food chains and predator-prey cycle

• 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
• How does a food chain differ from a food web?

  A food chain shows one interaction chain
• What is the starting point of all food chains?

  A producer, like a green plant
• What does "photosynthetic" mean?

  Organisms produce glucose using sunlight
• What is biomass in the context of plants?

  Incorporated biological molecules in plants
• Who are the primary consumers in a food chain?

  Organisms that eat producers
• What is the role of secondary consumers?

  They feed on primary consumers
• What does the term "tertiary consumer" refer to?

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

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

  About 100 joules
• How much energy might be passed on to the owl?

  About 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 prey and predators change over time?

  They cycle up and down together
• What does it mean when predator and prey populations are "out of phase"?

  Predator population lags behind prey population
• What happens when the owl population is low?

  The mouse population increases
• What occurs when there are many mice available?

  The owl population starts to increase
• What happens when the owl population becomes too high?

  Mouse population declines due to predation
• Why does the cycle of predator and prey populations repeat?

  Due to time needed for population changes
• What is the main reason for population cycles in ecosystems?

  Time taken for populations to change
• 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 are the stages of the predator-prey cycle?

  1. Low predator population, increasing prey
  2. High prey population, increasing predator
  3. High predator population, declining prey
  4. Declining predator population, rising prey
• What is the significance of energy loss in food chains?

  • Energy decreases at each trophic level
  • Only a fraction is passed to the next level
  • Impacts population sizes and ecosystem dynamics