Biology of Plants: Making Food - MBGnet
The purpose of photosynthesis is to convert theenergy in photons (the infinitesimally smallpackets of energy that make up light) into thechemical bonds of sugar molecules.
Plants(and animals that eat plants) can then store theenergy and get it back out when they need it bybreaking those chemical bonds. The tricky part ofphotosynthesis is that it takes a very preciseamount of energy to form a particular chemicalbond. Furthermore, the photons from differentcolors of light contain different amounts ofenergy.
You probably know the colors ofthe spectrum (Red, Orange, Yellow, Green, Blue,Indigo, Violet); well, those colors are inascending order of energy -- a photon of bluelight has more energy than a photon of red light(this is true because of Planck's Law, which aphysicist could explain better than I).
Aparticular pigment molecule (like chlorophyll) isspecialized for absorbing a particular color oflight and converting the light energy into theappropriate amount of chemical energy for making achemical bond (actually there are many othermolecules that help the pigment perform thisenergy conversion, but only the pigment itself canabsorb the light). Chlorophyll just absorbs blueand red light; it hardly absorbs any green lightat all, so the green gets reflected back to oureyes, which is why leaves appear green. Otherpigments that plants have in their leaves absorblight of different colors, so they reflect red,orange, yellow, or blue light and appear to bethose colors to our eyes. Because the white lightcoming from the sun is actually made up of photonsof all the different colors, it is veryadvantageous to the plant to have many pigmentsthat can absorb such a wide range of the availablecolors of light.
There are about 300 thousand known species of plants
Plants undergo photosynthesis to produce energy for themselves (and ultimately humans). Light and water are needed to perform this process. But, how do the plants get the water and light into their cells?
Below are things that plants need for photosynthesis:
Carbon dioxide (A colorless, naturally occurring odorless gas found in the air we breathe. It has a scientific symbol CO2. CO2 is produced by burning carbon and organic compounds. It is also produced when plants and animals breathe out during respiration)
Light (Even though both natural and artificial light is OK for plants, natural sunlight is usually great for photosynthesis because they have other natural UV properties that help the plant)
Chlorophyll (This is the green pigment found in the leaves of plants)
Nutrients and minerals (Chemicals and organic compounds which the plant roots absorb from the soil)