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Re: The single-celled parasite known as Toxoplasma gondii infects more [#permalink]
Good RC!
1. E ( must is too extreme even in the passage it has been mentioned that
Quote:
In fact, cats are a necessary component in the reproductive cycle of Toxoplasma
, it is necessary not a must condition)

2.E
(In first paragraph
Quote:
It can even penetrate the tight barrier that normally protects the brain from most pathogens

Please see the last line of the second paragraph
Quote:
Without this transport mechanism, Toxoplasma could not reach the better-protected areas of the body.
hence we can conclude that d-cells are able to penetrate protected areas such as brain)

3.D
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Re: The single-celled parasite known as Toxoplasma gondii infects more [#permalink]
nikhilpoddar wrote:
anyone else ???


The second paragraph performs which of the following functions in the passage?
It describes a paradox that scientists were unable to resolve for some time.
It explains the effectiveness of a lethal biological pathogen.
It describes the mechanism by which a biological event occurs in humans.
It demonstrates how an infectious agent enters the human body.
It introduces information that is essential to understanding the role of Toxoplasma in human development.
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Re: The single-celled parasite known as Toxoplasma gondii infects more [#permalink]
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nikhilpoddar wrote:
OA
D
E
C


What is source of these passage?
How 'E' can be answer for second question no where its stated that dendritic cell can penetrate brain membrane
its Taxoplasma(mentioned in passage 1)
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Re: The single-celled parasite known as Toxoplasma gondii infects more [#permalink]
can some one please elaborate on the Ans.

1- D (how is it possible, Para 1 says it can can pass through human immune system and is detected much later due to the symptoms caused..)
Why is A wrong -- passage says the water is contaminated by cat droppings containing mould -- via soil and water(but the pathogen itself dosent goto soil to contaminate it)

2- E ( 2nd para never says that they are produced by lump nodes --they only travel towards lymp nodes when encountered by pathogens)
* B is clearly given in passage why not B? :-p

Any one can shed some light please.
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Re: The single-celled parasite known as Toxoplasma gondii infects more [#permalink]
Aristocrat wrote:
nikhilpoddar wrote:
OA
D
E
C


What is source of these passage?
How 'E' can be answer for second question no where its stated that dendritic cell can penetrate brain membrane
its Taxoplasma(mentioned in passage 1)



HEY,
first of all, this is inference question.....the answer choice will not be stated as it is in the passage , rather it will be distorted. For the E can be inferred
from the passage. Taxoplasma can penetrate human brain ( mentioned in the first paragraph)..but Taxoplasma can move to the body only by using Dendritic cell
( mentioned in the last line of 2nd paragraph).
SO dendritic cell can penetrate brain membrane.
hope it helps!!!!
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Re: The single-celled parasite known as Toxoplasma gondii infects more [#permalink]
Can someone please explain the first question.
"Scientists have long been puzzled by this ability of Toxoplasma to parasitize the human body without triggering an immune response and without an appreciable presence in the bloodstream."
So how can D be the correct answer?
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Re: The single-celled parasite known as Toxoplasma gondii infects more [#permalink]
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ronr34 wrote:
Can someone please explain the first question.
"Scientists have long been puzzled by this ability of Toxoplasma to parasitize the human body without triggering an immune response and without an appreciable presence in the bloodstream."
So how can D be the correct answer?


We are asked to determine which one of the five choices is NOT true of Toxoplasma, according to the passage. In other words, four of the five choices are stated in the passage and one choice is not. The choice that is not stated is the correct answer.

(A) The passage explicitly states that Toxoplasma can contaminate soil and water.

(B) The passage explicitly states that Toxoplasma enters the human body through contaminated food.

(C) The passage explicitly states that Toxoplasma alters the behavior of human dendritic cells.

(D) CORRECT. The word "incapable" in this answer choice is too strong; the passage does not state that the human body cannot detect Toxoplasma. Rather, it merely indicates that Toxoplasma does not trigger the body's immune system in the same way as other parasites. We have no information about the human body's ability to detect free-floating Toxoplasma cells.

