Given the paragraph, fill the missing words or phrase using the given choices on the box to complete the information about the cell membrane. Write your answer on a separate sheet of paper.

The cell membrane also known as the (1) __________ is a biological membrane that separates the interior from the exterior of the cell and protects the cell from its environment. The cell membrane consists of four various parts. The (2) ____________, is a part of the membrane, a double layer molecule which is like a tadpole. The head is known to be (3) ____________________, and the tail is known to be (4) _______________________. The (5) ________________ is a part of the membrane which is a special arrangement of amino acids. This provides a hydrophilic passageway for water and large molecules. The (6) ___________________ is another part of the membrane which extends across the cell membrane and serve as a nametag of the cell. Also, (7) ___________________ is another part of the membrane. These proteins are located within the cell surface membrane. They are like blobs with antennas. They can bind to the corresponding ligands to initiate signaling pathways because they have a special sensing structure. The (8) __________ embedded in the phospholipids serves as a transportation passageway for some of the molecules needed by the cell. Transport may occur by (9) __________ and osmosis across the membrane. It can also occur when a vesicle attaches to the cell membrane from the inside and then opens to form a pocket, expelling its contents to the outside called (10) _____________. The cell membrane may also envelope something on the outside and surround it, taking it into the cell called (11) __________ or (12) ___________. There are also processes where molecules move across a membrane from a region of (13) ___________ to a region of high concentration, and this requires a source of (14) ________ to "pump" the molecules uphill in concentration. Such processes are called (15) _______________.​