Q22 - Some types of organisms originated through endosymbios

[SchneiderME01]

I'm sorry I honstly don't even know where to begin with this question I've read it multiple times and just seem to get lost

I think this is an inference question

So that would mean that this is a set of facts without a premise or conclusion so more likely then not the correct answer will synthesize facts

but that's about as far as I can get so any help would be greatly appreciated

[timmydoeslsat]

I'm sorry I honstly don't even know where to begin with this question I've read it multiple times and just seem to get lost

I think this is an inference question

So that would mean that this is a set of facts without a premise or conclusion so more likely then not the correct answer will synthesize facts

but that's about as far as I can get so any help would be greatly appreciated

It is in the inference family of questions, but most strongly supported question stems are often less strict. In other words, the correct answer may be not be something that must be true, but is very close to it.

This is a stimulus without a conclusion, which is often the case for inference questions.

We are told that some organisms originate by one organism engulfing another organism. The one that was eaten becomes part of the one that ate it.

So in other words, this is an endosymbiotic situation according to the stimulus:

Organism A engulfs Organism B

We now have an organism called Godzilla.

It is no longer called Organism A, as it now has Organism B functioning with it, so it differs from its old self in a respect.

The first part of the stimulus is used to acquaint you with endosymbiosis.

We are next told about an unusual nucleomorph found in a plant, we will call it Plant C. We are told that a nucleomorph is a structure that contains DNA and resembles a nucleus.

We are told that there are 2 versions of a gene in the DNA in the nucleomorph of this plant.

We are told that if the nucleomorph were not the remains of an engulfed organism's nucleus, then one would expect to find 1 version of the gene.

So from our information given in the stimulus, we know that we have two versions, so we are looking at the real possibility of this nucleomorph being the remains of an engulfed organism's nucleus.

This would give us support to postulate that Plant C originated from endosymbiosis.

Answer choices:

A) Contain nucleomorph ---> Organism originated through endosymbiosis

We have no justification for us to believe that endosymbiosis is necessary for containing a nucleomorph.

B) Attractive wrong answer here. We know that some genetic information of another organism is found in the nucelomorph of Plant C. However, we are not told that all of the genetic material of another organism is found there. Plus, we were told that during endosymbiosis one organism engulfs part of another organism. So it could be the case that not all of the organism was used.

C) We have no information as to how nucleomorphs originate. You could be born with one before endosymbiosis took place.

D) 2 organisms undergo endosymbiosis ---> At least 1 of them contains a nucleomorph.

We do not have justification as to the makeup of organisms before endosymbiosis. It could be true that nucleomorphs are formed only after endosymbiosis.

E) This has the most support for it.

We have a situation of 2 versions of a gene being found in the nucleomorph of Plant C.

~Remains of engulfed organism's nucleus ---> Expect 1 version of gene

We have 2, so we can expect that this may be the remains of an engulfed organism's nucleus.

That would support the idea of Plant C having originated from endosymbiosis.

[maryadkins]

Thanks for that super explanation and breakdown.

Just a small note to add to (C):

(C) is about nucleomorphs, generally. We're told in the stimulus that a nucleomorph is a structure that contains DNA and resembles a cell nucleus. That's all we know about them generally--as timmydoeslsat noted, we don't know how they originated.

[lhermary]

The problem I have with answer E is that it says Chlorarachniophytes (meaning all chlorarachniphytes). It seems like we are using an assumption here. If it had said this chlorarachniophytes then I would know that E is the right answer. But it doesn't, so I'm left confused. What am I missing?

[einuoa]

Going to take a whack at answering your question,

In the text, it says that "...has been discovered with in a plant KNOWN as a chlorarachniophyte..." and when they say known as, it identifies the species of the plant, so let's replace chlorarachinophyte with daisies, then by definition, the group daisies would encompass all daisies...blue daisies, yellow daisies, etc.

So answer E is supported because the nucleomorph has to have undergone endosymbiosis because it has part of something else in it, and so maybe ALL chlorarachinophytes have to have this process, or else they aren't called chlorarachinophytes!

Hope that clears it up.

[jwms]

My problem with (E) is the 'emerged as the result of' ... I thought that was too much of a leap. Thoughts on how I can get over this line of thinking?

[jsdulberg]

Same as the above.

At first I choose B because of the "all of" statement, then I switched it E.

If something is "engulfing" something then why isn't it reasonable to assume that all of the genetic material is inside of it?

On the other hand, why is it reasonable to conclude that this Chlorasomething plant "emerged" as a result of "two organisms having undergone endosymbiosis"????? Why "two"? Why not four, or five...

Thus, seems to me B is "the most strongly supported."

Annoyed.

