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Nearly a century ago, biologists found that if they separate

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New post 13 Aug 2016, 00:30
Can somebody please explain how to solve this type of question.

9.Which of the following circumstances is most comparable to the impasse biologists encountered in trying to resolve the debate about cell determination (lines 12-18)?
(A) The problems faced by a literary scholar who wishes to use original source materials that are written in an unfamiliar foreign language
(B) The situation of a mathematician who in preparing a proof of a theorem for publication detects a reasoning error in the proof
(C) The difficulties of a space engineer who has to design equipment to function in an environment in which it cannot first be tested
(D) The predicament of a linguist trying to develop a theory of language acquisition when knowledge of the structure of language itself is rudimentary at best
(E) The dilemma confronting a foundation when the funds available to it are sufficient to support one of two equally deserving scientific projects but not both

Thanks in advance.
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Nearly a century ago, biologists found that if they separated an invertebrate animal embryo into two parts at an early stage of its life, it would survive and develop as two normal embryos. This led them to believe that the cells in the early embryo are undetermined in the sense that each cell has the potential to develop in a variety of different ways. Later biologists found that the situation was not so simple. It matters in which plane the embryo is cut. If it is cut in a plane different from the one used by the early investigators, it will not form two whole embryos.

A debate arose over what exactly was happening. Which embryo cells are determined, just when do they become irreversibly committed to their fates, and what are the “morphogenetic determinants” that tell a cell what to become? But the debate could not be resolved because no one was able to ask the crucial questions in a form in which they could be pursued productively. Recent discoveries in molecular biology, however, have opened up prospects for a resolution of the debate. Now investigators think they know at least some of the molecules that act as morphogenetic determinants in early development. They have been able to show that, in a sense, cell determination begins even before an egg is fertilized.

Studying sea urchins, biologist Paul Gross found that an unfertilized egg contains substances that function as morphogenetic determinants. They are located in the cytoplasm of the egg cell; i.e., in that part of the cell’s protoplasm that lies outside of the nucleus. In the unfertilized egg, the substances are inactive and are not distributed homogeneously. When the egg is fertilized, the substances become active and, presumably, govern the behavior of the genes they interact with. Since the substances are unevenly distributed in the egg, when the fertilized egg divides, the resulting cells are different from the start and so can be qualitatively different in their own gene activity.
The substances that Gross studied are maternal messenger RNA’s—products of certain of the maternal genes. He and other biologists studying a wide variety of organisms have found that these particular RNA’s direct, in large part, the synthesis of histones, a class of proteins that bind to DNA. Once synthesized, the histones move into the cell nucleus, where section of DNA wrap around them to form a structure that resembles beads, or knots, on a string. The beads are DNA segments wrapped around the histones; the string is the intervening DNA. And it is the structure of these beaded DNA strings that guide the fate of the cells in which they are located.
It can be inferred from the passage that the morphogenetic determinants present in the early embryo are
(A) located in the nucleus of the embryo cells
(B) evenly distributed unless the embryo is not developing normally
(C) inactive until the embryo cells become irreversibly committed to their final function
(D) identical to those that were already present in the unfertilized egg
(E) present in larger quantities than is necessary for the development of a single individual



The main topic of the passage is
(A) the early development of embryos of lower marine organisms
(B) the main contribution of modern embryology to molecular biology
(C) the role of molecular biology in disproving older theories of embryonic development
(D) cell determination as an issue in the study of embryonic development
(E) scientific dogma as a factor in the recent debate over the value of molecular biology



According to the passage, when biologists believed that the cells in the early embryo were undetermined, they made which of the following mistakes?
(A) They did not attempt to replicate the original experiment of separating an embryo into two parts.
(B) They did not realize that there was a connection between the issue of cell determination and the outcome of the separation experiment.
(C) They assumed that the results of experiments on embryos did not depend on the particular animal species used for such experiments.
(D) They assumed that it was crucial to perform the separation experiment at an early stage in the embryo’s life.
(E) They assumed that different ways of separating an embryo into two parts would be equivalent as far as the fate of the two parts was concerned.



It can be inferred from the passage that the initial production of histones after an egg is fertilized takes place
(A) in the cytoplasm
(B) in the maternal genes
(C) throughout the protoplasm
(D) in the beaded portions of the DNA strings
(E) in certain sections of the cell nucleus



It can be inferred from the passage that which of the following is dependent on the fertilization of an egg?
(A) Copying of maternal genes to produce maternal messenger RNA’s
(B) Synthesis of proteins called histones
(C) Division of a cell into its nucleus and the cytoplasm
(D) Determination of the egg cell’s potential for division
(E) Generation of all of a cell’s morphogenetic determinants



