Parthenogenesis is a form of reproduction in which a female reproduces without mating. She produces an egg containing a single...
GMAT Information and Ideas : (Ideas) Questions
Parthenogenesis is a form of reproduction in which a female reproduces without mating. She produces an egg containing a single offspring whose DNA, or genetic material, comes entirely from its mother. Among birds, parthenogenesis has been found in a handful of species, including pigeons and turkeys. When scientists at the San Diego Zoo analyzed the DNA of the zoo's California condors (a species of vulture), they discovered that two individuals weren't genetically similar enough to any of the males in the condor enclosure to be their offspring. However, both had hatched from eggs laid by females in the enclosure. Thus, the scientists concluded that ______
Which choice most logically completes the text?
at least one of those individuals' mothers was born as a result of parthenogenesis.
California condors may reproduce through parthenogenesis in zoos but not in the wild.
the mothers of the two individuals probably reproduced through parthenogenesis.
California condors reproduce through parthenogenesis only if females lack sufficient access to males.
Step 1: Decode and Map the Passage
Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| Parthenogenesis is a form of reproduction in which a female reproduces without mating. |
|
| She produces an egg containing a single offspring whose DNA, or genetic material, comes entirely from its mother. |
|
| Among birds, parthenogenesis has been found in a handful of species, including pigeons and turkeys. |
|
| When scientists at the San Diego Zoo analyzed the DNA of the zoo's California condors, they discovered that two individuals weren't genetically similar enough to any of the males in the condor enclosure to be their offspring. |
|
| However, both had hatched from eggs laid by females in the enclosure. |
|
Main Point and Argument Flow
Main Point: Scientists discovered evidence of parthenogenesis in California condors when DNA analysis showed two individuals couldn't be offspring of available males despite being hatched by enclosure females.
Argument Flow: The passage first defines parthenogenesis and establishes its occurrence in birds, then presents a specific case study where scientists found genetic evidence suggesting parthenogenesis occurred in California condors at the San Diego Zoo.
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 two individuals that: (1) Aren't genetically similar enough to any males in the enclosure to be their offspring, and (2) Were hatched from eggs laid by females in the enclosure.
- Since parthenogenesis means reproduction without mating (where offspring get DNA entirely from mother), and these chicks can't be from the available males but came from enclosure females, the logical conclusion is that these females reproduced through parthenogenesis.
at least one of those individuals' mothers was born as a result of parthenogenesis.
✗ Incorrect
- This suggests the mothers themselves were born through parthenogenesis, but the evidence is about how these specific two individuals were born, not their mothers.
California condors may reproduce through parthenogenesis in zoos but not in the wild.
✗ Incorrect
- Makes a broad claim about zoo vs. wild reproduction patterns. The passage gives no information about wild condor reproduction.
the mothers of the two individuals probably reproduced through parthenogenesis.
✓ Correct
- Directly states that the mothers reproduced through parthenogenesis. Perfectly matches our evidence: if the chicks can't be from available males but came from enclosure females, those females must have reproduced without mating.
California condors reproduce through parthenogenesis only if females lack sufficient access to males.
✗ Incorrect
- Makes a claim about when condors use parthenogenesis (only when lacking male access). The passage doesn't establish this causal relationship.