Question:medium
Two plants are grown. One is engineered to express green fluorescent protein and the other to express firefly luciferase. Which plant will glow in the dark?
Two plants are grown. One is engineered to express green fluorescent protein and the other to express firefly luciferase. Which plant will glow in the dark?
Show Hint
One protein needs external light to be seen, the other makes its own light by a chemical reaction.
Updated On: Jun 24, 2026
- Both plants will glow
- Neither plant will glow
- Plant expressing green fluorescent protein will glow
- Plant expressing firefly luciferase will glow
Show Solution
The Correct Option is D
Solution and Explanation
The trick to this question is the difference between two ways of producing visible light. Green fluorescent protein works by fluorescence: it captures incoming high-energy light and re-radiates it as green light, so it is only visible when an external lamp shines on it. Take that excitation light away, as happens in a dark room, and the GFP plant stays dark. Firefly luciferase works by chemiluminescence instead. The enzyme catalyzes oxidation of luciferin using ATP, magnesium, and oxygen, and the energy released by that chemical reaction is emitted directly as photons of visible light. Since the light is generated internally rather than borrowed from a lamp, the luciferase plant shines on its own and remains visible even with all room lights switched off. Therefore, in true darkness it is the firefly luciferase plant that glows, while the GFP plant does not. \[\boxed{\text{Plant expressing firefly luciferase will glow}}\]
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