ecology

• Population


  Number of a species living in one place
• Community


  Number of different species living in the same place
• Habitat


  Place where organisms/population live
• Ecosystem


  All organisms/all species and their physical environment
• Ecology


  The study of the interaction of the organisms in an ecosystem with their environment. This is made up of biotic or living factors and abiotic or non–living factors.
• Invasive species


  Species from a different area that compete/replace the native species
• How to use quadrats

  1. Quadrats must be placed at random

  2. Several same size quadrats must be used to calculate an average

  3. Count the number of organisms

  4. Multiply to get the total in the whole area
• How to use a quadrat to estimate total plant mass in a large area of land

  1. Quadrats must be placed at random

  2. Weigh plant mass in each quadrat

  3. Several quadrats should be used to calculate an average

  4. Multiply to get total mass in the whole area of land
• Biodiversity


  Number and relative abundance of the different species in an ecosystem
• Abiotic factors


  • Non-living factors
• Biotic factors


  • Living factors
• Biotic factors


  • Pathogens (disease)
  • Predation
  • Presence of pollinating insects
  • Invasive species (Competition)
• Abiotic factors


  • light intensity
  • Temperature
  • Water availability
  • Soil conditions (pH, nitrate levels, etc)
  • Oxygen concentration (e.g. in a lake)
• Large areas of the Earth dominated by a specific type of vegetation are called biomes. Temperature grassland and tropical rainforest are two examples of biomes.
• Food chain


  Shows the feeding relationships between trophic levels / Shows how energy is transferred from one living organism to another via food
• Food web


  All of the food chains in an ecosystem
• Trophic level


  Each feeding stage in a food chain/web
• Producers


  Contain chlorophyll inside chloroplasts to absorb sunlight energy to carry out photosynthesis
• Consumers


  An organism that gets its energy by feeding on other organisms (can be primary, secondary or tertiary, depending on where it is in the food chain)
• Herbivores


  Animals that eat producers
• Carnivores


  Animals that eat consumers/other animals
• Decomposers


  Microorganisms (usually bacteria and fungi) that break down / digest dead or waste organic material
• Pyramid of number


  • The size of the bar reflects the number of each species
• Pyramid of biomass


  • The size of the bar reflects the mass (g/kg) of each species
• Why not all the energy available in one trophic level is transferred to the next?
• Carbon cycle


  1. Carbon dioxide is released into the air through respiration, combustion, and decomposition

  2. Carbon dioxide is removed from the air through photosynthesis
• In tropical rainforests, decomposition occurs at a faster rate because it is warmer, there is more moisture, dead matter and decomposers.
• Nitrogen cycle


  1. Nitrogen fixation: Nitrogen fixing bacteria convert nitrogen gas from N2 into nitrates/ammonia/ammonium

  2. Decomposition: Decomposers break down dead animals and plants, releasing nitrogen into the soil as ammonia

  3. Nitrification: Nitrifying bacteria convert ammonium into nitrite or nitrite into nitrate

  4. Denitrification: Denitrifying anaerobic bacteria break down nitrates into nitrogen gas
• Car exhaust fumes contain air pollutants including carbon monoxide and sulfur dioxide.
• Sulphur dioxide and carbon dioxide dissolve in water in air to form acid rain (sulphuric acid and carbonic acid).
• Carbon monoxide


  A harmful air pollutant because it attaches/binds irreversibly to haemoglobin forming carboxyhaemoglobin, which results in less oxygen transport in the blood. Less oxygen results in less aerobic respiration, which can be fatal.
• Greenhouse gases


  Gases that trap heat and contribute to global warming
• Examples of greenhouse gases

  • Water vapour
  • Carbon dioxide
  • Nitrous oxide
  • Methane
  • CFCs
• Human activities that increase greenhouse gases concentrations in the atmosphere

  1. Burning of fossil fuels (coal, oil) in power stations

  2. Exhaust fumes from motor vehicles engines (combustion of petrol)

  3. Fertilisers use

  4. Intensive farming

  5. Aerosol sprays, refrigerators and air conditioning units use

  6. Deforestation
• Human activities that decrease greenhouse gases concentrations in the atmosphere

  1. Reduce use of fossil fuels

  2. Use renewable energy (solar, wind, waves, biofuels)

  3. Reduce deforestation/plant more trees

  4. Travel by public transport (bus, train), bicycle, walking, hybrid cars
• Greenhouse gases


  Gases that trap heat/infrared radiation and prevent it from escaping to space, contributing to the increase in air temperature referred to as global warming
• Consequences of global warming

  • Ice caps melt/rise of sea levels/flooding
  • Climate change/extreme weather
  • Loss of habitat/extinction/effect on food webs/effect on crop growth
• Natural causes of extinction

  • Disease/infection/virus/bacteria
  • Habitat loss/loss of food source/lack of food/food supply
  • Predation
  • Natural disaster/flood/tsunami/meteor/earthquake
• Anthropogenic causes of extinction

  • Hunting/killed by humans
  • Deforestation
• Negative effect of increased levels of CO2 in the atmosphere

  • Greenhouse effect/global warming
  • Ice caps melt/sea levels rise/flooding
  • Climate change/extreme weather
  • Habitat destruction
  • Extinction/effect on food webs
  • Migration/change in distribution/spread of disease/spread of pests