Natural selection could not occur without environment, and a act on animal.
The color produced by one milligram of platinum cobalt in one liter of dissolved water is fixed as one unit of color in platinum-cobalt scale.
"Answer DThe outermost layer of old epidermal cells are sloughed off and replaced every 15 to 30 days. The sebaceous glands secrete sebum which maintains the skin pH between 3 and 5. Bacteria which metabolize sebum live as opportunistic pathogens on the skin and cause skin infections."
Answer:
Bacteria cause disease by secreting or excreting toxins (as in botulism), by producing toxins internally, which are released when the bacteria disintegrate (as in typhoid), or by inducing sensitivity to their antigenic properties (as in tuberculosis).
btw :
stay safe! :3