In 1994, a team of scientists led by David McKay began studying the meteorite ALH84001, which had been discovered in Antarctica in 1984.Two years later, the McKay team announced that ALH84001, which scientists generally agree originated on Mars, contained compelling evidence that life once existed on Mars. This evidence includes the discovery of organic molecules in ALH84001, the first ever found in Martian rock. Organic molecules--complex, carbonbased compounds--form the basis for terrestrial life. The organic molecules found in ALH84001 are polycyclic aromatic hydrocarbons, or PAH's. When microbes die, their organic material often decays into PAH's.
Skepticism about the McKay team's claim remains, however. For example, ALH84001 has been on earth for 13,000 years, suggesting to some scientists that its PAH's might have resulted form terrestrial contamination. However, McKay's team has demonstrated that the concentration of PAH's increases as one looks deeper into ALH84001, contrary to what one would expect from terrestrial contamination.The skeptic's strongest argument, however, is that processes unrelated to organic life can easily produce all the evidence found by McKay' steam, including PAH's. For example, star formation produces PAH's. Moreover, PAH's frequently appear in other meteorites, and no one attributes their presence to life processes. Yet McKay's team notes that the particular combination of PAH's in ALH84001 is more similar to the combinations produced by decaying organisms than to those originating form nonbiological processes.
Q1:
The passage asserts which of the following about the claim that ALH84001 originated on Mars?

A. It was initially proposed by the McKay team of scientists.
B. It is not a matter of widespread scientific dispute.
C. It has been questioned by some skeptics of the McKay team's work.
D. It has been undermined by recent work on PAH's.
E. It is incompatible with the face that ALH84001 has been on Earth for 13,000 years.
Q2:
The primary purpose of the passage is to

A. describe new ways of studying the possibility that life once existed on Mars
B. revise a theory regarding the existence of life on Mars in light of new evidence
C. reconcile conflicting viewpoints regarding the possibility that life once existed on Mars
D. evaluate a recently proposed argument concerning the origin of ALH84001
E. describe a controversy concerning the significance of evidence from ALH84001
Q3:
The passage suggests that the fact that ALH84001 has been on earth for 13,000 years has been used by some scientists to support which of the following claims about ALH84001?

A. ALH84001 may not have originated on Mars.
B. ALH84001 contains PAH's that are the result of nonbiological processes.
C. ALH84001 may not have contained PAH's when it landed on Earth.
D. The organic molecules found in ALH84001 are not PAH's.
E. The organic molecules found in ALH84001 could not be the result of terrestrial contamination

Ans1: B
Ans2: E
Ans3: C

1b, because - no one disputes that the ALH84001 originated in Mars.

2e, because - the PAH evidence found in ALH84001 is a matter of debate over the possibility that Life existed on Mars

d is wrong because no one is discussing the origins of ALH84001

3b, Refer to - "For example, ALH84001 has been on earth for 13,000 years, suggesting to some scientists that its PAH's might have resulted form terrestrial contamination. " Meaning that the PAHs were not present when ALH84001 entered earth.

B/E/B

Q2 the evidence found in AH13123134234 is the main point and wether it is significant to state that there was life on mars.

Q3 one rebutal: PAH could have resulted from teresstial contamination. But the strongest rebutal: PAH can emerger from nonbiological processses, like with other stars.

I agree on Q3 to C

I was answering the question about why generally evidence of PAH is doubtful on AH23423

But the question specifically addresses the fact, that AH23234 has been on earth for 13,000 years. This is directly pointed to the first rebulta, bout the teresstial contamination.

nb. yes I know I cannot do this on d-day

B/E/C

The third one is a bit tricky.

The skeptics may say that the rock could be contaminated both through biological or non-biological process after it landed on earth. The skeptics don't really care how it was contaminatedt.

However, the skeptics want to say that the rock didn't have the material when it landed on Earth first.

So the choice should be C.

BEC
_________________

Flying from shadow to the light

my answer is BEC

I got most of the Questions wrong in this RC..

My weakness area is inference in RCs..

how do I improve in Inference in RCs?
_________________

hope is a good thing, maybe the best of things. And no good thing ever dies.

Who says you need a 700 ?Check this out : http://gmatclub.com/forum/who-says-you-need-a-149706.html#p1201595

My GMAT Journey : end-of-my-gmat-journey-149328.html#p1198742