9 - Ecosystems - Indicators & Decay Flashcards
What are indicator species?
- Species that can give you indicators about pollution levels
How can indicator species suggest polluted water?
- If raw sewage or fertilisers are released into a river, microorganisms will increase and use up the oxygen (eutrophication)
- Invertebrates like bloodworms and sludgeworms have adapted to live in polluted conditions
- Large amounts of these indicate polluted water
How can indicator species suggest clean water?
- Invertebrates like stonefly larvae and freshwater shrimps are good indicators as they’re very sensitive to dissolved oxygen in water
- If you find stonefly larvae, it indicates clean water
How can indicator species suggest air pollution?
- Particular types of lichen are very sensitive to sulfur dioxide in the atmosphere, meaning the number and type of them are good indicators of the level of air pollution
- Bushy lichen need cleaner air than other lichen, like crusty
- Blackspot fungus on rose leaves is also sensitive to sulfur dioxide, so if present = clean air
What are some of the ways you can use indicator species to measure pollution?
- Simple surveys to see if a species is present or absent from an area : tells you simply if an area is polluted, not how polluted
- Counting the number of times an indicator species appears in an area : gives number value, good for comparing how polluted one area is to another
Using indicator species may not always be accurate to exactly HOW much pollution is present
What are some of the ways you can use non-living indicator species to measure pollution?
- Dissolved oxygen meters & chemical tests used to accurately measure the conc of dissolved O in water to show the lvl of pollution
- Electronic meters & lab tests used to accurately measure the conc of sulfur dioxide in air to show lvl of pollution
Why do things decompose?
- Things decompose because of Microorganisms (like soil bacteria and fungi)
- Living things are made of elements taken from around them; when they die/release waste, decomposition returns these elements
How does temperature affect decomposition?
- Warm temperatures increase the rate of decomposition as enzyme-controlled microbes speed up in hotter conditions
- Enzymes will denature if it gets too hot
How does water content affect decomposition?
- Decay is faster in moist environments as organisms involved need water to survive and carry out the biological process
How does oxygen availability affect decomposition?
- The rate increases where there is plenty of oxygen available
- Microorganisms need oxygen for respiration
- Some decomposers don’t need oxygen, but work slower anyways
How does temperature affect decomposition in food preservation?
- Storing food in a fridge lowers the rate that the decomposers can reproduce at
- Freezing food can also stop it entirely
How does water content affect decomposition in food preservation?
- Drying food removes the water microorganisms need to survive/reproduce
- Adding salt/sugar has the same effect ; water lost through osmosis
How does oxygen availability affect decomposition in food preservation?
- Food stored in airtight containers stops microorganisms and oxygen getting in
- Like tin cans; once food in, can is sealed and sterilised to kill any microorganisms present
How is compost made? What are the ideal conditions for it?
- Compost is decomposed organic matter that can be used as fertiliser
- Produced fastest in warm, moist conditions with plenty of water available
How do you calculate the rate of decomposition?
Eg. If asked to calculate rate from a graph, find the amount of time (eg 7 days, 12 hours) then draw a line straight up to the line of best fit
Then divide the amount(of x) by the amount of time that passed