[mrosa1210]

This is my first post on the forum. Please let me know if my thought process makes sense/is correct. This question is definitely challenging. All of the science terms threw me off and with the stimulus being 11 lines long it's definitely one of the more dense questions.

My approach to really get at the core is to create a square around the unfamiliar terms and then place a parenthesis around the definition of the term. This helps me read through the bare bones of the argument. The terms I squared off include:

Endosymbosis (the engulfing of one organism so that a part of[b][b] the former becomes a functioning part of the latter.
Nucleomorph (a structure that contains DNA + resembles a cell nucleus)
Chlorarachniophyte (a PLANT that has an unusual nucleomorph [DNA/nucleus])

The stimulus tells us that the chlorarachniophyte has two versions of a gene (found in the nucleomorph)

The key to answering this question is the last sentence which includes a conditional statement:
[b]If the nucleomorph were not the remains of an engulfed organism's nucleus (Endosymbosis), one would expect to find only a single version of this gene

LOGIC TRANSLATION: /Endosymbosis---> 1 Gene

Since we were told that the chlorarachniophyte has two versions we can then conclude the CONTRAPOSITIVE:

/1 gene ---> Endosymbosis. OR it can be read as: 2 genes--> Endosymbosis

Meaning that the chlorarachniophyte formed from endosymbosis (the engulfing of part of one organism to form another). This seems to be a common argument structure - an argument where evidence is provided to demonstrate the contrapositive. And so the answer will be just that - the contrapositive.

A curve ball for me the first time around was that the last sentence uses definitions and then the answer choices use the terms. Hence, this is why I now follow the method of creating a square around terms (I usually circle terms such as only, some, most to help me when I look back to confirm the correct answer choice and use squares to identify terms).

Now for the answer choices:
A most strongly supported question is essentially an inference question type. The correct answer choice will be the most provable answer choice (the AC that does not contradict the stimulus and is 90% true).

A) We do not know how nucleomorphs originated.

B) We do not know if the nucleomorph holds ALL of the genetic material. Just because PART of one organism is engulfed by another does not mean that all of its genetic material is in the latter's nucleomorph.

C) We do not know how nucleomorph's originated.

D) The definition of endosymbosis does not require that one of the organisms contains a nucleomorph.

E) Is the contrapositive of the last statement. CORRECT AC.

[robinzhang7]

Hey all,

Thanks for the responses so far. When I was solving this question, I initially looked for the contrapositive of the the rule statement in the stimulus which led me to suspect that the correct answer would follow along the lines of: "The nucleomorph are the remains of an engulfed organism's nucleus." However, that seems like it's nowhere to be found. Instead, correct answer choice (E) states that these chlora. EMERGED AS A RESULT of 2 organisms having undergone endosymbiosis.

I do not think that "The nucleomorph is the remains of an engulfed organism's nucleus" is the same thing what answer choice (E) states. Why? Because all we can actually infer from the stimulus is that the nucleomorph holds 2 versions of DNA (its own and then an engulfed organism's) through endosymbiosis. How can we possibly make a giant leap from the existence of a nucleomorph to a statement concerning the origin of chloras????

Thanks so much!

[maryadkins]

Remember that this is a "most strongly supported" question. The answer may not be 100% provable based solely on what you're told in the stimulus. Such is the case with (E) for the point you noted, but it's still the best answer.

[Vivi]

Thanks for providing those thoughts... Following the upstairs...

Explanation 1:

"E) Is the contrapositive of the last statement. CORRECT AC."

2 genes -> E

how could its contrapositive become as "C emerges as result of e"?

and Explanaton 2:

"Remember that this is a "most strongly supported" question. The answer may not be 100% provable based solely on what you're told in the stimulus. Such is the case with (E) for the point you noted, but it's still the best answer."

Even though not 100% approvable, the good question posted below/from upstairs seemed not addressed.

' "The nucleomorph is the remains of an engulfed organism's nucleus" is the same thing what answer choice (E) states. Why? Because all we can actually infer from the stimulus is that the nucleomorph holds 2 versions of DNA (its own and then an engulfed organism's) through endosymbiosis. How can we possibly make a giant leap from the existence of a nucleomorph to a statement concerning the origin of chloras????'

Might any Master care more efforts in spelling the details?

Many thanks

[ohthatpatrick]

Howdy. Here's my take.

Because there are two version of the gene, we know that [a nucleomorph inside chlorachniophyte] is the remains of an engulfed organism's nucleus.

So something inside Chlora's is the remains of an engulfed organism's nucleus.

Is it something inside just ONE Chlora or inside ALL of them?

It seems like it's in all of them, as the facts are generalized for the whole species ("a weird nucleo has been discovered within a plant known as a chlora")

So every chlora has the remains of an engulfed organism's nucleus inside of it.

