In 1918, a Worldwide Epidemic of Influenza a Resulted in the Deaths

question 8

Multiple Choice

In 1918, a worldwide epidemic of influenza A resulted in the deaths of 40-50 million people. This strain of influenza A, known as H1N1-referring to the genotypes of the viral surface proteins, hemagglutinin (H) and neuraminidase (N) -was shown to be derived from an avian virus that adapted to infect and grow in human cells. Interestingly, by 1957, the H1N1 strains of Influenza A had completely disappeared from the human population, to be replaced by new strains (H2N2) that contained three gene segments from avian origin. The most likely explanation for the disappearance of the early twentieth century form of H1N1 Influenza A virus is:

• A) The replacement by a more pathogenic strain of Influenza A in 1957
• B) The slow accumulation of mutations in the 1918 Influenza A virus that impaired its infectivity in humans
• C) The changes in human living conditions leading to spread of Influenza A from pigs into humans, rather than from birds
• D) High levels of existing immunity in the human population to the H1N1 surface antigens
• E) The greater mobility of the human population due to the rapid increase in airplane travel

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Definitions:

Electron Microscope

A type of microscope that uses a beam of electrons to create an image of the specimen with much higher resolution than a light microscope.

Selectively Permeable Membrane

A membrane that allows certain molecules or ions to pass through it by diffusion and occasionally specialized processes, crucial in maintaining the cell environment.

Osmosis

The movement of water molecules through a selectively permeable membrane from a region of lower solute concentration to one of higher concentration.

Protein

Large biomolecules, or macromolecules, composed of one or more long chains of amino acid residues, crucial for the structure, function, and regulation of the body's tissues and organs.