CELPIP Reading Part 3Reading for Information Practice

A. Many geckos can run across walls and ceilings even when a surface appears too smooth for claws. Their feet do not rely on liquid glue, and they do not create sealed suction cups against the wall. Instead, broad toe pads carry branching structures that make extremely close contact with tiny irregularities in the surface. This system works on many materials, although dust, moisture, and surface texture can alter its effectiveness. For the gecko's ability to climb varied surfaces, this wider context prevents one striking feature from being mistaken for the whole story during a quick first inspection.

B. Each toe pad contains rows of microscopic hairs, and every hair divides into much finer flattened tips. The enormous number of tips gives the foot a wide combined contact area despite their minute individual size. When those tips approach a surface closely, weak molecular attractions collectively produce enough force to support the animal. No single contact is powerful, but millions acting together create reliable adhesion that can be controlled quickly. Together, these details place microscopic adhesion structures on gecko feet within a broader pattern shaped by the surrounding environment over a meaningful period of time.

C. A gecko attaches a toe by placing it down and pulling slightly so the fine tips align with the surface. Changing the angle reduces contact, allowing the toe to peel away without requiring a large upward force. This directional control lets the animal alternate firm grip and rapid release during each running step. Tendons and muscles coordinate the toes, so the microscopic structures operate as part of a larger movement system. This combination helps explain why attachment and release during movement cannot be understood from one feature alone or from one brief observation.

D. Loose particles can cover the fine tips, yet ordinary walking may remove some dirt and restore performance. Water affects species differently because toe structure, skin chemistry, and the surface being crossed all matter. Researchers have created dry adhesive materials inspired by the general principle of many angled microscopic contacts. Manufactured versions still face challenges involving durability, contamination, and repeated use over large areas. For microscopic adhesion structures on gecko feet, relationships among these features matter because a change in one may influence several others within the same setting over time.

E. Not given in any of the above paragraphs.