Which wavelengths of light does chlorophyll primarily absorb?

• A. Green and yellow wavelengths
• B. Blue and red wavelengths
• C. Infrared and ultraviolet wavelengths
• D. Orange and indigo wavelengths

Answer: (B)

Chlorophyll, the green pigment found in plants, primarily absorbs light in the blue and red wavelengths of the electromagnetic spectrum. This absorption is crucial for photosynthesis, as it allows chlorophyll to utilize light energy to convert carbon dioxide and water into glucose and oxygen.

The blue light has shorter wavelengths, and chlorophyll molecules effectively capture this energy. Red light, on the other hand, has longer wavelengths and is also efficiently absorbed by chlorophyll. The combination of these two absorption peaks maximizes the energy harvested for photosynthesis, making blue and red light the most critical for plant growth and energy capture.

Chlorophyll reflects green light, which is why plants appear green; this reflection means that green wavelengths are not utilized effectively for photosynthesis. The other wavelengths, such as infrared and ultraviolet, do not play a significant role in chlorophyll's light absorption, nor do orange and indigo wavelengths contribute primarily to the photosynthetic process. Thus, the ability of chlorophyll to absorb blue and red wavelengths is fundamental to its role in enabling photosynthesis and supporting plant life.