The answer to one of the most rudimentary questions about the heart re

Question

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Passage # 120, Date: 30-May-2020
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The answer to one of the most rudimentary questions about the heart remains deeply enigmatic: can our hearts repair themselves? The answer has been steeped in controversy for over a century, but recent findings are helping to resolve the issue.

In 2009, a paper in the journal Science gave definitive evidence that the human heart is capable of self-renewal. Somewhat surprisingly, nuclear bomb tests during the Cold War had made this discovery possible; these detonations caused a sharp increase in the levels of radioactive carbon-14 in the atmosphere, which after being absorbed by plants in the form of carbon dioxide, entered the human food chain. By using a technique called radiocarbon dating, the Swedish research team were able to use the elevated levels of carbon-14 in human DNA to retrospectively calculate the age of heart cells. They found that 1% are renewed every year at the age of 25, and that this rate decreases to 0.45% by the age of 75.

This landmark study set the stage for an ongoing worldwide effort to exploit the heart's innate regenerative capacity to tackle disease. Back in 2011, to promote this research, the British Heart Foundation released evocative television adverts which depicted an animated talking zebra fish who explains how they can already repair their own hearts. Initially, it was thought that these fascinating creatures used a specialized source of stem cells to achieve such a feat. As it turns out though, it is the cells they are already endowed with, their pre-existing heart cells, which divide and repopulate the organ in times of trouble. This raised another question: where do new cells in the human heart come from? Again, stem cells seemed intuitively to be the most reasonable candidates – they are self-renewing, and have the power to become any one of the major cell types in the heart.

Recently however, a group at Harvard Medical School published a paper in the journal Nature giving strong evidence against this idea. They showed that, like the zebra fish, we too generate new heart cells from pre-existing ones, and that this phenomenon increases during a heart attack. This discovery is potentially a game changer for the field at large, for it suggests that our hearts possess zebra fish-like regenerative mechanisms – only on a much more diminished scale. Many researchers now believe that if we can figure out why this is, we may eventually be able to safely boost the regenerative capacity of our hearts for therapeutic gain.   1 
 B 
 1. The primary purpose of the passage is to

A. recognize the similarities in the functioning of the hearts of humans and zebra fish
B. chronicle recent research findings about a capability of a human organ
C. evaluate the studies conducted about a physiological phenomenon
D. identify how to boost the functioning of a human organ for therapeutic gain
E. offer various explanations for the self-regenerative ability of the human heart

2 
 D 
 2. According to the passage, the research group at Harvard Medical School would be likely to disagree with which of the following?

A. Humans are similar to zebra fish in that human heart cells are generated from pre-existing ones
B. Pre-existing heart cells are responsible for the renewal of heart cells in humans
C. Stem cells have the potential for self-renewal and can become any of the major types of heart cells
D. Self-renewing stem cells are responsible for the regeneration of heart cells in humans
E. The scale of cell regeneration in humans is much more diminished as compared to that of zebra fish

3 
 C 
 3. The author of the passage refers to the contents of the 2009 paper published in Science magazine as “somewhat surprising” most probably because:

A. The sharp increase in the levels of radioactive carbon-14 in the atmosphere due to the nuclear tests was unexpected
B. Until the Cold War period, radiocarbon dating had not been used to study human organs and physiological processes
C. The primary objective of nuclear bomb tests during the Cold War had not been to study self-renewal of the human heart
The Swedish research team had not anticipated that the radioactive carbon-14 would enter the human food chain
E. The radiocarbon dating techniques available during the Cold War period had not been advanced enough to be used to study the age of heart cells

globaldesi · Accepted Answer

Official answers:
1. B
A: The similarity is only mentioned in passing. Not the primary objective. C: The author of the passage is not 'evaluating' the studies – he is just reporting them. D: This is mentioned as a future direction at the end of the passage. Not the primary purpose. E: No 'explanations' are offered.
2. D
The research group at Harvard Medical School showed that, like the zebra fish, humans too generate new heart cells from pre-existing ones. So they would agree with what is mentioned in options A, B and E. The researchers have not disputed the fact that stem cells are capable of self-renewal and are capable of becoming any type of heart cells.Their finding is only that while stem cells may be capable of doing this, they do not do this in humans. (So option C is wrong) This is contrary to the idea that stem cells are responsible for self-renewal of the human heart (lines 20-21). Option D says exactly this, and is the right answer.
3. C
Line 5 gives us a clue to the right answer: “Somewhat surprisingly, nuclear bomb tests during the Cold War had made this discovery possible” The surprise is directed at the fact that a discovery about a physiological phenomenon was made possible through something quite unrelated. i.e. a nuclear bomb test. All answer options except C mention extra information related to the method and findings of the study, whereas C talks about something about how the discovery was made. Option C makes inherent sense, and is thus the right answer

