Yellow a wavelength of 550 nm and has a bandwidth of 20–30 nm. Autumn leaves, yellow flowers, bananas, oranges and other yellow fruits all contain carotenoids, yellow and red organic pigments that are found in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some bacteria and some fungi. They serve two key roles in plants and algae: they absorb light energy for use in photosynthesis, and they protect the green chlorophyll from photodamage. In late summer, as daylight hours shorten and temperatures cool, the veins that carry fluids into and out of the leaf are gradually
Energy energy flows in physical and biological systems by expressing energy units in human terms: it provides a "feel" for the use of a given amount of energy. Sunlight's radiant energy is also captured by plants as "chemical potential energy" in photosynthesis, when carbon dioxide and water (two low-energy compounds) are converted into the high-energy compounds carbohydrates, lipids, and proteins. Plants also release oxygen during photosynthesis, which is utilized by living organisms as an electron acceptor, to release the energy of carbohydrates, lipids, and proteins. Release of the energy stored during photosynthesis as heat or light may be triggered suddenly by