AAMC Bio Question Pack Volume 1 #6

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7+ Year Member
Sep 28, 2016
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Hello all,

In Q Pack, Biology number 6. I understand that C and D is clearly out. But among A and B, both is possible. I went with B and the answer is A. In such kind of similar cases, how would you know which one is more likely to be correct. For me, I choose B because the passage said that only certain antibodies are able to eradicate the infection so I thought B correctly summarizes what the passage is saying. Please help me. Thanks

In case you are wondering, the question is as follows:
Which of the statements explains most plausibly why host antibodies are ineffective against H.pylori?

A. Antibody proteins maybe denatured in the harsh environment of the stomach.
B. Antibodies are not generally effective against bacteria.
C. H.pylori infection may suppress the activity of the immune system
D. Antibodies are not secreted from host tissues into extracellular spaces.

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H. pylori exists in the stomach acid, releasing certain enzymes (such as urease) to make it more hospitable for it to thrive. Nonetheless, the pH is way too low for antibody proteins to be secreted. They will be denatured before they can act on the bacteria. That's why A is the best choice.
First of all, generalizing in the answer choice is usually not a good idea. Here, it's saying that antibodies "generally" do not work against bacteria, which is not true because antibodies, in fact, serve a primary purpose of attacking bacteria and other invaders.