Question

Approximately what wavelength of light is best absorbed by chlorophyll a, the pigment that participates directly in the light reactions?a) 435nmb) 525nmc) 680nmd) One cannot tet from this graph

Answer 1

Chlorophyll a best absorbs light at a wavelength of approximately 680 nm, which is in the red part of the spectrum.

Step-by-step explanation:

The wavelength of light best absorbed by chlorophyll a, which participates directly in the light reactions of photosynthesis, centers at approximately 680 nm (option 'c'). This is because chlorophyll a absorbs well in the red part of the spectrum, and also has an absorption peak at around 450 nm in the blue range.

Plant physiologists refer to the light in the range of 700 nm to 400 nm as photosynthetically active radiation because this is the range that plant pigments, including chlorophyll a, are able to absorb.