In the transmission experiment, what molecule is put in a box for monochromatic light to shine through?

In the transmission experiment, what molecule is put in a box for monochromatic light to shine through?

• A. Opsin
• B. Rhodopsin
• C. Retinal
• D. Photopigment

Answer: (B)

Rhodopsin is the molecule put in the box because it is the photopigment in rod cells—the form that actually absorbs light and initiates the photochemical change when photons hit it. In a transmission experiment, you want a substance that directly absorbs light at specific wavelengths, so shining monochromatic light through a solution of rhodopsin lets you map its absorption spectrum. Opsin alone doesn’t absorb visible light effectively, retinal by itself isn’t in the pigment form that absorbs light in this context, and “photopigment” is a general category rather than the specific molecule used. Rhodopsin, being the complete photopigment (opsin plus retinal), is the correct choice.

Rhodopsin is the molecule put in the box because it is the photopigment in rod cells—the form that actually absorbs light and initiates the photochemical change when photons hit it. In a transmission experiment, you want a substance that directly absorbs light at specific wavelengths, so shining monochromatic light through a solution of rhodopsin lets you map its absorption spectrum. Opsin alone doesn’t absorb visible light effectively, retinal by itself isn’t in the pigment form that absorbs light in this context, and “photopigment” is a general category rather than the specific molecule used. Rhodopsin, being the complete photopigment (opsin plus retinal), is the correct choice.