chapter 12 science

• physical factors (affecting environments)

  1. light
  2. temperature
  3. water
  4. air
  5. minerals
  6. pH (acidity/alkalinity)

  • measured using data loggers, probes
• structural adaptations - physical characteristics or features of an organism that help it to survive

  : porcupine fish (sharp spikes to protect from enemies)
• behavioural adaptations - ways an organism behaves in order to survive

  : clownfish (hides in tentacles of sea anemone)
• population - group of organisms of the same kind
• community - different populations living together in the same habitat
• habitat - place where organisms live and interact
• ecosystem - community of organisms in a habitat that interact with one another and with their physical environment
• ecology - study of the interactions between living and non-living things
• 1.predator-prey relationship

  predator -> animal that lives by killing and eating other animals (eg. eagles)

  prey -> animal that is killed and eaten by another animal (eg. mice)
• 2. mutualism - relationship between two organisms in which both organisms benefit from each other

  : eg. butterflies feed on nectar, help to pollinate flowers
• 3. parasitism - relationship between two organisms in which one benefits at the expense of the other

  : eg. fleas suck on mammals' blood
• symbiosis - overall term to show relationship between organisms
• food chain - feeding relationship between organisms
• food web - made of inter-linked food chains
• producer - any green plants

  : absorb light energy from the sun, make food through photosynthesis, pass on to other organisms
• first trophic level - producers

  second trophic level - primary consumers

  third trophic level - secondary consumers
• respiration

  : releases energy stored in food
• photosynthesis

  : make energy from the sun available to other organisms
• energy loss

  1. heat energy during respiration
  2. in faeces
  3. excretory waste (from chemical reactions) -> eg. carbon dioxide from respiration
  4. uneaten body parts
• motor vehicles

  _emit greenhouse gases, contribute greatly to global warming
• flow of energy

  • producers absorb light energy from sun, used to produce food via photosynthesis (stores chemical potential energy)
  • respire to release energy required for their life processes (eg. transport of substances)
  • consumers obtain energy by feeding on plants or animals, respire to release energy stored in food
  • release energy stored in undigested food, passed out as faeces
  • decomposers feed on remains of dead organisms and faeces, release energy via respiration
• flow of energy

  
  

  : at each stage, about 90% of energy is released into the environment as heat energy

  : last organism in the food chain receives least amount of energy from the sun

  : flow of energy is one-directional or non-cyclical
• flow of nutrients

  • when producers are eaten by consumers, nutrients in them are transferred to the consumers
  • when consumers are eaten by their predators, nutrients in them are passed on
  • decomposers break down faeces of organisms and remains of dead organisms, return nutrients in them to the environment

  : flow of nutrients in an ecosystem is cyclical
• decomposers

  : break down faeces, remains of dead organisms, release nutrients to soil (which are then absorbed by plants)