Final answer:
Livor mortis is caused by gravity pulling blood to the lowermost parts of the body after metabolic processes stop, not by bacterial activity or a drop in body temperature.
Step-by-step explanation:
Livor mortis, also known as postmortem lividity, is the purplish discoloration that appears on the lowermost parts of a corpse due to gravity causing blood to settle. This process occurs after the body's metabolic processes stop, which means that cells no longer produce ATP and thus no longer maintain the body's functions, including circulation. Without the force of a pumping heart and active circulation, gravity pulls the blood down to the parts of the body that are closest to the ground, creating the distinct discoloration that is characteristic of livor mortis.
It's important to note that while bacterial activity can play a role in the decomposition process of a body, it is not the cause of livor mortis. Bacterial activity contributes to later stages of decomposition, such as putrefaction. When considering the direct causes of livor mortis, it is the cessation of the body's metabolic processes and the influence of gravity on the static blood that are the primary factors.