The answer is A.
Why: The heart is part of an organism, so that doesn't exactly count. Soil is not alive, and neither is clay. Therefore, Bacteria must be it. Bacteria is a living thing, and can function by itself.
The nitrogen containing amino group is recycled while the remainder of the molecule is excreted in the urine
Every cell of the organism has the same DNA sequence and same genes. However, not all genes are expressed in every single cell at the same time. Only those genes necessary for a specialised function of a specialised cell are expressed in the specialised cell. For example, skin cells have some different proteins than nerve cells. Genes responsible for those "skin proteins" are activated in skin cells and are turned off in nerve cells.
It would be c. It can bond with other atoms through ionic and covenant bonds.<span />