Nutrient cycles — Paper 2 · IGCSE Biology (9-1) 0970

36 The diagram shows part of the nitrogen cycle. Which change is caused by the action of denitrifying bacteria? nitrogen gas in the air D A plants death nitrate in B feeding the soil death animals C faeces and urine

1 marks

Answer: D

This question in 0970/22 Oct/Nov 2018

36 Decomposers play an important role in the carbon cycle. They release carbon dioxide. Which process is responsible for this? A feeding B fossilisation C photosynthesis D respiration

1 marks

Answer: D

This question in 0970/21 May/June 2019

36 The diagram shows part of the nitrogen cycle. At which stage is denitrification occurring? nitrogen in the atmosphere A B nitrogen animals nitrates in plants D nitrites ammonium C compounds

1 marks

Answer: B

This question in 0970/22 Oct/Nov 2019

39 Which process in the nitrogen cycle is involved in the breakdown of amino acids in living organisms? A deamination B decomposition C denitrification D digestion

1 marks

Answer: A

This question in 0970/21 May/June 2020

40 When a river is polluted by fertiliser, the following processes may occur. 1 increased aerobic respiration of decomposers 2 increased growth of producers 3 decreased oxygen concentration in the water What is the correct sequence for these processes? A 1 → 2 → 3 B 1 → 3 → 2 C 2 → 1 → 3 D 2 → 3 → 1

1 marks

Answer: C

This question in 0970/21 May/June 2020

36 Bacteria are active in the nitrogen cycle. Which process in the nitrogen cycle is carried out by nitrifying bacteria? A the conversion of nitrogen gas to ammonia B the conversion of nitrogen gas to nitrates C the conversion of ammonia to nitrates D the conversion of nitrates to nitrogen

1 marks

Answer: C

This question in 0970/22 Oct/Nov 2020

36 The diagram shows part of the nitrogen cycle. atmospheric nitrogen 1 proteins and 5 amino acids urea in animals ammonium 7 4 2 3 proteins and death and nitrates amino acids decomposition in plants 6 ammonium Which processes are carried out by bacteria? A 1, 2, 3 and 4 B 1, 2, 4 and 5 C 1, 2, 5 and 6 D 1, 2, 6 and 7

1 marks

Answer: D

This question in 0970/22 Oct/Nov 2021

40 If the nitrate concentration in a lake increases, fish may die due to the events listed. 1 increased aerobic respiration by decomposers 2 increased decomposition of dead producers 3 increased growth of producers 4 reduction in dissolved oxygen Which sequence of events would lead to the death of the fish? A 1  3  2  4 B 2  1  4  3 C 3  2  1  4 D 3  4  1  2

1 marks

Answer: C

This question in 0970/22 Oct/Nov 2021

35 The diagram shows the water cycle. Four different processes are numbered. 4 3 1 2 Which row identifies the processes correctly? condensation evaporation precipitation transpiration A 1 4 3 2 B 2 1 4 3 C 3 2 1 4 D 4 3 2 1

1 marks

Answer: C

This question in 0970/21 May/June 2022

35 The diagram shows part of the carbon cycle. carbon dioxide in the atmosphere X X X fossil consumers producers fuels decomposers Which process is shown by the arrows labelled X? A combustion B fossilisation C photosynthesis D respiration

1 marks

Answer: D

This question in 0970/22 May/June 2022

36 The diagram shows the nitrogen cycle in the ocean. Which stage represents nitrification? atmosphere nitrogen A nitrate B upper part D phytoplankton of the sea with sunlight zooplankton and fish lower part nitrate ammonia of the sea without sunlight C

1 marks

Answer: C

This question in 0970/22 Oct/Nov 2022

37 During the nitrogen cycle, which process releases nitrogen gas into the air? A decomposition B denitrification C nitrification D nitrogen fixation

1 marks

Answer: B

This question in 0970/22 Oct/Nov 2023

38 Which organisms remove nitrate ions from soil? A denitrifying bacteria and nitrogen-fixing bacteria in root nodules B denitrifying bacteria and plants C nitrifying bacteria and plants D nitrogen-fixing bacteria in root nodules

1 marks

Answer: B

This question in 0970/21 May/June 2024

35 Which process in the nitrogen cycle removes nitrogen gas from the atmosphere? A decomposition B denitrification C nitrification D nitrogen fixation

1 marks

Answer: D

This question in 0970/22 Oct/Nov 2024

37 A farmer has a small pond on their farm land. One year, most of the organisms in the pond die. The next year, the farmer decreases their use of nitrate fertilisers and fewer organisms in the pond die. Which statement explains why this will help increase the number of organisms living in the pond? A There is a decrease in dissolved oxygen due to an increase in decomposition. B There is a decrease in dissolved oxygen due to an increase in photosynthesis. C There is an increase in dissolved oxygen due to a decrease in decomposition. D There is an increase in dissolved oxygen due to a decrease in photosynthesis.

1 marks

Answer: C

This question in 0970/22 Oct/Nov 2024

36 A student investigated the effect of high temperature on the production of nitrate ions in soil. Two samples of soil were taken. One sample was heated to 100 °C. All the nitrate ions were completely removed from both soil samples. Ammonium ions were then added to both soil samples. After two weeks, both soil samples were tested for the presence of nitrate ions. The results are shown. nitrate ions soil sample present or absent not heated to 100 °C present heated to 100 °C absent Which statement explains the results? A Heating the soil broke down the nitrate ions. B Heating the soil increased the activity of denitrifying bacteria. C Heating the soil killed nitrifying bacteria. D Heating the soil killed nitrogen-fixing bacteria.

1 marks

Answer: C

This question in 0970/21 May/June 2025

37 The diagram shows part of the nitrogen cycle. organic material nitrogen gas X ammonium ions nitrate ions What is the process labelled X in the diagram? A decomposition B denitrification C nitrification D nitrogen fixation

1 marks

Answer: C

This question in 0970/22 May/June 2025

36 Which process needs microorganisms to break down protein to produce ammonium ions? A decomposition B denitrification C nitrification D nitrogen fixation

1 marks

Answer: A

This question in 0970/22 Oct/Nov 2025