What answers a number of questions like such as who, what, where, what kind, why, and how?

________ is the membrane that forms the covering of bones, except at their articular surfaces

a. Epiphysis b. Diaphysis c. Periosteum d. Compact bone

Molecules that do not trigger an immune response on their own but can become immunogenic when combined with larger molecules are called:

a. HLA antigens. c. Haptens. b. MHC antigens. d. Immunogens.