You see a purple light and immediately receive a mild electric shock. This happens several times. You eventually cringe at the sight of the purple light. The first time you saw that light it was a(n) ______________
Fill in the blank(s) with the appropriate word(s).
Ans: neutral stimulus
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Your patient was cut by a rusty nail. You vaccinate her for tetanus. How does one of her B cells produce antibodies against C. tetani?
A. Each antigen is coded for by a unique gene in the human genome; the correct gene is activated to produce the antigens against C. tetani. B. Recombination of different gene segments in B cells after exposure to C. tetani creates a unique structural gene. The cell then produces lots of that specific antibody. C. Post-translational modification of a generic antibody protein changes it from a generic form to the correct specialized form against C. tetani. D. Recombination of different gene segments in maturing B cells creates a unique structural gene. Upon exposure to C. tetani, the cell is stimulated to produce lots of the specific antibody expressed by that gene.
Which genetic mechanism is most likely responsible for the evolutionary origin of new and complex plant structures,
such as flowers?
a. gene duplication b. asexual reproduction c. genes coding for flower development d. mutations in noncoding regions e. gene splicing
The density of water is greatest at
A) -4°C. B) 0°C. C) 4°C. D) 100°C.
An important mediator of a type I hypersensitivity reaction is
a. complement. b. antigen-antibody immune complexes. c. T cells. d. histamine.