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The single-celled parasite known as Toxoplasma gondii

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Re: The single-celled parasite known as Toxoplasma gondii [#permalink]

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New post 04 Sep 2016, 23:29
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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 [#permalink]

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New post 26 Apr 2017, 23:28
7 minutes 40 seconds
All correct 2nd question took time. :) .
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Re: The single-celled parasite known as Toxoplasma gondii [#permalink]

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New post 27 Apr 2017, 20:13
can anyone provide me with the explanation of last question.
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Re: The single-celled parasite known as Toxoplasma gondii [#permalink]

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New post 26 Jan 2018, 00:02
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 [#permalink]

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New post 26 Jan 2018, 02:00
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 [#permalink]

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New post 27 Jan 2018, 23:55
nikhilpoddar wrote:
The single-celled parasite known as Toxoplasma gondii infects more than half of the world's human population without creating any noticeable symptoms. Once inside the human body, Toxoplasma rapidly spreads to the heart and other organs. 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. 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. Recent research, however, has shed light on the ways in which Toxoplasma achieves its remarkable infiltration of the human body.

Though there are few individual Toxoplasma cells coursing freely in the blood of an infected person, scientists have discovered that the parasite is quite common in certain cells, known as dendritic cells, involved in the human immune system. Dendritic cells are found in the digestive tract and frequently come into contact with the various pathogens that enter the human body through food and water. When the dendritic cells encounter pathogens, they travel to lymph nodes and relay this information to other immune cells that then take action against the reported pathogen. Scientists have found, however, that Toxoplasma is capable of hijacking dendritic cells, forcing them from their usual activity and using them as a form of transportation to infect the human body quickly. Without this transport mechanism, Toxoplasma could not reach the better-protected areas of the body.

Toxoplasma invades the human body through consumption of the undercooked meat of infected animals, primarily pigs and chickens. Other animals, such as cats, can become infected as well. 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. Toxoplasma creates egg-like cysts, known as oocysts, in the cats' intestines. These oocysts are shed in the cats' droppings and contaminate ground water and soil, eventually finding their way into the food chain. Because 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.
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

[Reveal] Spoiler:
D


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.
-They are more numerous in the digestive tract than in any other part of the human body.
-Most dendritic cells of persons infected with Toxoplasma carry the parasite.
-They are the only cells capable of being infected by Toxoplasma.
-They are able to penetrate the membranes surrounding the brain.

[Reveal] Spoiler:
E


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.
-They will collect in the lymphatic system.
-They will not reproduce.
-They will be detected after several weeks.
-They will be destroyed by other pathogens in the bloodstream.

[Reveal] Spoiler:
C


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 the infectious agent reproduces itself.
E) It introduces information that is essential to understanding the role of Toxoplasma in human development.

[Reveal] Spoiler:
C




Can Anyone explain for Q3..how the ans is C?
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The single-celled parasite known as Toxoplasma gondii [#permalink]

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New post 09 Feb 2018, 00:05
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 [#permalink]

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New post 17 Feb 2018, 12:31
nikhilpoddar wrote:

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 the infectious agent reproduces itself.
E) It introduces information that is essential to understanding the role of Toxoplasma in human development.

[Reveal] Spoiler:
C
[/box_in][/box_out]



why its not D? please help
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Re: The single-celled parasite known as Toxoplasma gondii [#permalink]

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New post 17 Feb 2018, 12:52
rocko911 wrote:
nikhilpoddar wrote:

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 the infectious agent reproduces itself.
E) It introduces information that is essential to understanding the role of Toxoplasma in human development.

[Reveal] Spoiler:
C
[/box_in][/box_out]



why its not D? please help



Where do you see D mentioned in the passage. It's not. It can't be D.

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Re: The single-celled parasite known as Toxoplasma gondii   [#permalink] 17 Feb 2018, 12:52

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