Paper 2 Ecosystems

Question 1

Describe how invertebrate animals are used as water pollution indicators. [2]

Answer 1

some species of invertebrates are only found in unpolluted water and other only in highly polluted water

so by looking at what species are in the water you can see how polluted it is

Question 2

Evaluate the use of indicator species as evidence of pollution. [3]

Answer 2

they are sensitive to pollution so useful indicators of unpolluted areas

if they are absent from an area there might be another reason

measuring numbers over time can indicate changes in pollution

Question 3

Explain why compost heaps produce compost most quickly in sunny places [1]

Answer 3

warmth from the sun will increase the rate of growth of microorganisms in the heap, so they break down the materials in the heap faster

Question 4

Human bodies that are thousands of years old have been found in acid bogs.

They show very little signs of decay. Suggest why. [2]

Answer 4

waterlogged so no oxygen available for microorganisms to respire

acidic so enzymes/bacteria/microorganisms not active/dead