What is the main idea of the passage?

A slime mold's local feedback can shape efficient, adaptable networks without conscious planning or a central brain. (The passage explains exploration, reinforcement, caution about consciousness, and multiple forms of network quality.)

Why might a slightly longer network be useful?

An extra route can preserve connections if another part is damaged. (The fourth paragraph contrasts absolute shortness with loops that improve resilience under disruption.)

What does “redundant” mean in the second paragraph?

unnecessary because another route already serves the connection (The redundant paths fade as the network retains routes that connect the food efficiently.)

What happens to well-used tubes?

They strengthen. (The opening paragraph says useful tubes strengthen while poorly used tubes may shrink.)

Slime Mold Finds a Short Route: Level 4 Reading Comprehension Questions

A slime mold spreading across damp wood has no brain or central planner. In one stage of its life, however, the organism forms a pulsing network that moves nutrients through branching tubes. The network changes: useful tubes strengthen, while poorly used ones may shrink.

In laboratory demonstrations, researchers place food at several points on a surface and let a slime mold grow among them. At first, its branches explore many directions. Over time, routes that connect food efficiently can remain while redundant paths fade. The final network may resemble a compact transport map.

This result does not mean the slime mold draws a map, understands distance, or solves a problem consciously. Local chemical and physical responses can produce organized behavior at a larger scale. Flow through a tube affects that tube's future size, creating feedback across the living network.

Efficiency also has more than one meaning. The shortest set of connections might break if one link is damaged. A network with an extra loop can be longer but more resilient. Researchers therefore compare length, travel efficiency, and tolerance of disruption rather than awarding the organism one score. The slime mold is interesting because coordination emerges without a command center. Countless local adjustments preserve routes that work under particular conditions. What looks like a decision from above can grow from feedback distributed through the whole body.

Comprehension questions