Scientist: Some consumer groups claim that the economic benefits of genetically engineered foodstuffs may be offset by hidden health risks to humans. However, the risk is minimal. In most cases of deliberate alteration of a plant's genetic structure only a single gene in about 750,000 has been changed. Since the change in the organism's genetic structure is so slight, it cannot have effects significant enough to be worrisome.
Which one of the following, if true, most weakens the scientist's argument?The scientist argues that changing only one gene is too small a genetic change to create serious health risks.
The key weakness is that even one gene change can sometimes have a major
biological effect.
(A) The genetically engineered plants that have been developed so far have few advantages over plants that are not genetically engineered.
This does not weaken the scientist’s argument about health risk. It questions the benefits of genetically engineered plants, not whether a small genetic change can be dangerous.
(B) Whatever health risks there are in food from genetically altered plants may be somewhat reduced by other factors such as enrichment of the plants' vitamin and mineral content.
This does not weaken the argument. If anything, it suggests that possible risks may be reduced.
(C) Scientists have yet to determine, for each characteristic of some plants and animals used for food, the precise location of the genes that determine that characteristic.
This is too general. It shows incomplete knowledge about genes, but it does not directly show that changing one gene can create serious health risks.
(D) There are plants that are known to be toxic to some animals and whose toxicity is known to be affected by the alteration of a single gene.
This is correct. If changing a single gene can affect a plant’s toxicity, then the scientist is wrong to assume that a one-gene change is too slight to have significant effects.
(E) Research has shown that those consumers who are most strongly opposed to genetically altered foods tend to be ill-informed on the issue.
This does not weaken the scientist’s argument. It attacks some opponents of genetically altered foods, but it does not show that the health risk is significant.
Answer: (D)