Reading Comprehension

PT105 · S3 · P1 · Q1 Invertebrate Schooling

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Until recently, many biologists believed that invertebrate "schools" were actually transient assemblages, brought together by wind, currents, waves, or common food sources.

Topic

Schooling behavior in invertebrates and its advantages and drawbacks

Framework

Old / New

Main Point

Recent research has shown that many invertebrates, contrary to earlier belief, do form structured schools like fish do, and schooling brings a variety of benefits and some costs. (The Most Valuable Sentence appears at the end of the first paragraph: )

P1: Shifting Beliefs About Invertebrate Schooling

Until recently, scientists thought invertebrate groupings were just temporary and caused by environmental factors, but new research shows many actually form true schools, much like fish do.

P2: How Invertebrate Schools Work

Invertebrates that school do so in an organized way, maintaining consistent positioning; their grouping is pretty stable unless disturbed by predators.

P3: Passive Benefits of Schooling

Schooling, despite being risky and making the animals more visible, actually helps members avoid predators by making them harder to track individually, increasing group vigilance, and improving individual survival odds.

Which one of the following best expresses the main idea of the passage?

The optimal size of a
Too Narrow
As soon as we see the subject noun is "the optimal size of a school", we should be heading on. The main topic is invertebrates, so we'd expect them to be the subject noun. Optimal school size comes up only in the last two sentences of the passage, and the passage says circumstances dictate the optimal size. It never ranks competition as the primary factor.
4% picked this
The internal structure of a
Unsupported
As soon as we see the subject noun is "the internal structure of a group of invertebrates", we should be heading on. The main topic is invertebrates, so we'd expect them to be the subject noun. The passage describes a school's internal structure in the second paragraph and its defensive maneuvers in the fourth, but never says the first determines the second.
1% picked this
Although in many respects invertebrate
Unsupported
The opening concession clause sounds like our main point. The main clause sounds like the passage was primarily written to explain differences between schooling fish and schooling invertebrates. The passage repeatedly says invertebrate schools behave "as fish do" and "like schooling fish." It never identifies a respect in which the two differ.
6% picked this
Correct
Certain invertebrates have been discovered
Why this is right
The first paragraph reports the discovery that crustaceans and other invertebrates form schools, and the third through fifth paragraphs lay out the benefits that researchers assume explain the behavior.
Skill tested: Main Point · how this choice captures the passage's function is the move to repeat next time.
88% picked this
Invertebrate schooling is more directed
Unsupported Comparison
The passage covers both predator avoidance and food finding but never weighs one purpose against the other.
2% picked this

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