unit three: life on earth

• What is the definition of biodiversity?

  The variety and relative abundance of living organisms.
• What does an ecosystem consist of?

  A specific area and the non-living factors of that area.
• What is a habitat?


  A place where an organism lives.
• How is a population defined?

  The total number of one type of organism.
• What is a community in ecological terms?

  All the organisms living in the ecosystem.
• What defines a species?

  A group of organisms that can interbreed to produce fertile offspring.
• What is a niche in ecology?


  The role an organism plays within a community.
• What does a food chain indicate?

  The direction of energy flow in an ecosystem.
• What is a food web?

  A combination of a number of food chains.
• What factors can affect an organism's niche?

  • Competition
  • Resources (e.g., light)
  • Predation
• What is an animal that eats only plant material called?

  Herbivore
• What is an animal that eats only other animal material called?

  Carnivore
• What is an animal that eats both plant and animal material called?

  Omnivore
• What is the process by which plants make their own energy?

  • Photosynthesis
  • Converts light energy into chemical energy
• How do herbivores lose most of their energy?

  Herbivores lose most of their energy through heat, movement, and undigested materials.
• What are the two types of competition that exist between organisms?

  • Interspecific Competition: competition between different species
  • Intraspecific Competition: competition within the same species
• What is the purpose of sampling in an ecosystem?

  Sampling is a way of finding out what species are present in an ecosystem without counting every single organism.
• What can sampling organisms help determine?

  It helps to find out the abundance and distribution of species.
• What are some biotic factors that can affect an ecosystem?

  • Grazing
  • Disease
  • Availability of food
  • Competition
  • Number of predators
• How are quadrats used in sampling techniques?

  Quadrats are placed randomly to count the number of organisms present.
• What is a source of error when using quadrats for sampling?

  Incorrect counting can be a source of error.
• How can errors in quadrat sampling be minimized?

  Only count organisms where they are present.
• How are pitfall traps used in sampling techniques?


  They are buried containers that trap organisms overnight.
• What is a source of error when using pitfall traps?

  Predation can affect the results of pitfall traps.
• How can errors in pitfall trapping be minimized?

  Check the traps regularly.
• What are some abiotic factors that can be measured in an ecosystem?

  • pH
  • Temperature
  • Light intensity
  • Moisture
• How is moisture measured in soil?

  Using a moisture meter by placing the clean probe into the soil.
• What is a source of error when measuring moisture in soil?

  Sample contamination from previous readings can be a source of error.
• How can errors in moisture measurement be minimized?

  Wipe the probe between each reading.
• How is light intensity measured?

  Using a light meter directed towards the light source.
• What is a source of error when measuring light intensity?


  Standing in front of the sensor can affect the readings.
• How can errors in light intensity measurement be minimized?

  Don't stand in front of the sensor.
• How is temperature measured in an ecosystem?

  Using a thermometer without covering the sensor.
• What is a source of error when measuring temperature?

  Temperature may change throughout the day.
• How can errors in temperature measurement be minimized?

  Take several readings at the same time of day.
• What is the level of water pollution for a Stonefly Nymph?

  Unpolluted
• What is the level of water pollution for a Caddis Fly Larva?

  Unpolluted
• What is the level of water pollution for a Rat-tailed Maggot?

  Polluted
• What is the level of water pollution for a Mayfly Nymph?

  Unpolluted
• What is the process by which plants produce their own food?

  Photosynthesis