According to the passage, the morphogenetic determinants present in the unfertilized egg cell are which of the following?
(A) Proteins bound to the nucleus
(B) Histones
(C) Maternal messenger RNA’s
(D) Cytoplasm
(E) No beaded intervening DNA



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Re: Nearly a century ago, biologists found that if they separate  [#permalink]

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New post 23 Mar 2017, 09:14
All correct except the 3rd one in 20 mins... Need to work with my pacing..... Can anyone please explain the ans of question 3? It seems easy to others, but I have definitely messed up with something.
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Re: Nearly a century ago, biologists found that if they separate  [#permalink]

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New post 24 Mar 2017, 18:43
Explanation of question 3:

the passage states,
"an unfertilized egg contains substances that function as morphogenetic determinants. They are located in the cytoplasm of the egg cell;"
"The substances that Gross studied are maternal messenger RNA’s"
"these particular RNA’s direct, in large part, the synthesis of histones"
It follows that the since the RNA is located in the cytoplasm, the histones are synthesized in the cytoplasm.
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New post 04 May 2017, 06:07
Explanation of all OA's would be helpful. I got absolutely destroyed in this passage, especially with inference Q's.
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Re: Nearly a century ago, biologists found that if they separate  [#permalink]

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New post 19 May 2017, 21:51
arunavamunshi1988 wrote:
All correct except the 3rd one in 20 mins... Need to work with my pacing..... Can anyone please explain the ans of question 3? It seems easy to others, but I have definitely messed up with something.


As per Q3, According to the passage, when biologists believed that the cells in the early embryo were undetermined, they made which of the following mistakes?
(A) They did not attempt to replicate the original experiment of separating an embryo into two parts.
(B) They did not realize that there was a connection between the issue of cell determination and the outcome of the separation experiment.
(C) They assumed that the results of experiments on embryos did not depend on the particular animal species used for such experiments.
(D) They assumed that it was crucial to perform the separation experiment at an early stage in the embryo’s life.
(E) They assumed that different ways of separating an embryo into two parts would be equivalent as far as the fate of the two parts was concerned.

As mentioned in the 1st para, especially these sentence "Later biologists found that the situation was not so simple. It matters in which plane the embryo is cut. If it is cut in a plane different from the one used by the early investigators, it will not form two whole embryos.", the problem is that the biologists use result of a particular case to emphasize generalization for all cases. They did not consider what will happen if the cut is made in a different plane (different ways of separating an embryo.......). That's why (E) is correct.

All other options cannot be inferred from the passage.
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Re: Nearly a century ago, biologists found that if they separate  [#permalink]

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New post 28 May 2017, 23:51
Can anyone explain question 1?.
Where is it mentioned remotely about the quantity of morphogenetic determinants?
Is the logic this :- an embryo can be separated to form two separate individual embryos and so morpho-determinants are subsequently used for tow embryos instead of one?
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Re: Nearly a century ago, biologists found that if they separate  [#permalink]

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New post 02 Jun 2017, 14:58
Quote:
It can be inferred from the passage that the morphogenetic determinants present in the early embryo are
(A) located in the nucleus of the embryo cells
(B) evenly distributed unless the embryo is not developing normally
(C) inactive until the embryo cells become irreversibly committed to their final function
(D) identical to those that were already present in the unfertilized egg
(E) present in larger quantities than is necessary for the development of a single individual

kkrrsshh wrote:
Can anyone explain question 1?.
Where is it mentioned remotely about the quantity of morphogenetic determinants?
Is the logic this :- an embryo can be separated to form two separate individual embryos and so morpho-determinants are subsequently used for tow embryos instead of one?

Yes, that's the correct logic! Although the "substances that function as morphogenetic determinants" are not evenly distributed, when the fertilized egg splits, at least some of the substances will go to each of the two new embryos if both are to "survive and develop as two normal embryos". If an early embryo only contained the exact quantity necessary for development, it would be impossible for the embryo to split and develop as two normal embryos.
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Re: Nearly a century ago, biologists found that if they separate  [#permalink]

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New post 09 Jun 2017, 00:28
Hi, can anybody explain me how Maternal Messenger RNA's are considered the morpho determinants?
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New post 09 Jun 2017, 02:14
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veepee wrote:
Hi, can anybody explain me how Maternal Messenger RNA's are considered the morpho determinants?


