Q23 - In an experiment, scientists

[Nina]

totally lost in this one. any help will be appreciated!

Thanks a lot!

[ManhattanPrepLSAT1]

This one is a classic example of a flawed comparison. It concludes that resistance to pesticides would be passed from domesticated crop plants to its relatives that are considered weeds. Why? Because in an experiment with radishes, flower color was passed from domesticated radishes to wild radishes.

Well this doesn't make perfect sense. Maybe there is some difference between flower color and resistance to pesticides. If the two traits are comparable, sure. But if there's a difference, then maybe not. To strengthen this argument we'll look for a stronger connection between these two traits. Answer choice (E) does this, although it may be difficult to see on a first read. If it's more difficult for flower color to be transferred than other genetic traits, that makes it easier for resistance to pesticides to be transferred.

Incorrect Answers
(A) is irrelevant or may even weaken the argument by making it more difficult for genetic traits to be passed from domesticated plants to wild plants.
(B) is irrelevant, since it doesn't address the rate at which resistance to pesticides would be passed.
(C) weakens the argument by reducing the connection between radishes and crop plants in general.
(D) weakens the argument by reducing the connection between the experiment with radishes and the conclusion about genetic modifications to plants.

[kyuya]

Stimulus breakdown:

- put domestic radishes in the same field with wild ones
- within several generations, the wild radishes began to show the same flower colour as the domesticated ones


Conclusion :

- because the flower colour was passed on from domestic ---> wild radishes ...
-...then that means resistance to pesticides (often genetically engineered trait) would be passed on from domesticated crops to their relatives who are weeds

So what's the issue?

1.) We are assuming that the flower trait was similarly genetically modified
2.) We are assuming that radishes aren't otherwise extremely unrepresentative of other crops for any multitude of reasons

We must now strengthen the connection.

A.) This is irrelevant. It makes the connection that wild plants more easily pass on genetic traits to domestic relatives than otherwise, but how does this make a connection between radishes and other domesticated crops and their weed relatives? It actually doesn't. The fact we know one way is easier than the other is of no relevance because we aren't concerned with that connection in the first place.

B.) Again, this tells us nothing about strengthening the connection the author has made in the stimulus. It only gives us further information about the experiment in question.

C.) This clearly weakens the argument. If radishes are not representative (this touches on one of the assumptions I address in the top of this post) then we cannot draw any conclusions from radishes.

D.) This answer choice takes a bit to break down.

Lets explore the implication of this language. If flower colour of domesticated radishes is NOT introduced via genetic engineering, then that means it is a natural occurrence. Why is this actually bad for the stimulus?

It is bad because it is trying to make a connection with pesticide resistance which the author clearly states is "often genetically engineered ". This once again, much like (C) weakens the connection of radishes being representative of crops in general (or the crops the author is interested in, anyway).

E.) Here is the correct answer, pretty subtle but you have to break down the language a bit.

If it is more difficult for flower colour to be transferred between domesticated to wild radishes for almost ANY OTHER trait, it implicitly means that resistance to pesticides being passed on would be EASIER for crops that have a relative plant species than the experiment of radishes.

That makes it more likely than the radish experiment, and we already know the radish experiment indeed worked. So we can safely draw our conclusion this is a strengthener.

[zen]

I want to add a bit of my thoughts on answer choice (D).

This choice is wrong because it weakens the connection postulated in the stimulus: that traits of the domestic radish were passed onto their wild counterparts.
It seems to present a possible problem with conclusion as it would then make the conclusion have to reach farther-- if the domestic radishes' color had not been genetically engineered, then it does not seem as plausible to use a comparison between non-genetically engineered traits being passed on to infer that genetically engineered traits would pass on in the same fashion. If these trait's can't be passed on in the same fashion, then it does not seem likely we could conclude that we would see an analogous situation and the conclusion would not obtain.

(A)- We care about traits of domestic radishes picked up by wild radishes, not the opposite-- traits of wild radishes picked up by domestic radishes.

(B)- Does not strengthen the conclusion that genetically engineered traits would work too based upon the experiment; this merely provides more detail about the first experiment-- if anything, this is a premise booster and it does not solidify the comparison made in the stimulus.

(C)- If radishes are not representative of other crops, then we can't conclude similar effects will occur regarding the passing of traits on other crops, as it could be the case this is only a special characteristic of radishes and not other crops.

(E)- Correct, because it seems to strengthen by saying if the flower color is the hardest trait to pass on or transfer, most other traits would be easier to transfer e.g. genetically engineered traits would be easier to transfer.