Final answer:
The false statement regarding antibody structure is c. Fab is the domain that provides antibodies with their individual effector functions; instead, Fab is responsible for antigen binding while the Fc portion is involved in immune responses.
Step-by-step explanation:
Regarding the statements about antibody structure, the false statement is c. Fab is the domain that provides antibodies with their individual effector functions.
The Fab region, or fragment of antigen binding, is actually responsible for the specificity of antigen binding. This region of the antibody interacts with the epitope on the antigen.
The Fc portion, or constant domain, is involved in the destruction of pathogens by facilitating various immune responses such as phagocytosis and complement activation.
While the variable region determines binding specificity, it's the constant domain of the heavy chain that determines the immunological mechanism of action of the antibody class.
Therefore, the statement a. regarding the Fc portion being involved in the destruction of the pathogen is true, as is b. indicating minimal diversity in the constant region when compared to the variable region.
Lastly, statement d. is true each Ig isotype is composed of one of five possible heavy chain isotypes and one of two possible light chain isotypes.