There are exchanges that happen continuously in our bodies. One exchange is the gas exchange, or respiratory, system. This is the system where carbon dioxide is released from the lungs into the air, and oxygen is taken into the lungs from the air. This exchange happens in the air sacs of the lungs called the alveoli.
The answer is
Carbon because your dealing with coal
A nucleus is the control center of a cell.
The DNA in eukaryotic cells is enclosed in the nucleus, while the DNA in prokaryotic cells is not separated from the rest of the cell's contents.
