NEW HERE? LEARN MORE
closeclose
Last visit was: 24 Apr 2024, 17:54 It is currently 24 Apr 2024, 17:54
Decision Tracker
My Rewards
New posts
New comers' posts

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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

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

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
User avatar
L
Sajjad1994
GRE Forum Moderator
Joined: 02 Nov 2016
Posts: 13958
Own Kudos [?]: 32888 [5]
Given Kudos: 5776
GPA: 3.62
Send PM
CAT Tests Forum Quiz Mode
"Urodeles," a class of vertebrates that includes newts and salamanders [#permalink] New post   Updated on: 07 Apr 2020, 23:58
3
Kudos
2
Bookmarks
Expert Reply
Question 1
00:00
A
B
C
D
E

Difficulty:

5% (low)

based on 355 sessions

90% (02:10) correct 10% (02:02) wrong
Hide Show timer Statistics
Question 2
00:00
A
B
C
D
E

Difficulty:

45% (medium)

based on 345 sessions

62% (01:34) correct 38% (01:43) wrong
Hide Show timer Statistics
Question 3
00:00
A
B
C
D
E

Difficulty:

95% (hard)

based on 74 sessions

32% (02:01) correct 68% (01:58) wrong
Hide Show 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.


3. In the last sentence of the passage (lines 20–25), the author implies that

(A) reproductive fission and regeneration in certain planaria differ solely in the quantity of new planaria produced.
(B) planaria that reproduce sexually use the process of dedifferentiation to regenerate entirely new animals.
(C) asexual reproduction is related to regeneration in planaria but not in urodeles.
(D) the genetic makeup of planaria created through regeneration would be the same as in those created through reproductive fission.
(E) those planaria that reproduce by splitting themselves in two are more likely to regenerate using the same mechanism.



Source: Master GMAT
Difficulty Level: 600
ShowHide Answer Question #1
Official Answer
C
ShowHide Answer Question #2
Official Answer
C
ShowHide Answer Question #3
Official Answer
E

Originally posted by Sajjad1994 on 14 Jan 2017, 00:51.
Last edited by Sajjad1994 on 07 Apr 2020, 23:58, edited 6 times in total.
Added third question.
User avatar
D
Kurtosis
Current Student
Joined: 13 Apr 2015
Posts: 1436
Own Kudos [?]: 4545 [0]
Given Kudos: 1228
Location: India
Send PM
GMAT ToolKit User Reviews Badge
Re: "Urodeles," a class of vertebrates that includes newts and salamanders [#permalink] 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
avatar
S
Lowkya
Manager
Manager
Joined: 11 Apr 2018
Posts: 100
Own Kudos [?]: 46 [0]
Given Kudos: 139
Location: India
GPA: 4
WE:Information Technology (Computer Software)
Send PM
GMAT ToolKit User
Re: "Urodeles," a class of vertebrates that includes newts and salamanders [#permalink] 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
avatar
S
Lowkya
Manager
Manager
Joined: 11 Apr 2018
Posts: 100
Own Kudos [?]: 46 [0]
Given Kudos: 139
Location: India
GPA: 4
WE:Information Technology (Computer Software)
Send PM
GMAT ToolKit User
Re: "Urodeles," a class of vertebrates that includes newts and salamanders [#permalink] 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
User avatar
L
AliciaSierra
Director
Director
Joined: 17 Mar 2014
Posts: 756
Own Kudos [?]: 608 [0]
Given Kudos: 1348
Send PM
GMAT ToolKit User Reviews Badge
"Urodeles," a class of vertebrates that includes newts and salamanders [#permalink] New post   16 Jan 2019, 06:33
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
User avatar
P
Vinit800HBS
Tutor
Joined: 29 Dec 2018
Posts: 91
Own Kudos [?]: 152 [2]
Given Kudos: 187
Location: India
Schools: HBS '22 Wharton '22 Stanford '22
GRE 1: Q170 V163
Send PM
Re: "Urodeles," a class of vertebrates that includes newts and salamanders [#permalink] New post   11 May 2019, 11:41
2
Kudos
Expert Reply
ammuseeru

The statement says “unspecialised cells” grow to form a limb bud.
The option states “specialised cells” which is not correct.

Hope it’s clear now

Posted from my mobile device
User avatar
S
prototypevenom
Manager
Manager
Joined: 12 Nov 2018
Posts: 78
Own Kudos [?]: 39 [0]
Given Kudos: 63
Send PM
Re: "Urodeles," a class of vertebrates that includes newts and salamanders [#permalink] New post   11 May 2019, 22:49
took a whopping 13mins for this. I need to improve timings.

p1)U- regenerative 1,2,3,4,5,6 and etc
Pl-minced gives new births

p2) U-1)clock 2) wounds heals 3) bones, skin, and blood cells lose identity become ELB "dediff" -> blast...

p3)1) neoblasts = unspecialised and stem state
2)neoplasm move and form B
3) reproductive fission <- asexual
reproduction species-poor fission
User avatar
S
Arpitkumar
Manager
Manager
Joined: 30 May 2018
Posts: 55
Own Kudos [?]: 44 [0]
Given Kudos: 121
Concentration: General Management, Marketing
Schools: IIMA PGPX"20 INSEAD Jan '19 HBS '21
GMAT 1: 750 Q49 V45
GPA: 3.45
WE:Other (Retail)
Send PM
Re: "Urodeles," a class of vertebrates that includes newts and salamanders [#permalink] New post   08 Apr 2020, 07:02
Need help with the last question , wanted to understand why is E the correct answer option ? GMATNinja , @sajjadahmed ??
User avatar
L
Sajjad1994
GRE Forum Moderator
Joined: 02 Nov 2016
Posts: 13958
Own Kudos [?]: 32888 [2]
Given Kudos: 5776
GPA: 3.62
Send PM
CAT Tests Forum Quiz Mode
Re: "Urodeles," a class of vertebrates that includes newts and salamanders [#permalink] New post   08 Apr 2020, 08:06
2
Kudos
Expert Reply
Arpitkumar wrote:
Need help with the last question , wanted to understand why is E the correct answer option ? GMATNinja , @sajjadahmed ??


Official Explanation


3. In the last sentence of the passage (lines 20–25), the author implies that

Difficulty Level: 650

Explanation

The idea in the final sentence of this passage is difficult to grasp, making this question difficult to answer. The sentence says essentially that those species of planaria that do not engage in reproductive fission (i.e., splitting) are less likely to regenerate themselves in this way.

Choice (E) expresses the same essential idea conversely: species of planaria that reproduce asexually (by fission or splitting) are the ones that are more likely to be able to regenerate in the same way.

The correct answer is (E).
User avatar
VerbalBot
Non-Human User
Joined: 01 Oct 2013
Posts: 17213
Own Kudos [?]: 848 [0]
Given Kudos: 0
Send PM
Re: "Urodeles," a class of vertebrates that includes newts and salamanders [#permalink] New post   04 Jul 2023, 07:23
Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
GMAT Club Bot
gmatclubot
Re: "Urodeles," a class of vertebrates that includes newts and salamanders [#permalink]
04 Jul 2023, 07:23
Moderators:
GMATNinja
GMAT Club Verbal Expert
6920 posts
GMATNinjaTwo
GMAT Club Verbal Expert
238 posts
Sajjad1994
GRE Forum Moderator
13958 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions