As an amateur naturalist I have a passion to know how things work. In college I once saw the chemical reactions involved in photosynthesis laid out on a large poster. This all-important method plants use to make food for themselves (and ultimately us) was incredibly long and complex. It is so complex that I’m tempted to simply say that plants bring in carbon dioxide and water, add sun energy, then a miracle happens and out comes oxygen and food. Let me try to elaborate on the miracle part.
Photosynthesis occurs in green structures found in leaves called chloroplasts. As mentioned the ingredients for making food include water from the plant roots, carbon dioxide that enters the leaf through pores called stomata, and sun energy. The recipe is as follows: take 6 carbon dioxide molecules, combine with 6 water molecules in the chloroplast-mixing bowl. Use sun energy to blend well and recombine the carbon, oxygen, and hydrogen atoms into a glucose sugar that has 6 carbon, 12 hydrogen, and 6 oxygen atoms. Six oxygen molecules will float to the top of the bowl and can be poured off into the atmosphere for later breathing. The plant may store the glucose molecule for later use as energy, or link glucose molecules in long chains to form carbohydrates such as starches and cellulose (wood) for use as construction material for building stems, flowers, etc.
While on the subject of food production, we might as well cover food consumption. Green plants must have energy to function just like us animal kingdom types, and so there is a way to get energy from glucose sugar (food). You need to remember this: energy in glucose is stored in the bonds that hold the molecule together. To form a glucose molecule, sun energy had to be added. When the molecule is broken down, energy is released. So the recipe for making energy from glucose sugar is as follows: You need a mixing bowl located in each cell called a mitochondria (mi-toe-con-dree-ah). It has the ability to pull molecules apart. Place one molecule of glucose and 6 oxygen molecules in the bowl and stir until the glucose breaks down to 6 carbon dioxide and 6 water molecules, and energy is released for use as needed. The water and carbon dioxide is poured out into the atmosphere where it is available to be taken up by the plant to turn it back to food, which is a very neat cycling event.
The same glucose breakdown to produce energy is done in animals as well, but we must go through the added step of eating something that has stored food. Bread from wheat is food stored in a form of starch made from carbohydrates, which are long chains of glucose. The steak that we eat for energy is animal muscle made of proteins, which are made from glucose molecules derived from the green grass the cow ate. Next time you eat a big porterhouse, ponder the wonder of what you are eating.