B9 ECOSYSTEMS

• What is an organism?

  a single living individual
• What is a population?

  all the organisms of the same species in an area
• What is a community?

  all the populations in an area
• What is an ecosystem?

  all the living organisms (the community) and the non-living components in an area
• What is an ecosystem?

  all the living organisms (the community) and the non-living components in an area
• What is a parasite?

  An organism that feeds on another organism (the host) while they are living together
• Give examples of parasites

  fleas, head lice, tapeworms, mistletoe
• What is mutualism?

  when two organisms live closely together in a way that benefits them both
• What type of sampling is done with quadrats?

  random sampling


  
  

  What type of sampling is done with belt transects?

  systematic sampling
• What is the term for producing drinking water from salty (sea) water

  desalination
• Why are belt transects used?

  to see how a change in a factor affects a population
• How can you calculate the number of organisms in an area using data from quadrats?


  divide the total area by the area of one quadrat and then multiply your answer by the mean number of organisms in one quadra
• Why would repeating the transect multiple times and comparing the results be a good idea?

  it would help to average out any random variables
• FISH FARMING-growing one kind of fish in an area, the fish are fed and the waste they produce is removed from the tanks
• Give two disadvantages of fish farming

  the waste can pollute the local area, changing conditions so that some local species die out;

  diseases from the farmed fish (such as lice) can spread to wild fish and kill them
• Give an advantage of fish farming

  it reduces fishing of wild fish
• Give two disadvantages of the introduction of non-indigenous species to an ecosystem

  they may reproduce rapidly as the have no natural predators in the new area; they may out-compete native species for food or other resources
• Give an advantage of the introduction of non-indigenous species to an ecosystem

  they may provide food for native species
• What is eutrophication?

  an excess of nutrients such as phosphates and nitrates in water from fertilisers dissolving in rain water
• How can eutrophication lead to a loss of biodiversity?

  -Plants and algae grow more quickly and block light to deeper water

  -deeper plants die

  -bacteria decompose the dying plants and take oxygen from the water;

  -fish die due to lack of oxygen
• Why should humans maintain local and global biodiversity?

  
  

  humans should respect other organisms;

  people enjoy seeing variety of organisms in different habitats;

  some organisms have an important role in ecosystems;

  some species are particularly useful to humans.
• Give advantages for reforestation

  restores habitat for endangered species;

  reduces concentration of CO2 in the air due to photosynthesis;

  tree roots bind the soil and minimise soil erosion;

  reduces the range of temperature variation in the local climate
• nitrogen fixing bacteria-Convert nitrogen gas into nitrates

  nitrifying bacteria do-Convert ammonia into nitrates

  denitrifying bacteria do-Convert nitrates into nitrogen gas

  decomposers in the nitrogen cycle-they convert waste matter into ammonia
• What is the process where plants such as peas, beans or clover are grown in a field every few years?

  Crop rotation
• What is the benefit of crop rotation?

  Increases nitrate levels in the soil
• Why do leguminous plants (beans, peas, clover) increase nitrate levels in the soil?

  The root nodules contain nitrogen fixing bacteria which convert nitrogen gas into nitrates.
• How crop rotation increases nitrate levels in soil

  Farmers often grow crops such as peas, beans or clover as these crops can form nitrate, as they have nitrogen-fixing bacteria in their roots. This will increase the nitrate content and fertility of the soil.