biology unit3

• organisms which can interbreed to produce fertile offspring are described as a species
• a population is the number of any one species in an area
• a community is all of the different species living in an area
• an ecosystem consists of all the community of organisms living in a habitat and the non living components with which they interact
• biodiversity is a term used to describe the variety (and number) of living organisms in a particular ecosystem or area
• species can be described based on how and what they obtain as their food
• a producer is a green plant which makes its own food through the process of photosynthesis
• a consumer is an organism which eats other organisms
• consumers can be described based on which type of organisms they eat:

  herbivores-organisms eat plant materials

  carnivores-organisms eat other animals

  omnivores-organisms eat both plant and animal materials
• organisms which hunt and kill other animals are known as predators
• organisms which are hunted and killed are known as prey
• a food chain is used to show the feeding relationships between organisms. it represents the order in which energy is transferred from one organism to another
• the arrows in a food chain represent the direction of energy flow
• food webs show feeding relationships between organisms in many different linked food chains
• a niche is a role an organism plays within a community
• an organism's niche can include:

  
  

  how the organism makes use of resources in its ecosystem (light and nutrient availability)

  the conditions it can tolerate (temperature)

  how the organism interacts with other organisms in the community (competition, parasitism, predation)
• Red Fox

  
  

  predator which is active at night

  feeds on small mammals, insects, amphibians, and fruit

  provides blood for parasites such as blackflies and midges

  in competition with badgers
• when resources are in short supply, competition occurs
• plants compete for:

  water

  light

  minerals

  space
• animals compete for:

  food

  water

  mates

  territory
• there are 2 types of competition
• interspecific competition occurs amongst individuals of different species for one or a few resources the require
• intraspecific competition occurs amongst individuals of the same species and is for all resources required, intraspecific competition is more intense than interspecific competition
• distribution describes where organisms are found within a particular area
• biotic factors are living factors which affect an organisms distribution
• biotic factors:

  disease

  food availability

  grazing

  predation

  competition for recources
• abiotic factors are non living factors which affect an organisms distribution
• abiotic factors:

  light intensity

  moisture

  pH

  temperature
• if food availability, disease, competition, predation, grazing is higher than the number of species, the biodiversity in an area will decrease
• if light intensity is high, plant will grow and thrive and biodiversity will be high
• the distribution of species is affected by temperature, moisture, and pH, most species surviving with a normal range of these factors
• indicator species indicate the pollution levels or environmental quality by their presence or absense
• blood worms and rat tailed maggots are only found in polluted waters
• mayfly nymphs and fresh water shrimp are only found in clean waters
• lichens are found of tree bark and are only present when pollution levels are low
• instead of counting every single organism we use sampling techniques to produce an estimate number of organisms present
• to ensure enough data is collected to provide a representative result, many samples are taken, which increases reliability of the results
• quadrats are equipment used to estimate the number of plants or slow moving animals in an area
• pitfalls estimate the number of small animals such as invertebrates in a grassy area or in leaf litter
• transect lines are lines across a habitat or part of a habitat