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
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Erythrovirus412
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usefulcreature
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ceilidh.erickson
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If we're asked to EXPLAIN a surprising finding / discrepancy / paradox, first we have to discover why the finding is surprising --> we have to infer what the EXPECTED result would have been.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
Given: The virus elevates the body's white blood cell count --> infected people have more white blood cells
You would expect: Infected people have a higher proportional white blood cell count than uninfected people do.
Surprising Result: the proportion of white blood cells compared to red blood cells in their bodies was similar to that of an uninfected person
How to explain: We know that white blood cell counts are going up. If the proportion stays the same, though, that must mean that the red blood cell count is also going up.
A. An infected body can sometimes attempt to stimulate its immune system by producing an unusually high number of white blood cells
This does the opposite of what we're looking for - it would support the idea that there was a HIGHER proportion of white blood cells, not the same.
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
Same as above - this would indicate red blood cell levels going DOWN, not up.
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.
Irrelevant to the proportion of white:red blood cells.
D. The virus multiplies by increasing the number of its host cells
This would indicate red blood cells going up - correct!
E. Most people infected by the virus develop fever two weeks after being infected, but show no other symptoms of the disease
Symptoms are irrelevant to the proportion question.
Answer D is the only one that addresses an increasing number of red blood cells - the virus' host cells.
Last edited by ceilidh.erickson on Mon Mar 07, 2016 8:17 am, edited 1 time in total.
Ceilidh Erickson
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ceilidh.erickson
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For more on how to approach these EXPLAIN A DISCREPANCY question types, see here:
https://www.beatthegmat.com/resolve-the- ... tml#717366
https://www.beatthegmat.com/critical-rea ... tml#725224
https://www.beatthegmat.com/when-there-i ... tml#716501
https://www.beatthegmat.com/centralia-s- ... tml#544276
https://www.beatthegmat.com/cr-t155437.html#548469
https://www.beatthegmat.com/resolve-the- ... tml#717366
https://www.beatthegmat.com/critical-rea ... tml#725224
https://www.beatthegmat.com/when-there-i ... tml#716501
https://www.beatthegmat.com/centralia-s- ... tml#544276
https://www.beatthegmat.com/cr-t155437.html#548469
Ceilidh Erickson
EdM in Mind, Brain, and Education
Harvard Graduate School of Education
EdM in Mind, Brain, and Education
Harvard Graduate School of Education
ceilidh.erickson wrote:If we're asked to EXPLAIN a surprising finding / discrepancy / paradox, first we have to discover why the finding is surprising --> we have to infer what the EXPECTED result would have been.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
Given: The virus elevates the body's white blood cell count --> infected people have more white blood cells
You would expect: Infected people have a higher proportional white blood cell count than uninfected people do.
Surprising Result: the proportion of white blood cells compared to red blood cells in their bodies was similar to that of an uninfected person
How to explain: We know that white blood cell counts are going up. If the proportion stays the same, though, that must mean that the red blood cell count is also going up.
D. The virus multiplies by increasing the number of its host cells
This would indicate red blood cells going up - correct!
Answer D is the only one that addresses an increasing number of red blood cells - the virus' host cells.
Hi Erikson,
D suggests that by increasing the No of host's cells, the red blood cells outnumber the white blood cells. I get confused here.
An increase in the host's cells might refer to the white blood cells, the red blood cells, or both.
Pls help clarify how "host's cells" refers to "red blood" cells.
Thanks
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The truth is that you have found a weakness in this question.peter456 wrote:Hi Erikson,
D suggests that by increasing the No of host's cells, the red blood cells outnumber the white blood cells. I get confused here.
An increase in the host's cells might refer to the white blood cells, the red blood cells, or both.
Pls help clarify how "host's cells" refers to "red blood" cells.
Thanks
While the prompt does state that the Erythrovirus412 infects human beings by adhering to red blood cells, neither the prompt nor answer choice D makes entirely clear that the virus's host cells are the red blood cells of human beings. The red blood cells mentioned in the prompt could be those of the salmon or the red blood cells may be those of human beings and yet somehow not the "host cells" of the virus.
So in order to use answer choice D to explain the finding, you have to assume that given what is said in the prompt "adhering to red blood cells" means that some or all of the "host cells" of the virus are the red blood cells of human beings, and that white blood cells are not "host cells".
That having been said, that assumption is fairly safe, as given any reasonable understanding of the other answer choices, none of the other answer choices explain the finding.
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ceilidh.erickson
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I think the misunderstanding is actually this: the answer choice says "host cells," not "host's cells." In medical terminology, a "host cell" is specifically the cell that embodies a particular pathogen. Since we're told that these viruses "infects human beings by adhering to red blood cells," then the red blood cell are the HOST cell. (Think of "host" as just a modifier describing the type of cell).peter456 wrote: Hi Erikson,
D suggests that by increasing the No of host's cells, the red blood cells outnumber the white blood cells. I get confused here.
An increase in the host's cells might refer to the white blood cells, the red blood cells, or both.
Pls help clarify how "host's cells" refers to "red blood" cells.
Thanks
If the answer choice had been written "host's" (possessive), then you would be right - the human would be the host (presumably), and any human cell could be the host's cell.
This is just a quirk of English usage - not an issue you're likely to run into often. The moral here, if there is one, is to read carefully! Don't make assumptions about what's written.
Ceilidh Erickson
EdM in Mind, Brain, and Education
Harvard Graduate School of Education
EdM in Mind, Brain, and Education
Harvard Graduate School of Education
