Final answer:
Pigment molecules absorb specific wavelengths of light, determining their color. Chlorophyll a absorbs blue and red, appearing green. Carotenoids absorb blue and green, reflecting longer wavelengths.
Step-by-step explanation:
Each type of pigment molecule absorbs specific wavelengths of light, which can be seen in its absorption spectrum. For example, chlorophyll a absorbs wavelengths from the blue (around 400-500 nm) and red (around 650-700 nm) parts of the spectrum, but it does not absorb green light, which is why it appears green as this color is reflected or transmitted. Carotenoids such as ß-carotene are known to absorb blue and green light typically in the range of 400-500 nm, reflecting the longer yellow, red, and orange wavelengths which give them their distinctive color. Lastly, other pigments like chlorophyll b absorb blue and red-orange light (around 450-550 nm and around 600-650 nm).