Fre points

How do the uv rays cause damage?   what exactly causes the skin to burn;   can you be more specific about this mechanism?   3. how do photosensitive medications increase a person's sensitivity to sunlight and therefore increase their risk of getting burned?     what kind of medications can increase photo-sensitivity, can you think of some examples?

The germs that cause infections are mainly spread in what three ways? a. immunization, mucous membranes, not washing hands b. germ-laden droplets, direct contact with body fluids, insects c. hand hygiene, sickness, immunization d. not enough sleep, low oral hygiene, germs

Wjat are substances intentionally added to food to produce a desired effect?