When plants are in the sunlight they can make a sugar called glucose. This is slightly different from the sugar (sucrose) which you put into your tea. Glucose contains three chemical elements:Carbon, Hydrogen, Oxygen. All the carbon needed for photosynthesis comes from carbon dioxide. All the hydrogen comes from water. When plants use carbon dioxide and water to make glucose there is a lot of oxygen left over. Here is a word equation: Light CarbonDioxide + Water >>>>>>>>>>>>>>>>>>>>>>>>>>>> Glucose + Oxygen Chlorophyll Carbon dioxide and water are inorganic chemicals, whereas glucose is an organic chemical. Plants need energy to convert carbon dioxide and water into glucose; this energy comes from sunlight. Plants can also use artificial light providing that it contains the right frequencies (colours). Light energy is trapped by a green chemical called chlorophyll. In photosynthesis, light energy is converted into chemical energy. When animals and plants respire, the chemical energy in glucose can be converted into other forms of energy e.g. Kinetic energy. Plants can make enough glucose on a sunny day to last them through the night and through lots of cloudy dark days, but they cannot store up lots of glucose. What they do is convert the extra glucose into starch. When they need to use the energy, they can turn the starch back into glucose. Starch can be stored in leaves or other parts of the plant. They can turn glucose into sucrose: This is a sugar carried around the plant in special tubes called phloem. Photosynthesis results in an increase in biomass; i.e. There is more carbohydrate in the plant. They can turn some of the glucose into fat or protein. They have to make lots of different chemicals to grow, but the two most important ones are fats and proteins. To do this they need energy (growth requires energy from glucose). Plants also have to make a very special chemical called DNA: This is the hereditary chemical of all animals and plants. They must also make lots of new chlorophyll.
