Topic 7 - Ecology and Material Cycles Flashcards
(47 cards)
population
total number of organisms of one species living in habitat
community
total number of organisms of all species living in a habitat
ecosystem
a community of organisms along with abiotic parts of their environment
what is interdependence?
when species in an ecosystem depend on each other for resources
- a change in population of one species can have a big effect on another species
mutualism
a relationship between two organisms from which both benefit
parasitism
a relationship between two organisms from which the parasite takes what it needs but host doesn’t benefit
abiotic factor
- a non living factor that affects the population of species and therefore the ecosystem
biotic factor
- a living factor that affects the population of species and therefore the ecosystem
4 examples of abiotic factors
- temp
- light intensity
- amount of water
- level of pollution
competition
when organisms within a community are in competition for limited resources so they can reproduce and survive
predation
as the population of prey increase the population of predators increase
as population of predators increase the population of prey will decrease
what is meant by the distribution of organisms?
where in the ecosystem that organism is mostly found ( which habitat )
2 main ways to study distribution of organisms
- quadrats ( random block sampling )
- transects
what are quadrats?
- a square frame enclosing a known area
- divided into smaller sub-squares making it easier to count organisms
Method 1 : Quadrats
- divide area into grid and use RNG to pick random co-ordinates
- place a quadrat down on that co-ordinate within first sample space
- count abundance of species within the quadrat
- repeat steps 1- 3 for that sample space and record mean for the s.s
- repeat above steps for other sample spaces
when do you use transects?
when abiotic factors change gradually across a habitat which is an environmental gradient
Method 2 : Transects
- mark out a line ( environmental gradient ) in the sample space using a tape measure
- place quadrats along the line and count abundances of organism as you go along
- record other relevant abiotic factors
- repeat above steps placing quadrats next to each other in a line
energy transfer in food chains
energy is transferred through food chains when organisms eat the biomass of other organisms.
how is energy lost from food chains?
- at each trophic level, animals need to respire to transfer energy to life processes
- energy transferred to surroundings by heat
- undigested material lost in faeces
- not all of the organism is eaten like bones
why are shorter food chains better?
- more efficient for top consumers
- less energy is lost/wasted at each trophic level
- fewer t.l better
what is biodiversity? Why is it so important?
- variety of living organisms in an ecosystem
- ecosystems with a higher biodiversity can adapt to changes more easily
- biodiverse ecosystems have fewer species that rely on just 1 organism
3 ways humans reduce biodiversity
- eutrophication
- fish farming
- introduction of non indigenous species
explain why the sun is needed at the start of all food chains?
- it provides energy needed for producers / green plants
- (which are at the start of the food chain), to photosynthesise
- the plant produces biomass
- which is passed on through the food chain by animals eating each other
eutrophication (part 1: algal blooms )
- farmers put fertilisers which are rich in nitrates on their fields
- heavy rain can wash excess nitrate ions into rivers. this process is called leaching and causes eutrophication
- excess nitrates encourage algae to reproduce rapidly
- forms algal blooms which prevent light from reaching underwater plants
