ecosystem and material cycles

• what are the different levels of organisation in an ecosystem

  individuals

  population

  communities
• what is an individual

  a single organism
• What is a population?

  All the organisms of one species in a habitat
• what is a community

  all the organisms of different species living in a habitat
• what is an ecosystem

  A community of organisms along with all the non-living (abiotic) conditions
• what does interdependent mean

  organisms depend on each other for things like food and shelter in order to survive and reproduce
• what is mutualism

  a relationship between two organisms, from which both organisms benefit
• what is an example of mutualism

  bees and flowering plants -

  when bees visit flowers to get nectar, pollen is transferred to their bodies. The bees then spread the pollen to other plants when they land on their flowers. The bees get food and the flowers get help reproducing
• what do parasites do in a community

  they live in or on another organism

  the parasites takes what it needs to survive, but the host doesn't benefit. e.g. fleas are parasites to mammals such as dogs
• what are environmental changes caused by

  abiotic(non-living) and biotic(living) factors
• what are abiotic factors

  temperature

  amount of water

  light intensity

  levels of pollutants
• how does temperature affect communities

  if there is a rise in temperature they may be a change in species living in that habitat - meaning they may be no prey for predators
• how does the amount of water affect communities

  if the soil becomes waterlogged or too dry, the population of some plant species may decrease
• how does light intensity affect communities

  plants(trees) grow and provide more shade, grasses may not be able to grow and will be replaced by fungi(mosses) as they are able to cope with lower light intensity
• how does the level of pollutants affect communities

  the air pollutants may stop some plants growing

  e.g. lichen is unable to survive if the concentration of sulfur dioxide is too high
• what are some biotic factors

  competition

  predation
• how does competition affect communities

  as organisms compete with other species for the same resources there may not be enough for both so the species that is better adapted will get the food and survive
• how does predation affect communities

  is the number a specific predator decreases, then the number of their prey increases because fewer of them are being eaten
• what do animals often compete for

  mates

  food

  territory
• what may a species rely on another species for

  food

  shelter

  seed dispersal

  pollination
• what can you use to study the distribution of small organisms

  a quadrat
• how to use a quadrat to study the distribution of small organisms

  1)measure total area

  2)split total area into 1m^2 squares

  3)place a 1m^2 quadrat at a random point(using random number generator)

  4)count all the organisms you're interested in within the quadrat

  5)repeat the steps 3 and 4 lots of times

  6)work of mean(total no. organisms/ no. quadrats)

  7) repeat in another area and then compare the means
• what do you use when studying a distribution along a gradient

  belt transects
• how to use belt transects to study distribution along a gradient

  1) mark out a line in the area you want to study

  2) collect the data along the line using quadrats placed next to each other- or at regular intervals

  3) collect the data by counting all the organisms of the species percentage area of a quadrat covered by a particular type of organism

  4) you could also collect other data like the light intensity by using a light meter

  5) repeat steps 1 and 2 several times and find the mean number for each quadrat

  6) plot a graph to see if the changing abiotic factor is correlated with a change in the distribution of the species you're studying.
• how do you determine the number of organisms in a given area using quadrats and belt transects

  work out the mean

  mean = total no. of organism / no. of quadrats
• what is passed along in food chains

  SOME energy
• what is biomass

  The mass of living material that makes up an organism
• what happens when a plant/animal eat another animal or absorb nutrients

  it uses some energy for respiration and the rest is stored in its body as biomass
• what is each stage in a food chain called

  trophic level
• what happens to the energy that is used by an organism

  movement but most energy is transferred to the surroundings by heat
• what happens to the energy that isn't stored in as biomass

  it isn't transferred to the next trophic level
• what happens to the energy that is stored as biomass

  some will go to the next trophics level but it doesn't all get transferred because not all of the organism has been eaten(e.g. bones) and because not all of it can be digested when eaten
• what happens to the undigested material

  is lost from the food chain in faeces
• why do you hardly get food chains with more than 5 trophic levels?

  so much energy is lost at each stage that there's not enough to support more organisms.
• what do pyramids of biomass show

  how much creatures at each level of a food chain would weigh if you put them together- also shows how much energy there is at each stage in the food chain
• what happens each time you go up one trophic level

  the mass of the organisms go down because most of the biomass(energy) is lost and so does not become biomass in the next level up. This is why it has a pyramid shape
• what is the order of pyramid biomass (top to bottom)

  tertiary consumer

  secondary consumer

  primary consumer

  producer
• rules for drawing biomass

  bars equally spread around midpoint

  bars touching

  producer at bottom

  length of each bar is proportional to the amount of biomass available at each trophic level
• advantage and disadvantage of pyramid of biomass

  a: takes into account the sizes of the organisms which usually results in pyramid shape

  
  

  d: organisms need to be killed and only sample data can be used
• how to calculate efficiency of energy transfers between trophic levels

  efficiency =

  (energy transferred to next level / energy available before) X 100