Logical Reasoning

PT102 · S3 · Q4 Scientists analyzing air bubbles

A free, expert breakdown of this official LSAT Logical Reasoning question.

  • Save & drill this skill — build targeted practice sets from questions like this one

  • Video walkthroughs — watch every question solved step by step

  • 81 official LSATs — as questions, timed sections & full-length tests

Start practicing free

Scientists analyzing air bubbles that had been trapped in Antarctic ice during the Earth’s last ice age found that the ice-age atmosphere had contained unusually large amounts of ferrous material and surprisingly small amounts of carbon dioxide.

Curious Fact

How come there's so much ferrous material and so little carbon dioxide in this air bubble from Earth's last ice age? (why does it seem like the air back then had more Iron and less CO2?)

Hypothesis

The ferrous material caused an increase in algae (such as diatoms), which suck up the CO2 from the atmosphere.

Evaluate

Any time we're evaluating Curious Fact / Explanations, we have two pressure points to consider: - is there some other way to explain the curious fact? - how plausible is the author's way of explaining it?

Goal

Since this is Weaken, we either want an answer to - provide some other way to explain why the atmosphere had high ferrous and low CO2 or - make it less plausible that ferrous material from the atmosphere led to more algae, which led to less CO2.

4.

Which one of the following, if true, would most seriously undermine the scientist’s hypothesis?

  1. Diatoms are a microscopic form

    No Impact

    Diatoms are just one example of Antarctic algae; the scientist isn't especially concerned with diatoms. Whether diatoms have changed or not changed since the last ice age has no bearing on this conversation.

    11% picked this

  2. Computer models suggest that a

    Strengthens

    This makes the author's hypothesis sound more plausible, since it corroborates the link between high ferrous and more algae.

    1% picked this

  3. The dust found in the

    No Impact

    I don't think we were ever assuming that the dust was pure ferrous material. It doesn't change anything to learn that there were other minerals in there too. The existence of other minerals in the air bubble doesn't suddenly become an alternate explanation for why there was high ferrous and low CO2 in the ancient atmosphere.

    23% picked this

  4. Correct

    Sediment from the ocean floor

    Why this is right

    This hurts the plausibility of the author's story. The author thought: more ferrous, more algae (f.e. diatoms), less CO2 If there were more Antarctic algae such as diatoms during this last ice age, then we would expect to find more diatom shells in the sediment of the ocean floor. If we're not finding more diatom shells, then it doesn't seem like there were more diatoms during that time period, which makes the scientist's hypothesis seem a bit less convincing.

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

    61% picked this

  5. Algae that currently grow in

    No Impact

    The storyline never involved the algae being harmed by ferrous material; to the contrary, the scientist thought that ferrous material promoted more algae. So, if anything, this answer goes with the hypothesis, not against it.

    5% picked this

Continue the review in LSAT Lab

Save this question, watch the video walkthrough, and drill similar questions in your LSAT Lab account.

Save and practice this skill
LSAT Lab

Turn this review into a targeted study plan.

Save this question, drill more like it, watch the video walkthrough, and track your progress in your LSAT Lab account.

Start practicing free