Question

Difficulty: MediumSupporting Claims with Evidence and Details

The sentences below are from a draft of an essay about gecko adhesion. Arrange the sentences in the most logical order to support the claim that geckos rely on microscopic structures and physical forces to climb smooth surfaces.

  1. 1Geckos can climb smooth vertical walls and even walk upside down on ceilings due to millions of microscopic hairs, called setae, on their toes.
  2. 2Each of these setae splits into hundreds of even smaller, spatula-shaped tips called spatulae.
  3. 3When these spatulae come into close contact with a surface, weak electromagnetic attractions known as van der Waals forces are generated between the molecules of the gecko's foot and the wall.
  4. 4Although an individual molecular bond is weak, the cumulative effect of billions of spatulae contacting a surface creates an adhesive force strong enough to support the gecko's entire weight.

Answer

The correct order of the sentences starts with the general introduction of setae on geckos' toes, followed by the description of how setae split into spatulae, followed by the explanation of how spatulae generate van der Waals forces, and concluding with the explanation of the cumulative strength of these forces.
The logical flow must progress from the general structure to the specific sub-structure, then to the physical force it generates, and finally to the overall result of that force. The sentence introducing setae must be first to set up the paragraph's claim. The sentence describing 'these setae' splitting into 'spatulae' must follow. Then, the sentence explaining the molecular forces generated by 'these spatulae' is positioned. Finally, the sentence summarizing the cumulative effect of these forces concludes the paragraph.

Step-by-Step Solution

1
Identify the topic sentence that establishes the central claim.
The sentence stating that geckos can climb smooth walls due to millions of microscopic hairs called setae on their toes is the topic sentence.
It introduces the main subject (geckos' climbing ability) and the primary mechanism (setae) without relying on prior context.
2
Find the sentence that details the structure introduced in the topic sentence.
The sentence explaining that 'Each of these setae splits into hundreds of even smaller, spatula-shaped tips called spatulae' follows next.
The pronoun phrase 'these setae' directly refers back to the 'setae' introduced in the first sentence, creating a logical transition and introducing 'spatulae.'
3
Locate the sentence explaining the function of the spatulae.
The sentence stating that 'When these spatulae come into close contact with a surface, weak electromagnetic attractions known as van der Waals forces are generated...' is placed third.
It uses the referent 'these spatulae' to build upon the definition in the second sentence and explains the physical force they generate.
4
Determine the concluding sentence showing the cumulative result.
The sentence beginning with 'Although an individual molecular bond is weak, the cumulative effect...' is placed last.
It refers to the 'individual molecular bond' (van der Waals forces from the third sentence) and concludes by demonstrating how this cumulative effect supports the gecko's weight, reinforcing the central claim.

Key Concept

Supporting Claims with Evidence and Details
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