Final answer:
The structure of the antigen receptor on the T cell is determined before the cell is exposed to a pathogen.
Step-by-step explanation:
False. The structure of the antigen receptor on the T cell is actually determined before the cell is exposed to a pathogen. T cells have antigen receptors on their surface that bind to specific antigens. These receptors are created through a process called gene rearrangement that occurs during T cell development in the thymus. The genetic information for the receptor is already present in the T cell's DNA, and it is expressed on the cell surface once the T cell matures.