Different wavelengths of light can be absorbed by particular organelles within cells, such as mitochondria or the nucleus.

“different wavelengths of light are also best absorbed by particular so-called organelles within your cells. What are organelles? Organelles are the different compartments and different functions within a given cell. So for instance, your mitochondria, which are responsible for generating ATP and energy in your cells, those exist at a particular depth, at a particular location within a cell. They're not all at the cell surface. They sit somewhat deeper in the cell. The nucleus of your individual cells contains DNA, and that sits at a particular depth or location within your cell.”