Questions: During flu season, the influenza virus infects many people. During infection, the virus binds to proteins on the outside of a cell and tricks that cell into allowing the virus to enter the cell. Once inside, the virus infects the cell and forces the cell to make more viruses that can then go on to infect more cells. What type of cell transport is the virus using to get into the cell? exocytosis phagocytosis receptor-mediated

The answer is the third one: receptor-mediated endocytosis.

Explanation for each option:

1. Exocytosis: This is a process where cells expel materials in vesicles by fusing them with the plasma membrane. It is the opposite of endocytosis and is not used by viruses to enter cells. Therefore, this option is incorrect.

2. Phagocytosis: This is a type of endocytosis where large particles, such as bacteria or dead cells, are engulfed by the cell. It is often referred to as "cell eating." While it is a form of endocytosis, it is not typically how viruses like the influenza virus enter cells. Therefore, this option is incorrect.

3. Receptor-mediated endocytosis: This is a specific type of endocytosis where cells absorb metabolites, hormones, proteins – and in this case, viruses – by the inward budding of the plasma membrane, which contains proteins with receptor sites specific to the molecules being absorbed. The influenza virus uses this method to enter cells by binding to specific receptors on the cell surface. Therefore, this option is correct.

In summary, the influenza virus uses receptor-mediated endocytosis to enter cells during infection.