6. In human B cells and T cells are matured in the

A. bone marrow and thymus respectively
B. lymph nodes and spleen respectively
C. bursa and thymus respectively
D. none of these

7. An example of mosaic antigen is

A. virus
B. bacteria
C. a hapten
D. protein

8. T cells are the source of

A. interleukin
B. interferon
C. lymphotoxin
D. all of these

9. The primary B cell receptor is

A. IgD
B. IgG
C. IgA
D. IgE

10. It is highly valued if the lymphocytes derived from the lymph node or tonsil tend to undergo fusion at

A. high frequencies
B. moderate frequencies
C. low frequencies
D. at no frequency