Practice Test 7

The glow of a firefly on a warm summer evening is a magical sight, but it is not magic—it is chemistry. This phenomenon, known as bioluminescence, occurs when a chemical called luciferin mixes with an enzyme called luciferase, oxygen, and a special energy-carrying molecule. This reaction produces light without generating much heat, which is why fireflies are sometimes called “cold lights.” The primary function of these flashes is communication. Each firefly species has its own unique flashing pattern, a sort of Morse code used to attract mates. A male will flash a specific sequence, and if a female of the same species is interested, she will flash back a particular response. This light is also a defense mechanism, as the firefly’s blood contains a chemical that tastes bitter to predators. The bright flash serves as a warning: “I taste bad, don’t eat me!”