Because of the proximity and likeness of Mars to Earth, scientists

Question

Because of the proximity and likeness of Mars to Earth, scientists have long speculated about the possibility of life on Mars. As early as the mid 17th century, astronomers observed polar ice caps on Mars, and by the mid-19th century, scientists discovered other similarities to Earth, including the length of day and axial tilt. But in 1965, photos taken by the Mariner 4 probe revealed a Mars without rivers, oceans or signs of life. And in the 1990s, it was discovered that Mars, unlike Earth, no longer possessed a substantial global magnetic field, allowing celestial radiation to reach the planet's surface and solar wind to eliminate much of Mars's atmosphere over the course of several billion years.

More recent probes have focused on whether there was once water on Mars. Some scientists believe that this question is definitively answered by the presence of certain geological landforms. Others posit that different explanations, such as wind erosion or carbon dioxide oceans, may be responsible for these formations. Mars rovers Opportunity and Spirit, which have been exploring the surface of Mars since 2004, have both discovered geological evidence of past water activity. These findings substantially bolster claims that there was once life on Mars.   1 
 1. The passage is primarily concerned with which of the following?

(A) disproving a widely accepted theory
(B) initiating a debate about the possibility of life on Mars
(C) presenting evidence in support of a controversial claim
(D) describing the various discoveries made concerning the possibility of life on Mars
(E) detailing the findings of the Mars rovers Opportunity and Spirit

2 
 2. Each of the following discoveries is mentioned in the passage  EXCEPT

(A) Wind erosion and carbon dioxide oceans are responsible for certain geological landforms on Mars.
(B) Mars does not have a substantial global magnetic field.
(C) Mars does not currently have water activity.
(D) The length of day on Mars is similar to that on Earth.
(E) The axial tilt of Mars is similar to that of Earth.

3 
 3. The passage suggests which of the following about polar ice caps?

(A) Until recently, the ones on Mars were thought to consist largely of carbon dioxide.
(B) The ones on Mars are made almost entirely of frozen water.(C) They are also found on Earth.
(D) Their formation is tied to length of day and axial tilt.
(E) They indicate that conditions on the planet Mars were once very different than they are at present.

4 
 4. It can be inferred from the passage that scientists would be more likely to suspect that Mars once held life if there were evidence of which of the following features?

(A) Carbon dioxide oceans
(B) Celestial radiation and solar wind
(C) High daily level of sunlight reaching the planet's surface
(D) Volcanic eruptions
(E) A significant global magnetic field

Sajjad1994 · Accepted Answer

Official Explanation

1. The passage is primarily concerned with which of the following?

Explanation

(A)  There is no widely accepted theory, just speculation. Plus, that speculation is more positive than negative!  (Out of scope)

(B)  The passage does discuss a potential theory (that there may once have been life on Mars), but the passage itself does not initiate any debate. Rather, it reports on various findings and opinions of others.  (Out of scope)

(C)  The earliest mentioned interest in Mars was in the mid-seventeenth century; this is not recent.  (One word off)

(D) CORRECT.  The passage does describe various discoveries made in the mid-seventeenth and mid-nineteenth centuries, as well as more recently, concerning the possibility of life on Mars.

(E)  The passage does discuss this, but the rovers are passage detail; they are not the overall point of the passage.  (True but not right)

2. Each of the following discoveries is mentioned in the passage EXCEPT

Explanation

The question indicates that four of the answers are mentioned in the passage, so this is a detail EXCEPT question. The entire passage is about discoveries, so go straight to the first answer choice and try to find it in the passage.

(A) CORRECT.   The passage says only that wind erosion or carbon dioxide may be responsible for certain geological landforms, not that they are. This is an unusual form of an Extreme answer: though the word are is not an extreme word itself, it is more extreme than may. (Extreme)

(B) True.  The first paragraph says that Mars no longer possessed a global magnetic field.

(C) True.  The second paragraph says that Mars rovers Opportunity and Spirit...discovered geological evidence of past water activity.

(D) True.  The first paragraph states that scientists discovered similarities to Earth, including the length of day.

(E) True.  The first paragraph states that scientists discovered similarities to Earth, including the... axial tilt.

3. The passage suggests which of the following about polar ice caps?

Explanation

The word suggests points to an inference question. The passage mentions polar ice caps in the first paragraph:

As early as the mid-seventeenth century, astronomers observed polar ice caps on Mars, and by the mid-nineteenth century, scientists discovered other similarities to Earth, including the length of day and axial tilt.

