biology (yr9)

• An ecosystem is the interaction between a community of living organisms and their environment, it is two or more populations of organisms (usually more) in their environment.

  • A community is two or more populations of organisms.
  • An ecosystem is two or more populations of organisms.
  • A population is all the organisms of the same or closely-related species in an area.
• Organisms within an ecosystem are all connected within food chains and food webbs.
• The abundance is the number of organisms in an ecosystem and their distribution is affected by...

  • abiotic/non-living factors: light intensity, temperature, moisture, soil pH, minerals, wind intensity and CO2 levels.
  • biotic/living factors: food, predators, pathogens and competition.
• All photosynthesising plants and algae in an ecosystem compete for light, space, water and minerals from the soil. Animals in an ecosystem compete for food, mates and their territory.

  The organisms that is the best-adapted for the environment has the best chance of survival- survival of the fitest.
• Adaptions can be structural- the physical features, which allows them to compete, behavioral- behaviors which give them an advantage or physiological-processes which allow them to compete.
• Extremophiles are organisms that have special adaptions that enable them to live in the most extreme environments, geothermal vents, polar regions and deserts.
• Animal adaptions:

  • thick fur- to keep the animals warm.
  • camouflage- so it cannot be seen by predator or prey.
  • mimicry- looks like a dangerous/poisonous animal.
  • bright colours- warns off predators.
  • spikes/spines/horns- fends off predators.
• In a healthy, balanced ecosystem the number of predators and prey remain fairly constant.
• Usually, (in a graph it shows)

  • the number of predators increase when there is more prey.
  • the number of prey reduces due to there being more predators.
  • the number of predators reduces when there is less prey.
• Biodiversity is specifically the number of different species within a specific ecosystem. As the population grows, the pollution produced increases, causing significant issues.
• Water pollution: eutrophication- fertilisers into lakes and rivers. Toxic chemicals from factories.
• Air pollution-combustion: CO2 contributes to the greenhouse effect which lead to global warming- causing methane of ice caps, rise in the sea levels, change in climate. SO2 and NOx can cause rain. Particulates from smoke can cause smog.
• Land use: more people means more land needed- biodiversity is often significantly reduced when land is cleared for houses, roads, quarrying and farming often by deforestation.
• Human can maintain biodiversity by: introducing breeding programs, making National Parks, replanting hedgerows, reducing deforestation and the release of greenhouse gases.