How can the influenza virus infect individuals who have been previously infected and therefore produce antibodies
against this virus?
What will be an ideal response?
ANSWER: The influenza virus mutates and infectious viruses are produced with new combinations of H
and N proteins. Infection by a mutated virus means, therefore, that we see new antigens for
which we now have to make new antibodies. In the meantime, the virus attacks cells and the
symptoms of influenza develop.
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Wikelski and Romero (2003) found that large marine iguanas had higher reproductive success than smaller iguanas did. However, the large iguanas were generally in poor body condition because they could not eat enough; at higher temperatures their foraging efficiency improved, allowing them to eat more. Thus, Wikelski and Romero hypothesized that iguana size will _____ as global warming gradually increases air and water temperatures in the Galápagos Islands.
A) increase B) decrease C) stabilize around the mean body size D) remain unchanged, it is not clear that body size increases fitness
In cells that lack a cell wall, cytokinesis begins in which phase?
a. Cytophase b. Anaphase c. Interphase d. Telophase
As the electrical impulse moves through the cardiac conduction system it slows down at which structure to allow the
atria to finish their contraction? a. Purkinje fibers b. Bundle branches c. AV noded. SA node e. gap junctions
Many male songbirds are brightly colored. However, the color of the birds is determined by a balance of
A. natural selection against bright colors by predation and sexual selection in favor of bright colors. B. mutations that reduce bright colors and sexual selection in favor of bright colors. C. gene flow that reduces bright colors and natural selection in favor of bright colors. D. mutations that reduce bright colors and gene flow in favor of bright colors. E. natural selection against bright colors by predation and mutations that introduce bright colors.