Mutations<span> are changes in the DNA. A single </span>mutation<span> can have a large effect, but in many cases, change is based on the accumulation of many </span>mutations<span>. Gene flow is any movement of genes from one population to another and is an important source of the genetic </span>variation<span>.</span>
The answer is iron. Research has shown an increase in serum iron concentreation in athletes and a concomitant decrease in magnesium ions. The increase in iron concentration is thought to be attributed to tissue injury from the strenuous physical activity. The decrease in magnesium is due to demand by the skeletal muscles.
