Final answer:
The light-dependent reactions of photosynthesis involve photosystems within the thylakoid membranes that absorb light, with chlorophyll being the primary pigment. Chlorophyll absorbs blue and red wavelengths effectively. Using spectrophotometers, scientists can determine the specific wavelengths absorbed by plant pigments.
Step-by-step explanation:
The portion of the photosynthetic apparatus that absorbs light is composed of photosystems which are situated within the thylakoid membranes of chloroplasts. These photosystems include the pigment chlorophyll, which primarily absorbs light, along with accessory pigments like carotenoids. The light-harvesting complex in these photosystems absorbs photons, with the energy being transferred to the reaction center. Once at the reaction center, this energy is used to excite electrons which ultimately convert light energy into chemical energy during the process of photosynthesis.
Plants absorb energy from sunlight using these pigments, which can absorb different wavelengths of light due to their molecular structure. Chlorophyll, in particular, absorbs light most efficiently in the blue and red wavelengths but less in the green, which is why plants appear green to us.
With the help of instruments like spectrophotometers, scientists can generate absorption spectra to determine exactly which wavelengths of light are absorbed by the pigments in a plant. Short wavelengths of light have more energy than long wavelengths, but both can be used in photosynthesis depending on the pigments present in the photosynthetic organism.