Ecosystems and Material Cycles Flashcards
Individual definition
A single organism
Population definition
All organisms of one species in habitat
Community definition
All organisms of different species in a habitat
Ecosystem
Community of organisms along with all abiotic conditions
Interdependence definition
Organisms depend on each other (e.g. for food) as to survive and reproduce
Changes in a population of one species can impact other species in same community
Mutualism definition
Relationship between two organisms that benefits both
Examples of abiotic factors
Temperature
Amount of water
Light intensity
Levels of pollutants
Examples of biotic factors
Competition
Predation
Impacts of environmental changes
Population size may change
Distribution of population may change
Quadrant definition
Square from enclosing a known area
How to use quadrat to study distribution of small organisms
Place quadrat on ground at random point Count all wanted organisms in quadrat Repeat steps 1 and 2 Work out mean number of organisms within first sample area Repeat 1 to 4 for second sample area Compare the two means
How to estimate population size from small sample area
Scale up (extrapolate) mean to total area of habitat
How to use belt transfers to study distribution along a gradient
Mark out a line in wanted area to study
Collect data along line using quadrats placed adjacently or at regular intervals
Collect data by counting all organisms of wanted species or by estimating percentage cover
Can collect other data e.g. mean height
Repeat steps 1 to 3 and find mean number of organisms
Plot graphs to study distribution and changing abiotic factor
Why most food chains don’t get past 5 trophic levels
Much energy is lost at each trophic level so there is not enough left to support more organisms last 5 trophic levels
Usually fewer organisms at each higher trophic level
How energy is left in the food chain
Respiration
Heat
Inefficiency (e.g. undigested material)
Waste (e.g. not all of organism is eaten)
What pyramids of biomass show
How much each level of food chain would weigh if all put together
Also see how much energy is at each stage (biomass = energy)
Biodiversity definition
Variety of living organisms in an ecosystem
Eutrophication steps
Fertilisers enter water, adding excess nitrates in water
Excess nitrate cause algae to grow fast and block sunlight
Underwater plants can’t photosynthesise and die
Microorganisms feed on decomposing plants and increase in number
Organisms that need oxygen (e.g. fish) due to too many microorganisms using up oxygen too
How fish farms reduce biodiversity
Food added to nets creates huge waste, which can leak in to open water and cause eutrophication
Fish farms can be breeding ground for parasites, which can escape and kill wild animals
Predators can be lured into nets, get trapped and die
Farmed fish can escape and could cause problems for wild populations of indigenous species
How introduction of non-indigenous species can reduce biodiversity
They compete for resources better than indigenous species
Causes natural species to decrease in number or die out
Can also bring new diseases to habitat
