IB ESS HL 2.3.18 Bacterial Nitrogen-Cycle Roles Question Bank
Explain bacterial fixation, nitrification, denitrification and decomposition in the nitrogen cycle.
- Syllabus
- First assessment 2026
- Course
- ESS HL
- Level
- HL
Exam points
- identify each nitrogen-cycle transformation or impact
- trace the direction of nitrogen between stores
- evaluate human or bacterial effects using evidence
2.3.18 (HL)—Bacterial roles in nitrogen cycle question 1
[Maximum number: 4]
Outline the processes by which nitrogen in the atmosphere may eventually be found in the protein of a decomposer.
nitrogen cycles within ecosystems/is recycled in the Earth system;
b. nitrogen gas may diffuse into the soil;
c. nitrifying bacteria convert the nitrogen to ammonium/nitrites;
d. further bacteria convert the nitrites to nitrates;
e. lightning transforms/oxidises the nitrogen to nitrates;
f. nitrates are taken up by the roots of plants;
g. nitrates are transferred to the leaves of plants;
h. nitrates are assimilated into organic molecules/amino acids/proteins/nucleic acids in the plant;
i. the leaf/plant dies and enters the soil/becomes detritus; j. the proteins are consumed/absorbed by decomposers/detritivores/saprotrophs;
Note: Marking points may be credited if conveyed explicitly by an appropriate annotated diagram.
All question bank results loaded