GRE Reading Comprehension

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Source: XDF

Why during sickness should body temperature of warm-blooded animal rise? It has long been known that the level of serum iron in animals falls during infection. Garibaldi first suggested a relationship between fever and iron. He found that microbial synthesis of siderophores -substances that bind iron -- in bacteria of the genus Salmonella declined at environmental temperatures above 37°C and stopped at 40.3°C. Thus, fever would make it more difficult for an infecting bacterium to acquire iron and thus to multiply. Cold-blooded animals were used to test this hypothesis. Kluger reported that of iguanas infected with the potentially lethal bacterium A. hydrophilia, more survived at temperatures of 42°C than at 37°C, even though healthy animals prefer the lower temperature. When animals at 42°C were injected with an iron solution, however, mortality rates increased significantly.

Question List: 1 2

According to the passage, Garibaldi determined which of the following?

  • A That serum iron is produced through microbial synthesis
  • B That microbial synthesis of siderophores in warm-blooded animals is more efficient at higher temperatures.
  • C That only iron bound to other substances can be used by bacteria.
  • D That there is a relationship between the synthesis of siderophores in bacteria of the genus Salmonella and environmental temperature.
  • E That bacteria of the genus Salmonella require iron as a nutrient.

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