ecology

• • habitat - place where organism lives
  • population - all organisms of one species living in a habitat
  • community - populations of different species living in a habitat
• • abiotic factors - non-living factors of the environment
  • biotic factors - living factors of the environment
  • ecosystem - the interaction of a community of living organisms with non-living parts of their environment
• Plants compete for:

  • light
  • space
  • water
  • mineral ions (from soil)
• Animals compete for:

  • territory (space)
  • food
  • water
  • mates
• Interdependence is when each species within a community depend on each other for things such as food, shelter, pollination and seed dispersal.
• In some communities, the species and environmental factors are in balance, so populations stay constant - these are called stable communities.
• Abiotic factors

  • moisture level
  • light intensity
  • temperature
  • carbon dioxide level
  • wind intensity and direction
  • oxygen level
  • soil pH and mineral content
• Biotic factors

  • new predators
  • competition - one species may outcompete another
  • new pathogens
  • availability of food
• Adaptations include:

  • structural
  • behavioural
  • functional
• Structural adaptation - features of an organism's body structure like shape or colour

  • artic animals such as the artic fox have white fur to camouflage
  • animals in cold places have thick layers of fat and a low surface area to volume ratio to retain heat
  • animals in hot places have thin layers of fat and a large surface area to volume ratio to lose heat
• Behavioural adaptation


  Ways in which an organism behaves. Many species migrate to warmer climates during the winter to avoid problems in cold conditions.
• Functional adaptation - things that happen inside an organism's body like reproduction and metabolism

  • desert animals conserve water by producing little sweat and small amounts of concentrated urine
  • brown bears hibernate in winter, so they lower their metabolism to conserve energy
• Extremophiles are microorganisms that live in very extreme conditions. For example, they can live in very hot places, very salty places, and high pressure places...
• Food chain

  1. producers (like green plants) make their own food using energy from the sun by photosynthesis
  2. primary consumers
  3. secondary consumers
  4. tertiary consumers
• When a green plant produces glucose by photosynthesis, some of it is used to make other biological molecules - these are the plant's biomass (mass of living material).
• Biomass can be thought of as energy stored in a plant. This energy is transferred through living organisms in an ecosystem where organisms eat others.
• Predators are organisms that eat other organisms (prey). In a stable community, if the population of prey increases, the population of predators also increase. But this then decreases the number of prey, decreasing predators. Predator-prey cycles are always out of phase, and the up and down pattern continues.

  
• Environmental changes causes distribution of organisms to change. These can include:

  • temperature
  • availability of water (can cause animals to migrate)
  • composition of gases (air pollution)
• Environmental changes can be caused by seasonal factors, geographic factors or human interaction.
• Water on Earth is constantly recycled in the water cycle.

  • energy from sun makes water evaporate from land, sea, and plants - transpiration
  • warm water vapour carried upwards and condenses into clouds
  • water falls by precipitation, providing fresh water
  • drains into sea and process starts over

  A) precipitation

  B) condensation

  C) transpiration

  D) evaporation

  
• Plants turn elements like carbon, oxygen, hydrogen and nitrogen from soil and air into complex compounds that get passed up the food chain. These materials are returned to environment in waste products, or when organisms die and decay.
• Materials decay because they're broken down by microorganisms. For decay:

  • moisture
  • aerobic (oxygen rich) conditions
  • warm
  • presence of decomposers
• 1. CO2 removed from atmosphere by green plants in photosynthesis. Carbon is used to make glucose that turns into carbs, fats and proteins
  2. when plants respire, some carbon is returned to atmosphere as CO2

  A) respiration

  B) animal

  C) decay

  D) photosynthesis

  
• 1. when plants are eaten by animals, some carbon becomes fat and protein in body. Carbon moves through the food chain
  2. when animals respire, some carbon is returned to atmosphere as CO2
  3. when plants and animals die, other animals called detritus feeders and microorganisms feed on their remains. When they respire, CO2 is returned

  
• 1. animals also produce waste that is broken down by detritus feeders and microorganisms
  2. combustion of wood and fossil fuels releases CO2

  
• Compost is decomposed organic matter that is used as a natural fertiliser for crops and garden plants. The rate of decay depend on these factors:

  • temperature - warmer temperatures makes decomposing quicker because they increase the rate that enzymes work at.
  • water availability
  • oxygen
  • number of decomposers
• Biogas is produced by anaerobic digestion of organic waste, and is mainly made up of methane. Biogas can be made in a simple fermenter called a digester or generator. These need to be kept at a constant temperature. Biogas cannot be stored as a liquid, so it has to be used straight away.
• Two types of biogas generators

  • batch generators - make biogas in small batches. They are manually loaded with waste
  • continuous generators - make biogas all the time. Good for large-scale projects
• Biodiversity is the variety of different species of organisms on earth or within an ecosystem. High biodiversity is important because it ensure ecosystems are stable due to interdependance.
• The population of the world is rapidly increasing due to advancements in medicine and farming. This puts pressure on the environment as we take resource to survive. People also are demanding a higher standard of living, so more raw materials are being used. Many are used more quickly than being replaced, so we may run out.
• We also produce more waste like pollution, reducing biodiversity

  • water - sewage and toxic chemicals from industry pollute lakes, affecting plants and animals. Chemical used on land can be washed into water
  • land - toxic chemicals for farming. We bury nuclear waste underground, and dump waste in landfills
  • air - smoke and acidic gases can pollute air e.g. sulphur dioxide causing acid rain
• Temperature of earth is in balance with energy from sun and energy it radiates back into space. Atmospheric gasses act as an insulating layer, absorbing most of the energy that would normally be radiated back into space, and re-radiate it in all directions, increasing temperature.
• Greenhouse gases help to retain energy in the atmosphere, but the ones we are concerned about is methane and carbon dioxide. The earth is gradually heating up due to the increase in these gases - global warming (a form of climate change).
• Consequences of global warming - sea levels rising

  • higher temperatures cause seawater to expand and ice to melt
  • started to increase frequency of flooding
  • if sea levels continue to rise, it will be bad for organisms in low-lying areas, and could result in loss of habitat
• Consequences of global warming - changes in species distribution

  • distribution is changing as temperatures increase and amount of rainfall changes
  • species needing warmer temperatures are becoming more wide spread
  • species needing colder temperatures are becoming less spread
• Consequences of GW

  • migration patterns - some birds may migrate further north due to those areas becoming warmer
  • reduction in biodiversity - some species may be unable to survive, and there is a risk of extinction
• Humans reduce the amount of land available by building, quarrying, farming and dumping waste.
• Destruction of peat bogs

  • they are areas of land that are acidic and waterlogged. plants don't fully decay due to lack of oxygen.
  • carbon from plants is stored in the peat instead of being released into the atmosphere
  • peat bogs are often drained for land or fuel
• Peat bogs

  • when peat is drained, it comes into contact with more air so microorganisms start to decompose it
  • when these respire, they use oxygen and release carbon dioxide, contributing to global warming. CO2 is also released when peat is burned.
  • destroying bogs destroys habitats, so reduces biodiversity
• Deforestation is the cutting down of trees. It is done to clear land for animals, or to grow crops.