biology - paper 2 (ecology)

• habitat


  specific area where an organism lives which provides it with its resources
• population


  all organisms of one species living in same habitat
• community


  all populations of different species that live in same habitat and interact with each other
• abiotic factors


  non-living
• biotic factors


  living factors including all organisms
• ecosystem


  interaction of community of living organisms and non-living
• resource competition

  • organisms adapted to enviroment = survive, reproduce and compete
  • resources limited = organisms need to compete to survive and reproduce
  • plants = light, water, space and mineral ions
  • animals = food, water, mates and territory
• interdependence and competition 


  all organisms relying on each other to survive
• abiotic factors - non-living

  • moisture levels = plant hydration and animal water sources
• abiotic factors - non-living

  • moisture levels = plant hydration and animal water sources
  • light intensity = photosynthesis
  • temperature = metabolic rates
  • carbon dioxide levels = photosynthesis
  • wind intensity and direction = spread seeds
  • oxygen level = aquatic organisms respiration
  • soil pH and mineral content = plant nutrient/growth
• biotic factors - living

  • new predators = alter survival and reproduction
  • competition = multiple species need same limited resources
  • new pathogens = disease reduce population
  • availability of food = affects growth and reproductive success
• adaptations

  • structural = physical attributes: shape, colour, survival
• adaptations

  • structural = physical attributes: shape, colour, survival
  • behavioural = actions to survive
  • functional = bodily functions: metabolism, reproduction
• extremophiles

  bacteria adapted to living in extreme conditions
• food chains

  1. producers = plants = organisms create own food through photosynthesis
  2. primary consumers = herbivores
  3. secondary consumers = carnivores or omnivores
  4. tertiary consumers = top of food chain, no natural predators
• biomass


  total mass of living material

  represents amount of energy available

  organisms at top of food chain receive least amount of biomass from food
• required practical - quadrats

  1. place quadrat at random point
  2. count daises in quadrat
  3. repeat process several times
  4. calculate mean number $population =$$mean number of organisms per m^2 x total area of location m^2$
• water cycle

  1. energy from sun heats water in land and sea = evaporate and turn into water vapour
  2. transpiration = water evaporates from plants
  3. water vapour rises and condenses = clouds
  4. precipitation = rain
  5. water absorbed by soil
  6. animals and plants use water for chemical reactions necessary for life and return water to soil by sweating and urinating
  7. run off = water isn't absorbed by soil
  8. all water drains back into sea, cycle begins and starts with evaporation
• Carbon cycle


  1. CO2 removed from atmosphere by plants during photosynthesis

  2. Carbon used to make glucose and turned into organic materials --> carbs and fats

  3. Plants respire returning carbon to atmosphere as CO2

  4. Plants consumed by animals = carbon becomes part of animals bodies and moves through food chain

  5. Animal respiration = carbon returned to atmosphere as CO2

  6. Upon death plants, algae and animals broken down by microorganisms = DECOMPOSERS = release CO2 during respiration

  7. Plants and animals buried and exposed to high temperatures they turn to fossils fuels

  8. Burning fossil fuels (combustion) releases CO2 back

  9. Whole cycle repeats
• Carbon cycle is a process that repeats
• biodiversity 


  variety of different organisms on earth or in an ecosystem
• high biodiversity

  • crucial for stability of ecosystems
  • reduces dependence of one species on food and shelter
  • vital for human survival
  • human activities --> global warming, deforestation
• population growth and environmental impact

  population increasing rapidly

  advancements in medicine, farming and standard of living

  reduced deaths from diseases and hunger

  pressure on enviroment people consume more resources

  demand for raw materials for luxuries is increasing

  materials being used up faster than they are being replaced --> not sustainable
• escalating waste production

  • industrial waste = pollute lakes and rivers
  • agricultural chemicals = fertilisers = water pollution
  • solid waste = landfills filling up
  • air pollution = smoke, acid gases = acid rain = damage ecosystems
• problems from deforestation

  • less carbon dioxide taken in = trees absorb carbon dioxide during photosynthesis = less co2 removed from atmosphere
  • more carbon dioxide in atmosphere = trees store carbon in wood
  • less biodiversity = forests are home to many species = extinction
• peat bogs


  unique areas of land found in waterlogged and acidic areas
• why peat bogs are essential

  • acidic conditions means plant material doesn't fully decay --> lack of oxygen
  • partially decomposed plant matter becomes peat = carbon store
  • instead of releasing carbon into atmosphere the peat locks it away
  • bogs are crucial habitats for diversity of species maintaining biodiversity
• peat bogs face threats due to human activity

  • drained for farming = dries peat and leads to its decay = releasing stored carbon
• destruction of peat bogs negative impacts

  • contribute to global warming - release carbon dioxide
  • extraction not sustainable
  • loss of habitats reducing biodiversity
• global warming

  • carbon dioxide, methane and greenhouse gases accumulate in atmosphere and trap sun's heat
  • balance of energy from sun and energy radiates back into space
  • balance upset = global temperature rises
  • gases = act as insulating layer = allows sunlight in but not back out into space
• consequences of greenhouse effect

  • sea levels rise = melting of ice caps
  • increased flooding = higher sea levels
  • shifting ecosystem = ecosystems change
  • health impacts = illness
  • biodiversity loss = species can't adapt
• minimise effects on ecosystems and biodiversity

  • breeding programs = prevent endangered species from becoming extinct by breeding them
  • habitat protection = regenerating coral reefs and rainforests
• balancing biodiversity with human needs

  • economic factors = expensive
  • food security = protect crops instead for food
  • development = high demand for housing and agriculture