Influenza virus can exhibit constant mutation of viral glycoproteins, called antigenic ________, or alternatively antigenic ________, which is a more serious phenomenon caused by the exchange of a viral gene with that of another influenza virus strain.
A. drift; exchange
B. exchange; drift
C. shift; drift
D. drift; shift
Answer: D
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1.arteries 2.capillaries 3.veins 4.All of these contain oxygen at some point during the circuit.
Which sentence describes the width of a DNA double helix?
a. The width is greater where purines are present than where pyrimidines are present. b. The width is narrower where adenine is present than where cytosine is present. c. The width is constant. d. The width varies randomly.
Which of the following is TRUE at the end of telophase I in corn (2n = 20)?
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In Southern blotting, DNA molecules are immobilized on
A) silicon chips. B) nitrocellulose membranes. C) agarose. D) gold beads. E) paper.