OE #1 : Only option E correctly states that a controversy is described

OE #2 :The passage states scientist generally agree hence it is not a disputed matter.

OE #3 : This is a 'Supporting Ideas' questions. Lines 4-5 in second paragraph point to C

OE #4 : Answering 'Application' question involves applying information contained in the passage to a situation that is not described in the passage. The passage also indicates that if terrestrial contamination occurred with ALH84001, then, contrary to the findings of McKay’s team that showed PAH concentration increases as one looks deeper into ALH84001 (lines 21–22), the PAHs would be expected to be concentrated more toward the outer parts, or surface, of ALH84001

OE #5 : 'Evaluation' questions require understanding how a part of the passage functions within the passage as a whole. The final sentence of the first paragraph indicates that one source of PAHs is the decay of dead microbes.

OE #6: It is an inference question McKay’s team notes in { lines 29–34 }that the PAH combinations produced by organic processes can be distinguished from those produced by non organic processes

2: The passage says: "ALH84001, which scientists generally agree originated on Mars, contained compelling evidence that life once existed on Mars".

So, it looks the claim that ALH84001 originated on Mars, is not a matter of widespread scientific dispute. So, B is correct.

3: ALH84001 has been on Earth for 13,000 years, suggesting to some scientists that its PAHs might have resulted from terrestrial contamination.

Hence, C is correct because it says that ALH84001 may not have contained PAHs when it landed on Earth. Perhaps B comes close, but it says that ALH84001 contains PAHs that "are" the result of nonbiological processes. So, the presence of the definitive "are" tilts the balance against B.

6: Last sentence of the passage says: Particular combination of PAHs in ALH84001 is more similar to the combinations produced by decaying organisms than to those originating from non biological processes. Hence, D seems to be correct, because it is stating the same.

Refer to the following sentence: "McKay’s team has demonstrated that the concentration of PAHs increases as one looks deeper into ALH84001, contrary to what one would expect from terrestrial contamination." The word "contrary" suggests that we would expect the opposite to be true if the PAHs were the result of terrestrial contamination. In other words, if the PAHs were the result of terrestrial contamination, the concentration of PAHs would likely DECREASE as one looks deeper into (i.e. moves towards the center of) the meteorite. This matches choice (E).

This makes intuitive sense--imagine a huge ball of rock that lands on Earth with no PAHs. If the rock then becomes contaminated with PAHs while sitting on Earth for thousands of years, we would expect the contamination to affect the surface and then perhaps gradually seep in towards the center.

As for choice (B), if a meteorite contains PAHs that were a result of terrestrial contamination, then we would know nothing of its origin. Maybe it came from Mars, maybe it came from anywhere else in the galaxy. All we would know is that those terrestrial PAHs should not be viewed as evidence of LIFE wherever the meteorite came from. For example, if scientists could PROVE that the PAHs in ALH84001 were a result of terrestrial contamination, this would not change the generally accepted fact that ALH84001 came from Mars. It would simply mean that the PAHs are not evidence of life on Mars.


The last sentence of the first paragraph is: "When microbes die, their organic material often decays into PAHs." (a microbe is a microorganism).

So if you have microorganisms (i.e. bacteria) that die and decay, you'll often be left with PAHs. The presence of PAHs could be viewed as evidence that life may have existed. Thus, this sentence identifies a possible organic source (e.g. microbes) for the PAHs found in the ALH84001, as stated in choice (A).

As for choice (B), the sentence does not describe a FEATURE of PAHs or how PAHs differ from other types of organic molecules.

I hope that helps!
_________________

First of all, we do not know that it is from Mars just because concentration of PAHs increases with depth. If the PAHs were the result of terrestrial contamination, the concentration of PAHs would likely DECREASE as one looks deeper into (i.e. moves towards the center of) the meteorite. However, just because this is NOT the case does not necessarily mean the meteorite is from Mars.

Also, how the concentration varies with depth does not tell us anything about the TOTAL amount of PAHs in the meteorite. For example, imagine one meteorite with PAHs from terrestrial contamination and, thus, a higher concentration of PAHs toward the surface. Another meteorite could have PAHs from organic molecules and a higher concentration towards the center. However, the TOTAL number of PAHs in the second meteorite could be less than, equal to, or greater than the total number of PAHs in the first meteorite.

Again, how the concentration varies with depth doesn't tell us anything about the TOTAL number of PAHs. The first meteorite (terrestrial contamination) might have MORE total PAHs than the second (PAHs formed from organic life). Based on the information in the passage, we have no idea whether (D) would be true.

I hope that helps!
_________________

P1 - a rock found - Martian - organic + PAH
P2 - 2 opposition argument of P1 - evidence to break them.
main point - a theory is given and a debate an a topic is going on.

1. The primary purpose of the passage is to:

(A) describe new ways of studying the possibility that life once existed on Mars - no
(B) revise a theory regarding the existence of life on Mars in light of new evidence - no; this one is little part of the passage.
(C) reconcile conflicting viewpoints regarding the possibility that life once existed on Mars - in part it is true, but those viewpoints were broken later that is not covered.
(D) evaluate a recently proposed argument concerning the origin of ALH84001 - very weak; also not evaluate of this argument.
(E) describe a controversy concerning the significance of evidence from ALH84001 - best of the lot.
-----------------------------------------

2. The passage asserts which of the following about the claim that ALH84001 originated on Mars?
multiple claims made in both p1 and p2.

(A) It was initially proposed by the McKay team of scientists. - no; it was known prior to that.
(B) It is not a matter of widespread scientific dispute. - yes; all accepted that it was from mars. no dispute there.
(C) It has been questioned by some skeptics of the McKay team’s work. - no one did that.
(D) It has been undermined by recent work on PAHs. - no.
(E) It is incompatible with the fact that ALH84001 has been on Earth for 13,000 years. - no.

-----------------------------------------
3. 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?
PT - That this rock must have contaminated by now.

(A) ALH84001 may not have originated on Mars. - no
(B) ALH84001 contains PAHs that are the result of nonbiological processes. - no
(C) ALH84001 may not have contained PAHs when it landed on Earth. - yes; should be best of the lot.
(D) The organic molecules found in ALH84001 are not PAHs. - no
(E) The organic molecules found in ALH84001 could not be the result of terrestrial contamination. - yes; but 13000 yes has nothing to do with this fact.

------------------------------------------

4. The passage suggests that if a meteorite contained PAHs that were the result of terrestrial contamination, then one would expect which of the following to be true?
PT - from top to inside, contamination should decrease.

(E) The PAHs contained in the meteorite would be concentrated toward the meteorite’s surface. - yes

-------------------------------------------

5. Which of the following best describes the function of the last sentence of the first paragraph?
last sentence - The organic molecules found in ALH84001 are poly cyclic aromatic hydrocarbons, or PAHs. When microbes die, their organic material often decays into PAHs.

(A) It identifies a possible organic source for the PAHs found in ALH84001. - yes

-------------------------------------------

6. The passage suggests that McKay’s team would agree with which of the following regarding the PAHs produced by non organic processes?
Yet McKay’s team notes that the particular combination of PAHs in ALH84001 is more similar to the combinations produced by decaying organisms than to those originating from non biological processes.

(D) These PAHs are likely to be found in combinations that distinguish them from the PAHs produced by organic processes. - yes
_________________

Reconcile has a different meaning here. It means "to show that two seemingly contradictory things are somehow compatible".

Here is a more accurate look at the meaning of reconcile (the first meaning on that page).

"Reconcile conflicting viewpoints regarding X" means "show how conflicting viewpoints about X could be compatible with each other (even though they are "conflicting")".
_________________