Food Chains and Predator-Prey Cycles

• According to the video introduction, what should you be able to do by the end of the video?

  Use food chains to represent feeding relationships
• According to the video introduction, what else should you be able to do by the end of the video?

  Describe changes in predator and prey numbers over time
• What is one biotic factor that can affect organisms, as mentioned in a previous video?

  Source of food
• What do scientists use food chains for?

  To represent feeding relationships
• Where would the grass, rabbits and foxes food chain be found?

  UK
• What do both food chains presented in the video have in common at the start?

  They begin with a green plant
• What do scientists call the organisms at the beginning of a food chain?

  Producer
• What type of organism is typically the producer in most food chains?

  A green plant
• Why are producers extremely important in food chains?

  They synthesize complex molecules
• Which complex molecule do green plants produce through photosynthesis?

  Glucose
• What do green plants use energy from sunlight for?

  To make glucose by photosynthesis
• What do scientists call molecules such as glucose?

  Biomass
• What happens to biomass in a food chain?

  It is passed down to other organisms
• Why are producers the source of all the biomass in a community?

  They synthesize complex molecules
• What are organisms that eat the producers called?

  Primary consumers
• In the grass, rabbit, fox food chain, which organism is the primary consumer?

  The rabbit
• In the tree, caterpillar, bird food chain, which organism is the primary consumer?

  The caterpillar
• What are the animals that eat primary consumers called?

  Secondary consumers
• What is a secondary consumer?

  An animal that eats a primary consumer
• In a four-stage food chain, what is the producer?

  A tree
• In a four-stage food chain, what is the primary consumer?

  A caterpillar
• In a four-stage food chain, what is the secondary consumer?

  A small bird
• What is the tertiary consumer in the four-stage food chain?

  A bird of prey
• What does a tertiary consumer eat?

  A secondary consumer
• What are consumers that kill and eat other animals called?

  Predators
• In the grass, rabbit, fox food chain, which animal is the predator?

  The fox
• What is the animal that is being eaten called?

  Prey
• In the grass, rabbit, fox food chain, which animal is the prey?

  The rabbit
• In the tree, caterpillar, bird food chain, which animal is the predator?

  The bird
• In the tree, caterpillar, bird food chain, which animal is the prey?

  The caterpillar
• What does the graph shown represent?

  Populations of predator and prey in a community
• What happens to the numbers of predator and prey over time?

  They rise and fall in cycles
• What happens if the rabbit population increases due to a warm summer with plenty of grass?

  More rabbit offspring survive
• If the rabbit population increases, what happens to the fox population after some time?

  The fox population increases
• What happens when there are more foxes and more rabbits are eaten?

  The rabbit population falls
• What happens after the population of rabbits falls?

  The population of foxes also falls
• What happens when the number of foxes has fallen?

  More rabbits now survive and reproduce
• What happens after the population of rabbits increases again?

  The fox population increases again
• When is the predator-prey cycle true?

  Only in a stable community
• What is a stable community?

  One where biotic and abiotic factors are balanced