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 fireflys 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 dont 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? problem - solution compare - contrast cause - effect

Explanation:

The text first describes the components in the fire - fly's light - producing organ. Then it states that when oxygen is added to this mix, light is created. This shows a cause (adding oxygen to the mix) and an effect (creation of light). There is no problem - solution or compare - contrast structure present.

Answer:

cause - effect