B18 - Biodiversity and ecosystems Flashcards
What is biodiversity, and what does it ensure for an ecosystem?
-the variety of all the different species of organisms within an ecosystem
-ensures its stability, as it reduces the dependence of one species solely on another for food/shelter since there are more organisms to depend on
Why is there more pollution, and where can it occur in?
-increase in population and living standards, so more resources are used and also wasted
-water (from sewage/fertilisers)
-air (smoke/GGs)
-land (landfills/toxic chemicals)
What effect does an increasing human population have on ecosystems?
significantly reduces biodiversity by killing animals/plants and reducing habitat space due to humans using it for building/mining/farming/landfills
What is peat?
plant material that is rich in carbon, and can’t fully decay due to the acidic and anaerobic conditions it is formed in
it can’t decay because it is waterlogged and oxygen from the air can’t reach it
Why do we get rid of peat bogs, and why is it bad?
-destroyed for compost
-burnt as fuel (because of methane produced)
-decreases size of habitat and thus biodiversity (it is habitat for many organisms)
-peat’s decay/burning releases CO₂
Why does deforestation occur?
-to get wood/timber
-need land for rice fields/cattle (arable/pastoral farming)
-to grow crops for biofuels (eg fermented sugarcane for ethanol)
try not to mention the other geography reasons for urbanisation and tourism
What are some negative effects that arise due to acid rain?
-plants/animals are damaged (directly or through soil)
-skin irritation
-changes pH of large bodies of water
What effects arise from a change in climate?
-sea levels rising (+oceans release CO₂ as they warm up)
-loss of habitats
-animal migration patterns change
-more severe floods/droughts
-desertification
-food insecurity due to changing rainfall/temperature
(SLAM, DF)
Gases actually dissolve better in colder solvents in contrast to solids, as the increased thermal energy weakens the bonds between the water and gas molecules
How can we maintain biodiversity?
-breeding/regeneration programmes for endangered species and habitats
-reduce CO₂ emissions by some governments
-recycle resources rather than dumping them in landfills
-introducing hedgerows to monoculture farms
-reduce deforestation
Describe the process of eutrophication:
-rainwater causes fertiliser to leach into ground with the water and move into the lake, causing algae to grow a lot (algal bloom)
-they block light for the organisms below and plants die as they can’t photosynthesise, meaning no more oxygen gets produced in the water
-microorganisms use the remaining oxygen for respiration and to decay the plant matter
-everything else (eg fish) dies from a lack of oxygen for respiration
The decomposers using up the remaining oxygen has a larger effect on eutrophication than the plants not being able to photosynthesise to replenish oxygen
Why might many fish die if untreated sewage containing organic matter and bacteria entered the water?
-bacteria decomposes the organic matter, and they respire aerobically which uses up the oxygen in the river
-fish have less oxygen and can’t aerobically respire, so they have a reduced energy supply
-causes death of fish
How can trophic levels be represented?
-numbers showing the level they are at
-eg producer is level 1, primary consumer is level 2 etc
What are decomposers? How do they perform their function?
microorganisms that break down dead plant/animal matter by secreting enzymes into the environment, so that the organic matter gets digested into smaller soluble food molecules can diffuse into the organism
Name 2 examples of decomposers:
-bacteria
-fungi
What is biomass?
the mass of biological organisms
What do pyramids of biomass represent, and what do they look like?
-relative amount of biomass in each trophic level
-always a pyramid shape
Why is this biomass pyramid the most efficient for providing food for humans?
-more biomass transfer between trophic levels, less wasted
-very short food chain
