An interpreter reads one instruction at a time and carries out the actions implied by that instruction. It does not perform any translation. But a compiler translates the entire instructions.
A candidate key is a column, or set of columns, in a table that can uniquely identify any database record without referring to any other data. Each table may have one or more candidate keys, but one candidate key is unique, and it is called the primary key.
The processes both osmosis and diffusion come under passive transport and require no energy. The movement of solute from the region of higher concentration to the region of lower concentration is nothing but diffusion.