Name the step of decomposition in each case…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Name the step of decomposition in each case.
- An earthworm chews a dead leaf into small bits.
- Rain carries soluble salts of a dead leaf down into the soil.
- A fungus secretes enzymes on a fallen log, and the log is broken into simple substances.
- A dark, slowly decaying substance builds up in the soil.
- Microbes break down that dark substance and release nitrate.
Need a reminder? The key ideaShow
The five steps of decomposition are fragmentation, leaching, catabolism, humification and mineralisation. Lignin and chitin slow decomposition. Nitrogen and sugars speed it up. Warmth, moisture and oxygen favour it. A model: , with half-life .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) Fragmentation, by a detritivore.
Step 2. (b) Leaching, by water.
Step 3. (c) Catabolism, by the enzymes of fungi.
Step 4. (d) Humification. The dark substance is humus.
Step 5. (e) Mineralisation, which releases inorganic nutrients.
Answer: (a) fragmentation; (b) leaching; (c) catabolism; (d) humification; (e) mineralisation.
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