(E) The passage explicitly states that Toxoplasma can breed in a host cat only.
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Re: The single-celled parasite known as Toxoplasma gondii infects more [#permalink]
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Its fair to consider D as one of the option due to its strong tone "incapable". However, Option C states that " it affects the usual behavior of human cells".
Going by the same yardstick, i think the option should be specific: human dendritic cells. But since it does not, why is this statement (C) loosely accepted and not "Incapable" one (D)

Also there are million types of cells in human body so the statement should be SPecific.
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Re: The single-celled parasite known as Toxoplasma gondii infects more [#permalink]
Hi

1. The second paragraph performs which of the following functions in the passage?

A. It describes a paradox that scientists were unable to resolve for some time.
B. It explains the effectiveness of a lethal biological pathogen.
C. It describes the mechanism by which a biological event occurs in humans.
D. It demonstrates how an infectious agent enters the human body.
E. It introduces information that is essential to understanding the role of Toxoplasma in human development.

Please explain. i choose A
Doubt b/t A and C
Explain plzz..!!
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Re: The single-celled parasite known as Toxoplasma gondii infects more [#permalink]
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ssriva2 wrote:
dpo28 wrote:
Hi

1. The second paragraph performs which of the following functions in the passage?

A. It describes a paradox that scientists were unable to resolve for some time.
B. It explains the effectiveness of a lethal biological pathogen.
C. It describes the mechanism by which a biological event occurs in humans.
D. It demonstrates how an infectious agent enters the human body.
E. It introduces information that is essential to understanding the role of Toxoplasma in human development.

Please explain. i choose A
Doubt b/t A and C
Explain plzz..!!


even I choose A because of the last sentence in first para.Please explain this!


Hi

A: It can't be the appropriate choice because question is asking the role played by second para. If we think clearly, is second para all about describing how scientists resolve the paradox or is it describing a biological process mainly ?
Second para is mainly dealing with the description of how a process occurs.

If we look that way then only B and C seem appropriate. B is wrong because Toxoplasm is a parasite not a pathogen.
E is wrong because Toxoplasm don't play any role in human development rather they play role in destruction.
D is wrong because passage don't describe how it enters human body, the passage describes what it do inside the body (which can be done only after it has already been entered in the body)


Consider kudos if it was helpful :)
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Re: The single-celled parasite known as Toxoplasma gondii infects more [#permalink]
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e100 wrote:
Can someone explain third question?



3. Which of the following is the most likely outcome for Toxoplasma cells that invade the human body?

A. They will be destroyed by the immune system.
B. They will collect in the lymphatic system.
C. They will not reproduce.
D. They will be detected after several weeks.
E. They will be destroyed by other pathogens in the bloodstream.


The question asks us to infer something about Toxoplasma from the information given in the passage. When answering questions of this type, remember that GMAT
inferences are typically very close to the original text, although they never repeat information verbatim. Make sure to select an answer that is not stated explicitly but
can be inferred without making any additional assumptions.
(A) The passage does not suggest that the immune system will destroy Toxoplasma cells.
(B) The passage does not suggest that Toxoplasma collects in the lymphatic system.
(C) CORRECT. The passage states that Toxoplasma can reproduce only in a host cat. Therefore, any Toxoplasma cells that remain in the human body are not likely to reproduce.
(D) The passage does not suggest that Toxoplasma will be detected after several weeks.
(E) The passage does not suggest that Toxoplasma will be destroyed by pathogens in the bloodstream.
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Re: The single-celled parasite known as Toxoplasma gondii infects more [#permalink]
According to the passage, all of the following are true of Toxoplasma gondii EXCEPT
-it can contaminate ground water
-it enters the human body through the food chain
-it can alter the usual behavior of human cells
-the human body is incapable of detecting it
-it must find a host cat in order to reproduce

According to the 2nd para ,
Toxoplasma can alter the behaviour of the Dendritic Cells. Isn't option C too broad in scope to be right?
As for Option D , It isnt implied in the passage that it is not detected . Its only implied that no action is taken against the pathogen.

