IB Biology HL C4.2.5 Supply to Decomposers Topic Practice

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 ( $\mathrm{fmol}=10^{-15} \mathrm{~mol}$ ).

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