IB Biology HL C4.2.22 Recycling of All Chemical Elements Questions

Analyse ammonium and phosphorus sources, decomposition and uptake, then evaluate how agriculture, weather and human activity alter nutrient recycling in IB Biology HL C4.2.22.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Explain how decomposers return inorganic nutrients from detritus or waste for producer uptake, and distinguish recycling of matter from one-way energy flow.
  • Trace ammonium or other inorganic-nutrient sources and transformations through decomposition, uptake and recycling in an ecosystem nutrient cycle.
  • Evaluate how agriculture, weather or human activity disrupts nitrogen or phosphorus recycling through leaching, removal, fertiliser or altered decomposition.

IB Biology HL C4.2.22 Recycling of All Chemical Elements Questions question 1

[Maximum number: 2]

Where high amounts of ammonium ions are present in agricultural areas, gaseous ammonia can be released into the atmosphere. This ammonia can dissolve and be carried across distances and then be deposited through precipitation. In a study of the effects of deposition of ammonium in a forest, soil samples were taken starting at the forest edge next to an open field and moving toward the centre of the forest.

Figure for Question IB Biology HL C4.2.22 Recycling of All Chemical Elements Questions question 1 — IB Biology HL

List two sources of the ammonium in the forest soils apart from deposition in rainfall.

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