What is metabolic waste?

Answer:

All cells metabolize sources of energy to keep them ticking over in terms of making energy molecules they can use to do 'work' with, or making structural components for the cell. This involves breaking down larger molecules (catabolism) or using energy to build them (Anabolism). Inevitably there are left over pieces that are useless and may or may not be recyclable, hence metabolic waste. The cell will want to get ride of this waste as if its allowed to build up it will become toxic to the cell.

Novanet: The by-product of chemical reactions in the organism