1) Water accounts for 90% of the whole body.
Here, "accounts for" means "makes up, comprises":
"Skype now accounts for 12% of all international calling."
4)A large number of UN personnel in Haiti are unaccounted for .
"Unaccounted for" in this case means "missing or absent without explanation":
"A Fort Worth woman's son is among thousands unaccounted for in Haiti."
- For Teachers