Embedded in the cell membrane act as gates and transportation systems that allow selected substances to pass through the membrane.

Protein complexes

Explanation:

There is a lipid bilayer in which the protein molecules are embedded. They do not exist as single elements of the lipid membrane in a form of glycoproteins or membrane proteins, they work as diffusing complexes within the membrane. They perform important functions for the cell; such as ion and metabolite transport, signaling, cell adhesion, and migration.

the darker peppered moth species were favored due to the fact that the industrial revolution had made all the nearby trees a darker color instead of white.

answer >   yes we do, women; have three holes, urethral opening(pee hole, vagina, and the women pee/girls pee out of the urethra like the men do; only they have a single opening to pee/ejaculate.   (sorry if i'm too forward with this, but this is for a biology class, isn't it? )

hope that !         : )