Find all School-related info fast with the new School-Specific MBA Forum

It is currently 23 Oct 2014, 12:09

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Nearly a century ago, biologists found that if they

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Expert Post
Moderator
Moderator
User avatar
Joined: 01 Sep 2010
Posts: 2441
Followers: 312

Kudos [?]: 2618 [0], given: 696

Nearly a century ago, biologists found that if they [#permalink] New post 01 Feb 2013, 03:27
Expert's post
Complete discussion is given at the below mentioned link
nearly-a-century-ago-biologists-found-that-if-they-separate-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
_________________

COLLECTION OF QUESTIONS
Quant: 1. Bunuel Signature Collection - The Next Generation 2. Bunuel Signature Collection ALL-IN-ONE WITH SOLUTIONS 3. Veritas Prep Blog PDF Version
Verbal:1. Best EXTERNAL resources to tackle the GMAT Verbal Section 2. e-GMAT's ALL CR topics-Consolidated 3. New Critical Reasoning question bank by carcass 4. Meaning/Clarity SC Question Bank by Carcass_Souvik 5. e-GMAT's ALL SC topics-Consolidated-2nd Edition 6. The best reading to improve Reading Comprehension 7.Verbal question bank and Directories

Kaplan Promo CodeKnewton GMAT Discount CodesVeritas Prep GMAT Discount Codes
Expert Post
Verbal Forum Moderator
Verbal Forum Moderator
User avatar
Status: Preparing for the another shot...!
Joined: 03 Feb 2011
Posts: 1425
Location: India
Concentration: Finance, Marketing
GPA: 3.75
Followers: 129

Kudos [?]: 645 [0], given: 62

GMAT ToolKit User Premium Member
Re: Nearly a century ago, biologists found that if they separate [#permalink] New post 01 Feb 2013, 05:00
Expert's post
a toughie...!
@carcass...you must be playing at 40+ when such a passage had appeared. Jealous!!!
Coming back to question.
Its given in the passage that if one cuts an early embryo in proper plane, then the resulting parts may yield two individual beings. This "yielding" is helped by morphogenetic elements. (Sorry for bad English).
For the production of a single individual being, one morphogenetic element is sufficient but since even if you cut an early embryo into two, the two parts become respective individuals then the entire process seems to tell that morphogenetic elements are more than what is required for one individual.
+1E
Regards.
_________________

Prepositional Phrases Clarified|Elimination of BEING| Absolute Phrases Clarified
Rules For Posting
www.Univ-Scholarships.com

Manager
Manager
avatar
Joined: 07 May 2008
Posts: 80
Followers: 2

Kudos [?]: 36 [0], given: 11

Re: Nearly a century ago, biologists found that if they separate [#permalink] New post 02 Feb 2013, 02:49
C is indeed a close call, if not for a re-read this would have been the (incorrect) choice.
Md's are inactive until the egg fertilization not until the cell determination. Once the egg is fertilized, Md's become active and govern the fate of the cells.
D is just an assertion with no facts. A and B are incorrect choices derived from facts mentioned in the passage moreover either of the choices would not classify as 'inference'.
Expert Post
Moderator
Moderator
User avatar
Joined: 01 Sep 2010
Posts: 2441
Followers: 312

Kudos [?]: 2618 [0], given: 696

Re: Nearly a century ago, biologists found that if they separate [#permalink] New post 02 Feb 2013, 09:37
Expert's post
Marcab wrote:
a toughie...!
@carcass...you must be playing at 40+ when such a passage had appeared. Jealous!!!
Coming back to question.
Its given in the passage that if one cuts an early embryo in proper plane, then the resulting parts may yield two individual beings. This "yielding" is helped by morphogenetic elements. (Sorry for bad English).
For the production of a single individual being, one morphogenetic element is sufficient but since even if you cut an early embryo into two, the two parts become respective individuals then the entire process seems to tell that morphogenetic elements are more than what is required for one individual.
+1E
Regards.



good job man :)
_________________

COLLECTION OF QUESTIONS
Quant: 1. Bunuel Signature Collection - The Next Generation 2. Bunuel Signature Collection ALL-IN-ONE WITH SOLUTIONS 3. Veritas Prep Blog PDF Version
Verbal:1. Best EXTERNAL resources to tackle the GMAT Verbal Section 2. e-GMAT's ALL CR topics-Consolidated 3. New Critical Reasoning question bank by carcass 4. Meaning/Clarity SC Question Bank by Carcass_Souvik 5. e-GMAT's ALL SC topics-Consolidated-2nd Edition 6. The best reading to improve Reading Comprehension 7.Verbal question bank and Directories

Re: Nearly a century ago, biologists found that if they separate   [#permalink] 02 Feb 2013, 09:37
    Similar topics Author Replies Last post
Similar
Topics:
Experts publish their posts in the topic Nearly a century ago, biologists found that if they separated an inver Bunuel 0 10 Oct 2014, 07:38
Experts publish their posts in the topic Nearly a century ago, biologists found that if they egmat 5 28 Mar 2013, 10:49
Experts publish their posts in the topic Nearly a century ago, biologists found that if they carcass 1 28 Mar 2013, 09:40
7 Nearly a century ago, biologists found that if they separate amitjash 17 22 Jun 2010, 05:34
1 Nearly a century ago, biologists found that if they rahul 6 19 Feb 2005, 16:37
Display posts from previous: Sort by

Nearly a century ago, biologists found that if they

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.