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IB Biology HL 4.2.5 Supply to decomposers Question Bank

Practise IB Biology HL 4.2.5 by analysing detritus supply, microbial communities and bacterial roles in carbon cycling.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Analyse how detritus and organic matter supply affects decomposer and microbial communities.
  • Evaluate bacterial decomposition as a pathway in the carbon cycle.

C4.2.5—Supply to decomposers question 1

[Maximum number: 1]

Marine sediments form at the bottom of oceans. These sediments contain organic material from the surface waters. Scientists analysed samples drilled from the floor of the north Pacific Ocean, representing 86 million years of sedimentation. Graph A shows the data for oxygen concentrations in 28 metres of sediment and graph B shows the oxygen consumption per cell in 22 metres of sediment measured in femtomoles ( fmol=10−15 mol\mathrm{fmol}=10^{-15} \mathrm{~mol} ).

Figure for Question C4.2.5—Supply to decomposers question 1 — IB Biology HL

State a possible source of food for the microbial community in the sediments.

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