Numerical answer
1. Luciferin and luciferase together produce light through a chemical reaction called oxidation, releasing energy as photons rather than heat.
2. Deep-sea anglerfish use a luminous lure to draw curious prey within reach of their jaws.
3. Fireflies of the genus Photuris mimic the courtship flashes of other species to lure and consume unsuspecting males.
4. The bioluminescent bacterium Vibrio fischeri lives symbiotically inside the light organs of certain squid, providing the host with a controllable glow.
5. Squid and small fish use counter-illumination, emitting a ventral glow that erases their silhouette from predators below.
2. Deep-sea anglerfish use a luminous lure to draw curious prey within reach of their jaws.
3. Fireflies of the genus Photuris mimic the courtship flashes of other species to lure and consume unsuspecting males.
4. The bioluminescent bacterium Vibrio fischeri lives symbiotically inside the light organs of certain squid, providing the host with a controllable glow.
5. Squid and small fish use counter-illumination, emitting a ventral glow that erases their silhouette from predators below.
Show answer and solution
Answer: 4
Sentences 1, 2, 3 and 5 all describe uses or predatory/defensive applications of bioluminescent light (attracting prey, evading predators, deceptive mimicry) that build a coherent account of the trait's functional roles. Sentence 4, about a symbiotic bacterium residing in squid light organs, introduces a different topic — the biological partnership underlying one light source — that does not fit the passage's throughline of functional (offensive/defensive/signalling) uses of light, making it the odd one out.
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