In 2016 biological anthropologist Heather F. Smith and her team investigated the evolution of the appendix, an intestinal organ that...
GMAT Information and Ideas : (Ideas) Questions
In 2016 biological anthropologist Heather F. Smith and her team investigated the evolution of the appendix, an intestinal organ that is present in some mammals, including humans, but is generally thought to have no function. Studying 533 mammal species, the team found that the appendix has emerged independently across multiple lineages in separate instances and, significantly, hasn't disappeared after emerging in specific lineages. Moreover, the team determined that species with the organ tend to have higher concentrations of lymphoid tissue, which supports immune responses, in the cecum, the organ the appendix is attached to. Therefore, the team hypothesized that the appendix likely ______
Which choice most logically completes the text?
was once present in many nonmammal species but has since disappeared from those lineages.
has been preserved in certain mammal species because it benefits their immune systems.
will emerge in a greater number of mammal species because it may serve a necessary function in the immune system.
produced higher concentrations of lymphoid tissue in mammals in the past than it does currently.
Step 1: Decode and Map the Passage
Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| "In 2016 biological anthropologist Heather F. Smith and her team investigated the evolution of the appendix, an intestinal organ that is present in some mammals, including humans, but is generally thought to have no function." |
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| "Studying 533 mammal species, the team found that the appendix has emerged independently across multiple lineages in separate instances and, significantly, hasn't disappeared after emerging in specific lineages." |
|
| "Moreover, the team determined that species with the organ tend to have higher concentrations of lymphoid tissue, which supports immune responses, in the cecum, the organ the appendix is attached to." |
|
| "Therefore, the team hypothesized that the appendix likely ______" |
|
Provide Passage Architecture & Core Elements
Main Point: Smith's research suggests the appendix likely serves an immune function rather than being useless, based on its evolutionary persistence and association with immune-supporting tissue.
Argument Flow: The passage moves from the traditional view that the appendix has no function to presenting research evidence that challenges this assumption. The evidence shows the appendix has evolved independently multiple times and persists once it emerges, plus it's associated with immune-supporting tissue. This evidence logically leads to a conclusion that the appendix serves a beneficial function.
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
- The evidence shows three key things: (1) the appendix evolved independently multiple times across different lineages, (2) it doesn't disappear once it emerges, and (3) species with appendixes have more immune-supporting lymphoid tissue
- These findings all point in one direction - if something evolves repeatedly and sticks around, it's probably doing something useful
- The connection to immune-supporting tissue gives us a clue about what that useful function might be
- So the right answer should conclude that the appendix serves some beneficial function, most likely related to immune system support, which would explain why natural selection has preserved it across different mammal species
was once present in many nonmammal species but has since disappeared from those lineages.
✗ Incorrect
- Claims the appendix was once present in many nonmammal species but disappeared
- The passage only discusses mammals and gives no information about nonmammals
- Contradicts the evidence that the appendix persists once it emerges
has been preserved in certain mammal species because it benefits their immune systems.
✓ Correct
- States the appendix has been preserved because it benefits immune systems
- Perfectly matches the evidence: it persists once it emerges (preservation) and is associated with immune-supporting lymphoid tissue
- Directly follows from the research findings presented
will emerge in a greater number of mammal species because it may serve a necessary function in the immune system.
✗ Incorrect
- Predicts the appendix will emerge in more mammal species in the future
- Makes a speculative claim about future evolution rather than explaining current findings
- The evidence is about what has already happened, not future predictions
produced higher concentrations of lymphoid tissue in mammals in the past than it does currently.
✗ Incorrect
- Compares past and current lymphoid tissue concentrations
- The passage provides no information about historical changes in lymphoid tissue levels
- Focuses on tissue concentration changes rather than the appendix's functional role