The second half of the sentence states that scientists discovered other similarities to Earth, implying that polar ice caps are also a similarity between the two planets.

(A)  The passage does mention carbon dioxide, but not in the context of polar ice caps.  (Mix-up)

(B)  The passage does not provide any information about the content of polar ice caps.  (Out of scope)

(C) CORRECT.   The sentence says that scientists discovered other similarities to Earth, implying that the earlier discovery (polar ice caps) is also similar to what is found on Earth.

(D)  The passage mentions length of day and axial tilt as examples of other similarities to Earth, but it does not indicate that those had anything to do with the formation of polar ice caps.  (Out of scope)

(E)  It's possible that someone might believe this, but the passage does not provide any information to indicate that conditions were once very different.  (Out of scope)

4. It can be inferred from the passage that scientists would be more likely to suspect that Mars once held life if there were evidence of which of the following features?

Explanation

This is an inference question . Both paragraphs discuss characteristics that are possible indicators of life. Because there are so many, go straight to the answers and try to find them in the passage. But first, remind yourself that the passage also discusses characteristics that are incompatible with life.  Read carefully!

(A) The second paragraph mentions that carbon dioxide oceans, rather than water, might be responsible for certain land forms, and the passage makes clear that water is an important indicator of possible life. Carbon dioxide oceans, then, would weaken the evidence for water presence, and so would not increase the chances of life.  (Direct contradiction)

(B)  The first paragraph mentions celestial radiation and solar wind in the context of a scenario in which there is not life.  (Direct contradiction)

(C)  You might posit that abundant sunlight would improve the odds of life, but the passage does not provide any information about this.  (Out of scope)

(D)  The passage does not provide any information about volcanic eruptions.  (Out of scope)

(E) CORRECT.   The first paragraph indicates that Mars, unlike Earth, does not have a substantial global magnetic field and presents this information as a negative in the debate about life on Mars. The implication, then, is that a global magnetic field would be positive evidence in favor of life on Mars.

Hope it helps

jabhatta2 · Answer

VeritasKarishma   GMATNinja  - for question 3, why is E wrong ?

Reason why I chose E is because :

1) The passage does say, that astronomers observed polar ice caps on Mars in 17th century.

2) The passage then says, actually in 1965 -- the Mariner took photos of Mars and there were no rivers or oceans.

Thus, in the 17th century, ice caps were present on Mars and now in the 1960's onwards, ice caps are no longer there

The obvious inference is, the conditions on Mars changed because the ice-caps are no longer present as of 1960.

Hence the ice-caps indicated at one times, conditions were different so much so, that ice caps were possible on Mars at one time

KarishmaB · Answer

It is important to note the timelines here.

The first paragraph suggests that polar ice caps were observed in 17th century (no proof) and other similarities were observed in 19th century. This would suggest that life may exist on Mars to because it is similar to Earth.

But the second paragraph clarifies that things are not so. Upon close observation by more recent probes (perhaps 20th century), we know that there is no water now. The question is whether there was water at some point. The geographical features observed today could be because of water or they could be because of other things such as carbon dioxide oceans (what astronomers thought in 20th century so 17th century observations are annulled).

But the rovers have now (2004 onwards) discovered evidence that there was water at some point. When, we don't know.

Can we say that Mars was much different once? Polar ice caps do not indicate any such thing.

The only thing that the passage suggests about polar ice caps is that Earth has those too.

BhaveshGMAT · Answer

I don't understand explanation for Question 4.

I actually chose A as the answer for option 4. In the official explanation for A, as I understand, Carbon dioxide oceans and certain land formations are taken as absence of water on Mars. Can someone explain why? To me, it seems as if bringing outside knowledge.  VeritasKarishma   Sajjad1994

KarishmaB · Answer

Because of the proximity and likeness of Mars to Earth, scientists have long speculated about the possibility of life on Mars. 
The passage discusses possibility of life on Mars.

As early as the mid 17th century, astronomers observed polar ice caps on Mars, and by the mid-19th century, scientists discovered other similarities to Earth, including the length of day and axial tilt.  
Why astronomers thought that Mars may have life - similarities to Earth.

