天山-5 32 求助

shashaxz

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Q32:
Macrophages are cells that play a role in the response of the immune system of mice and
other mammals to invasive organisms such as bacteria. Unlike other mice, mice that are
genetically incapable of making these particular cells do not show elevated levels of
nitrates when infected with bacteria.
The statements above, if true, provide the most support for which of the following
conclusions?

A. Mice that are unable either to make macrophages or to make them in sufficient
numbers will protect themselves from bacterial infections in some other way.
B. Mice that show elevated levels of nitrates can easily fight off most types of
bacterial infections.
C. In mice, macrophages play a role in the production of nitrates or inhibit a process
by which nitrates are broken down or otherwise eliminated.
D. When a healthy mouse becomes infected with an invasive organism, the number
of macrophages in the mouse’s body decreases.
E. Injections of nitrates into mice that lack macrophages will not enhance the ability
of these animals’ immune systems to fight off infection.
Answer:
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The answer in the tianshan answer excel file is C, mine is E.

Judging from the statements of the issue, obviously the option C is beside the point. In the mice which are genetically incapable of making these macrophages , it is ill-conceived to establish the cause-effect relationship between the macrophages and nitrates.

If this issue has already been discussed, please give me a link.

Thank you very much for help.

[此贴子已经被作者于2005-10-24 10:28:30编辑过]

shashaxz

No repsonse?

give me a hand pls.

shzgtc800

Macrophages are cells that play a role in the response of the immune system of mice and
other mammals to invasive organisms such as bacteria. Unlike other mice, mice that are
genetically incapable of making these particular cells do not show elevated levels of
nitrates when infected with bacteria.
The statements above, if true, provide the most support for which of the following
conclusions?

Nothing about "injection" has ever been metioned so no conclusion about injection can be infered from the above description.   

From the sencond sentence, "unlike other mice, mice that ... " we know other mice capable of making the particular cells show elevated levels of nitrates when infected with bacteria. From the first sentence, macrophages are cells that play a role when normal mice infected with bacteria.  Based on these two points, we therefore infer that direct relation exists between levels of nitrates (N) and macrophages (M).  Even whitout awarness about what kind of efforts M does against N,  you can pick C easily as it is the olny option about both nitrate and macrophages.  Actually we can find M positively affect levels of N by analysis of sentence 1 & 2. The two possible functions of M in option C are exactly what make M's positive effects on N possible.

Hope the above help you understand this question.

steveyangxt

agree