Explain the difference between sequential and direct file access. A. Sequential access to data is used when the data has to be read from the start, in sequence. It is the norâ¦mal method of access for magnetic tape. Direct access is used when it is possible to jump directly to a file or data item without reading through all the items stored before it.
melanin (meËÂ·lÂ·nin), n a substance produced by melanocytes found in the deepest layer of the epidermis; protects the skin from the effects of the sun's harmful rays. Variations in skin color are a result of the level of melanin produced by each individual.
Layers of the Skin The Epidermis. The epidermis is the outermost layer of the skin, and protects the body from the environment. The thickness of the epidermis varies in different types of skin; it is only .05 mm thick on the eyelids, and is 1.5 mm thick on the palms and the soles of the feet. The epidermis contains the melanocytes (the cells in which melanoma develops), the Langerhans' cells (involved in the immune system in the skin), Merkel cells and sensory nerves.