Question

read the text.

the flying beetle known as the firefly or lightning bug is named for its most noticeable feature: its nighttime bioluminescence, or glow. the firefly’s light - producing organ contains calcium, the pigment luciferin, the light - producing enzyme luciferase, and the chemical adenosine triphosphate (atp). when oxygen is added to this mix, it creates light, and the insect glows. scientists don’t fully understand how the firefly makes its light blink, but one theory is that the firefly turns the light on and off by controlling the input of oxygen into the light - producing organ.

which organizational structure does this text primarily use?

compare - contrast

cause - effect

Explanation:

The text first introduces the firefly's bioluminescence, then details the substances in its light-producing organ, and explains that adding oxygen (cause) leads to the glow (effect). It also proposes a theory about oxygen control causing the blinking light, focusing on explaining what causes the firefly's light. No comparison between different subjects is made.

Answer:

cause-effect