Which term refers to the class of proteins that includes antibodies in the blood?

Which term refers to the class of proteins that includes antibodies in the blood?

• A. Immunoglobulins
• B. Antibody
• C. Antigen
• D. Parenteral

Answer: (A)

The key idea is that antibodies are part of a larger protein family called immunoglobulins. Immunoglobulins are the whole class of glycoprotein molecules produced by plasma cells that circulate in blood and other fluids to mediate humoral immunity. An individual antibody is a single immunoglobulin with a specific binding site for an antigen, but it’s one member of the broader immunoglobulin family. The other terms don’t fit: an antigen is what antibodies bind to, a parenteral refers to a route of administration, and “antibody” denotes a single molecule rather than the whole class.

The key idea is that antibodies are part of a larger protein family called immunoglobulins. Immunoglobulins are the whole class of glycoprotein molecules produced by plasma cells that circulate in blood and other fluids to mediate humoral immunity. An individual antibody is a single immunoglobulin with a specific binding site for an antigen, but it’s one member of the broader immunoglobulin family. The other terms don’t fit: an antigen is what antibodies bind to, a parenteral refers to a route of administration, and “antibody” denotes a single molecule rather than the whole class.