As used in the passage, 'dormant' most nearly means

inactive or resting (The tun is a state where 'metabolism almost halts,' so dormant means inactive or resting.)

Why do scientists study tardigrades in connection with other worlds?

Their survival hints at how life might endure harsh, alien conditions (The passage says scientists study them to understand how life might survive on other worlds because they endure extreme conditions.)

What does a tardigrade do when its surroundings dry out?

It expels water and curls into a tun (The text states it 'expels nearly all the water from its body and pulls in its legs,' forming a tun.)

The passage is mainly about:

how a nearly invisible animal survives extremes by entering a dormant state (The passage describes how the tiny tardigrade endures drying, cold, vacuum, and radiation by shriveling into a dormant tun, then revives years later with a single drop of water.)

The Toughest Animal You Can't See: Level 4 Reading Comprehension Questions

Among the most resilient creatures on Earth is one barely visible to the naked eye. The tardigrade, sometimes called a water bear, is a chubby, eight-legged animal smaller than a grain of sand. It lives in mossy patches, ocean sediments, and the films of water that cling to soil.

What makes the tardigrade remarkable is its response to harsh conditions. When its surroundings dry out, the animal expels nearly all the water from its body and pulls in its legs, shriveling into a dormant ball called a tun. In this suspended state its metabolism almost halts, and it can endure temperatures near absolute zero, the vacuum of space, and doses of radiation that would kill most life many times over. Years later, a single drop of water can revive it, and the tiny animal lumbers off as though nothing had happened.

Scientists study tardigrades to understand how life might survive on other worlds, and how delicate biological structures can be preserved through extreme stress.

Comprehension questions