explain why nonpolar compounds are generally able to diffuse across biological membranes without the aid of a specific transport system.

Explanation:

Non polar compound is formed when atoms of diamond molecule receives equal share of electrons.

nonpolar compound are usually more soluble in non polar solutes, such as benzene than in polar solvents such as water.

Non polar compound passes through biological membranes unaided because it requires the use of less energy to move from the aqueous solvent into the non polar region of the bilayer interior, and because the region is non polar.