Ecosystems and Material Cycles Flashcards
What is biodiversity?
the variety of living organisms in an ecosystem - this variety is affected by human interactions
What positive impact do humans have on biodiversity?
- conservation schemes
- reforestation
What negative impact do humans have on biodiversity?
- using fertilisers (leading to eutrophication)
- making fish farms
- introducing non-indigenous species
How does eutrophication impact biodiversity?
- too much fertiliser is applied, it rains and nitrates from the fertilisers find their way into bodies of water
- this leads to eutrophication (an excess of nutrients in the water)
- nitrates cause algae to grow and cover the water surface - so they will block out light to the rest of the species
- plants can no longer photosynthesise (as sunlight doesn’t reach them) - causing them to die
- The dying plants provide food to microorganisms which will thrive and use up oxygen
- this causes organisms that rely on oxygen for survival e.g. fish to die too
What is eutrophication?
An excess of nutrients in water - leading to reductions in biodiversity
How do fish farms reduce biodiversity?
- eutrophication - food is added to nets of fish in open water - creating huge amounts of waste which leaks into the open water - causing eutrophication/death of wild species
- farms act as a breeding ground for parasites which can then affect wild animals
- wild predators are attracted to the nets and get caught
- if farmed fish escape - causing problems for wild animals as non-indigenous species are introduced
How can the fish farm problem be reduced?
Fish can be kept in tanks rather than in open water
How are non-indigenous species introduced to areas?
Intentionally - e.g. for food or hunting
Unintentionally - e.g. as a stowaway in international cargo
How does the introduction of non-indigenous species reduce biodiversity?
- compete with indigenous species for resources - sometimes they are better at is so out-compete species - decreasing their numbers e.g. crayfish were introduced to the UK but they prey on and out-compete many river species
- can bring new diseases to a habitat which can affect and kill indigenous species
What are the levels of organisation in an ecosystem?
- individual - a single organism
- population - one species in a habitat
- community - all species living in a habitat
- ecosystem - a community of organisms with abiotic conditions
What is interdependence?
when organisms in a community depend on each other in order to survive - this means that a change in the population of one species can have a massive impact on other species in a community
What is mutualism?
A relationship between two organisms from which both organisms benefit
Give an example of a mutualistic relationship
bees and flowering plants - bee visits plants to collect nectar and plants are helped with reproduction (pollen transferred to other plants)
What is parasitism?
An organism that lives very closely with a host species - the parasite takes what it needs to survive but the host doesn’t benefit
Give an example of parasitism
fleas are parasites of mammals e.g. dogs - the fleas feed on their host’s blood but offer nothing in return
What causes environmental changes to a community?
abiotic and biotic factors
How do abiotic factors effect communities (4)?
- temperature
- amount of water
- light intensity
- levels of pollutants
Give an example of how temperature affect a community
distribution of bird species in Germany changing due to increased temperature - more european bee-eaters (a mediterranean species)
Give an example of how water levels affect a community
daisies grow best in slightly damp soils - population will decrease when these become waterlogged/too dry
Give an example of how light intensity affect a community
trees grow - providing more shade so grasses are replaced by fungi that grow in darker conditions
Give an example of how pollutant levels affect a community
lichen cant survive if sulfur dioxide concentration is too high
How do biotic factors effect communities (2)?
- competition
- predation
How does competition affect communities?
red and grey squirrels compete for the same resources - red squirrel population decreases as a result
How does predation affect communities?
if the number of lions decreases the number of gazelles might increase
What are some threats to biodiversity?
H - habitat destruction I - invading species P - population increase P- pollution O - overexploitation
What are the methods used to conserve biodiversity (3)?
- Reforestation
- Conservation schemes
- Maintaining biodiversity
What is reforestation?
when a deforested area is replanted with new trees
How does reforestation conserve biodiversity?
- large variety of trees means large biodiversity (so reforestation programmes need to be carefully planned)
- reduces carbon dioxide concentrations
- soil erosion is reduced as tree roots bind soil together
- affects local climate e.g. by reducing the range of temperatures in an area
How do conservation schemes prevent species from dying out (3)?
- protecting natural habitats
- protecting species in safe areas outside of their natural habitats (e.g. captive breeding programmes)
- seed banks used to store and distribute seeds of endangered plants
What are the benefits of maintaining biodiversity?
- protecting human food supply quality (e.g. overfishing has reduced fish supplies and conservation schemes can combat this)
- ensuring minimal damage to food chains (one species extinction has knock on effect to others)
- providing future medicines (many medicines come from plants - undiscovered plant species may contain new medicinal chemicals)
- cultural aspects (species may be important in national/cultural heritage e.g. bald eagle being conserved in the USA)
5, Ecotourism (people drawn to unspoilt landscapes with variety of species - ecotourism brings money into biodiverse areas) - provides new jobs e.g. in ecotourism and conservation schemes
What do you use to study the distribution of small organisms?
a quadrat - a square frame that encloses a known area (e.g. 1m^2)
How do you use a quadrat to compare how common an organism is in two areas?