But in 1965, photos taken by the Mariner 4 probe revealed a Mars without rivers, oceans or signs of life. And in the 1990s, it was discovered that Mars, unlike Earth, no longer possessed a substantial global magnetic field, allowing celestial radiation to reach the planet's surface and solar wind to eliminate much of Mars's atmosphere over the course of several billion years. 
Now astronomers know that Mars is not similar to Earth in many important ways. Hence, it suggests that lack of water, and lack of a substantial global magnetic field could mean no life on Mars.

More recent probes have focused on whether there was once water on Mars. 
Now the question arises that did Mars have water some time in the past?

Some scientists believe that this question is definitively answered by the presence of certain geological landforms.  
There are some landforms that one may believe were formed by water. (so perhaps life existed once in the past??)

Others posit that different explanations, such as wind erosion or carbon dioxide oceans, may be responsible for these formations. 
Others believe that those landforms do not imply water in the past. They could have been made by CO2 oceans or wind erosion. (So life may not existed even in the past!!)

Mars rovers Opportunity and Spirit, which have been exploring the surface of Mars since 2004, have both discovered geological evidence of past water activity. These findings substantially bolster claims that there was once life on Mars. 
Finally, it has been established that there was water on Mars once. So life could have existed in the past.

4. It can be inferred from the passage that scientists would be more likely to suspect that Mars once held life if there were evidence of which of the following features?

(A) Carbon dioxide oceans
(B) Celestial radiation and solar wind
(C) High daily level of sunlight reaching the planet's surface
(D) Volcanic eruptions
(E) A significant global magnetic field

Now, it is clear that the only factor that supports life is (E).

LaveenaPanchal · Answer

1. The passage is primarily concerned with which of the following?

(A) disproving a widely accepted theory  Incorrect. No theory discussed. 
(B) initiating a debate about the possibility of life on Mars.  Incorrect. No debate. The passage is most one sided. 
(C) presenting evidence in support of a controversial claim.  Incorrect. Findings are discussed but there is no controversy. 
(D) describing the various discoveries made concerning the possibility of life on Mars.  Correct. The passage revolves around the possibility of life on Mars. This is the main point. 
(E) detailing the findings of the Mars rovers Opportunity and Spirit.  Incorrect .Partial scope.

2. Each of the following discoveries is mentioned in the passage EXCEPT

(A) Wind erosion and carbon dioxide oceans are responsible for certain geological landforms on Mars.  Correct. This is a speculation and not a discovery. Others posit that different explanations, such as wind erosion or carbon dioxide oceans, may be responsible for these formations.  
(B) Mars does not have a substantial global magnetic field.  Incorrect. Mentioned. 
(C) Mars does not currently have water activity.  Incorrect. Mentioned. 
(D) The length of day on Mars is similar to that on Earth.  Incorrect. Mentioned. 
(E) The axial tilt of Mars is similar to that of Earth.  Incorrect. Mentioned.

3. The passage suggests which of the following about polar ice caps?

(A) Until recently, the ones on Mars were thought to consist largely of carbon dioxide.  Incorrect. 
(B) The ones on Mars are made almost entirely of frozen water.  Incorrect 
(C) They are also found on Earth.  Correct. As early as the mid 17th century, astronomers observed polar ice caps on Mars, and by the mid-19th century, scientists discovered  other similarities  to Earth, including the length of day and axial tilt. 
(D) Their formation is tied to length of day and axial tilt.  Incorrect. 
(E) They indicate that conditions on the planet Mars were once very different than they are at present.  Incorrect.

4. It can be inferred from the passage that scientists would be more likely to suspect that Mars once held life if there were evidence of which of the following features?

(A) Carbon dioxide oceans.  Incorrect. 
(B) Celestial radiation and solar wind.  Incorrect. 
(C) High daily level of sunlight reaching the planet's surface.  Incorrect 
(D) Volcanic eruptions.  Incorrect. 
(E) A significant global magnetic field.  Correct. This is suggested by the line "And in the 1990s, it was discovered that Mars, unlike Earth, no longer possessed a substantial global magnetic field,"

VerbalBot · Answer

Automated notice from GMAT Club VerbalBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.

Because of the proximity and likeness of Mars to Earth, scientists

Prep Toolkit

Top 5 GMAT Debrief Videos

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

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Reading Comprehension (RC) Questions

Because of the proximity and likeness of Mars to Earth, scientists

Prep Toolkit

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

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards