Organisation of an Ecosystem

• What is the definition of a population?

  A species that occupy the same habitat.
• What is the definition of a habitat?

  The place in which an organism lives.
• What is the definition of a community?

  Populations of different species interacting.
• What is the definition of an ecosystem?

  The interactions between biotic and abiotic factors.
• What do food chains show?

  Feeding relationships and energy flow between organisms.
• What is the definition of biomass?

  The total mass of living material.
• What are trophic levels?

  The stages in a food chain.
• What do arrows in a food chain represent?

  The direction of biomass transfer.
• Describe a simple food chain.

  • Producer
  • Primary consumer
  • Secondary consumer
  • Tertiary consumer
• What is a producer?

  An organism that makes its own food.
• What types of organisms are primary producers?

  Photosynthetic organisms like green plants and algae.
• What is a primary consumer?

  An organism that feeds on producers.
• What is a secondary consumer?

  An organism that feeds on primary consumers.
• What is a tertiary consumer?

  An organism that feeds on secondary consumers.
• What is a predator?

  A consumer that kills and eats other animals.
• What is prey?

  An animal that is killed and eaten by another animal.
• Describe the pattern of predators and prey in a stable community.

  The numbers of predators and prey rise and fall in cycles.
• Why are producers the first trophic level?

  They provide all biomass for the food chain.
• What piece of apparatus is used to measure the abundance and distribution of organisms in an area?

  Quadrat
• What piece of apparatus is used to study the distribution of organisms across a gradient?

  Belt transect
• What is meant by the term “mean” in abundance studies?

  The average number of organisms.
• How is the arithmetic mean calculated?

  Sum of each number of each organism divided by total.
• What is meant by the term “mode” in abundance studies?

  The most populous organism.
• What is meant by the term “median” in abundance studies?

  The middle value when arranged from lowest to highest.
• Describe how materials cycle through the living and non-living components of an ecosystem.

  • Organisms take in elements from surroundings.
  • Elements converted to complex molecules (biomass).
  • Elements transferred along food chains.
  • Returned to environment during excretion and decomposition.
• Give 3 molecules which are cycled through ecosystems.

  Oxygen, carbon dioxide, and water.
• Describe the carbon cycle.

  • Plants fix carbon dioxide during photosynthesis.
  • Organic molecules passed to organisms that eat plants.
  • Carbon dioxide released by respiration.
  • Burning fossil fuels releases carbon dioxide.
• Why is the carbon cycle important?

  Carbon-containing molecules are vital for growth and energy.
• Describe the water cycle.

  • Water evaporates from lakes and oceans.
  • Evaporated water condenses into clouds.
  • Returns as precipitation useful for life.
  • Water returns to rivers and oceans through runoff.
• Why is the water cycle important?

  It provides organisms with a continuous supply of water.
• Why are microorganisms important for the cycling of materials?

  They return carbon to the environment through decomposition.
• What is meant by decomposition?

  The breakdown of dead materials into simpler organic matter.
• How do decomposers break down dead matter?

  They release enzymes that catalyse the breakdown.
• What are the two types of decomposition?

  • Aerobic decomposition
  • Anaerobic decomposition
• What is the process of decomposition?

  The breakdown of dead materials
• Why is decomposition important for the environment?

  It returns mineral ions for other organisms
• What is meant by decomposition in biology?

  The breakdown of dead materials into simpler organic matter
• How do decomposers break down dead matter?

  They release enzymes that catalyze breakdown
• What are the two types of decomposition?

  Aerobic and anaerobic decomposition
• What factors affect the rate of decomposition?

  Oxygen availability, temperature, and water content