Biological magnification of pcbs has been found in the food web of the great lakes, where the concentration of pcbs in herring gull eggs, at the top of the food web, is nearly 5,000 times that in phytoplankton, at the base of the food web.

✿   this landform has a high elevation and a high relief

✿   this landform is a mountain

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.