls
• What happens when the owl population becomes too high?

  Mouse population declines due to predation
• What allows the mouse population to rise again?

  Decline in the owl population
• Why do predator-prey cycles not reach a steady equilibrium?

  It takes time for populations to change
• What is the main reason for the lag in predator population growth?

  Multiple generations of breeding are needed
• What are the main components of a food chain?

  • Producers (e.g., grass)
  • Primary consumers (e.g., mice)
  • Secondary consumers (e.g., owls)
  • Tertiary consumers (if present)
• What is the process of energy transfer in a food chain?

  1. Energy from the sun is captured by producers.
  2. Primary consumers eat producers.
  3. Secondary consumers eat primary consumers.
  4. Energy decreases at each level.
• What are the stages of the predator-prey cycle?

  1. Low predator population, increasing prey population.
  2. High prey population leads to increased predator population.
  3. High predator population causes a decline in prey population.
  4. Decline in predator population allows prey to rise again.