GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 24 Mar 2019, 20:40

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.

Close

Request Expert Reply

Confirm Cancel

"Urodeles," a class of vertebrates that includes newts and salamanders

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

 
Senior RC Moderator
User avatar
V
Status: Preparing GMAT
Joined: 02 Nov 2016
Posts: 2464
Location: Pakistan
GPA: 3.39
"Urodeles," a class of vertebrates that includes newts and salamanders  [#permalink]

Show Tags

New post Updated on: 16 Jan 2019, 07:42
2
1
Question 1
00:00
A
B
C
D
E

based on 212 sessions

88% (02:09) correct 12% (02:14) wrong

HideShow timer Statistics

Question 2
00:00
A
B
C
D
E

based on 208 sessions

57% (01:41) correct 43% (01:48) wrong

HideShow timer Statistics

"Urodeles," a class of vertebrates that includes newts and salamanders, have the enviable ability to regenerate arms, legs, tails, heart muscle, jaws, spinal cords, and other organs. "Planaria," simple worms, can be sliced and diced in hundreds of pieces, with each piece giving rise to a completely new animal. However, while both "urodeles" and "planaria" have the capacity to regenerate, they use different means to accomplish this feat.

In effect, a "urodeles" specimen turns back the biological clock. First, the animal heals the wound at the site of the missing limb. Then various specialized cells at the site, such as bone, skin, and blood cells, lose their identity and revert to cells as unspecialized as those in the embryonic limb bud. This process is called dedifferentiation, and the resulting blastema, a mass of unspecialized cells, proliferates rapidly to form a limb bud. Ultimately, when the new limb takes shape, the cells take on the specialized roles they had previously cast off.

In contrast, "planaria" regenerate using cells called neoblasts. Scattered within the planarian body, these neoblasts remain in an unspecialized, stem-cell state, which enables them at need to differentiate into any cell type. Whenever "planari"a are cut, the neoblasts migrate to the site and form a blastema by themselves. It is interesting to note that this mechanism is similar to that following reproductive fission in these animals, and that species incapable of this form of asexual reproduction have poorly developed regenerative capacities.

1. The primary purpose of the passage is to:

A describe the roles of blastemas in regenerating "urodeles" and "planaria."
B describe how "urodeles" use the process of dedifferentiation to regenerate.
C contrast the mechanisms by which "urodeles" and "planaria" accomplish regeneration.
D show how methods of cellular regeneration have evolved in different animal species.
E explain the link between reproductive fission and regeneration in simple worms.


2. All of the following are true of dedifferentiation in regenerating "urodeles" EXCEPT:

A the cells recover their specialized roles after the limb bud takes shape.
B it involves a regression by cells to an earlier stage of development.
C specialized cells migrate to the site of the blastema and proliferate rapidly.
D the healing of the wound at the site of the injury is the first step of the process.
E dedifferentiation is characterized by a loss, and then recovery, of cellular identity.



Source: Master GMAT
Difficulty Level: 600

_________________
New Project RC Butler 2019 - Practice 2 RC Passages Everyday
Final days of the GMAT Exam? => All GMAT Flashcards.
This Post Helps = Press +1 Kudos
Best of Luck on the GMAT!!

Originally posted by SajjadAhmad on 14 Jan 2017, 00:51.
Last edited by SajjadAhmad on 16 Jan 2019, 07:42, edited 3 times in total.
SC Moderator
User avatar
D
Joined: 13 Apr 2015
Posts: 1686
Location: India
Concentration: Strategy, General Management
GMAT 1: 200 Q1 V1
GPA: 4
WE: Analyst (Retail)
GMAT ToolKit User Premium Member
Re: "Urodeles," a class of vertebrates that includes newts and salamanders  [#permalink]

Show Tags

New post 14 Jan 2017, 08:30
First paragraph discusses about regenerative capacity of Urodeles and Planaria.
Second paragraph discusses about the mechanism of regeneration in Urodeles.
Third paragraph discusses about the mechanism of regeneration in Planaria.

1. The primary purpose of the passage is to:

A describe the roles of blastemas in regenerating "urodeles" and "planaria." - Incorrect. Partial scope.
B describe how "urodeles" use the process of dedifferentiation to regenerate. - Incorrect. Partial scope.
C contrast the mechanisms by which "urodeles" and "planaria" accomplish regeneration. - Correct.
D show how methods of cellular regeneration have evolved in different animal species. - Incorrect. Out of scope. Evolution of cellular regeneration is not discussed in the passage.
E explain the link between reproductive fission and regeneration in simple worms. - Incorrect. Reproductive fission is discussed only in the last paragraph. Also the link between fission and regeneration is nowhere discussed in the passage.

Answer: C

2. All of the following are true of dedifferentiation in regenerating "urodeles" EXCEPT:

A the cells recover their specialized roles after the limb bud takes shape. - Incorrect. True.
B it involves a regression by cells to an earlier stage of development. - Incorrect. True.
C specialized cells migrate to the site of the blastema and proliferate rapidly. - Correct. False. It must be unspecialized cells and not specialized.
D the healing of the wound at the site of the injury is the first step of the process. - Incorrect. True.
E dedifferentiation is characterized by a loss, and then recovery, of cellular identity. - Incorrect. True.

