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# The Erythrovirus412, which affects farmed Atlantic salmon

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Intern
Joined: 04 Oct 2018
Posts: 48
The Erythrovirus412, which affects farmed Atlantic salmon  [#permalink]

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27 Jan 2019, 23:57
2
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Difficulty:

75% (hard)

Question Stats:

47% (01:58) correct 53% (02:05) wrong based on 104 sessions

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The Erythrovirus412, which affects farmed Atlantic salmon, infects human beings by adhering to red blood cells. The virus elevates the body’s white blood cell count, indicating that the body is fighting an infection. Surprisingly, when a group of recently-infected people were tested, the proportion of white blood cells compared to red blood cells in their bodies was similar to that of an uninfected person.

Which of the following, if true, most helps to explain the surprising finding?

A - An infected body can sometimes attempt to stimulate its immune system by producing an unusually high number of white blood cells.

B - Ingestion of infected salmon by people whose immune system is already weak can destroy a significant proportion of red blood cells in the body.

C - The Nucleic Acid Test (NAT) used to detect the virus has revealed that the virus embeds itself in the plasma constituting the lining of a cell in addition to circulating through blood cells.

D - The virus multiplies by increasing the number of its host cells.

E - Most people infected by the virus develop fever two weeks after being infected, but show no other symptoms of the disease.
Math Expert
Joined: 02 Aug 2009
Posts: 7334
Re: The Erythrovirus412, which affects farmed Atlantic salmon  [#permalink]

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29 Jan 2019, 06:49
1
Skyline393 wrote:
The Erythrovirus412, which affects farmed Atlantic salmon, infects human beings by adhering to red blood cells. The virus elevates the body’s white blood cell count, indicating that the body is fighting an infection. Surprisingly, when a group of recently-infected people were tested, the proportion of white blood cells compared to red blood cells in their bodies was similar to that of an uninfected person.

Which of the following, if true, most helps to explain the surprising finding?

A - An infected body can sometimes attempt to stimulate its immune system by producing an unusually high number of white blood cells.

B - Ingestion of infected salmon by people whose immune system is already weak can destroy a significant proportion of red blood cells in the body.

C - The Nucleic Acid Test (NAT) used to detect the virus has revealed that the virus embeds itself in the plasma constituting the lining of a cell in addition to circulating through blood cells.

D - The virus multiplies by increasing the number of its host cells.

E - Most people infected by the virus develop fever two weeks after being infected, but show no other symptoms of the disease.

Let us rework on the para first..

E-virus attaches to RBC and results in decrease of WBC of the infected person.
But the ratio of RBC:WBC in infected person is found to be SAME as that in uninfected person.

Logically the $$\frac{RBC}{WBC}$$ should decrease in infected person as the denominator, that is WBC, is increasing.
So, what is happening here??
--- The choice should tell us that.
But, logically $$\frac{RBC}{WBC}$$ will remain same even with increase of WBC when
WBC decreases due to some other reason
RBC too increases in the infected person

Let us check the choices for above two reasons or anything else that solves the paradox.

A - An infected body can sometimes attempt to stimulate its immune system by producing an unusually high number of white blood cells.
A further increase in WBC,.. complicates the issue further... exactly opposite of what we are looking for

B - Ingestion of infected salmon by people whose immune system is already weak can destroy a significant proportion of red blood cells in the body.
A decrease in RBC in few people,..... firstly deals with a small set of people and secondly even if we accept it, it is exactly opposite of what we are looking for

C - The Nucleic Acid Test (NAT) used to detect the virus has revealed that the virus embeds itself in the plasma constituting the lining of a cell in addition to circulating through blood cells.
We are not interested in the way the virus behaves.... Out of scope

D - The virus multiplies by increasing the number of its host cells.
YES, something which talks of an increase of host cells, and what are the host cells here---- RBC. That means RBC increase and this is what we are looking for. A simultaneous increase in RBC keeps the proportion of RBC and WBC same

E - Most people infected by the virus develop fever two weeks after being infected, but show no other symptoms of the disease.
The point is of count of RBC and WBC and not the symptoms

D is the correct answer
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html
4) Base while finding % increase and % decrease : https://gmatclub.com/forum/percentage-increase-decrease-what-should-be-the-denominator-287528.html

GMAT Expert

Re: The Erythrovirus412, which affects farmed Atlantic salmon   [#permalink] 29 Jan 2019, 06:49
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# The Erythrovirus412, which affects farmed Atlantic salmon

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