Biology 5090 · O Level
Nutrient cycles
55 practice questions on Nutrient cycles, with worked solutions and instant marking.
Which organisms convert ammonium compounds into nitrates?
May/June 2015
In what way do nitrogen-fixing bacteria increase soil fertility?
May/June 2015
Fig. 5.1 illustrates several interactions occurring within an aquatic ecosystem.
May/June 2015
The diagram illustrates part of the carbon cycle. Which processes are X and Y?
May/June 2016
The diagram shows a river running from the mountains towards the sea. Trees are felled and cleared from the shaded area. After a rainstorm, what effect does this have on the nitrate ion content at X and at Y?
May/June 2016
Describe the way in which the nitrogen cycle makes nitrogen in the air available for protein in both plants and animals.
May/June 2016
The diagram illustrates part of the nitrogen cycle. Which process takes place at X?
May/June 2017
The diagram illustrates part of the nitrogen cycle. Which process takes place at X?
May/June 2017
Which part of the carbon cycle relies on bacteria and fungi being present in the soil?
May/June 2018
In the carbon cycle, which process puts carbon back into a food chain?
May/June 2018
The diagram illustrates part of the carbon cycle. What are the processes X and X?
May/June 2019
The diagram illustrates part of the carbon cycle. Which processes are X and Y?
May/June 2019
The diagram illustrates the carbon cycle.
May/June 2019
The diagram illustrates the transfer of carbon in the carbon cycle, in gigatonnes per year. How many gigatonnes of carbon are transferred by respiration each year?
May/June 2021
Which microorganisms take part in the decomposition of dead plant material?
May/June 2021
The diagram illustrates part of the carbon cycle. What are X, Y and Z?
May/June 2021
In liver cells, excess amino acids are broken down to make urea molecules.
May/June 2021
The diagram illustrates the nitrogen cycle. During which stages of the nitrogen cycle are nitrogen-fixing bacteria important?
May/June 2022
The diagram illustrates a section of the carbon cycle. Which row correctly identifies processes W, X, Y and Z?
May/June 2022
The diagram illustrates part of the carbon cycle. Which row gives the correct labels for the numbered boxes?
May/June 2023
The diagram illustrates a simplified nitrogen cycle. At stage X, which process occurs in the cycle?
May/June 2023
The carbon cycle is a vital part of every ecosystem. Carbon is moved repeatedly between living organisms and the atmosphere, as illustrated in Fig. 7.1.
May/June 2023
The graph illustrates atmospheric carbon dioxide concentration in a country from 1968 to 2000. Carbon dioxide concentration changes from year to year. What is the best explanation for these variations?
May/June 2024
What process is used to convert ammonia into nitrates?
May/June 2024
Soil with a higher water content provides favourable conditions for denitrifying bacteria to multiply. Which effects will be observed on the growth of plants in this soil?
May/June 2025
An ocean has been contaminated by an oil spill. Which factor is least likely to increase the rate at which microorganisms break down the oil?
Oct/Nov 2015
The diagram illustrates how the appearance of a leaf changes over time while it is lying on moist ground. Which kind of organism is most likely responsible for these changes?
Oct/Nov 2015
The diagram illustrates several stages in the nitrogen cycle. Which arrow shows the activity of nitrogen-fixing bacteria?
Oct/Nov 2015
The diagram illustrates how the appearance of a leaf changes over time while it is lying on damp ground. Which type of organism is most likely responsible for these changes?
Oct/Nov 2015
The diagram illustrates several stages in the nitrogen cycle. Which arrow shows the action of nitrogen-fixing bacteria?
Oct/Nov 2015
Describe the ways in which a bacterial cell is unlike a typical animal cell.
Oct/Nov 2015
What processes are involved in the carbon cycle?
Oct/Nov 2016
During which process is atmospheric nitrogen taken up in root nodules and joined with other compounds?
Oct/Nov 2016
In a fish tank, bacteria convert animal waste into forms that plants can use. The diagram illustrates some of the stages in this process. What are compounds 1, 2 and 3?
Oct/Nov 2017
At what point is carbon dioxide taken up, and at what point is it given out, by an ecosystem such as a tropical rainforest?
Oct/Nov 2017
At what point is carbon dioxide taken in, and at what point is it given out, by an ecosystem such as a tropical rainforest?
Oct/Nov 2017
Which organisms gain their energy only from dead organic matter?
Oct/Nov 2018
Which labelled arrow in the nitrogen cycle indicates nitrogen fixation?
Oct/Nov 2018
Fig. 1 shows a leaf just after it has fallen from a growing plant. Fig. 2 shows a leaf from the same plant a few months after it dropped onto the soil beneath.
Oct/Nov 2018
Certain bacteria function most successfully in waterlogged soils, where they can gain oxygen for respiration by breaking down nitrates. Nitrogen gas is then given off as a waste product. To which type of bacteria does this description refer?
Oct/Nov 2019
Certain bacteria are most successful in waterlogged soils, where they can get oxygen for respiration by breaking down nitrates. Nitrogen gas is given off as a waste product. To which type of bacteria does this description apply?
Oct/Nov 2019
The diagram displays the carbon cycle. What is process X?
Oct/Nov 2020
The diagram illustrates the nitrogen cycle. Which stage is performed by nitrifying bacteria?
Oct/Nov 2020
Which diagram shows the movement of carbon atoms through an ecosystem?
Oct/Nov 2021
The diagram illustrates the nitrogen cycle. Which stages include bacteria?
Oct/Nov 2021
Why is it important for carbon to be cycled in nature?
Oct/Nov 2021
The diagram illustrates part of the nitrogen cycle. Which processes are P, Q, R and S?
Oct/Nov 2021
Which kinds of microorganism perform decomposition in the nitrogen cycle?
Oct/Nov 2022
In the carbon cycle, through which process can carbon enter the atmosphere?
Oct/Nov 2022
Some bacteria and fungi function as decomposers. What is formed when decomposers decompose plant and animal protein?
Oct/Nov 2023
A group of students carried out an experiment to investigate the decay of leaves in garden soil. They placed leaves into bags with different mesh sizes, sealed the bags, and then buried them. Every month for 5 months, the bags were dug out and the overall percentage decrease in mass from the beginning of the experiment was worked out. The results are shown. What can the students conclude from these results?
Oct/Nov 2024
Which statements concerning the carbon cycle are correct?
Oct/Nov 2024
Trees in a forest require a continual supply of nitrates so that they can keep growing. The diagram illustrates some of the stages in the nitrogen cycle that supply the needed nitrates. Which stage in this cycle is not caused by living bacteria?
Oct/Nov 2025
The diagram illustrates the transfer of carbon within the carbon cycle in gigatonnes per year. How many gigatonnes of carbon are transferred by respiration each year?
Oct/Nov 2025
The diagram illustrates the nitrogen cycle. Which stages include bacteria?
Oct/Nov 2025