Plant primitive plants lacking some tissue types. Plants are photosynthetic, which means that they manufacture their own food molecules using energy obtained from light. The primary mechanism plants have for capturing light energy is the pigment chlorophyll. All green plants contain two forms of chlorophyll, chlorophyll "a" and chlorophyll "b". The latter of these pigments is not found in red or brown algae. The simple equation of photosynthesis is as follows:- 6CO + 6HO → (in the presence of light and chlorophyll) CHO + 6O By means of cells that behave like nerves, plants receive and distribute within their systems information
Carotenoid especially reds and purples, are due to other classes of chemicals. Carotenoids serve two key roles in plants and algae: they absorb light energy for use in photosynthesis, and they protect chlorophyll from photodamage. Carotenoids that contain unsubstituted beta-ionone rings (including beta-carotene, alpha-carotene, beta-cryptoxanthin and gamma-carotene) have vitamin A activity (meaning that they can be converted to retinol), and these and other carotenoids can also act as antioxidants. In the eye, lutein, meso-zeaxanthin, and zeaxanthin are present as macular pigments whose importance in visual function remains under clinical research in 2017. The basic building blocks of carotenoids are isopentenyl diphosphate