Final answer:
The constant region of an antibody determines its class or isotype, while the variable region determines its specificity.
Step-by-step explanation:
The statement is false. The constant region of an antibody molecule determines its class or isotype, whereas the variable region determines its specificity. The variable region is responsible for forming the antigen-binding site, which has unique patterns of amino acids that bind to target antigens. On the other hand, the constant region is involved in the antibody's mechanism of action, such as complement factor binding and binding to phagocytic cells during antibody-mediated opsonization.