vasuca10 wrote:
VeritasPrepHailey Mam Kindly guide for this question...I marked answer choice B as I thought that if virus kills algae and then the animals that prey on shellfish will be more, decreasing shellfish population.
Certainly,
vasuca10 - happy to provide my thoughts!
If we get started by taking a look at the question stem:
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Which of the following, if true, provides the most support for the conclusion of the argument?
We can see that we're looking at a strengthen question. So, we need something that fortifies the connection between evidence and conclusion. In this case, we want something that strengthens the use of the facts we've been given:
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Brown tides are growths of algae on the sea's surface that prevent sunlight from reaching marine plants below, thereby destroying not only the plants but also the shellfish that live off these plants.
and
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Biologists recently isolated a virus that, when added to seawater, kills the algae that cause brown tides.
to conclude that:
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Adding large quantities of this virus to waters affected by brown tides will therefore make it possible to save the populations of shellfish that inhabit those waters.
Let's take a look at our answers!
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A. When applied in large quantities, the virus not only kills the algae that cause brown tides but also many harmless kinds of algae.
This answer doesn't strengthen the force of our evidence. Knowing that the virus kills other varieties of algae certainly doesn't help reinforce that it could be used to save populations of shellfish. If anything, the virus holds the potential to disturb their ecosystem if it kills other, harmless, varieties of algae. This one's out.
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B. Marine animals that prey on shellfish avoid areas of the sea in which brown tides are occurring.
Hmm.. if the predators of shellfish avoid areas of brown tides, and we're proposing a plan of action that would get rid of brown tides, all this tells us is that the shellfish could encounter a new set of problems (those darn predators!) if the brown tides were effectively eliminated. This doesn't strengthen the force of the evidence, it
weakens it!
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C. The number of different kinds of virus present in seawater is far greater than many marine biologists had, until recently, believed.
Totally irrelevant to us here. We're suggesting adding large quantities of this virus that we already know has been seen to kill brown-tide-causing algae. So, the fact that there are different varieties does not matter at all to us here, as it does not impact the connection between evidence and conclusion. (Does it make sense to use the virus accomplish the goal of saving shellfish?)
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D. The presence of large quantities of the virus in seawater does not adversely affect the growth of marine plants.
Hey! This looks like the counter-part to what I mentioned in (A). If the shellfish live off plants, and we want to strengthen the use of the virus to save populations of shellfish, this answer option tells us that not only will the shellfish avoid destruction by brown tides, its ecosystem and food source will as well! This absolutely strengthens our plan of action and corresponding conclusion.
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E. The amount of the virus naturally present in seawater in which brown tides occur is neither significantly greater nor significantly less than the amount present in seawater in which brown tides do not occur.
Naturally present quantities don't matter to use here... our argument specifically notes that the
addition of large quantities of the virus will impact the brown tides and thus, the shellfish population. So, the naturally present levels do not matter to us, as they fall outside of the realm of the argument made.
It sounds like you analyzed the impact of (B) correctly, but misidentified the objective of our answer. Here, we wanted something that strengthens the potential use of this virus to save shellfish populations. (B), even in the light you described it in, weakens this argument, as it gives us reason to believe the use of the virus might not save the shellfish, and could instead just expose them to a whole new heightened threat! (poor shellfish!)
So, be sure you're identifying your task or job with the question and how wrong answers impact the argument in the wrong way. This should help you recognize these wrong answer types more consistently moving forward!
I hope this helps!