Which of the following is not a factor that weakens host defenses against infections?
A. Old age
B. Chemotherapy
C. Physical and mental stress
D. Genetic defects in immunity
E. Strong, healthy body
Answer: E
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A (n) ________ vector contains promoters that result in high-level transcription of the gene cloned within a multicloning site.
A. expression B. shuttle C. chimeric D. phage
What is the main role of red blood cells?
A. Carry sugars B. Carry oxygen C. Aid blood in clotting D. Fight off infections
On a field study in Costa Rica, you discover a new species of frog! After careful work to determine the size and range of the population, you conclude sadly that the species has very few individuals in an ever-shrinking limited range. The entire species could be wiped out at any time. When you write up your report on the frog, how should you describe its status?
A. Threatened B. Endemic C. Extinct D. Conservative E. Endangered
The protrusible rasping organ in a mollusk's mouth that is used to scrape food from the substrate is
A. a visceral mass. B. an ammonite. C. a radula. D. a veliger. E. composed of nacre.