PrepTest 103, Section 1, Question 12
On their way from their nest to a(60 more words not shown)
The statements above, if true,(8 more words not shown)
- AMost ants forage(12 more words not shown)
- BMost ants that(20 more words not shown)
- CIf any ants(31 more words not shown)
- DIf any ants(27 more words not shown)
- EIf any Saharan(28 more words not shown)
Reading the argument
The trail disappears just when the ants would need it.
Pheromones help ants find their way between food and the nest, but above 45 degrees Celsius those chemicals evaporate almost immediately without leaving a trace. So ants out in that heat can't count on a lasting pheromone trail to guide them home. Maybe they have another way to navigate, such as remembering the route. We aren't told what that other way would be.
What we’re looking for
The question asks what these facts most strongly support. My prediction is limited: in conditions where the pheromones vanish, ants generally can't use them for navigation. The Sahara's typical afternoon temperatures give us a setting in which that limitation matters.
Working the answers
- A
We don't know when most ants look for food. The heat problem applies where temperatures rise above 45 degrees Celsius, and we haven't been told that most ants live in places that reach that temperature. Ants elsewhere could forage in the afternoon and still use pheromones.
- B
The passage names the Sahara as one place with very hot afternoons. That doesn't mean most ants that navigate without pheromones live there. They could live in many other places, hot or otherwise. We have no count or distribution of those ants.
- CCorrect
If ants in the Sahara search for food only in the afternoon, they are generally active when temperatures make pheromone trails disappear. Those ants therefore generally don't use pheromones to guide them between the food and their nest.
The wording fits the limits of the evidence. The passage says such temperatures are typical of Saharan afternoons, and C says “generally.” It doesn't need every afternoon to be equally hot, nor does it claim that we have established the existence of ants with this exact schedule.
- D
Another way to navigate need not involve another substance. Perhaps the ants remember a route or use landmarks. Those are possibilities, not facts we need to prove; they show why ruling out pheromones doesn't establish that the replacement must be a heat-resistant chemical.
- E
We don't know how efficiently these ants find food at different temperatures. If they use another navigation method that works equally well in the heat, their efficiency needn't decline. The evidence limits the use of one kind of trail; it doesn't measure overall foraging performance.
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