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

Trace how detritivores and decomposers return inorganic nutrients to producers, follow carbon through ecosystem stores and distinguish recycled matter from one-way energy in IB Biology SL C4.2.22.

Exam points

Explain how decomposers and detritivores convert dead organic matter, detritus and waste into inorganic nutrients that producers can reuse.
Trace carbon and other required chemical elements through organisms, detritus, soil or water and back to producers, distinguishing recyclable matter from non-recyclable energy.

[Maximum number: 2]

The bar chart shows the mass of animal feed required to produce one kilogram of meat, egg or milk (kg dry matter in feed per kg of output).

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

Feed conversion ratio / kg dry matter in feed per kg of output

Outline two ways in which agricultural production of animals may change the cycling of nutrients (for example phosphorous or nitrogen) in ecological systems.

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a	animals remove nutrients from systems by feeding/being eaten;
b	nutrients added to systems by fertilizers/manure;
c	fertilizer/manure/organic matter run-off can affect other ecosystems;
d	deforestation results in leaching/loss of nutrients;
e	pesticides may affect decomposers;

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