AQA GCSE Biology (8461), Higher tier · Ecology › Biodiversity and human interaction
Practise Waste management. 11 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
the standard of living has increased, so each person uses more resources
(e)
it kills plants and animals
Question 2Medium6 marks
Burning coal in power stations releases acidic gases such as sulfur dioxide. These gases dissolve in rain water. Scientists measured the pH of the water in lakes in one region and counted the number of fish species in each lake. {table} shows the results.
[object Object]
(a) Describe the relationship shown in {table}.[1]
(b) Suggest why fewer species of fish live in more acidic lakes.[2]
(c) Acidic gases released in one country can reduce biodiversity in another country. Suggest why.[1]
(d) Explain why rapid growth in the human population can lead to more pollution.[2]
Show the answer and mark scheme
(a)
as the pH decreases (more acidic), the number of fish species decreases
(b)
some species cannot survive at low pH (e.g. the acid damages gills / kills eggs)
enzymes in the fish may be denatured at low pH
the plants and invertebrates that fish eat are killed, so there is less food
(c)
the gases are carried by the wind / clouds and fall as acid rain in other countries
(d)
more people use more resources / burn more fuel
(so) more waste / pollutants are produced, which cause pollution unless handled properly
Question 3Hard6 marks
Sewage from a village is sometimes released into a river without being treated.
Explain how untreated sewage entering a river could reduce the biodiversity of the river.[6]
Show the answer and mark scheme
sewage contains organic matter and mineral ions such as nitrate and phosphate
the mineral ions cause rapid growth of algae (and plants) in the water
a layer of algae at the surface blocks light, so plants below cannot photosynthesise and die
bacteria (decomposers) feed on the organic matter in the sewage and on the dead algae and plants
the number of bacteria increases, and they use oxygen in aerobic respiration
so the concentration of dissolved oxygen falls
fish and invertebrates that need a high concentration of oxygen die or move away
only a few species that can tolerate low oxygen survive, so biodiversity falls
sewage may also contain pathogens or toxic chemicals that kill organisms
Marked with levels of response: the full level descriptors are in the app.