Question 63·Hard·Text Structure and Purpose
Many ecologists have long attributed recent declines in marsh sparrow populations to nest flooding caused by rising sea levels. Suspecting that another factor might be more influential, Chiara Ricci and colleagues monitored hundreds of nests at various elevations and recorded predation, water levels, and proximity to sources of artificial light (such as dock lamps). They discovered that, regardless of elevation, nests situated near artificial lighting experienced the highest failure rates. On the basis of these findings, Ricci’s team now argues that nocturnal predators attracted to light, rather than inundation by water, are the principal threat to the birds’ breeding success.
Which choice best describes the overall structure of the text?
For SAT “overall structure” questions, first break the passage into chunks (usually sentences) and label what each one does—background belief, hypothesis, method, result, conclusion, prediction, etc. Then condense that into a simple outline (for example: old explanation → study description → results that challenge old explanation) and scan the choices for the one that matches this order without adding extra elements that never appear in the passage, such as historical debates, equal support for multiple views, or predictions about future research.
Hints
Focus on the first sentence’s role
Ask yourself: is the idea in the first sentence something brand new, or is it described as what many experts already believe?
Look at what Ricci’s team is actually doing
In the second sentence, are the researchers just giving opinions, or are they carrying out a specific kind of scientific activity? Identify whether this looks like proposing ideas, testing them, or something else.
Decide how the findings relate to the original idea
Do the results about nests near artificial light make the original flooding explanation stronger, weaker, or leave it unchanged? Think about whether the passage ends in agreement with the original explanation or in a challenge to it.
Eliminate choices that add things not in the passage
Check each answer for extra elements that shift the passage’s conclusion (for example, claiming the original explanation is supported, or claiming multiple causes are endorsed). If the passage never does that, those choices are likely wrong.
Step-by-step Explanation
Identify what the first sentence is doing
Read the first sentence: it says that many ecologists have long attributed the decline in marsh sparrows to nest flooding from rising sea levels.
This is not a new idea; it is an existing, widely held explanation for the problem (the population decline). So the passage begins by giving background: what most experts currently think is causing the problem.
Understand the role of the second sentence
The second sentence introduces Chiara Ricci and colleagues and describes what they did: they monitored hundreds of nests, at different elevations, and recorded predation, water levels, and proximity to artificial light.
This sentence is about research methods—how they gathered data to examine possible causes (including the original idea of flooding and another possible factor, light-related predation). It shows they are testing which factors might really explain nest failure.
Summarize the findings and conclusion
The third sentence gives the key result: nests near artificial lighting had the highest failure rates, regardless of elevation. That means nest flooding from higher water levels (which depends on elevation and water levels) did not best explain the failures.
The fourth sentence explains what the researchers now argue based on those findings: nocturnal predators attracted to light are the principal threat, rather than water inundation. So their results challenge the earlier, widely accepted explanation and support a different main cause.
Match this structure to the answer choices
Now convert that sentence-by-sentence analysis into a simple structure:
- First, the passage states a widely accepted explanation for a problem (ecologists blame flooding for sparrow declines).
- Second, it describes how researchers tested possible causes (monitoring nests with data on predation, water, and artificial light).
- Third, it reports results that call the original explanation into question and support a different main cause (predators attracted to light, not flooding).
The only choice that matches this sequence is:
D) It presents a widely accepted explanation for a problem, describes how researchers tested that explanation, and then reports results that call the explanation into question.