45) For the successful development of a vaccine to be used against a pathogen, it is necessary
that _____.
A) the surface antigens of the pathogen stay the same
B) all of the surface antigens on the pathogen be identified
C) the pathogen has only one epitope
D) the major histocompatability (MHC) molecules are heterozygous
46) The switch of one B cell from producing one class of antibody to another class of antibody
that is responsive to the same antigen is due to _____.
A) the rearrangement of V region genes in that clone of responsive B cells
B) a switch in the kind of antigen-presenting cell that is involved in the immune response
C) a patient’s reaction to the first kind of antibody made by the plasma cells
D) the rearrangement of immunoglobulin heavy-chain C region DNA
47) The number of major histocompatability (MHC) protein combinations possible in a given
population is enormous. However, an individual in that diverse population has a far more limited
array of MHC molecules because _____.
A) the MHC proteins are made from several different gene regions that are capable of
rearranging in a number of ways
B) MHC proteins from one individual can only be of class I or class II
C) each of the MHC genes has a large number of alleles, but each individual only inherits two
for each gene
D) once a B cell has matured in the bone marrow, it is limited to two MHC response categories
48) A bone marrow transplant may not be appropriate from a given donor (Jane) to a given
recipient (Jane’s cousin Bob), even though Jane has previously given blood for one of Bob’s
needed transfusions, because _____.
A) even though Jane’s blood type is a match to Bob’s, her major histocompatability (MHC)
proteins may not be a match
B) a blood type match is less stringent than a match required for transplant because blood is
more tolerant of change
C) for each gene, there is only one blood allele but many tissue alleles
D) Jane’s MHC class II genes are not expressed in bone marrow