Assimilation (from similis, lat. = similar), in biology, is the transformation or the change of external (outside) substances and materials (e.g. the food we eat) into substances and materials inside the body that help the body to grow and function (work) normally. This is done by making the food we eat, for example, react with different acids and enzymes (chemicals that make different substances react faster) to release the vitamins and minerals needed by our body. When this happens, it is called a 'chemical breakdown' because it uses chemicals to "break" the food into the substances that makes it up. It can also be made faster by the churning of the stomach (when the stomach rumbles). When this happens it is called a 'physical breakdown' because it uses a physical force (a force done by the movement of an object) to "break" the food into the substances that makes it up.
Examples of biological assimilation [change]
- Photosynthesis, a process whereby carbon dioxide and water are transformed into a number of organic molecules in plant cells.
- Nitrogen fixation from the soil into organic molecules by symbiotic bacteria which live in the roots of certain plants, such as Leguminosae.
- The absorption of nutrients into the body after digestion in the intestine and its transformation in biological tissues and fluids.