So that they don't argue over results when two types of measurements equal the same thing but are just put differently
There would be an increase in dead matter and a lack of nutrients in the soil.
Decomposers break down dead matter, so without them there will be an increase.
They then return the nutrients from the dead matter to the soil, so there will be a lack of nutrients in the soil.
Examples of decomposers are mushrooms and earthworms.
Muscle cells, because they require a lot of energy. The function of mitochondria is to convert sugars into energy, so naturally there would be many mitochondria in muscle cells.
Hope this helps :)