ecology

• ECOSYSTEM

  the interaction of a community of living organisms with the non-living parts of their environment
• population

  all the organisms of a particular species that live in the habitat
• community

  all the populations of different species that live together in a habitat
• habitat

  where an organism lives
• interdependence

  all species depend on other species in some way
• structural adaptations


  physical features
• behavioural adaptations

  the way an organism behaves or acts
• functional adaptations

  processes inside an organism - in their metabolism
• extremophiles

  bacteria and archaea which live in extreme environments: areas of high pressure ,high temp, polar environments etc
• A model that shows how energy passes from organism to organism is called a food chain.
• Organisms at the very start of a food chain that can create glucose using photosynthesis are known as producers.
• primary consumers feed on producers
• Tertiary consumers are organisms that eat secondary consumers. 
• As energy passes along a food chain, most of the energy is lost
• what is a predator?


  An animal that hunts and kills other animals for food
• An organism that is killed and eaten by a predator is known as prey.
• Quadrats are square frames, that have been subdivided into lots of smaller squares. We can use them to sample a habitat and estimate the size of a population.
• Transects are used to observe and record changes in species distribution across an area.
• why is recycling nutrients important for all living organisms?

  It provides the nutrients that living organisms use to grow and reproduce
• Water cycle

  1. Water from lakes, rivers, oceans, and the soil, evaporates into water vapour, and rises into the atmosphere.
  2. Water can also evaporate from plants in a process called transpiration.
  3. As the water vapour accumulates it can condense to form clouds.
  4. Later, the water will fall as rain, which we call precipitation.
  5. The water will then seep into the soil, flow into rivers or lakes, and be taken up by plants. 
  6. The whole cycle then repeats over and over. 
• Evaporation requires energy
• Which three processes in the carbon cycle release carbon dioxide into the atmosphere?


  combustion, decomposition, respiration
• carbon cycle

  1. Carbon enters the atmosphere as carbon dioxide from respiration and combustion.
  2. Carbon dioxide is absorbed by producers to photosynthesise - to produce glucose.
  3. Animals feed on plants, passing the carbon compounds along the food chain. Most carbon is exhaled as carbon dioxide during respiration. they eventually die.
  4. Dead organisms are eaten by decomposers and carbon in their bodies is returned to the atmosphere as carbon dioxide. In some conditions decomposition is blocked, plant and animal material may then be available as fossil fuel in the future for combustion.
• what is decay?


  The breakdown of organic matter by the action of decomposers
• Detritus feeders


  small animals like worms and woodlice that feed on dead organic matter.
• how does oxygen affect the rate of decomposition?

  Higher oxygen ➔ more aerobic respiration ➔ more energy available ➔ faster growth and decomposition 
• how does temperature affect the rate of decomposition?

  Higher temperature ➔ particles have more kinetic energy & enzymes are closer to optimum temperature ➔ higher rate of reactions ➔ more decomposition 

  However, if temperature rises too high, it will denature enzymes, decreasing the rate of reaction and therefore decreasing the rate of decomposition.
• how does water content affect the rate of decomposition?

  
  

  Decomposers need water to survive, so the rate of decomposition increases in moist conditions. 

  However, if the soil becomes waterlogged then the oxygen levels will fall, which will decrease the rate of decomposition. 
• Decomposers need water to survive, so the rate of decomposition increases in moist conditions. 

  However, if the soil becomes waterlogged then the oxygen levels will fall, which will decrease the rate of decomposition. 
• Biogas generators are large containers in which animal or plant waste is left to decay anaerobically. Importantly, there cannot be any oxygen in the container. If there is oxygen, the microorganisms will respire aerobically and won't produce as much methane. Once the biogas is removed from the tank, a sludgy material is left over, which contains a high density of useful minerals. This can be spread on fields like fertiliser. 
• what is biodiversity?


  the variety of living things on earth, or within a particular ecosystem
• why is maintaining a high biodiversity important?

  200,000 species are pollinators, more than half of new medical drugs are derived from living organisms, it increases the stability of the ecosystem so that changes are less likely to have adverse effects
• Which two of the following substances contribute most to water pollution?

  fertiliser from agriculture, sewage from cities
• which substances contribute the most to air pollution?

  smoke from combustion, acidic gases from burning fossil fuels
• what substances contribute most to land pollution?

  nuclear waste and landfill
• breeding programmes

  reduce the chance they'll go extinct, breeding in captivity builds up numbers and increases the population, maintains biodiversity
• field margins (strips around the field where anything can grow) and hedgerows are used by farmers to increase biodiversity as it provides new habitats and different food sources
• An alternative to breeding programs could be to make the habitat a protected area. This would make the habitat safe so that the species could recover naturally. 
• greenhouse effect

  1. Solar radiation from the sun passes through the atmosphere and hits the earth.
  2. Some of this energy is reflected straight back towards space, while some is absorbed by the earth and then reemitted towards space.
  3. Some of the reemitted energy makes it all the way to space, but much is absorbed by small molecules called greenhouse gases. 
  4. These molecules then reemit the energy and the whole process of absorption and emission can happen over and over again. 
  5. This trapped energy keeps the atmosphere warmer and more stable than it would otherwise be. 
• problems with deforestation

  1. There will be fewer trees carrying out photosynthesis and absorbing carbon dioxide from the atmosphere. This means there is more carbon dioxide contributing to global warming. 
  2. Deforestation often involves burning the trees, which releases carbon dioxide into the atmosphere.
  3. It destroys animals' habitats, meaning that fewer species can survive. This reduces biodiversity.