Answer:
Ion
Explanation:
An Ion is exactly as stated it bears either a positive or negative charge.
Answer:
Must be able to reproduce.
Explanation:
All organism are able to reproduce.
Answer:
Mechanical barriers — which include the skin , mucous membranes , and fluids such as tears and urine — physically block pathogens from entering the body. Chemical barriers — such as enzymes in sweat , saliva , and semen — kill pathogens on body surfaces.