Fuels from fermentation In India only animal waste is fed in (there are taboos against using human waste), this produces high quality gas but little amounts of fertiliser. Biogas can be produced on a large scale, or on a small scale. For example, a small biogas...
The kidneys Our bodies need to get rid of waste products. Three waste products our bodies must excrete are CO2, urea and sweat. This is known as homeostasis (controlling conditions inside the body). Liver Urea (a waste product from the breakdown of amino acids)...
Diffusion Materials like oxygen, carbon dioxide and glucose enter and leave cells by diffusion. Diffusion occurs when particles spread. They move from a region where they are in high concentration to a region where they are in low concentration. Diffusion happens when...