carouselambra · Answer

SajjadAhmad   globaldesi

Can you please explain why C is correct and not B?
C says : The primary objective of nuclear bomb tests during the Cold War had not been to study self-renewal of the human heart
The Swedish research team had not anticipated that the radioactive carbon-14 would enter the human food chain.

Nowhere in the passage, it has been mentioned that the nuclear bomb's primary objective took a U-turn. The passage merely mentions another usage of nuclear bomb (which was a surprise and people did not know this usage until the Cold war).

This line in the passage indicates 'B' as the correct option -  nuclear bomb tests during the Cold War had made this discovery possible 
Please let me know the fault in my thought process?

kntombat · Answer

Hey  Sajjad1994 , how much time should one devote to passages like this, I got all the answers correct and I took 5 mins.

Sajjad1994 · Answer

5 minutes is excellent time for this one I think up to 7 minutes are fine for such a passage.

Good Luck

AryaSwagat · Answer

For QN 2
A. Humans are similar to zebra fish in that human heart cells are generated from pre-existing ones.  They may agree as their hearts are capable of regeneration 
B. Pre-existing heart cells are responsible for the renewal of heart cells in humans.  Its the fact they have discovered so they should agree 
C. Stem cells have the potential for self-renewal and can become any of the major types of heart cells Capability of stem cells for self renewal already stated in the previous passage which is most likely a fact, so they should agree to it  
D. Self-renewing stem cells are responsible for the regeneration of heart cells in humans.  The para starts with the sentence  Recently however, a group at Harvard Medical School published a paper in the journal Nature giving strong  evidence against this idea   the idea is stem cells written in the previous para. So they disagree that stem cells are the reason.  
E. The scale of cell regeneration in humans is much more diminished as compared to that of zebra fish  A part of their finding

So Answer D

dazzler97 · Answer

For Q1, why is B more appropriate than E ?

Sajjad1994 · Answer

While the passage does touch upon different explanations and perspectives regarding the self-regenerative ability of the human heart, the primary emphasis is on presenting recent research findings and their implications. The passage does not extensively explore various explanations, but rather it primarily focuses on the chronological progression of research in this area.

Option (E)  suggests that the passage offers various explanations for the self-regenerative ability of the human heart. However, the passage is more centered around presenting recent research findings, especially from the 2009 study and subsequent work, rather than delving into a variety of explanations. The primary goal is to chronicle and inform the reader about the evolving understanding of the heart's capability for self-renewal based on scientific research.

Therefore, while the passage does touch on some explanations, they are not the central focus, leading to option (B) being a more accurate representation of the passage's primary purpose.

Raman109 · Answer

1. The primary purpose of the passage is to

A. recognize the similarities in the functioning of the hearts of humans and zebra fish - Limited in scope. 
B. chronicle recent research findings about a capability of a human organ - chronicle can mean detail the development of. Ok. 
C. evaluate the studies conducted about a physiological phenomenon - The passage just reports the findings and doesn't critically evaluate. 
D. identify how to boost the functioning of a human organ for therapeutic gain - Limited in scope.
E. offers various explanations for the self-regenerative ability of the human heart - The author just reported that it happens, but why it happens is not the focus of the passage. 
For example, the author says, "They found that 1% are renewed every year at the age of 25 and that this rate decreases to 0.45% by age 75." But does it try to uncover "why" this happened, or why it is 1% and 1.2%, or why it reduces with age? No. The author is just presenting the facts. No explanation.

Even when the author talks about the researchers at Harvard, "They showed that, like the zebrafish, we too generate new heart cells from pre-existing ones, and that this phenomenon increases during a heart attack." Does he try to explain why and how the new heart cells do this? And why does it happen during a heart attack? No. He just reports.

The answer to one of the most rudimentary questions about the heart re

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The answer to one of the most rudimentary questions about the heart re

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

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My Rewards