Reading Comprehension

PT7 · S3 · P3 · Q20 Crop Bacteria

A free, expert breakdown of this official LSAT Reading Comprehension 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

Cultivation of a single crop on a given tract of land leads eventually to decreased yields.

Topic

Using bacteria — including genetically altered ones — to suppress plant pathogens and improve crop yields.

Framework

Present Debate. The author lays out the technique, walks through the genetic-alteration extension, and presents proponents' and opponents' arguments before closing with a hopeful note.

Main Point

Beneficial soil bacteria like Pseudomonas fluorescents already improve crop yields by suppressing pathogens; proponents argue genetic alteration of bacteria could extend these benefits, while opponents worry about deliberate release. Proponents counter that specific alterations (like removing the frost-damage gene from P. syringae) make the altered strain safer than the original.

P1: Beneficial bacteria suppress pathogens

Continuous cultivation increases harmful soil bacteria; rotation breaks this. Even without rotation, soils become "suppressive" — partly because bacteria like P. fluorescents outcompete the pathogens. Treating wheat (and sugar beets, cotton, potatoes) seeds with these bacteria increases yields.

P2: Genetic alteration as the next step

Proponents suggest genetically altered bacteria could be even more useful — for example, releasing nonpathogenic P. syringae to crowd out the frost-damage variety. Opponents object to large-scale releases of altered bacteria. Proponents counter that the alteration is just removing the gene for frost damage, making the strain safer than the original.

P3: Even more ambitious uses

Some proponents go further: combining traits from different bacteria (e.g., transferring insecticidal-compound genes into corn-root pseudomonads). Such bacteria are hard to develop and may struggle in natural soil. Still, proponents see excellent prospects, and many hope risk-assessment efforts will satisfy opponents and let research go forward.

20.

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

Pseudomonas syringae bacteria are primitive
No Impact
Whether the bacteria are primitive or genetically simple doesn't give us any way to argue that removing one specific gene introduces new safety risks or fails to prevent frost damage.
0% picked this
The altered bacteria are derived
No Impact
We know the original strain is parasitic and causes damage, frost damage to be specific! The altered bacteria theoretically won't cause frost damage. We need an answer to say, "no, it'll still cause frost damage" or to say "removing that frost damage gene is going to make this altered version even more dangerous". This answer does neither of those things.
20% picked this
Current genetic-engineering techniques permit the
No Impact
The fact that we can make a bunch of these altered bacteria doesn't tell us anything about whether they are safer / less safe / equally safe to the original strain of the bacteria.
1% picked this
Correct
Often genes whose presence is
Why this is right
This gives us a way to say that removing that one gene could cause PROBLEMS! That gene was responsible for the harmful trait of "frost damage", but it might need to be present to prevent other harmful traits (like leaking lead into the soil or being poisonous to bees). So this is giving us a way to say, "removing a gene that causes a harmful trait won't necessarily make a plant safer, because removing that gene might lead to OTHER harmful characteristics that were suppressed by that gene, when it was present."
Skill tested: Weaken · how this choice captures the passage's function is the move to repeat next time.
75% picked this
The frost-damage experiments with Pseudomonas
No Impact
This is sort of a common sense idea about the prevalence / dominance of the strain. Naturally, we'd have to release a lot of it for it to crowd out the unaltered version of the bacteria. But we aren't here to analyze what quantity we need for it to be effective at displacing the original strain. We're just trying to analyze whether the altered strain will be safer than the original strain. Maybe someone would try to argue, "this new strain isn't going to lead to a reduction in frost damage, because you won't make enough of it to displace the original strain, so therefore it's not safer", but that's not how you'd judge whether it's safer. If we invented a new car seat that was safer for children to ride in, we wouldn't judge whether it was a safer seat by analyzing how many families have actually bought and installed it. It's prevalence in the field doesn't help us assess whether it is a fundamentally safer option.
4% 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