Topic 9: Ecosystems & Material Cycles

• What is an individual part of?

  A species
• Where does an individual live within a population?

  In its habitat
• What do many different populations interacting in the same habitat create?

  A community
• What is the relationship between populations in a community?

  They are often dependent on each other
• What is an ecosystem?

  The interaction of a community with non-living parts of the environment
• How are organisms adapted in an ecosystem?

  They are adapted to live in the conditions of their environment
• What happens when organisms need the same resources?

  They compete for it
• What are the types of competition that can occur in ecosystems?

  • Competition within a species
  • Competition between different species
• What resources do plants compete for?

  Light, space, water, and mineral ions
• What resources do animals compete for?

  Space, food, water, and mating partners
• What is an abiotic factor?

  A non-living factor
• What is required to explain the effect of a change in an abiotic factor?

  You need to be able to explain it
• What are some abiotic factors that can affect a community?

  1. Light intensity
  2. Temperature
  3. Moisture levels
  4. Soil pH and mineral content
  5. Wind intensity and direction
  6. Carbon dioxide levels
  7. Oxygen levels for aquatic animals
• Why is light intensity important for plants?

  It is required for photosynthesis
• How does light intensity affect plant growth?

  The rate of photosynthesis affects the rate at which the plant grows
• What role do plants play in ecosystems?

  They can be food sources or shelter for many organisms
• How does temperature affect photosynthesis?

  Temperature affects the rate of photosynthesis
• Why do both plants and animals need water?

  To survive
• How does soil pH affect the ecosystem?

  It affects the rate of decay and how fast mineral ions return to soil
• Why do different species of plants thrive in different nutrient concentration levels?

  Different species have varying nutrient requirements
• How does wind intensity affect plants?

  Wind affects the rate of transpiration in plants
• What is transpiration?

  The movement of water from root to leaves in plants
• How does transpiration affect plant temperature?

  It affects the temperature of the plant
• How do carbon dioxide levels affect plants?

  CO₂ affects the rate of photosynthesis in plants
• How do oxygen levels vary for aquatic animals?


  Levels in water vary greatly compared to air
• What do most fish need to survive?

  A high concentration of oxygen
• What is a biotic factor?

  A living factor
• What is required to explain the effect of a change in a biotic factor?

  You need to be able to explain it
• What are some biotic factors that can affect a community?

  1. Food availability
  2. New predators
  3. New pathogens
  4. Competition
• How does food availability affect populations?


  More food means organisms can breed more successfully
• What happens when a new predator is introduced to a community?

  It can affect the populations of other species
• What is the impact of new pathogens on a population?

  They can wipe out populations quickly if there is no resistance
• How does competition affect species in a community?

  If one species is better adapted, it will outcompete the other
• What does interdependence describe?

  How organisms depend on other organisms for vital services
• What are some vital services organisms depend on from each other?

  Food, shelter, and reproduction
• What can the removal or addition of a species to a community affect?


  It can affect the populations of others greatly
• What is a stable community?

  A community where all biotic and abiotic factors are in balance
• What happens to population sizes in a stable community?

  They remain roughly constant
• What happens when biotic or abiotic factors are lost from a community?


  It is very difficult to replace them
• What are examples of stable communities?

  • Tropical rainforests
  • Oak woodlands
  • Coral reefs