Which of the following statements are fundamental to the clonal selection theory of how the adaptive immune system functions?
I.Each lymphocyte has a unique membrane receptor that recognizes one antigen.
II.When the lymphocyte binds an antigen, it is activated and begins dividing to form many identical 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 and III
B) only II and IV
C) only I, II, and IV
D) only II, III, and IV

Question

Quizplus · Accepted Answer

The clonal selection theory proposes that each lymphocyte has a unique and specific receptor that binds to one antigen. When the receptor binds an antigen, the lymphocyte is activated and begins dividing to form many identical copies of itself, which can then recognize and attack the same antigen. Cloned cells descended from the activated lymphocyte persist even after the pathogen is eliminated, forming memory cells that provide long-term immunity. The statement III is incorrect because cloned lymphocytes have almost identical receptors, not slight differences, and they are selected by the lymphatic system, not the spleen, for removal if they do not bind an antigen. Therefore, the correct answer is C, which includes statements I, II, and IV.

Which of the Following Statements Are Fundamental to the Clonal