Critical Reasoning

Mars (Fill in): It is theoretically possible that bacteria developed on Mars early in its history and that some were carried to Earth by a meteorite. However, strains of bacteria from different planets would probably have substantial differences in protein structure that would persist over time, and no two bacterial strains on Earth are different enough to have arisen on different planets. So______________________________________________.
(What would be the best option to complete the passage?)
A. Whether or not bacteria actually developed on Mars.
B. Its likely it is that Martian bacteria were transported from Earth.
C. Martian bacteria could have been carried to Earth by means other than meteorites.
D. All bacteria now on Earth could have arisen from transported Martian bacteria.
E. There could have been strains of bacteria that originated on Earth and later died out.

jamesk486 wrote:Mars (Fill in): It is theoretically possible that bacteria developed on Mars early in its history and that some were carried to Earth by a meteorite. However, strains of bacteria from different planets would probably have substantial differences in protein structure that would persist over time, and no two bacterial strains on Earth are different enough to have arisen on different planets. So______________________________________________.
(What would be the best option to complete the passage?)
A. Whether or not bacteria actually developed on Mars.
B. Its likely it is that Martian bacteria were transported from Earth.
C. Martian bacteria could have been carried to Earth by means other than meteorites.
D. All bacteria now on Earth could have arisen from transported Martian bacteria.
E. There could have been strains of bacteria that originated on Earth and later died out.

A is a possibility but the question is a bit awkward.
B - not suggested by passage
C - out of scope. Mode of transportation is not relevant
E - Possible but it still doesn't address the concern of bacteria from multiple planets.

Is it D? not sure though...

IMO C

With Jayhawkk --D is answer

jamesk486, what is the OA...

Statement said it is almost impossible bacteria on Earth is frpm Mars. But the direction changes when the passage says that the difference in protein structure from different planets will persist over time, but it is not the case on Earth. So the bacteria can’t be form Mars, that take scare of C, D . E is out of scope. B also, we not questioning Martian bacteria in Mars, I would; say A even though I am not 100% convinced

isisalaska wrote:Statement said it is almost impossible bacteria on Earth is form Mars. But the direction changes when the passage says that the difference in protein structure from different planets will persist over time, but it is not the case on Earth. So the bacteria can’t be form Mars, that take scare of C, D . E is out of scope. B also, we not questioning Martian bacteria in Mars, I would; say A even though I am not 100% convinced

Isis, can you please explain how you got "it is almost impossible bacteria on Earth is form Mars". Just wanted to see how we can make this inference.

Yes, maybe I went to far infering, I though that It is theoretically possible that bacteria developed on Mars you could assume that bacteria is from Mars, but now I have second thoughts because one thing is "being developed somewhere" and another "being from somewhere". Maybe bacteria was from a different planet and developed in Mars, or maybe bacteria was from Mars...I don't know...what is right answer?

If no two bacterial strains on Earth are different enough to have arisen on different planets, then either all the bacteria strains came from another planet or

a)Bacteria could have developed from another planet but didn't reach Earth,
b)Bacteria wasn't developed at all. (Remember the statement is unclear whether these actually happened or not but stated that these two events were possible)

So A or D. I'm going with A (is that the exact wording of the answer choice? it sounds incomplete).

IMO A..here is why:

the conclusion states that "no two bacterial strains on Earth are different enough to have arisen on different planets"
and it has been said that "strains of bacteria from different planets would probably have substantial differences in protein structure"

Now there could only be 1 option...either all the bacterias on earth are from Mars or none of them are from Mars...and A is only option that states that...though D is close but can be negated becoz it is imp that where the bacteria is developed rather than the mode of transportation...

OA pl. ?

I would go for D.
The passage says that all of earth’s have a similar protein structure and hence should be from one source. Therefore it should all be from earth or all from mars. D paraphrases this correctly. By saying ‘All bacteria could have arisen’ it leaves the room for a possibility that perhaps all bacteria may not have arisen from Mars and hence arisen from earth or any other planet.
A – Incorrect. The sentence does not make sense.
B – Incorrect. The statement allows interpretation that there is both bacteria originated from mars and earth currently on earth. We know this is not true as all bacteria seem to have come from one source.
C – Incorrect. Mode of transportation is not the point of the argument.
E – Incorrect. Goes out of scope of the argument.

I also think D

The Question states the bacteria on the earth have same protein structure even though they have arisen by different planets.But bacteria on different planets have different protein structures.

so the bacteria on the earth have been transported by the same planet ie Mars

(D) only satisfies the above condition.


Suggest me if iam wrong

My answer is D and i am sure about it.

jamesk486 wrote:Mars (Fill in): It is theoretically possible that bacteria developed on Mars early in its history and that some were carried to Earth by a meteorite. However, strains of bacteria from different planets would probably have substantial differences in protein structure that would persist over time, and no two bacterial strains on Earth are different enough to have arisen on different planets. So______________________________________________.
(What would be the best option to complete the passage?)
A. Whether or not bacteria actually developed on Mars.
B. Its likely it is that Martian bacteria were transported from Earth.
C. Martian bacteria could have been carried to Earth by means other than meteorites.
D. All bacteria now on Earth could have arisen from transported Martian bacteria.
E. There could have been strains of bacteria that originated on Earth and later died out.

Here the conclusion is that on earth all the bacteria are from the same planet as none of the two bacteria shown different protein structure....

With 1st statement, author states that its is theoretically possible that bacteria developed on mars but he never states that bacteria can't be developed on any other planet.

So Choice A is partially incorrect. We can keep it aside until we can have some good choice.
B: Simply out of scope.
C: Simply out of scope, as its clearly mentioned by author about the mode of transportation.
D: Seems most promising, as it retain the fact the above stated conclusion.
E: Again out of scope, as there is no traces of such bacteria is found.

As out of A and D, D is more near to the conclusion, so D is the best answer to this question.

D is the answer, let me know the real answer.