Q5 - One of the advantages of Baccillus Thuringeniensis(BT)

[kimjy89]

I tried to find an answer that made B.t toxins less preferable, but all of them seem to make B.t less preferable. I wasn't sure why D was the best answer.

Thank you.

[bbirdwell]

You are correct in stating that we need to find an answer choice that makes Bt toxins less preferable to chemical insecticides. That's an excellent re-phrase of the question.

Let's take a quick look at the argument's important elements and then move on to the choices.

Conclusion:
Bt toxins preferable to chemical insecticides for use in pest management.

Premises:
Bt toxins are specific to certain insects.
No known effects on mammals or birds.
Tendency to kill target pests without affecting insects that prey on those targets. (ie specificity)

We can weaken this conclusion by damaging one of the above premises somehow, or by bringing a new consideration altogether. Ultimately, focusing on the conclusion itself will be the most valuable approach.

(A) This supports the conclusion. If a stated advantage of Bt is that is specific, we can safely infer that harming a "greater number of species" (i.e. being non-specific) is not a good thing.

(B) So what? It doesn't need to be effective against ALL insects in order to be preferable.

(C) So what? It doesn't need to harm weeds to be preferable as a component of insect pest management.

(D) Ah. This weakens. If insects build up resistance to Bt, and not to chemicals, this is a strike against the use of Bt. Notice how this choice doesn't make Bt toxins a totally stupid idea. It doesn't need to -- that's not our task here. It does, however, clearly suggest that Bt toxins MAY NOT be "preferable" to chemicals by giving a reason against Bt and a reason for chem.

(E) So what? The question is whether Bt toxins are preferable to chemicals as part of insect pest control. Birds aren't a part of the conclusion, or the argument, at all.

Does that help?

[esnanees]

I understand why the rest of the ans choices are wrong. But i can not seem to come up with a concrete reason why ans D is right. The premise stating "In addition......often a particular toxin will kill pest species but not affect insects that prey upon the species" is a bit confusing to me with regards to ans choice D.

So if the species are killed, it means the insects have no food to keep them growing. How does ans D stating that the insects build more resistant to BT weakens the argument because the toxin does not affect the insects anyway.

Can someone help me understand what i am missing in the stimulus? Thanks.

[khaleesiwantstodolaw]

The premise stating "In addition......often a particular toxin will kill pest species but not affect insects that prey upon the species" is a bit confusing to me with regards to ans choice D.

So if the species are killed, it means the insects have no food to keep them growing. How does ans D stating that the insects build more resistant to BT weakens the argument because the toxin does not affect the insects anyway.

Can someone help me understand what i am missing in the stimulus? Thanks.

I think you're confusing which particular insect species the stimulus is talking about. When the stimulus says that B.t. toxins kill "pest" species but not insects that prey upon "pest" species, it is talking about two types of insects - the pest species are the harmful kind but the "insects that prey upon (pest) species" are insects that eat the harmful pest insects, so in a way they are "beneficial". This is the reason why B.t. toxins are preferable to insecticides. Not only do the toxins kill the harmful pest insects but they also dont kill the insects that prey upon pest insects. So in a way they are doubly effective in killing the harmful pest insects.

Answer choice D weakens the argument because it is only talking about the harmful pest insects and not the insects that prey upon the pest insects. In other words, if the harmful pest insects develop resistance more readily to the B.t toxins compared to the insecticides then the advantage of using toxins is lost (or at least diminished). This weakens the argument.

I hope that clears it up for you!

[roflcoptersoisoi]

B.tx toxins have no detrimental effects on mammals or birds
Have limited range of toxicity, meaning they don’t effect insects that prey upon the species

Therefore B.tx toxins is preferably to chemical insecticides for use in insect pest management programs

Gap: chemical insecticides don’t have characteristics that make its use better for these management programs.

(A) We’re talking about pest insects, we don’t necessarily care that chemical insecticides cause harm to a greater number of insect species. Eliminate, has no bearing on our argument
(B) Once again, we’re talking about pest insects, Bt.x toxins don’t necessarily have to be effective against all insects. This has no bearing on our argument
(C) Again, who gives a flying f**ck. We’re trying to argue whether or not Bt.toxins are preferable to chemical insecticides for insect pest management programs. This doesn’t come close to making a dent in our argument.
(D) This looks good, keep for now
(E) Irrelevant.

The answer is clearly (D), if insects which include pest insects build immunity to Bt.x easier than they do against chemical insecticides, perhaps the former isn’t preferable than the latter for the insect pest management program.