Please explain.
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Re: The single-celled parasite known as Toxoplasma gondii infects more [#permalink]
According to the passage, all of the following are true of Toxoplasma gondii EXCEPT
-it can contaminate ground water
-it enters the human body through the food chain
-it can alter the usual behavior of human cells
-the human body is incapable of detecting it
-it must find a host cat in order to reproduce

I was confused between A and D. First time, I chose A,
because there is a sentence 'These oocysts are shed in the cats' droppings and contaminate ground water~'
So I think water is contaminated not Toxoplasma but oocysts.
However, D is totally wrong, because scientests have found the fact that Toxoplasma is capable of hijacking dendritic cells.
It means that human body is capable of detecting Toxoplama gondii.
So OA is D.(Question 1 is hard to me..)



It can be inferred from the passage that which of the following statements is true of dendritic cells in the human body?
-They are produced by the lymphatic system.
-> incorrect. They are produced in the cat's intestines.
-They are more numerous in the digestive tract than in any other part of the human body.
-> Not mentioned
-Most dendritic cells of persons infected with Toxoplasma carry the parasite.
-> Wrong. Dendritic cells are hijacked by Toxoplasma, but it is hard to like C
Let's suppose there are x,yzC positions.
Hijacking is happened in z, we cannot say most dendritic cells are infected.
-They are the only cells capable of being infected by Toxoplasma.
-> Not mentioned about 'only cells'.
-They are able to penetrate the membranes surrounding the brain.
-> correct.



Which of the following is the most likely outcome for Toxoplasma cells that invade the human body?
-They will be destroyed by the immune system.
-> incorrect.
There is a clue in 1st sentence of 2nd paragraph
'scientists have discovered the parasite is quite common in certain cells,
known as dendritic ceels, involved in the human immune system,
: If A is correct, Toxoplasma cells cannot detected in certain cells, involved in the human immune system
-They will collect in the lymphatic system.
-> Not mentioned.
-They will not reproduce.
-> Correct
In last sentence, there are clues.
1. In fact, cats are a necessary component in the reproductive cycel of Toxoplasma,since the animal's intestines are the parasite's sole breeding ground.
2. Toxoplasma must somehow find its way into a new host cat in order to reproduce
: So C is correct
-They will be detected after several weeks.
-> Not mentioned
-They will be destroyed by other pathogens in the bloodstream.
-> Not mentioned



The second paragraph performs which of the following functions in the passage?

: 2nd paragraph explains about mechanism how Toxoplasma cells are not detected in human body.

A) It describes a paradox that scientists were unable to resolve for some time.
-> resolve? wrong.
B) It explains the effectiveness of a lethal biological pathogen.
-> effectiveness? wrong. 2nd paragraph just explains the mechanism.
C) It describes the mechanism by which a biological event occurs in humans.
-> correct
D) It demonstrates how the infectious agent reproduces itself.
-> 'reproduce' is mentioned in last paragraph, not 2nd paragraph
E) It introduces information that is essential to understanding the role of Toxoplasma in human development.
-> incorrect. There is no rold of Toxoplasma in human development.
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Re: The single-celled parasite known as Toxoplasma gondii infects more [#permalink]
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Q1- According to the passage, all of the following are true of Toxoplasma gondii EXCEPT
-it can contaminate ground water - Clearly given
-it enters the human body through the food chain - Clearly given
-it can alter the usual behavior of human cells - It does so for the dendritic cells. Hold this one.
-the human body is incapable of detecting it - Hold this
-it must find a host cat in order to reproduce - Clearly given
Between C and D, since option C applies to a specific type of cell,that can pass. Also D is strengthened as the para 1 says that no immune response is generated by the body and it's still a puzzle.
hence ans- Option D

Q2-It can be inferred from the passage that which of the following statements is true of dendritic cells in the human body?
-They are produced by the lymphatic system. - Nowhere given
-They are more numerous in the digestive tract than in any other part of the human body. - are they even present in other part, unsure. Cancel this out.
-Most dendritic cells of persons infected with Toxoplasma carry the parasite. - Nowhere particularly mentioned
-They are the only cells capable of being infected by Toxoplasma. - Where has this been 'explicitly' mentioned?
-They are able to penetrate the membranes surrounding the brain. 'It can even penetrate the tight barrier that normally protects the brain from most pathogens. Yet, the blood of infected persons carries very few free-floating Toxoplasma cells. '