Hi,

Just read the 2nd paragraph and the beginning of the 3rd paragraph, then you're gonna see why

"Studying sea urchins, biologist Paul Gross found that an unfertilized egg contains substances that function as morphogenetic determinants. They are located in the cytoplasm of the egg cell; i.e., in that part of the cell’s protoplasm that lies outside of the nucleus. In the unfertilized egg, the substances are inactive and are not distributed homogeneously. When the egg is fertilized, the substances become active and, presumably, govern the behavior of the genes they interact with. Since the substances are unevenly distributed in the egg, when the fertilized egg divides, the resulting cells are different from the start and so can be qualitatively different in their own gene activity.
The substances that Gross studied are maternal messenger RNA’s—products of certain of the maternal genes"


Hope this helps.
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Re: Nearly a century ago, biologists found that if they separate  [#permalink]

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New post 10 Jun 2017, 05:25
3
1. It can be inferred from the passage that the morphogenetic determinants present in the early embryo are
(A) located in the nucleus of the embryo cells -It is the opposite of what the passage states. The passage states that these are present in the cytoplasm, which is outside the nucleus.
(B) evenly distributed unless the embryo is not developing normally - The are not homogeneous in distribution
(C) inactive until the embryo cells become irreversibly committed to their final function -No such thing stated
(D) identical to those that were already present in the unfertilized egg -This means to say that a new set of determinents were generated which are identical to those present in the cell earlier. This is completely absurd.
(E) present in larger quantities than is necessary for the development of a single individual -CORRECT. When the cells divide they still are able to develop.


2. The main topic of the passage is
(A) the early development of embryos of lower marine organisms - Wrong due to highlighted part of option. Nowhere its stated.
(B) the main contribution of modern embryology to molecular biology - No such thing stated in the passage.
(C) the role of molecular biology in disproving older theories of embryonic development - The molecular biology doesn't disprove anything.
(D) cell determination as an issue in the study of embryonic development - CORRECT. "Later biologists found that the situation was not so simple. It matters in which plane the embryo is cut. If it is cut in a plane different from the one used by the early investigators, it will not form two whole embryos. Which embryo cells are determined" - This part states the complete picture of the entire passage
(E) scientific dogma as a factor in the recent debate over the value of molecular biology -Irrelevant


3. According to the passage, when biologists believed that the cells in the early embryo were undetermined, they made which of the following mistakes?
(A) They did not attempt to replicate the original experiment of separating an embryo into two parts. -Irrelevant
(B) They did not realize that there was a connection between the issue of cell determination and the outcome of the separation experiment. -They did realise this
(C) They assumed that the results of experiments on embryos did not depend on the particular animal species used for such experiments. -Irrelevant
(D) They assumed that it was crucial to perform the separation experiment at an early stage in the embryo’s life. They did realise this
(E) They assumed that different ways of separating an embryo into two parts would be equivalent as far as the fate of the two parts was concerned. -CORRECT. They initially did this mistake, because when they came to know that cutting the cell in different ways will lead to different outcomes, they realised there are different ways to cut the cells, and each way won't result in equivalent fate.


4. It can be inferred from the passage that the initial production of histones after an egg is fertilized takes place
(A) in the cytoplasm -CORRECT. The determinants can be found in cytoplasm. RNA, being a determinent, was initially present in cytoplasm. Therefore histones should be in the cytoplasm initially
(B) in the maternal genes -wrong
(C) throughout the protoplasm -wrong
(D) in the beaded portions of the DNA strings -wrong
(E) in certain sections of the cell nucleus -wrong


5. It can be inferred from the passage that which of the following is dependent on the fertilization of an egg?
(A) Copying of maternal genes to produce maternal messenger RNA’s -RNA are products of maternal genes.
(B) Synthesis of proteins called histones -CORRECT. When the eggs are unfertilised, the determinents are inactive. When the eggs fertilize the determinents get into action by synthesis of histones
(C) Division of a cell into its nucleus and the cytoplasm -Wrong
(D) Determination of the egg cell’s potential for division -The cells' seperation potential is not given anywhere
(E) Generation of all of a cell’s morphogenetic determinants -These determinants are already present in the cell


6. According to the passage, the morphogenetic determinants present in the unfertilized egg cell are which of the following?
(A) Proteins bound to the nucleus -Wrong
(B) Histones -Wrong
(C) Maternal messenger RNA’s -CORRECT
(D) Cytoplasm -Wrong
(E) No beaded intervening DNA -Wrong
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Re: Nearly a century ago, biologists found that if they separate  [#permalink]

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New post 13 Oct 2017, 07:35
GMATNinja,

How are we supposed to determine who the target audience is for this paper? I have never come across a question like this, and I find the answer perplexing. This could have been directed at any audience.

My gripe with the answer E is that we are forced to assume these students are not freshmen with a high school level background.

Any help on this would be greatly appreciated!
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Nearly a century ago, biologists found that if they separate  [#permalink]

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New post 21 Dec 2017, 07:26
It is taken from this article.
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Re: Nearly a century ago, biologists found that if they separate  [#permalink]

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New post 22 Dec 2017, 07:21
hazelnut wrote:
It is taken from this article.


Thanks for the article, but this still does not help define who the audience is.

