Which cell structure is made of a bilayer of phospholipids and
encloses all cells?

The cell structure is the plasma membrane also known as the cell membrane.

Explanation:

The plasma membrane is the thin coat of lipids (phospholipids) that surrounds and encloses a cell, also can be called the cell membrane

of those who start drinking before they're 15 will develop alcohol dependence

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.