AP BIOLOGY

Detailed explanation-1: -Carotenoids absorb blue light as well, passing the energy on to chlorophyll. Chlorophyll absorbs light in the red region. Because red light has the highest absorption by chlorophyll, it is the most effective wavelength for photosynthesis.

Detailed explanation-2: -Chlorophyll a is the most abundant pigment in plants. Chlorophyll a absorbs light mostly 430nm (blue) and 662nm (red) wavelength light. It reflects green light so it appears green to us.

Detailed explanation-3: -When a photon reaches the chlorophyll a in the reaction center, that chlorophyll can receive the energy because it absorbs photons of longer wavelengths than the other pigments.

Detailed explanation-4: -Generally, plants are very sensitive to low intensities of red light; during the night, 1 µmol∙m–2∙s–1 of red light can inhibit flowering of short-day plants and promote flowering of some long-day plants because of phytochrome’s sensitivity to red light (Figure 1).

Detailed explanation-5: -For example, blue (B) and red (R) light are the most effectively utilized wavelengths during plant photosynthesis because the absorption spectra of the photosynthetic pigments mainly focus on the B (400–500 nm) and R (600–700 nm) light spectra.