Food chains, pyramid of numbers and adaptations

• Food chain


  A series of organisms where each member is eaten by the next member
• Food web


  A network of interconnected food chains
• Food chain


  1. Producer (green plant)

  2. Primary consumer (eats producer)

  3. Secondary consumer (eats primary consumer)

  4. Tertiary consumer (eats secondary consumer)
• Carnivore


  • Only eats animals
• Herbivore


  • Only eats plants
• Omnivore


  • Eats plants and animals
• All organisms in an ecosystem depend on each other
• Food chains show the flow of energy from one organism to another
• Food chains show the feeding relationships between organisms
• Food webs show all the food chains in an ecosystem interacting with each other
• If one animal dies or decreases in size

  Its predator will starve and their species will decrease, while their prey will increase
• Pyramid of numbers


  A special type of bar chart that shows the population or number of each organism in a food chain
• The producer in the food chain always goes at the bottom of the pyramid of numbers
• Energy is lost to the surroundings as we go from one level to the next in a food chain, so there are usually fewer organisms at each level
• Adaptation


  A feature that makes a species suited to its environment
• Adaptations of cacti


  • No big leaves and small surface area to minimise evaporation
  • Round shape to store water inside
  • Spikes to protect from predators
  • Large root system to soak up water
• Adaptations exist because they give a survival advantage
• Types of adaptations


  • Ability to survive in dry conditions
  • Ability to survive in fast flowing water
  • Ability to survive in extreme winds
  • Ability to survive in salt water
• Energy transfer between trophic levels is not very efficient as only about 10% of the energy is passed on at each stage.
• This means that there are fewer organisms at higher trophic levels than lower ones.
• The amount of energy available decreases with each step along the food chain due to respiration by organisms and waste products being excreted or lost through other means.