Which description of antigenic drift and antigenic shift in the influenza virus is incorrectly matched?
A) Antigenic shift: May result in a pandemic outbreak due to widespread lack of immunity.
B) Antigenic drift: A host vaccinated against an influenza strain before antigenic drift may lack effective immunity and be susceptible to infection.
C) Antigenic drift: Spontaneous mutation leads to a minor change in HA or NA spikes.
D) Antigenic shift: Often leads to viral strains with new features such as increased infectivity or expanded host range.
E) Antigenic drift: Often involves reassortment of viral strains in an animal host followed by a "species jump" to humans.
Answer: E
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World human population in 2009 is approximately
A. 670 million. B. 1.8 bilion. C. 4.6 billion. D. 6.7 billion. E. 10 billion.
Which of the following are key elements of detrital food webs?
a. Fungi b. Herbivores c. Carnivores d. Plants
Which of the following is involved in proofreading during DNA replication?
A) 5' to 3' exonuclease activity of DNA polymerase B) 3' to 5' exonuclease activity of DNA polymerase C) 5' to 3' endonuclease activity of DNA polymerase D) 3' to 5' endonuclease activity of DNA polymerase E) RNA polymerase
When we metabolize our food, we produce heat that helps to keep us warm. Which of the following best describes why?
A) Producing ATP from ADP is exothermic; therefore, energy is released in the form of heat. B) When we break down food, all energy in the food is directly released in the form of heat. C) When we break down our food, the reactions are not 100 percent efficient; therefore, energy is lost as heat. D) Chewing is exothermic; therefore, energy is released in the form of heat when we eat food.