In a three-year study of parasitic infections by Anomotaenia brevis tapeworms in Temnothorax nylanderi ants, entomologist Susanne Foitzik and colleagu...
GMAT Information and Ideas : (Ideas) Questions
In a three-year study of parasitic infections by Anomotaenia brevis tapeworms in Temnothorax nylanderi ants, entomologist Susanne Foitzik and colleagues found something unexpected: rather than reducing its host's fitness, as is typical of parasites, A. brevis greatly extends the lifespan of a T. nylanderi worker ant and seems to halt the effects of aging. Furthermore, those infected receive special treatment, ceasing their share of labor to sustain the colony and remaining in the nest as uninfected workers feed, groom, and transport them. By contrast, the researchers observed that uninfected workers in parasitized colonies have shortened lifespans, most likely because the ______
Which choice most logically completes the text?
Worker ants do not reproduce, but they do take care of their siblings.
Worker ants do not reproduce, but they are well cared for by other ants.
Worker ants reproduce at a very slow rate, so they evolve slowly.
All of the above
Step 1: Decode and Map the Passage
Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| "In a three-year study of parasitic infections by Anomotaenia brevis tapeworms in Temnothorax nylanderi ants, entomologist Susanne Foitzik and colleagues found something unexpected:" |
|
| "rather than reducing its host's fitness, as is typical of parasites, A. brevis greatly extends the lifespan of a T. nylanderi worker ant and seems to halt the effects of aging." |
|
| "Furthermore, those infected receive special treatment, ceasing their share of labor to sustain the colony and remaining in the nest as uninfected workers feed, groom, and transport them." |
|
| "By contrast, the researchers observed that uninfected workers in parasitized colonies have shortened lifespans, most likely because the ______" |
|
Provide Passage Architecture & Core Elements
Main Point: A. brevis tapeworms unusually benefit their ant hosts by extending lifespans, but this creates negative consequences for uninfected workers in the same colonies.
Argument Flow: The passage establishes that this tapeworm defies typical parasite behavior by helping infected ants live longer and receive special care. However, this creates a contrasting problem—uninfected workers in these colonies actually have shorter lifespans, and we need to determine why this happens.
Step 2: Interpret the Question Precisely
This is a fill-in-the-blank question asking us to choose the best logical connector. The answer must create the right relationship between what comes before and after the blank.
Step 3: Prethink the Answer
- From our analysis, we know that infected workers stop contributing labor but receive intensive care from uninfected workers
- This creates a logical burden situation where uninfected workers must:
- Do their own normal work
- Compensate for the work that infected workers are no longer doing
- Provide additional care services to infected workers who contribute nothing to colony maintenance
- So the right answer should explain that uninfected workers have shortened lifespans because they're overburdened by having to do extra work while also caring for infected workers who contribute nothing to colony maintenance
Worker ants do not reproduce, but they do take care of their siblings.
✗ Incorrect
- Suggests uninfected workers get infected through caring for infected ones
- This doesn't explain shortened lifespans—if they got infected, they'd actually live longer according to the passage
- Misses the burden/workload issue entirely
Worker ants do not reproduce, but they are well cared for by other ants.
✓ Correct
- Directly addresses the workload burden: uninfected workers must compensate for infected workers' lost contributions
- Also accounts for the additional care responsibilities
- This double burden logically explains why their lifespans would shorten
- Matches our prethinking perfectly
Worker ants reproduce at a very slow rate, so they evolve slowly.
✗ Incorrect
- Focuses on predator escape abilities rather than lifespan causes
- High activity helping with predator avoidance wouldn't logically cause shortened lifespans
- Doesn't connect to the established care burden
All of the above
✗ Incorrect
- Discusses typical lifespan ranges in non-parasitized colonies
- Doesn't explain why uninfected workers in parasitized colonies specifically have shortened lifespans
- Students might think this provides context about normal lifespans, but it doesn't address the specific causal relationship the question asks for