Q3- Which of the following is the most likely outcome for Toxoplasma cells that invade the human body?
-They will be destroyed by the immune system. - the immune system cannot understand them, so no!
-They will collect in the lymphatic system. - where is this said? No!
-They will not reproduce. - CORRECT. They can only reproduce inside a cat's body! '. In fact, cats are a necessary component in the reproductive cycle of Toxoplasma, since the animal's intestines are the parasite's sole breeding ground. '
-They will be detected after several weeks. - Cannot be infered
-They will be destroyed by other pathogens in the bloodstream.- NO. Nowhere mentioned

Q4- The second paragraph performs which of the following functions in the passage?
A) It describes a paradox that scientists were unable to resolve for some time. - Hold this
B) It explains the effectiveness of a lethal biological pathogen. - 'effectiveness?' - Nonsense
C) It describes the mechanism by which a biological event occurs in humans. -Hold this
D) It demonstrates how the infectious agent reproduces itself. - NO IT DOES NOT
E) It introduces information that is essential to understanding the role of Toxoplasma in human development. - Lol. toxoplasma and Human Development- Poles apart
Now between A and C.
Now although A seems tempting, there is no 'paradox' Paradox means contradiction. There's no contradiction here. It is just another topic that was unclear but latest research has shed some light on it. No opposing views. Hence, it is wrong. Correct answer hence is C.

Hope this helps. Hit Kudos if it does or if you like it :)
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Re: The single-celled parasite known as Toxoplasma gondii infects more [#permalink]
This looks very much unlike the GMAT Standard RC , So much Confusion

Question 1

Why not choice C - It talks of human cell , specifically its dendritic cell , so we can narrow down to C ,

but wait :p :dream:

Choice E is a strong contender because (even rodent can be a host for Toxoplasma)

para 3 :-
" Toxoplasma must somehow find its way into a new host cat in order to reproduce, it cannot kill its current host. Instead, it waits for the host, usually a small rodent, to be eaten by a cat, thus providing Toxoplasma the opportunity to reproduce"


Question 4 can not be A , even i answered A , i think it is wrong , because its not describing the Paradox , which is " the ability of Toxoplasma to parasitize the human body without triggering an immune response and without an appreciable presence in the bloodstream " , it is resolving the paradox by telling the biological mechanism.
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Re: The single-celled parasite known as Toxoplasma gondii infects more [#permalink]
GovindAgrawal wrote:
can anyone provide me with the explanation of last question.


(A) provide specific examples of animals that can carry Toxoplasma CORRECT
(B) provide specific examples of animals that are often eaten by cats ''Toxoplasma invades the human body through consumption of the undercooked meat'' suggests that the example animals are eaten by human
(C) provide specific examples of other animals whose dendritic cells are exploited by Toxoplasma Same as B
(D) provide specific examples of animals in which Toxoplasma can breed Cats' intestines are the sole breeding ground of the parasites. None of the pig or chicken's business.
(E) provide specific examples of animals that are immune to Toxoplasma Really? Not heard of it.
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Re: The single-celled parasite known as Toxoplasma gondii infects more [#permalink]
I have doubt on option B of question 2.

In the second paragraph the passage states that:
"Dendritic cells are found in the digestive tract"

I think, the chances of whether "ARE FOUND" part of this sentence gives us "CAN BE FOUND" or "ONLY FOUND" is 50%-50%. This sentence alone neither EXPLICITLY or IMPLICITLY tells us which one.

I simply cannot 100% infer that "ARE FOUND" = "CAN BE FOUND" (in other words "they can be in other parts of the body")

Though I am also aware that we cannot 100% infer that "ARE FOUND" = "ONLY FOUND"

Please, help me understand this.
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Re: The single-celled parasite known as Toxoplasma gondii infects more [#permalink]
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