C1.3.5 Absorption of Specific Wavelengths of Light by Different Photosynthetic Pigments

What is a photon?

a particle or unit of light with a discrete amount of energy

What is a pigment?

A chemical compound that gives an organisms color through selective wavelength absorption

What is the role of pigments in photosynthesis?

They are responsible for the absorption of light

What is the relationship between color, wavelength and photon energy in EMR?

red - longest wavelength, purple - shortest wavelength

photons with shorter wavelengths have more energy

How is light energy transformed into chemical energy in pigments?

Pigments have a structure where an electron in a molecule use energy obtained by absorbing a photon of light to jump to a higher, unstable energy level(a.k.a. electrons within the pigment molecule are excited by photons). Photosynthetic pigments can then pass excited electrons to other molecules, and much of the energy carried by the excited electrons ends up in carbon compounds.

Why are only some wavelengths of light absorbed by certain pigments?

For any photosynthetic pigment, only specific amount of energy results in excitation of electrons. Therefore, only the specific wavelengths of light that supply the specific amounts of energy are absorbed.

Why do plants tend to look predominantly green?

Chlorophylls, the main photosynthetic pigment, only absorbs red and blue light, while reflecting green light, for only the former supplies the specific amount of energy needed to excite electrons in chlorophyll.

What are accessory pigments in photosynthesis?

photosynthetic pigments that absorb other colors of light (ex. red, blue, yellow) that the primary pigments (chlorophyll a & b) do not