Does the excretory system require energy

Is this correct if not can u correct me

What are the advantages of using the metric system? designed as a decimal system making conversions simpler more accurate system of measurement has prefixes that correspond to an amount to use with all base units used by the entire scientific community

If i had 2 m naoh solution, what does the 2 m stand for? 2 molar, but 2 of a solute in 1