How are the different types of protists classified? a. by their method of obtaining nutrition. b. by their method of movement. c. both a & b. d. none of these.

keratinization

Explanation:the human skin covers the body of the human.it forms a barrier that helps prevent the entry of harmful microorganisms into the body.it also protects the body against ultraviolet rays and is involved in the regulation of body temperature.

The skin is made up of two layers;the epidermis and the dermis.the two layers are anchored together by the basement membrane.the epidermis contains keratinocytes ,which produces the tough protein called keratin.keratin helps to protect the skin.

The upper part of the skin contains older keratinocytes,which are constantly being removed.they are replaced by the newer cells.as the keratinocytes move upwards in the epidermis,they produce keratin and die off , completely filled with keratin.