hazelnut wrote:
In response to viral infection, the immune systems of mice typically produce antibodies that destroy the virus by binding to proteins on its surface. Mice infected with the herpesvirus generally develop keratitis, a degenerative disease affecting part of the eye. Since proteins on the surface of cells in this part of the eye closely resemble those on the herpesvirus surface, scientists hypothesize that these cases of keratitis are caused by antibodies to the herpesvirus.
Which of the following, if true, most helps to support the scientists’ reasoning?
(A) Other types of virus have surface proteins that closely resemble proteins found in various organs of mice.
(B) Mice that are infected with the herpesvirus but do not develop keratitis produce as many antibodies as infected mice that do develop keratitis.
(C) Mice infected with a new strain of the herpesvirus that has different surface proteins did not develop keratitis.
(D) Mice that have never been infected with the herpesvirus can sometimes develop keratitis.
(E) There are mice that are unable to form antibodies in response to herpes infections, and these mice contract herpes at roughly the same rate as other mice.
Step 1: Read the question stem: Which of the following, if true, most helps to support the scientists’ reasoning?
This looks like a Strengthen the Argument question
Step 2: Summarize the argument to yourself so you full understand its structure
PREMISE: infection --> antibodies bind to virus' proteins and kills it
PREMISE: mice with herpesvirus develop keratitis in eye
PREMISE: proteins on eye resemble herpesvirus proteins
CONCLUSION:
antibodies to herpesvirus CAUSE keratitis Step 3: Read each answer choice while reminding yourself of the argument's conclusion.
(A) Other types of virus have surface proteins that closely resemble proteins found in various organs of mice.
Does this strengthen the conclusion that
antibodies to herpesvirus CAUSE keratitis?.
No. This information has no bearing on the conclusion.
ELIMINATE
(B) Mice that are infected with the herpesvirus but do not develop keratitis produce as many antibodies as infected mice that do develop keratitis.
Does this strengthen the conclusion that
antibodies to herpesvirus CAUSE keratitis?.
No. This information actually hurts the conclusion.
ELIMINATE
(C) Mice infected with a new strain of the herpesvirus that has different surface proteins did not develop keratitis.
Does this strengthen the conclusion that
antibodies to herpesvirus CAUSE keratitis?.
YES!
If the herpesvirus is altered, then the antibodies do not cause keratitis.
This definitely strengthens the conclusion.
KEEP C
(D) Mice that have never been infected with the herpesvirus can sometimes develop keratitis.
Does this strengthen the conclusion that
antibodies to herpesvirus CAUSE keratitis?.
No. It just tells us that other things may also cause keratitis. That's fine, but it doesn't address whether or not the
antibodies to herpesvirus cause keratitisELIMINATE
(E) There are mice that are unable to form antibodies in response to herpes infections, and these mice contract herpes at roughly the same rate as other mice
Does this strengthen the conclusion that
antibodies to herpesvirus CAUSE keratitis?.
No, this has nothing to do with keratitis
ELIMINATE
Answer: C
Cheers,
Brent