Free SAT Practice Question

Question 1 of 1
ID: SAT-RW-II-033
Section: SAT Reading & Writing (RW) – Information and Ideas
Topic: Central Ideas and Details
Difficulty level: Easy

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A firefly's glow is a chemical event, not a spark of heat. Inside special cells in the insect's lower abdomen sits a compound called luciferin. When oxygen reaches these cells, an enzyme named luciferase lets the oxygen combine with the luciferin, and that reaction releases its energy almost entirely as light rather than as warmth. Because so little heat escapes, the glow is often called cold light. The firefly times its flashes by controlling how much oxygen flows to the light-producing cells, switching the signal on and off as it draws air in.

According to the text, what most directly produces the light of a firefly's glow?

AThe firefly's glow gives off more light than the glow of any other kind of insect.

BThe firefly regulates the flow of oxygen to its cells to switch its flashes on and off. On this account the insect’s control over its oxygen supply is what switches the flashes on and off, a fact about timing rather than about the light-making reaction itself.

CA reaction in which oxygen combines with luciferin, enabled by the enzyme luciferase, releasing its energy as light.

DHeat building up in the insect's abdomen is released as a visible spark.

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