Which cells alert the adaptive immune system when they detect antigens?
a. eosinophils
b. B and T cells
c. macrophages
d. dendritic cells
e. cytokines
ANSWER: d
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The sum total of all the microbes in a certain environment is termed the ________.
A. phylogeny B. microbial niche C. domain D. microbiome E. biofilm
Which of the following is true concerning a morphological phylogenetic tree with 15 characters and 23 changes, and a molecular phylogenetic tree with 150 characters and 345 changes that contain the same taxa?
A. The molecular tree is a better estimate of the true relationships of the taxa. B. The molecular tree is the true representation of the relationships between the taxa. C. The morphological tree is the better estimate of the true relationships between the taxa because it has a shorter length. D. The morphological tree is the true representation of the relationships between taxa as it has the shorter length.
The clonal selection theory states that
A. all T cells are exact clones of each other. B. all B cells are exact clones of each other. C. when a B or T cell is stimulated by encountering the correct antigen, it divides to form a clone of cells that will respond to the same antigen. D. when a B or T cell is stimulated by encountering the correct antibody, it divides to form a clone of cells that will respond to the same antibody.
Watson and Crick's model of the structure of DNA was published in:
A) 1975. B) 1949. C) 1961. D) 1923. E) 1953.