Which of the following statements are fundamental to the clonal- selection theory of how the adaptive immune system functions?
I. Each mature lymphocyte has a unique membrane receptor that recognizes one antigen.
II. When the lymphocyte binds an antigen, the lymphocyte is activated and begins dividing to form many ident copies of itself.
III. Cloned lymphocytes have slight differences and are selected by the spleen for removal if they do not bind an antigen.
IV. Cloned cells descend from an activated lymphocyte and persist even after the pathogen is eliminated.
A) only I, II, and IV
B) only II and IV
C) only I and III
D) only II, III, and IV
E) I, II, III, and IV

Question

Quizplus · Accepted Answer

The clonal-selection theory proposes that each mature lymphocyte (B or T cell) has a unique membrane receptor that recognizes one antigen (statement I). When a lymphocyte binds to an antigen, it is activated and begins dividing to form multiple identical copies of itself (statement II), which are called clones. These clones have slight variations in their receptors and are selected by the spleen for removal if they do not bind an antigen (statement III). The activated lymphocyte gives rise to the clones, which persist even after the pathogen is eliminated (statement IV). Therefore, statements I, II, and IV are fundamental to the clonal-selection theory.

Which of the Following Statements Are Fundamental to the Clonal-