Answer: C
Senior RC Moderator
User avatar
V
Status: Preparing GMAT
Joined: 02 Nov 2016
Posts: 2464
Location: Pakistan
GPA: 3.39
Re: "Urodeles," a class of vertebrates that includes newts and salamanders  [#permalink]

Show Tags

New post 21 May 2018, 05:32
1
Formatted the Question
_________________
New Project RC Butler 2019 - Practice 2 RC Passages Everyday
Final days of the GMAT Exam? => All GMAT Flashcards.
This Post Helps = Press +1 Kudos
Best of Luck on the GMAT!!
Manager
Manager
avatar
B
Joined: 11 Apr 2018
Posts: 119
Location: India
GPA: 4
WE: Information Technology (Computer Software)
GMAT ToolKit User CAT Tests
Re: "Urodeles," a class of vertebrates that includes newts and salamanders  [#permalink]

Show Tags

New post 15 Jun 2018, 03:49
1. The primary purpose of the passage is to:

A describe the roles of blastemas in regenerating "urodeles" and "planaria." - True, but it is not the primary purpose.
B describe how "urodeles" use the process of dedifferentiation to regenerate. - True, but it is not the primary purpose.
C contrast the mechanisms by which "urodeles" and "planaria" accomplish regeneration. - This the primary purpose.
D show how methods of cellular regeneration have evolved in different animal species. - False, there is no talk about evolution in the passage.
E explain the link between reproductive fission and regeneration in simple worms. - It does speak about it at the end of the passage but this is not the primary purpose.

Correct choice: C
Manager
Manager
avatar
B
Joined: 11 Apr 2018
Posts: 119
Location: India
GPA: 4
WE: Information Technology (Computer Software)
GMAT ToolKit User CAT Tests
Re: "Urodeles," a class of vertebrates that includes newts and salamanders  [#permalink]

Show Tags

New post 15 Jun 2018, 03:54
2. All of the following are true of dedifferentiation in regenerating "urodeles" EXCEPT:

A the cells recover their specialized roles after the limb bud takes shape. - True, clearly stated in the passage.
B it involves a regression by cells to an earlier stage of development. - True, the passage tells that specialized cells to lose their identity and become unspecialized.
C specialized cells migrate to the site of the blastema and proliferate rapidly. - False, the passage does not speak about this migration at all.
D the healing of the wound at the site of the injury is the first step of the process. - True, clearly stated in the passage.
E dedifferentiation is characterized by a loss, and then recovery, of cellular identity. - True, as it can be inferred that loss refers to specialized cells turning into unspecialized and recovery refers to them turning back into specialized.

Correct choice: C
Senior Manager
Senior Manager
avatar
P
Joined: 17 Mar 2014
Posts: 433
GMAT ToolKit User Premium Member Reviews Badge CAT Tests
Re: "Urodeles," a class of vertebrates that includes newts and salamanders  [#permalink]

Show Tags

New post 16 Jan 2019, 06:33
SajjadAhmad wrote:
Source: http://www.petersons.com

"Urodeles," a class of vertebrates that includes newts and salamanders, have the enviable ability to regenerate arms, legs, tails, heart muscle, jaws, spinal cords, and other organs. "Planaria," simple worms, can be sliced and diced in hundreds of pieces, with each piece giving rise to a completely new animal. However, while both "urodeles" and "planaria" have the capacity to regenerate, they use different means to accomplish this feat.

In effect, a "urodeles" specimen turns back the biological clock. First, the animal heals the wound at the site of the missing limb. Then various specialized cells at the site, such as bone, skin, and blood cells, lose their identity and revert to cells as unspecialized as those in the embryonic limb bud. This process is called dedifferentiation, and the resulting blastema, a mass of unspecialized cells, proliferates rapidly to form a limb bud. Ultimately, when the new limb takes shape, the cells take on the specialized roles they had previously cast off.

In contrast, "planaria" regenerate using cells called neoblasts. Scattered within the planarian body, these neoblasts remain in an unspecialized, stem-cell state, which enables them at need to differentiate into any cell type. Whenever "planari"a are cut, the neoblasts migrate to the site and form a blastema by themselves. It is interesting to note that this mechanism is similar to that following reproductive fission in these animals, and that species incapable of this form of asexual reproduction have poorly developed regenerative capacities.
1. The primary purpose of the passage is to:

A describe the roles of blastemas in regenerating "urodeles" and "planaria."
B describe how "urodeles" use the process of dedifferentiation to regenerate.
C contrast the mechanisms by which "urodeles" and "planaria" accomplish regeneration.
D show how methods of cellular regeneration have evolved in different animal species.
E explain the link between reproductive fission and regeneration in simple worms.


2. All of the following are true of dedifferentiation in regenerating "urodeles" EXCEPT:

A the cells recover their specialized roles after the limb bud takes shape.
B it involves a regression by cells to an earlier stage of development.
C specialized cells migrate to the site of the blastema and proliferate rapidly.
D the healing of the wound at the site of the injury is the first step of the process.
E dedifferentiation is characterized by a loss, and then recovery, of cellular identity.




Hello SajjadAhmad,

Could you please provide explanation of question-2. I am not getting why is answer-C. In 2nd paragraph it is specially mentioned that "This process is called dedifferentiation, and the resulting blastema, a mass of unspecialized cells, proliferates rapidly to form a limb bud."

Thanks,
Amm
GMAT Club Bot
Re: "Urodeles," a class of vertebrates that includes newts and salamanders   [#permalink] 16 Jan 2019, 06:33
Display posts from previous: Sort by

"Urodeles," a class of vertebrates that includes newts and salamanders

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Copyright

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

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

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®.