Examkin

Soru

Zorluk: OrtaMain Point

Ornithologist: Many evolutionary biologists have long maintained that the pigmentation of avian eggshells evolved primarily as camouflage to protect clutches from visual predators. However, several cavity-nesting bird species whose eggs are concealed within completely dark tree hollows consistently lay heavily speckled eggs, where crypsis confers no survival advantage against predators. Furthermore, recent biomechanical tests reveal that the specific pigment molecules involved significantly strengthen the crystalline matrix of the shell in calcium-scarce habitats. Therefore, structural reinforcement, rather than camouflage, was likely the initial evolutionary factor driving eggshell pigmentation.

Which of the following most accurately expresses the main conclusion of the ornithologist's argument?

  1. A
    Eggshell pigments provide crucial structural reinforcement to eggshells when birds nest in calcium-scarce habitats.
  2. Avian eggshell pigmentation was likely first selected for because it reinforced shell structure rather than because it provided camouflage.Cevap
  3. C
    Visual camouflage confers no evolutionary benefit whatsoever to any bird species that produces speckled eggshells.
  4. D
    The pigmentation of bird eggshells initially evolved primarily to protect clutches from detection by visual predators.
  5. E
    Cavity-nesting bird species face significantly greater dietary calcium deficiencies than birds that construct open nests.

Cevap

Avian eggshell pigmentation was likely first selected for because it reinforced shell structure rather than because it provided camouflage.
The correct answer accurately restates the argument's final deduction: that structural reinforcement, rather than crypsis (camouflage), was the original evolutionary driver of eggshell pigmentation. This overarching claim is logically supported by both the observation about cavity-nesting birds and the biomechanical data regarding calcium-poor habitats.

Adım Adım Çözüm

1
Identify the opposing view and background context
The argument opens by noting the traditional view: eggshell pigmentation evolved primarily for camouflage against predators.
Recognizing the opposing position helps pinpoint where the author pivots to present their own thesis.
2
Isolate the supporting evidence and intermediate findings
The author presents two premises: cavity nesters lay speckled eggs despite no camouflage advantage, and pigments strengthen shells in calcium-deficient conditions.
Distinguishing supporting premises from the final conclusion prevents mistakenly selecting intermediate conclusions or supporting facts.
3
Extract the author's ultimate deduction
Introduced by the conclusion indicator 'Therefore,' the author asserts that structural reinforcement, not camouflage, was likely the initial evolutionary driver.
The main point must represent the final claim supported by all other evidence in the stimulus.

Anahtar Kavram

Distinguishing the main conclusion from supporting premises and background counterarguments.
Tahmini Süre:1m 15s
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Konular

Main Point

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