What do you mean ???????????
The 3 main regions of the brain are the cerebrum, cerebellum, brainstem.
The cell membrane is semi-permeable, kind of like a filter to let some molecules in and keep larger molecules out
To perform this test to check if gold is real, make a light, tiny scratch on the item using a small nail file. Choose a spot that is not noticeable if possible. Use a dropper to apply a small drop of nitric acid to the scratch. If there is no reaction, then the piece is probably made from real gold.
