biology topic 7 - ecology

• What is a habitat ?


  the place where an organism lives
• what is population?


  all of the organisms of one species living in a habitat
• what is community ?

  the populations of different species living in a habitat
• what are abiotic factors ?

  non-living factors of the environment e.g temperature
• what are biotic factors ?

  living factors of the environment e.g food
• what is an ecosystem ?

  the interaction of a community of living organisms (biotic) with non living (abiotic) parts of their environment
• what do organisms compete with other species for ?

  same resources
• what do plants need ?

  light,space,water and mineral ions (nutrients) from the soil
• what do animals need?

  space (terrority) , food ,water and mates
• what is interdependence ?


  where in a community , each species depends on other species for things such as food,shelter , pollination and seed dispersal
• what does the interdependnace of all living things in an ecosystem mean ?

  that any major change in the ecosystem such as the species being removed can have far-reaching effects
• organism - black fly larvae

  effect of loss of stonefly larves

  effect on population

  effect of loss of stonefly larves - less competition for algae and more likely to be eaten by predators

  effect on population - increase and decrease
• give example of abiotic factors :

  • moisture level
  • light intensity
  • temperature
  • carbon dioxide level - for plants
  • wind intensity and direction
  • oxygen level - for aquatic animals
  • soil ph and mineral content
• Give examples of biotic factors :

  • New predators arriving
  • competition- one species may outcompete another so that numbers are too low to breed
  • new pathogens
  • availability of food
• a change in environment could be an increase of decrease in an abiotic factor e.g an increase in temperature. these changes can affect the size of populations in a community. this means they also affect the population sizes of other organism that depend on the,
• a change in the environment could be the introduction of a new biotic factor e.g a new predator or pathogen . these changes can also affect the size of populations in a community which can have knock off effects because of interdependence
• biotic factor increase or decrease : a new predator 


  a new predator could cause a decrease in the prey population

  red and grey squirrels live in the same habitat and eat the same food . grey squirrels outcompete with red squirrels -s o the population of red squirrels is decreasing
• abiotic factor - decrease in light intensity, temperature or level of carbon dioxide

  a decrease in light intensity, temperature or level of carbon dioxide could decrease the rate of photosynthesis in a plant species .this could affect plant growth and cause a decrease in population size
• abiotic factor - decrease in mineral content 


  a decrease in the mineral content of the soil (e.g a lack of nitrates) could cause nutrient deficiencies. this could also affect plant growth and cause a decrease in population size
• list 3 adaptations :

  • structural
  • behavioural
  • functional
• what are structural features ?


  features of an organism’s body structure - such as shape or colour
• give examples of structural adaptations:

  • Artic animals like the artic fox have white fur enabling them to camouflage against the snow. this helps them avoid predators and sneak up on prey
  • animals that like in cold places like whales have a thick layer of blubber (fat) and a low surface area to volume ratio to help them retain heat.
  • animals that live in hot places like Camels have a thin layer of fat and a rage surface area to volume ratio to help them lose heat
• what are behavioural adaptations?

  ways that organisms behave - many species e.g swallows migrate to warmer climates during the winter to avoid the problems of living in cold conditions
• what are functional adaptations ?

  things that go inside an organisms body that can be related to reproduction and metabolism
• give examples of functional adaptations :

  • desert animals conserve water by producing very little sweat and small amounts of concentrated urine
  • brown bears hibernate over winter- they lower their metabolism which conserves energy, so they don’t have to hunt when there’s not much food about
• what are extremophiles and give an example ?

  organisms that are adapted to live in very extreme conditions - bacteria

  some can live at high temperatures (e.g in hot volcanic vents) and others can live in places with a high salt concentration (e.g very salty lakes) or at high pressure (e.g deep sea vents)
• explain one structural adaptation a penguin has to its environment?

  • has flippers so that it can swim for food
  • a thick layer of fat so it retains heat
  • a low surface area to volume ratio so it retains heat
• what do food chains show ?


  what’s eaten by what in an ecosystem
• what do food chains start with ? what?

  • food chains start with a producer
  • producers make (produce ) their own food using energy from the sun
• what are producers eaten by ?

  primary consumers
• what are primary consumers eaten by ?

  secondary consumers
• what are secondary consumers eaten by ?

  tertiary consumers
• what are predators ?

  consumers that hunt or kill other animals
• what are producers usually ?

  green plants or algae - they make glucose by photosynthesis
• 1.what happens when a green plant produces glucose ?

  2What are these biological molecules?

  1. some of it is used to make other biological molecules in the plant
  2. these biological molecules are the plants biomass- the mass of living material
• when is energy transferred through living organisms in ecosystem ?

  when organisms eat other organisms
• the population of any species is limited by the amount of ———

  food available
• if the population of the prey increases , then so will the population of the predator

  However as the population of predators increases, the number of prey will decrease
• using transects practical :

  1. mark out a line in the area you want to study using a tape measure
  2. then collect data along the line
  3. you can do this by just counting all the organisms you’re interested in that touch the line
  4. or you can collect data by using quadrants - there can be placed next to each other along the line or at intervals
• what is the distribution of an organism ?

  where an organism is found