Reading ComprehensionDifficulty: Medium

PT7 S3 P3 Q20 Explanation

Crop Bacteria

A free, expert breakdown of this official LSAT Reading Comprehension question.

TopicsWeakenScience

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Passage

Cultivation of a single crop on a given tract of land leads eventually to decreased yields. One reason for this is that harmful bacterial phytopathogens, organisms parasitic on plant hosts, increase in the soil surrounding plant roots. The problem can be cured by crop rotation, denying the pathogens a suitable host for seeds with fluorescent pseudomonads. Similar treatment of sugar beets, cotton, and potatoes has had similar results.

These improvements in crop yields through the application of Pseudomonas fluorescents suggest that agriculture could benefit from the use of bacteria genetically altered for specific purposes. For example, a form of phytopathogen altered to remove its harmful properties could be released into the environment in quantities favorable to its competing with and to cause frost damage, thereby rendering it safer than the phytopathogen from which it was derived.

Some proponents have gone further and suggest that genetic alteration techniques could create organisms with totally new combinations of desirable traits not found in nature. For example, genes responsible for production of insecticidal compounds have been transposed from other bacteria into pseudomonads that colonize corn roots. Experiments of this kind are difficult of opponents and create a climate in which such research can go forward without undue impediment.

What this question is testing

Weaken

Anticipate

This is a Weaken question. The proponents' specific claim is: removing the frost-damage gene makes the altered P. syringae safer than the original. They're assuming removal of the gene only removes a problem — it doesn't cause new ones.

The strongest weakener says: actually, removing that gene could cause new problems. Maybe the harmful gene was preventing other harms, or the bacterium needs it for something we're not anticipating.

Goal

Looking for an answer that undermines the assumption that gene removal is harmless. Be wary of:

Answers that talk about the original strain being parasitic — the proponents already accept that

Answers about commercial production methods — those don't attack the safety logic

Answers about needing sufficient quantities — that's about effectiveness, not safety

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
20.

Which one of the following, if true, would most seriously weaken the proponents’ argument regarding the safety of using altered Pseudomonas syringae bacteria

Answer choices

  1. No Impact0% picked this

    Pseudomonas syringae bacteria are primitive and have a simple

    Whether the bacteria are primitive or genetically simple doesn't bear on whether removing one specific gene introduces new safety risks. This information is neutral with respect to the proponents' argument.

  2. No Impact19% picked this

    The altered bacteria are derived from a strain that is parasitic to plants and can

    The proponents already grant that the original strain is parasitic and harmful — that's why they say the altered version, with the harmful gene removed, is safer. Restating the original strain's harmfulness doesn't weaken the comparison; it's the proponents' own premise.

  3. No Impact0% picked this

    Current genetic-engineering techniques permit the large-scale commercial production of

    Commercial production capability is about scaling up; it doesn't bear on the proponents' safety argument. The argument is whether the altered strain is safer than the original — production volume doesn't change that.

  4. Correct75% picked this

    Often genes whose presence is responsible for one harmful characteristic must be present in order to

    Why this is right

    The proponents argue the altered strain is safer because the harmful gene was removed. That argument assumes removing that gene causes no new harms. If the gene is sometimes necessary to prevent other harmful characteristics from emerging, then removing it might unleash those new harms — making the altered strain potentially less safe than proponents claim. This directly weakens the proponents' safety inference.

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

  5. No Impact5% picked this

    The frost-damage experiments with Pseudomonas syringae bacteria indicate that the altered variety would only replace the normal strain

    This addresses effectiveness (whether the altered strain will outcompete the original), not safety. The proponents' safety argument is about what happens once released, not about what release quantity is needed for the desired effect.

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