PrepTest 158, Section 3, Question 24
Scientist: Some consumer groups claim that the economic(60 more words not shown)
Which one of the following,(7 more words not shown)
- AThe genetically engineered(17 more words not shown)
- BWhatever health risks(25 more words not shown)
- CScientists have yet(23 more words not shown)
- DThere are plants(24 more words not shown)
- EResearch has shown(19 more words not shown)
Reading the argument
One gene could still matter a great deal.
The scientist points to the small fraction of the plant's genetic structure being changed: usually one gene out of about 750,000. But why should the size of that fraction tell us how important the changed gene is? Suppose that one gene affected whether eating the plant increased a cancer risk. Altering it could matter even while nearly everything else stayed the same. That is a possibility to investigate, not a fact established here.
We don't need to settle a real-world debate about genetically engineered food. The consumer groups' worries don't become correct merely because they raise them, and the scientist's reassurance doesn't become correct merely because the change sounds small. We need evidence connecting the change with its effects.
What we’re looking for
For a weakener, I'd look for an example showing that changing just one gene can have a serious consequence. That would directly challenge the scientist's reason for treating the risk as too small to worry about.
Working the answers
- A
Having few advantages isn't the same as posing a health risk. A plant could offer little improvement over an ordinary plant and still be harmless. The scientist's argument here concerns the significance of the risk from a small genetic change, not whether the products deliver worthwhile benefits.
- B
Reducing whatever risks exist wouldn't challenge the scientist's reassurance. It also wouldn't establish the missing claim about whether a single altered gene can have a significant effect. The question isn't answered by pointing to other features that might offset a risk; B gives us no evidence against the reasoning we identified.
- C
Not knowing the precise location of every relevant gene doesn't show that changing one gene can cause a significant health effect. It identifies a limit to scientists' knowledge without connecting that limit to the particular inference from a small change to minimal risk. D gives us a much more direct challenge.
- DCorrect
A single-gene alteration can affect a plant's toxicity to animals. Toxicity is a consequence that can matter to health, so this undermines the assumption that changing only one gene must produce effects too slight to worry about.
D doesn't establish that the foods in question harm humans, and it doesn't even say every such alteration increases toxicity. It shows that one gene can affect a medically relevant property. That is enough to weaken the scientist's blanket dismissal of concern based on how few genes changed.
- E
Poorly informed opponents could still raise a concern that happened to be valid. Their level of knowledge doesn't establish the effects of changing a gene. We need evidence about the plants and their effects, not a reason to dismiss the people expressing concern.
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