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# When the nineteenth-century German bacteriologist Robert Koch identifi

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When the nineteenth-century German bacteriologist Robert Koch identifi  [#permalink]

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Updated on: 17 Jan 2019, 01:43
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68% (02:16) correct 32% (02:15) wrong based on 523 sessions

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When the nineteenth-century German bacteriologist Robert Koch identified a particular bacterium as responsible for cholera, Max von Pettenkoffer, a physician, expressed his skepticism by voluntarily drinking an entire bottle of the allegedly responsible bacteria. Although von Pettenkoffer took his failure to come down with the disease as a refutation of Koch's hypothesis that cholera was caused by bacteria, Koch argued that von Pettenkoffer had been protected by his own stomach acid. The acid secreted by the stomach, Koch explained, kills most ingested bacteria.

Which of the following, if true, provides the most evidence to support Koch's counterargument?

A. Peptic ulcers, often associated with excessive secretions of stomach acid, are common in certain areas characterized by low rates of cholera.

B. As von Pettenkoffer later admitted that he had previously had cholera, it is probable that he had developed antibodies that protected him from a second attack.

C. Cholera is endemic in areas in which poor sanitation results in high concentrations of cholera bacteria in drinking water.

D. Although stomach acid kills most ingested bacteria, large numbers of e. coli bacteria nonetheless manage to make their way to the lower intestine of the digestive tract.

E. Cholera bacteria ingested with bicarbonate of soda, a neutralizer of stomach acid, is more likely to result in cholera than if the bacteria is ingested alone.

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Originally posted by Anamika2014 on 06 Sep 2014, 12:35.
Last edited by Bunuel on 17 Jan 2019, 01:43, edited 1 time in total.
Renamed the topic and edited the question.
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Re: When the nineteenth-century German bacteriologist Robert Koch identifi  [#permalink]

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06 Sep 2014, 13:03
1
Hi Anamika,

The best strategy to attack this question is to use Process of Elimination (PoE).

After reading the passage, we can see that Koch's counterargument is that von Pettenkoffer's stomach acid killed the ingested cholera bacteria resulting in him not getting infected.
We need to find which of the answer choices best supports this statement.

Answer choice A isn't relevant to this argument, so we can eliminate it.
Answer choice B provides an explanation for why von Pettenkoffer didn't get infected, but it doesn't support Koch's theory about stomach acid.
Answer choice C isn't relevant to this argument, so we can eliminate it.
Answer choice D talks about how stomach acid allows some bacteria to survive. This would weaken Koch's counterargument.
Answer choice E provides an alternative to neutralize the stomach acid and make infection more likely. This statement supports Koch's counterargument because it wouldn't allow the stomach acid to kill the cholera bacteria.

So, Answer Choice E is the only answer that supports Koch's argument.

Hope that helps! Good luck studying!

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Re: When the nineteenth-century German bacteriologist Robert Koch identifi  [#permalink]

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04 Apr 2016, 08:26
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Though A is a strong contestant, A is not the answer because there is Koch never explained the more the acid is secreted the better a person is protected from cholera.

But E says that when a neutralizer of acid is added there is more chances of a person getting cholera which clearly is anevidence that acid kills the ingested bacteria.
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Re: When the nineteenth-century German bacteriologist Robert Koch identifi  [#permalink]

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17 Jan 2019, 01:44
Anamika2014 wrote:
When the nineteenth-century German bacteriologist Robert Koch identified a particular bacterium as responsible for cholera, Max von Pettenkoffer, a physician, expressed his skepticism by voluntarily drinking an entire bottle of the allegedly responsible bacteria. Although von Pettenkoffer took his failure to come down with the disease as a refutation of Koch's hypothesis that cholera was caused by bacteria, Koch argued that von Pettenkoffer had been protected by his own stomach acid. The acid secreted by the stomach, Koch explained, kills most ingested bacteria.

Which of the following, if true, provides the most evidence to support Koch's counterargument?

A. Peptic ulcers, often associated with excessive secretions of stomach acid, are common in certain areas characterized by low rates of cholera.

B. As von Pettenkoffer later admitted that he had previously had cholera, it is probable that he had developed antibodies that protected him from a second attack.

C. Cholera is endemic in areas in which poor sanitation results in high concentrations of cholera bacteria in drinking water.

D. Although stomach acid kills most ingested bacteria, large numbers of e. coli bacteria nonetheless manage to make their way to the lower intestine of the digestive tract.

E. Cholera bacteria ingested with bicarbonate of soda, a neutralizer of stomach acid, is more likely to result in cholera than if the bacteria is ingested alone.

KAPLAN OFFICIAL EXPLANATION:

E

After reading the stem for question 27, we go to the stimulus with eyes peeled for Koch's counterargument. Koch, we learn, is unconvinced by von Pettenkoffer's dramatic demonstration. When, after drinking a bottle of bacteria, von Pettenkoffer doesn't develop cholera, he claims to have proved that the bacterium doesn't cause cholera. Koch disagrees, saying that von Pettenkoffer's stomach acid killed the bacteria before it could affect him. Be careful; we don't want to strengthen Koch's original argument-that the bacterium causes cholera, but rather his second argument-that von Pettenkoffer's stomach acid killed the bacteria. (E) says that when the cholera bacteria is ingested with bicarbonate of soda, a stomach acid neutralize^ it's more likely that the person will develop the illness. (E), then, shows that acidity has an inhibiting effect on cholera bacteria, exactly as Koch argued.
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Re: When the nineteenth-century German bacteriologist Robert Koch identifi   [#permalink] 17 Jan 2019, 01:44
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