In many agricultural environments, the banks of streams are kept forested to protect water quality, but it's been unclear what...
GMAT Craft and Structure : (Structure) Questions
In many agricultural environments, the banks of streams are kept forested to protect water quality, but it's been unclear what effects these forests may have on stream biodiversity. To investigate the issue, biologist Xingli Giam and colleagues studied an Indonesian oil palm plantation, comparing the species richness of forested streams with that of nonforested streams. Giam and colleagues found that species richness was significantly higher in forested streams, a finding the researchers attribute to the role leaf litter plays in sheltering fish from predators and providing food resources.
Which choice best states the main purpose of the text?
It discusses research intended to settle a debate about how agricultural yields can be increased without negative effects on water quality.
It explains the differences between stream-protection strategies used in oil palm plantations and stream-protection strategies used in other kinds of agricultural environments.
It describes findings that challenge a previously held view about how fish that inhabit streams in agricultural environments attempt to avoid predators.
It presents a study that addresses an unresolved question about the presence of forests along streams in agricultural environments.
Step 1: Decode and Map the Passage
Part A: Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| 'In many agricultural environments, the banks of streams are kept forested to protect water quality,' |
|
| 'but it's been unclear what effects these forests may have on stream biodiversity.' |
|
| 'To investigate the issue, biologist Xingli Giam and colleagues studied an Indonesian oil palm plantation,' |
|
| 'comparing the species richness of forested streams with that of nonforested streams.' |
|
| 'Giam and colleagues found that species richness was significantly higher in forested streams,' |
|
| 'a finding the researchers attribute to the role leaf litter plays in sheltering fish from predators and providing food resources.' |
|
Part B: Provide Passage Architecture & Core Elements
Main Point: A study by Giam and colleagues found that forested streams in agricultural environments have higher species richness than nonforested streams, helping to clarify the previously unclear relationship between streamside forests and biodiversity.
Argument Flow: The passage begins by establishing that while forests along streams are maintained for water quality in agricultural areas, their effects on biodiversity were unknown. It then presents Giam's research as an investigation into this question, reporting that forested streams showed significantly higher species richness, which the researchers explain through the beneficial role of leaf litter for fish.
Step 2: Interpret the Question Precisely
What's being asked? The main purpose of the text as a whole
What type of answer do we need? A statement that captures what the entire passage is trying to accomplish
Any limiting keywords? "Main purpose" - we need the primary, overarching goal, not just what one part does
Step 3: Prethink the Answer
- The right answer should capture that this passage is fundamentally about presenting research that investigated an unresolved question
- The passage starts by identifying something unclear (effects of forests on stream biodiversity), then presents a study that addressed this uncertainty, and reports the findings
- The right answer should mention that a study was conducted to address an unknown or unresolved issue about forests and streams in agricultural settings
It discusses research intended to settle a debate about how agricultural yields can be increased without negative effects on water quality.
- Focuses on agricultural yields and water quality
- The passage doesn't discuss agricultural yields at all - it's about biodiversity
- Misses that this was about an unresolved question, not settling a debate
It explains the differences between stream-protection strategies used in oil palm plantations and stream-protection strategies used in other kinds of agricultural environments.
- Claims the text explains differences between stream-protection strategies
- The passage only mentions one agricultural environment (oil palm plantation) and doesn't compare different protection strategies
- This isn't about comparing strategies but about studying biodiversity effects
It describes findings that challenge a previously held view about how fish that inhabit streams in agricultural environments attempt to avoid predators.
- Says findings "challenge a previously held view about how fish avoid predators"
- The passage doesn't mention any previously held view being challenged
- The study addressed an unclear area, not a controversial one
It presents a study that addresses an unresolved question about the presence of forests along streams in agricultural environments.
- Accurately describes this as "a study that addresses an unresolved question"
- Correctly identifies the setting as "agricultural environments"
- Matches our passage analysis showing the progression from unknown effects to research investigation
- Captures the main purpose: presenting research that tackled an unclear issue