Some archaea (single cell organisms) live in extremely salty water such as the great salt lake or the dead sea. most types of cells would shrivel and die in this very salty water. how do you think these archaea prevent water loss while living in very salty water?

Halophiles are extremophiles that thrive in environments with very high concentrations of salt. Halophiles prevent this loss of water by increasing the internal osmolarity of the cell by accumulating osmoprotectants or by the selective uptake of potassium ions. Hope this helps.

Molecules called lipids have long hydrocarbon chains that determine the way they act. they can be fats, oils, or hormones, and even exist in our cell membranes 

Cherries for sure do doubt