Absorption of radiation corresponding to what portion of the electromagnetic spectrum is most likely to excite Aequorea fluorophore, a green fluorescent protein used in biological experiments?

A. Ultraviolet

B. Infrared

C. Orange

D. Microwave

Explanation

Fluorescence is the emission of a lower-energy photon from a fluorophore excited by the prior absorption of a higher-energy photon. With this in mind, the Aequorea fluorophore must be excited by the absorption of a photon of higher energy (and frequency) than that associated with green visible light. Of the choices listed, only ultraviolet light, choice A, is of higher energy than green light. Even if we were not considering the green fluorescence of this organism, we could simply choose the highest-energy radiation as that which is most likely to promote fluorescence in general, making A the correct answer.

B. Infrared: incorrect. Photons corresponding to the infrared and microwave portions of the electromagnetic spectrum, as well as those corresponding to orange visible light, are of lower energy than those comprising green visible light.

C. Orange; incorrect. Photons corresponding to the infrared and microwave portions of the electromagnetic spectrum, as well as those corresponding to orange visible light, are of lower energy than those comprising green visible light.

D. Microwave; incorrect. Photons corresponding to the infrared and microwave portions of the electromagnetic spectrum, as well as those corresponding to orange visible light, are of lower energy than those comprising green visible light.

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