Which type of luminescence is produced by biological luciferin-luciferase systems?

• A. Chemiluminescence
• B. Bioluminescence
• C. Electrochemiluminescence
• D. Photoluminescence

Answer: (B)

Bioluminescence is light produced by a chemical reaction inside living organisms. In luciferin-luciferase systems, the enzyme luciferase catalyzes the oxidation of luciferin, releasing energy as photons. Because this reaction happens within a living organism, it’s called bioluminescence. While it’s a kind of chemiluminescence (light from a chemical reaction), the biological context is what defines it here.

In contrast, photoluminescence requires absorption of light to re-emit it (fluorescence/phosphorescence), electrochemiluminescence needs an electrical input to drive the reaction, and general chemiluminescence covers light from chemical reactions outside the biological context.