Fossil Fuels; Once they run out ,humans can not replacing them.
The answer should be C. many different
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.
Airborne nitrogen is one of the largest sources of pollution affecting the Chesapeake Bay and its tributaries. Excess nitrogen can fuel the growth of algae blooms, which can block sunlight from reaching underwater grasses and create low-oxygen “dead zones” that suffocate marine life.
Urine forms as some of the blood plasma spills out, some of these spilled plasma components are taken back up into the blood, and other material is selectively sent out to be added to the urine. In other words, there are three main things happening to form urine.
glomerular filtration (blood plasma spills out) bullet tubular reabsorption (some items are selectively reabsorbed into the blood) bullet tubular secretion (some blood plasma items are selectively sent out into the tubules)
