topic b7- ecology

• habitat

  the place an organism lives
• population

  all the organisms of one species living in a habitat
• community

  the population of different species living in a habitat
• abiotic

  non-living factors of the environment e.g. temperature
• biotic

  living factors of the environment e.g. food
• ecosystem

  the interaction of a community of biotic with the abiotic parts of their environment
• plants need

  • light
  • space
  • water
  • mineral ions from the soil
• animals need

  • space (territory)
  • food
  • water
  • mates
• plants and animals

  compete with the other species for these resources
• interdependence

  when a species depends on other species for resources e.g. food, shelter, seed dispersal, pollination
• stable communities

  population size is constant
• abiotic (non-living) factors

  • moisture level
  • light intensity
  • temperature
  • CO2 level (plants)
  • wind intensity + direction
  • 02 level (aquatic animals)
  • soil pH
  • mineral content
• a change in the environment could be an increase or decrease in an abiotic factor
• biotic (living)

  • new predators arriving
  • competition
  • new pathogens
  • availability of food
• a change in the environment could be the introduction of a new biotic factor
• structural adaptations

  features of an organisms body structure
• structural adaptations

  • camouflage- stop predators attacking them e.g. fox
  • thick layer of fat- to retain heat e.g. whale
  • thin layer of fat- to lose heat e.g. camel
• behavioural adaptations

  • way an organism behaves
  • e.g. birds migrate to warmer climates in the winter to avoid the cold conditions
• functional adaptations

  • reactions occurring inside the organism's body
  • conserve water -> very little sweat -> small amounts of concentrated urine
  • hibernation -> lower metabolism -> conserve energy
• extremophiles

  • organisms adapted to live in very extreme conditions
  • e.g. high temperature, high pressure, high salt concentration
• food chains

  show what's been eaten in an ecosystem
• food chain

  • producer- e.g. a plant or an algae that makes glucose
  • biomass
  • primary consumer- eat producers
  • biomass
  • secondary consumer- eat primary consumer
  • biomass
  • tertiary consumer- eat secondary consumer
• food chain

  dandelions -> rabbit -> fox
• predator

  a consumer that kills and eats other animals (prey)
• biomass

  the mass of living material
• as the population of predators increase

  the number of prey decreases
• if the population of prey increases

  so will the population of the predators
• using quadrats

  gives quantitative data (numbers) about the distribution
• using quadrats

  1. place a 1m^3 quadrat on the ground at a random point within the first sample area e.g. use a random number generator
  2. count all the organisms within the quadrat
  3. repeat steps 1 and 2 10 times
  4. workout the mean number of organisms per quadrat in the first area:

  • mean= total number of organisms/ number of quadrats

  1. repeat steps 1-4 in the second sample area
  2. finally, compare the two means
• using transects

  shows the distribution of an organism along a line
• using transects

  1. mark out a line in the area you want to study using a tape measure
  2. then collect data along the line
  3. you can do this by counting the number of organisms that touch the line
  4. or you can use quadrats that are placed next to each other along the line
• the water cycle

  1. energy from the sun makes water evaporate making water vapour
  2. the water vapour is carried upwards when; when it gets higher up it cools and condenses to form clouds
  3. water falls from the clouds as precipitation (rain) onto land, where it provides fresh water for plants and animals
  4. it then drains into the sea and the process starts again
• the carbon cycle

  elements are cycled back to the start of the food chain by decay
• the carbon cycle- part 1

  1. co2 is removed from the atmosphere by green plants and algae during photosynthesis; the carbon is used to make glucose
  2. when the plants respire some carbon is returned to the atmosphere as CO2
  3. when the plants are eaten by animals, some carbon becomes part of the fats and proteins; the carbon then moves through the food chain
  4. when the animals respire some carbon is returned as CO2 to the atmosphere
• the carbon cycle- part 2

  5. when plants + animals die other animals + microorganisms eat their remains; when they respire CO2 is returned to the atmosphere

  6. animals also produce waste that is broken down by microorganisms

  7. the combustion of fossil fuels also releases CO2 back into the air

  8. so the carbon is being cycled constantly
• biodiversity

  the variety of different species within an ecosystem
• 1. high biodiversity (lots of species) ->
  2. reduced dependence of one species on another for things like food, shelter and the physical environment ->
  3. stable ecosystems
• human actions are reducing biodiversity e.g. deforestation, global warming

  for human species to survive, a high level of biodiversity is required
• as the population increases, more pressure is put on the environment

  as we make more things, more waste is produced
• waste

  1. water, sewage and toxic chemicals pollute lakes and rivers
  2. land, nuclear waste is buried underground
  3. air, smoke and acidic gases pollute the air e.g. acid rain