In this video, we're briefly going to talk about the absorption spectrum of photosynthesis. An absorption spectrum is really just a graph that shows the light absorption of pigment molecules. Notice that we're showing you a pigment light absorption spectrum. On the y-axis, the absorption of light is represented where low on the y-axis indicates a low amount of light being absorbed, and high on the y-axis represents a lot of light being absorbed. On the x-axis, we have the particular wavelength of light in nanometers, essentially showing you the visible wavelength of light. It's important to note that on this particular spectrum, we're showing you the curves for three different pigments: Chlorophyll a in green, Chlorophyll b in yellow, and the carotenoids in a dark orangish color. You can see the spectrums for each of these curves throughout this section.

These curves are showing the amount of light that's being absorbed at a particular wavelength. Wavelengths that fall into certain regions are mainly being absorbed. You can see these regions having the 'absorbed' label. Additionally, wavelengths in other regions are also mainly being absorbed, not by all the pigments, but by the collection of them together. However, in the middle region, most wavelengths, essentially greenish and yellowish, are not really being absorbed. We can assume that these wavelengths are being reflected. Since there are not a lot of peaks here, there is not a lot of absorption going on, so they are being reflected.

The biggest takeaway here is that different pigments are going to absorb and reflect different wavelengths of light, but collectively it is the amount of them and the particular wavelengths of light that are reflected that dictate the colors that we end up seeing in the plants. This concludes our brief introduction to an absorption spectrum, and we'll be able to get some practice as we move along in our course. I'll see you all in our next video.