Although pathogenic organisms constantly alight on the skin, they find

Para1:
Self sterilizing functionality prevents Pathogenic organisms (P) to alight on the skin .

Para2: Some reasons for preventing establishment of invaders.
Most interesting reason: metabolic activities of the resident flora and its explanation


Summary: Reasons why pathogens dnt alight on skin

1. The primary purpose of the passage is to

(A) offer an analysis of metabolic processes
>>it is just one part of 2nd para

(B) detail the ways in which bacteria and fungi can be inhibited
>>it is just one part of 2nd para

(C) describe mechanisms by which the skin protects itself against pathogens-CORRECT
>> matches our pre-thinking

(D) analyze the methods whereby biological systems maintain the status quo
>>>>it is just one part of 1st para

(E) provide a specific example of the skin’s basic defenses against pathogens
>>passage says some reasons why pathogens don't alight on skin and how skin protects against them


2. The “resident flora” mentioned in line 16 refer to

The most interesting defense mechanism, however, results from the metabolic activities of the resident flora. Unsaturated fatty acids, an important component of the lipids in sebum collected from the skin surface, inhibit the growth of several bacterial and fungal cutaneous pathogens. These acids are a metabolic product of certain gram-positive members of the cutaneous community, which break down the more complex lipids in freshly secreted sebum.

>> means:
Unsaturated fatty acids in lipids in sebum at skin surface: because of this P cant grow
These products are from metabolic product of c community which breaks lipids in S.


Metabolic activities of the resident flora == metabolic product of certain gram-positive members of the cutaneous community, which breaks lipids in S.


(A) “Unsaturated fatty acids” (line 17)
(B) “sebum collected from the skin surface” (lines 18-19)
(C) “bacterial and fungal cutaneous pathogens” (lines 19-20)
(D) “certain gram-positive members of the cutaneous community” (lines 21-22)-CORRECT
(E) “more complex lipids” (lines 23)


3. Among the natural defenses of the skin against pathogenic organisms are all of the following EXCEPT the

(A) dryness of the skin
>> too arid for some species( if you don’t know meaning of arid , you can look for other choices first)

(B) acidity of the skin
>> The skin is too acid

(C) tendency of the pathogens toward homeostasis-CORRECT
>> the tendency of all well-developed ecosystems toward homeostasis or the maintenance of the status quo.-> definitely it is not talking about tendency of the pathogens toward homeostasis

(D) shedding of surface layers of the skin
>> The constant shedding of the surface skin

(E) metabolic breakdown of lipids
>> Lipids in sebum collected from the skin surface, inhibit the growth of several bacterial and fungal cutaneous pathogens. Interesting defense mechanism, however, results from the metabolic activities


4. The author presents her material in which of the following ways?

(A) Stating a problem and then supplying a solution
>>topic: pathogenic organisms constantly alight on the skin ( the passage didn’t mention it’s a problem that skin can not protect and hwo can skin protect)-

(B) Presenting a phenomenon and then analyzing reason for it-CORRECT
>> phenomenon: skin do self protection
Then reasons how skin save against pathogens

(C) Providing information and then drawing a conclusion from it
>>this passage talks only about many reasons of how skin protect with each other after the topic was in initiated at first line of passage.

(D) Making a general statement and then arguing by analogy
>>no arguments; just reasons

(E) Making an inference and then developing it by illustration
>> just reasons of skin protection against pathogens