Habitat destruction — Paper 2 · IGCSE Sciences - Co-ordinated (9-1) 0973

13 One of the problems with the overuse of fertilisers is the eutrophication of lakes and rivers. What effect does this have on the water? oxygen bacterial concentration activity A decreases decreases B decreases increases C increases decreases D increases increases

1 marks

Answer: B

This question in 0973/22 May/June 2019

13 Some of the stages of eutrophication are listed. 1 death of organisms requiring dissolved oxygen in water 2 increased availability of nitrate and other ions 3 increased decomposition after death of producers 4 reduction in dissolved oxygen What is the correct order of these stages in eutrophication? A 2 → 1 → 4 → 3 B 2 → 3 → 4 → 1 C 3 → 2 → 4 → 1 D 3 → 4 → 1 → 2

1 marks

Answer: B

This question in 0973/21 Oct/Nov 2019

13 Which line shows how the oxygen concentration of the water changes after excess fertiliser has entered a stream? A oxygen B concentration of the water C D distance downstream fertiliser run-off

1 marks

Answer: B

This question in 0973/21 May/June 2020

13 Which line shows how the oxygen concentration of the water changes after excess fertiliser has entered a stream? A oxygen B concentration of the water C D distance downstream fertiliser run-off

1 marks

Answer: B

This question in 0973/22 May/June 2020

13 What decreases as a result of deforestation? A available habitats B atmospheric carbon dioxide C flooding D soil loss

1 marks

Answer: A

This question in 0973/21 May/June 2021

13 Which row is correct for eutrophication? effects of nitrates result of increase in source of nitrates on producers decomposers A fertilisers increase growth carbon dioxide decreases B fertilisers decrease growth oxygen increases C sewage decrease growth carbon dioxide increases D sewage increase growth oxygen decreases

1 marks

Answer: D

This question in 0973/22 May/June 2021

13 Which flowchart correctly shows the stages of eutrophication? A B C D increased nitrates decreased nitrates decreased nitrates increased nitrates decrease in decrease in increase in increase in producers producers producers producers decrease in increase in decrease in increase in decomposition decomposition decomposition decomposition decrease in increase in decrease in increase in aerobic respiration anaerobic respiration anaerobic respiration aerobic respiration by decomposers by decomposers by decomposers by decomposers increase in reduction in increase in reduction in oxygen oxygen oxygen oxygen increase in death of increase in death of organisms organisms organisms organisms

1 marks

Answer: D

This question in 0973/21 May/June 2022

13 When fertiliser is washed into lakes, it leads to changes in the oxygen concentration and the population of algae. algae oxygen time Which statement explains the change in oxygen over time? A The algae use up the oxygen for photosynthesis. B Decomposer bacteria use up the oxygen for respiration. C Nitrates react with the oxygen. D The algae use up the oxygen for respiration.

1 marks

Answer: B

This question in 0973/22 May/June 2022

13 What is an undesirable effect of deforestation? A It increases the oxygen concentration of the atmosphere. B It leads to erosion and loss of soil. C It makes land available for agriculture. D It pollutes the air with methane.

1 marks

Answer: B

This question in 0973/21 Oct/Nov 2022

13 What causes eutrophication? A combustion of fossil fuels B cutting down of forests C discarded plastic rubbish D overuse of nitrogen-containing fertiliser

1 marks

Answer: D

This question in 0973/21 May/June 2023

13 The flow diagram shows the consequence of the overuse of fertilisers on farm land. leaching fast growth death of fast growth death of → → → → fertiliser of algae algae of X fish Which group of organisms is represented by X? A decomposers B fish C invertebrates D plants

1 marks

Answer: A

This question in 0973/22 May/June 2023

13 The list shows changes that occur in a lake which is polluted by fertiliser. 1 Decomposers feed on aquatic plants. 2 Growth of algae increases. 3 Oxygen levels decrease in the lake. 4 Aquatic plants die. In which order do these changes occur? A 2  4  1  3 B 2  3  4  1 C 3  4  2  1 D 3  4  1  2

1 marks

Answer: A

This question in 0973/21 May/June 2024

13 Which line shows how the oxygen concentration of the water changes after excess fertiliser has entered a stream? A B oxygen concentration of the water C D distance downstream fertiliser run-off

1 marks

Answer: B

This question in 0973/22 May/June 2024