However, in the form of N2, nitrogen is unusable by all organisms except for a few primitive bacteria that are capable of converting N2 gas to ammonia (NH3). This process of conversion is called nitrogen fixation, and makes the nitrogen available for use by organisms.
1 Simple carbohydrates have very simple chemical structures and are made of small molecules. 2  Complex carbohydrates have very complex structures while the molecules are large, unlike simple carbohydrates.
Simple carbohydrates are composed of small molecules generally monosaccharaides and disaccharides, which are rapidly absorbed such as glucose and sucrose. Simple carbohydrates has a high glycemic index and increases blood glucose level rapidly resulting in high insulin levels and more hunger. Complex carbohydrates are larger molecules which are broken down to monosaccharaides e.g. starches and fibers. Complex carbohydrates has a low glycemic index, increases blood glucose level more slowly but for a longer time resulting in lower insulin level and less hunger.