Neurons, also known as nerve cells, send and receive signals from your brain. While neurons have a lot in common with other types of cells, they're structurally and functionally unique. Specialized projections called axons allow neurons to transmit electrical and chemical signals to other cells.
If oxygen is present, then glucose can be broken all the way down into carbon dioxide and water. This process is called aerobic respiration because it requires air (oxygen). In the absence of oxygen, the cell uses a process called anaerobic fermentation. or simply fermentation.
Much change is due to random genetic drift rather than positive selection. Some are harmful and are likely to be eliminated by natural selection – by death of the embryo, for instance. ...
