Carbohydrates are the entirely composed of recycled materials – carbon and water.
Water we all know about – we know about rain and evaporation, the two factors principally responsible for the recycling of water in our environment.
Carbon is also recycled, but most people are not sure how.
Let’s consider the simple case of wood. Wood ultimately is a carbohydrate. When it is burned it releases CO2 into the atmosphere. Later on the same CO2 molecule is converted back to wood by photosynthesis.
We could write the reaction this way:
carbon dioxide + water = trees + oxygen
in simplified chemical terms, it would look like this:
CO2 + H2O = CH2O + O2
There are of course other ways of returning carbon to the atmosphere. When we breathe is, for example, we breathe in oxygen and we breathe out carbon dioxide. The carbon ultimately comes from the carbohydrates in the food that we eat. So we breathe in oxygen, we breathe out carbon dioxide, it is converted to a banana which we then eat a year later, and the carbon is returned to our bodies.
So for plants to grow they need water and carbon dioxide. Most people know about the first one, but few people realise how much plants love carbon dioxide – check out this video
More on carbohydrates later.