Decomposition

Question 1

if water is polluted what indicator species reinforce this

Answer 1

bloodworms or sludge worms

Question 2

if water quality is good what indicator species show this

Answer 2

stonefly larvae

freshwater shrimps

Question 3

how does water pollution occur

Answer 3

raw sewage or fertilisers (both containing nitrates) are released into a body of water, such as a stream or pond
This causes microorganisms in the water to increase in number
As these microorganisms respire, they use up the oxygen in the water

Question 4

what indicator species show air quality is good

Answer 4

lichen as it is sensitive to sulphur dioxide from cars

and blackspot fungus on rose leaves

Question 5

what are disadvantages of indicator species

Answer 5

can’t give accurate numerical (quantitative) figures for exactly how much pollution is present

Question 6

What does the rate of decay depend on

Answer 6

• temperature - if too high denature if too low slow
• water content - required for biological processes and survive
• oxygen - aerobic respiration

Question 7

how can food be preserved

Answer 7

• storing in fridges lowers temperature and slows does rate of reproduction
• airtight cans and vacuum closed prevent microorganisms from entering and removes air killing microbes
• drying removes water for survival and reproduction and salt wand sugar make lose water by osmosis

Question 8

what is compost and why is it important

Answer 8

natural fertiliser of decomposed organic matter produced quickest when warm moist and plenty of oxygen ensuring recycling of material by plants for growth