Introduction to Biochemistry - Quiz 2.5.4

Of the phospholipid shown above, those with a cylindrical shape are more likely to be found in the outer leaflet of the membrance, while lipid with a conical shape are more likely to be found in the inner leaflet.

Scrambase moves lipids down their concentration gradient, in either direction.
Floppase moves lipids against their concentration gradient, from inner to outer membrane.
Flippase moves lipids against their concentration gradient, from outer to inner membrane.
Scrambase actively promotes membrane compositional symmetry.

In the endoplasmic reticulum.

Sphingomeylin is synthezised in the lumen of the golgi apparatus and is transported to the plasma membrane by vesicles Sphingomeylin will first be incorporated into the outer leaflet of the plasma membrane.

This is because the inside of the vesicle contains the material that the cell wants to secret, so that will face outside after the vesicle merge with the plasma membrane.