What processes are involved in getting a tan and then having it fade away?

To understand the tanning process one first needs to realize that the skin is comprised of several different types of cells. Each type of cell has a specific function. The cells involved primarily in the tanning process are called melanocytes. Melanocytes are located at the base of the epidermis between the epidermis and the dermis below. Melanocytes use the amino acid tyrosine to produce melanin. This melanin leaves the melanocytes and travels up through the epidermis where it reacts with the UVA and UVB radiation through a chemical reaction darkening the pigmentation of the skin. As we already know the skin consists of three layers of tissue: The epidermis or outer layer, the dermis or inner layer and the subcutaneous layer

Explanation:

To understand the tanning process one first needs to realize that the skin is comprised of several different types of cells. Each type of cell has a specific function. The cells involved primarily in the tanning process are called melanocytes. Melanocytes are located at the base of the epidermis between the epidermis and the dermis below. Melanocytes use the amino acid tyrosine to produce melanin. This melanin leaves the melanocytes and travels up through the epidermis where it reacts with the UVA and UVB radiation through a chemical reaction darkening the pigmentation of the skin. As we already know the skin consists of three layers of tissue: The epidermis or outer layer, the dermis or inner layer and the subcutaneous layer

phylogenetic tree is the tree of life or evolution tree. it shows the different branches of evolution. the sequence goes like tissues - coelom - backbone - endoskeleton - segmentation