What is the difference between an absorption spectrum and an action spectrum?
The correct answer and explanation is:
An absorption spectrum and an action spectrum are related to light and photosynthesis but serve different purposes in understanding how organisms interact with light.
An absorption spectrum refers to the range of wavelengths of light that a pigment absorbs. When light passes through or is absorbed by a substance, certain wavelengths are absorbed while others are transmitted or reflected. In the context of photosynthesis, pigments like chlorophyll absorb light at specific wavelengths, mostly in the blue and red regions, and less in the green region. The absorption spectrum helps identify which wavelengths of light are most effectively absorbed by pigments for use in photosynthesis.
An action spectrum, on the other hand, refers to the relationship between the wavelengths of light and the rate of a biological process, such as photosynthesis. It shows the effectiveness of different wavelengths in driving the process. For photosynthesis, the action spectrum typically overlaps with the absorption spectrum but is more directly linked to the output of the process. This spectrum is determined by measuring the rate of photosynthesis under different light wavelengths.
To summarize, while both spectra are related to light and photosynthesis, the absorption spectrum focuses on the wavelengths absorbed by pigments, and the action spectrum is concerned with the overall efficiency of those wavelengths in facilitating a biological process. The action spectrum provides insight into how absorbed light is used to drive processes like photosynthesis, while the absorption spectrum reveals the specific light wavelengths a pigment is most effective at capturing. Together, they give a comprehensive view of light’s role in biological systems.