What could have caused that?

We could say that endosymbiosis caused it, which would be supported by the information since the information describes that endosymbiosis is a way of achieving the weirdness going on with chlora.

Or we could say that _____??______ caused it? Anything we would say would have NO support, because the information didn't give us any alternative ways of thinking about how an organism would appear to have part of a different, engulfed organism inside of it, as a functioning part (not just in its tummy).

So if the confusion is,
"hey, I know that Endosymb is a POSSIBLE way to explain to the chlora's funky nucleo,
but I don't know that Endosymb is the ONLY way to explain the chlora's funky nucleo", then you're right.

But the Endosymb way of explaining it IS supported by the information (though not proven by it).

[jamiezheng]

How can we possibly make a giant leap from the existence of a nucleomorph to a statement concerning the origin of chloras????

got the same question. i thought the wording made it too much of a causal relationship, saying that chl is emerged as the result of the process of two organisms going through endo.

but after thinking about it for a while, it has to be true bc you gotta have all the necessary parts (water, cellulose,etc... what else..) to form a plant (ie. chl), or else, i think, chl will not form or will come up with an incomplete one. so there isnt really that much a big leap here. (had to pick E also bc all the other choices are way off)

typed this down bc i was initially really confused at this point too and hope to clear my thoughts . im open to opinions and corrections

[HGranger]

I had the same question about making a logical connection to the Chlora having emerged as the result of two organisms having undergone endosymbiosis.

My thinking when I was doing the problem was that two cells combining into one cell doesn't create an entire plant. That doesn't make sense. Cells are minuscule and plants are big and leafy.

Reading through these posts and really thinking about it, I realized that this question is probably playing with our misconceptions. Who's to say we aren't talking about alien cells and plants that aren't very large and very small, respectively, relative to what we think we remember from high school biology (at least in my case)? And that this alien situation isn't being blanketed in convincing scientific terminology? Or that the plant in question isnt some sort of algae like thing that could grow that way?

Granted, the alien thing is silly, but it isn't our job to be critical with inference questions, so the alien thing could be the case and we would just have to accept it, especially because we can only choose the answer that is "most strongly supported."

I hope I'm thinking about this the right way--this question really stumped me because of the stretch I thought we had to make to get to (E), and no one had really addressed it, so here I am, putting my two cents in.

[WesleyC316]

I originally crossed out (E) because I misread the first sentence. I thought when species A engulfed species B, it's still species A. But turns out it actually became species C. Answer choice (E) is well supported.

[StratosM31]

B) We do not know if the nucleomorph holds ALL of the genetic material. Just because PART of one organism is engulfed by another does not mean that all of its genetic material is in the latter's nucleomorph.

To be honest I’m not sure if I can agree with your explanation. From what I remember having been taught, the DNA of an organism contains all of its genetic material. So, if this nucleomorph contains DNA, it does contain all the genetic material of the organism it belongs to. Not sure if we can ask ourselves whether it is all the DNA or not: since it's the "remains" of an engulfed organism's nucleus, it could be the case that only part of its total DNA is in the nucleomorph (so, though, would it be reasonable to still call it “DNA” then?). But it could also be the case that all the DNA survived.

The more obvious reason why I think this choice is wrong is because it does not specify that it is talking about this, specific, unusual nucleomorph from the stimulus. I understood "a nucleomorph" to mean “any” nucleomorph in the plant. Who is telling me that the plant, before the engulfing happened, did not itself have nucleomorphs anyway, which did not come into contact with the other organism and thereforoe do not have its genetic material? If so, it would not have "another organisms" genetic material at all...

[Laura Damone]

I'm actually a big fan of Mrosa1210's explanation of B. I think it represents the cleanest most succinct way to eliminate the answer, and it is, in fact, the reason I got rid of B myself.

I don't know whether everything that can reasonably be called DNA contains all one's genetic material, but I do know that the LSAT would not ask a question that hinged on that sort of knowledge. Also, while I agree that it is certainly possible that the nucleomorph contains all the DNA of the other organism, it still isn't well-supported. That means we can still eliminate B because it's too strong.

Regarding your reason for eliminating, be careful equating "a" with "any." Sometimes, that's exactly right, but other times it isn't. It's all a matter of context. In the context of this question, I think the meaning of "a" is unclear. And since it could reasonably mean "one nucleomorph" or "any nucleomorph," I don't think that's grounds for dismissal.

Still, good thinking on this! You're clearly turning a very critical eye towards these problems, and that's exactly what you need to be doing. Next time, remember that the LSAT won't require you to have science knowledge, so try to make your eliminations based on what you're told in the stimulus, not on what you know in the real world.

Hope this helps!