Also, isn't this listed as OG?
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New post 02 Apr 2018, 17:42
PUNEETSCHDV wrote:
@ anshunadir

and target audience is like tone of passage. find tone and also check key words like so many scientific terms used here. . the tone is just informing, there are no sides to take at all, nothing to criticize or nothing to support. its just knowledge sharing . some knowledge being given to a person interested in this subject. we are down to B and E. I eliminated B because scientists specializing in subject will be already knowing all this but this looks nice like a lecture to students. just a brief introduction before a lesson on subject. so E. other options are easily eliminated. kindly revert back if u have doubt with any of those ??


why not option D in this case (question 1) ...

Would option D cater to folks who want to learn about "new species" ...this too me sounds like new embroyos
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New post 05 Apr 2018, 13:31
jabhatta@umail.iu.edu wrote:
PUNEETSCHDV wrote:
@ anshunadir

and target audience is like tone of passage. find tone and also check key words like so many scientific terms used here. . the tone is just informing, there are no sides to take at all, nothing to criticize or nothing to support. its just knowledge sharing . some knowledge being given to a person interested in this subject. we are down to B and E. I eliminated B because scientists specializing in subject will be already knowing all this but this looks nice like a lecture to students. just a brief introduction before a lesson on subject. so E. other options are easily eliminated. kindly revert back if u have doubt with any of those ??


why not option D in this case (question 1) ...

Would option D cater to folks who want to learn about "new species" ...this too me sounds like new embroyos


If you've ever read a published scientific study you'll know that scientist to scientist communication is typically written in a way that is all but incomprehensible to the layman. This passage is clearly educational in nature and the overview of the topic given is overly broad for an audience that would already be familiar with it. If the intended audience were molecular biologists there would be no need to explain what a morphogenetic determinant is for example, because that audience would already know.
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New post 24 May 2018, 08:08
One of the toughest passage I 've ever gone through. Need explanations for question 2 , question 4 ( POE of B ) , question 5 (POE of E ) & question 9 ( POE of B ) . Thanks in advance.
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Re: Nearly a century ago, biologists found that if they separate  [#permalink]

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New post 25 May 2018, 00:47
carcass wrote:
Complete discussion is given at the below mentioned link
http://gmatclub.com/forum/nearly-a-cent ... 96221.html


Nearly a century ago, biologists found that if they separated an invertebrate animal embryo into two parts at an early stage of its life, it would survive and develop as two normal embryos. This led them to believe that the cells in the early embryo are undetermined in the sense that each cell has the potential to develop in a variety of different ways. Later biologists found that the situation was not so simple. It matters in which plane the embryo is cut. If it is cut in a plane different from the one used by the early investigators, it will not form two whole embryos.
A debate arose over what exactly was happening. Which embryo cells are determined, just when do they become irreversibly committed to their fates, and what are the “morphogenetic determinants” that tell a cell what to become? But the debate could not be resolved because no one was able to ask the crucial questions in a form in which they could be pursued productively. Recent discoveries in molecular biology, however, have opened up prospects for a resolution of the debate. Now investigators think they know at least some of the molecules that act as morphogenetic determinants in early development. They have been able to show that, in a sense, cell determination begins even before an egg is fertilized.
Studying sea urchins, biologist Paul Gross found that an unfertilized egg contains substances that function as morphogenetic determinants. They are located in the cytoplasm of the egg cell, i.e., in that part of the cell’s protoplasm that lies outside of the nucleus. In the unfertilized egg, the substances are inactive and are not distributed homogeneously. When the egg is fertilized, the substances become active and, presumably, govern the behavior of the genes they interact with. Since the substances are unevenly distributed in the egg, when the fertilized egg divides, the resulting cells are different from the start and so can be qualitatively different in their own gene activity.
The substances that Gross studied are maternal messenger RNA’s—products of certain of the maternal genes. He and other biologists studying a wide variety of organisms have found that these particular RNA’s direct, in large part, the synthesis of histones, a class of proteins that bind to DNA. Once synthesized, the histones move into the cell nucleus, where sections of DNA wrap around them to form a structure that resembles beads, or knots, on a string. The beads are DNA segments wrapped around the histones; the string is the intervening DNA. And it is the structure of these beaded DNA strings that guides the fate of the cells in which they are located.


It can be inferred from the passage that the morphogenetic determinants present in the early embryo are

1 located in the nucleus of the embryo cells

2 evenly distributed unless the embryo is not developing normally

3 inactive until the embryo cells become irreversibly committed to their final function

4 identical to those that were already present in the unfertilized egg

5 present in larger quantities than is necessary for the development of a single individual

E is the OA




Can you help to explain E as an OA? Why can't be D?
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Re: Nearly a century ago, biologists found that if they separate  [#permalink]

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New post 21 Jun 2018, 08:02
Where can I see the reasoning of each answer?
Re: Nearly a century ago, biologists found that if they separate &nbs [#permalink] 21 Jun 2018, 08:02

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