Logical Reasoning

PT114 · S2 · Q22 Some types of organisms originated

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Some types of organisms originated through endosymbiosis, the engulfing of one organism by another so that a part of the former becomes a functioning part of the latter.

Information

Some organisms form from endosymbiosis, when organism X engulfs organism Y, and Y becomes a functioning part of X.

We found a weird nucleomorph within a plant called a chlorarachniophyte.

Two versions of a gene were found in the nucleomorph.

If the nucleomorph were not the remains of an engulfed organism's nucleus, then we would expect to find only a single version of the gene.

Evaluate

Yikes! This is one of the harder Science-laden stimuli we'll see in LR.

We can get started, though, by focusing on what we typically read Inference paragraphs looking for:

1. overlapping information 2. conditional / causal / math-y wording

Nucleomorphs is mentioned a few times, and engulfed organism shows up twice. The final sentence gives us a conditional rule, signified by if.

Inference questions love to provide a conditional and then provide a fact that triggers the contrapositive of the rule, to test us on whether we're shrewd enough to infer the outcome of that contrapositive.

We were told N were not remains → find only a of engulfed org's nuc single gene

Contrapositive find more than → N is remains of an a single gene engulfed org's nucleus

They told us that they did find "two versions of the gene".

So according to this rule, that nucleomorph is the the remains of an engulfed organism's nucleus. Where in the paragraph did we hear about "engulfed organism" before?

The first sentence said that endosymbiosis is a process in which one organism engulfs another. So is that what's going on with this nucleomorph?

Goal

While we can't be certain, it seems like we're being guided towards the suspicion that this nucleomorph (which we know from the final two ideas is the remains of an engulfed organism's nucleus) was involved in some endosymbiosis.

Endosymbiosis involves one organism engulfing another until the latter is part of the former. Since we know that this nucleomorph was part of an organism that was engulfed, and since we know that now it's hanging out inside a plant called a chlorarachniophyte, we could support the idea that the chlora plant engulfed the nucleomorph's former organism.

22.

Which one of the following is most strongly supported by the information above?

  1. Only organisms of types that

    Too Strong

    We're barely comfortable supporting the idea that this nucleomorph is the product of endosymbiosis. We can support that idea, but we can't prove it. So this answer, which is saying that "if an organism contains a nucleomorphs, it must have originated through endosymbiosis" is too strong. This was an unusual nucleomorph. So, even if this one did originate through endosymbiosis, there's no reason to think that this would be true of all organisms that have nucleomorphs. Inference questions love to put an answer in slot (A) that is very close to what we were anticipating.

    4% picked this

  2. A nucleomorph within the chlorarachniophyte

    Too Strong: all

    Nothing in this paragraph says anything as strong as "contains all the genetic material of some other organism". Furthermore, we think the nucleomorph was from the "other organism" that got engulfed by the chlorarachniophyte during endosymbiosis. This answer seems to be positing a third organism. You have the chlora, which ate the nucleomorph, but then the nucleomorph ate some other organism and got all of its genetic material?

    17% picked this

  3. Nucleomorphs originated when an organism

    Opposite Relationship

    We know that the nucleomorph was part of the organism that got engulfed (presumably by the chlorarachniophyte). This answer is saying that the chlorarachniophyte got engulfed by the nucleomorph.

    12% picked this

  4. Two organisms will not undergo

    Too Strong: unless

    There's no way from this passage to derive such a severe connection between endosymbiosis and nucleomorphs. We can support that this unusual nucleomorph had something to do with endosymbiosis (since we know it was part an organism that got engulfed). But we can't say, as this answer does, that every single case of endosymbiosis involves a nucleomorph.

    6% picked this

  5. Correct

    Chlorarachniophytes emerged as the result

    Why this is right

    Since we know that the nucleomorph is the remains of an engulfed organism's nucleus and now is within a chlorarachniophyte, it seemed supportable to say that the nucleo was in organism Y, which got engulfed during endosymbiosis by the chlora. The weird part about this answer, to me, was the idea that there were two separate organisms that combined into the chlora. But, if we check the wording of endosymbiosis, it is the origination of an organism. One organism engulfs another, and the engulfee is still a functioning part of the engulfer. But that doesn't mean the resulting organism is still called by the name of the engulfing organism. A new organism has originated from this process.

    Skill tested: Most Supported · how this choice captures the argument's function is the move to repeat next time.

    61% picked this

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