Sound waves are both compressional and longitudinal, (although we frequently draw them as transverse waves).
Longitudinal waves are where the particles of matter collide into one another, pushing them into the next and then oscillating back. This is how sound travels. This is also why sound can only travel through a medium, it cannot travel through a vacuum, as is shown here:
If a cell was to undergo all the activities, eg cell division my mitosis, it results in growth. When we were still zygotes, cell division happened by mitosis resulting in the grown ups we are now. Over division results in growth of cancer cells. And if the body exercises, Lymphocytes are produced more, resulting in more of them circulating in blood preventing disease attacks
