As the diagram is not given, hence let's generally describe the movement of molecules along the cell membrane.
Molecules can either pass through the cell without using energy through the process of passive transport. An example includes molecules of oxygen.
Molecules which are large and un-polar cannot move through the cell membrane easily. These molecules will require energy to move through the cell membrane. These molecules might move in with the help of the carrier or facilitated proteins. Examples include molecules of glucose.
Immunofluorescence or immunoperoxidase assays are commonly used to detect whether a virus is present in a tissue sample. These tests are based on the principle that if the tissue is infected with a virus, an antibody specific to that virus will be able to bind to it.