- place a 1m^2 quadrat on the ground at a random point within the first sample area (could be found by dividing the sample area up and using a random number generator to pick coordinates - this removes bias and makes sure the results are representative of the whole sample area)
- count the organisms within the quadrat
- repeat all this a few times
- work out mean no. of organisms per quadrat in this sample area
- repeat all this but in the second sample area
- compare the means
How do you estimate population size from a small sample area?
by scaling it up - find mean number of organisms per m2 and multiply the mean by the total area (obvious)
What do you use to study how distribution of organisms changes along a gradient
a belt transect - quatrats laid out along a line (e.g. in an area where abiotic factors change)
How do you use a belt transect to study distribution of organisms along a gradient?
- mark out a line in the area you want to study (e.g. from hedge to middle of field)
- collect data along this line using quadrats - counting all organisms in a quadrat or estimating percentage cover (how much of the are the organism covers)
- repeat this several times and then find the mean no. of organisms (of mean percentage cover) per quatrat
- data e.g. mean height of plants or abiotic factors in each quadrat can also be recorded
- plot graphs to see if changing abiotic factors correlates to a change in species distribution
What is an ecosystem?
all the organisms living in an area, with all the non-living conditions
How are materials recycled in an ecosystem?
- living things are made up of elements they take from the environment (e.g. plants take in carbon, oxygen and nitrogen) - these elements are converted into complex compounds (carb, protein and fat) that make up organisms - elements are passed along the food chain when animals eat each other - waste products and dead organisms are broken down my decomposers (e.g. microorganisms) - returned to the soil or air ready to be taken by plants and put in the food chain
What is an example of how a material can be recycled in an ecosystem?
The Carbon Cycle
How is carbon recycled?
- plants use the carbon from CO2 to make carbs, fats and proteins (through photosynthesis)
- animals eat plants - passing the carbon compounds to animals in a food chain
- plant/animal respiration releases CO2 back into air
- animals die and decomposed by microorganisms that release CO2 by respiration as they break down the material - decomposition maintains habitats e.g. nutrients are returned to soil and waste products dont pile up
- useful plant/animal products e.g. wood are burned (combustion) and more CO2 is released
What is the water cycle?
- solar energy makes water evaporate from land, sea, and plants (transpiration) turning it into water vapour
- warm water vapour is carried upwards where it cools and condenses to form clouds
- water falls from clouds as precipitation, providing organisms with fresh water
- water eventually drains into the sea and the process starts again
When do droughts occur?
when there isn’t enough precipitation in area
What methods can be used to produce potable water in areas of drought?
desalination (removing salts from water) - e.g. by distillation or reverse osmosis
How is thermal desalination used to produce potable water from salt water?
- in thermal desalination (distillation), water is boiled in a large enclosed vessel so that it evaporates - steam rises and travels down a pipe at the top of the vessel and condenses into pure water, the salt stays at the bottom
How does reverse osmosis work?
(a type of desalination)
- salt water is treated to remove solids and is then fed at a high pressure into a vessel containing a partially permeable membrane
- the pressure causes the water molecules to move in the opposite direction to osmosis (because it moves from high-low Salt concentration)
- as the water molecules are forced through the membrane, the salts are left behind, removing them from the water
How much of the atmosphere is nitrogen gas and what are its properties?
78% nitrogen gas - very unreactive so can’t be used directly by plants and animals, yet it is needed for making proteins for growth
How does the nitrogen cycle work?
- Nitrogen Fixation occurs: nitrogen is turned into mineral ions (e.g. nitrates) through:
- lightning (so much energy in a lightning bolt that its enough to make nitrogen react with oxygen in the air) and
- nitrogen-fixing bacteria (by turning ammonia in decaying matter into nitrites and then into nitrates) - plants absorb these mineral ions from the soil and use the nitrogen to make proteins - nitrogen is passed along the food chain in the form of proteins
- decomposers break down proteins in dead organisms and urea in animal waste into ammonia (which is then used by the nitrifying bacteria) - returning nitrogen to the soil (recycling nitrogen)
- nitrogen-fixing bacteria turns atmospheric N2 into ammonium ions
- denitrifying bacteria turns nitrates back to N2 gas (no benefit to organisms, often found in waterlogged soils)
- some nitrogen-fixing bacteria live in the soil, some live in nodules on the roots of legume plants - they have a mutualistic relationship as the bacteria get food and the plant gets nitrogen ions to make into proteins - when these plants decompose, the nitrogen stored in them and their nodules are returned to the soil
Why must farmers increase the amount of nitrates in soil?
crops take up nitrates from the soil as they grow but they are harvested rather than left to decompose the the nitrogen isn’t returned to the soil
How do farmers increase the amount of nitrates in the soil?
- crop rotation (different crops are grown each year in a cycle - usually including a nitrogen-fixing crop e.g. peas/beans which put nitrates back into the soil for crops the following year)
- fertilisers (spreading manure/compost recycles the nutrients left in plant/animal waste and returns them to the soil through decomposition - artificial fertilisers are also used but can be expensive)
What are the four different types of bacteria involved in the nitrogen cycle and what do they do?
- decomposers (decompose urea and proteins into ammonia which forms ammonium ions that plants use)
- nitrifying bacteria (turns ammonia in decaying matter into nitrites and then nitrates)
- nitrogen-fixing bacteria (turn atmospheric N2 into ammonia which forms ammonium ions)
- denitrifying bacteria (turns nitrates back to N2 gas, doesn’t benefit living things and is often found in waterlogged soils)
