Please help with these questions

Explain what causes the skin to burn in the sun? explain why people should avoid the sun if taking a photosensitive medication?

Asap during the past few weeks or months, have you noticed any exercises that have become too easy for you? do you think you need to increase the intensity in any of the three exercise areas in your workouts? evaluate your exercise progress in the three exercise areas (cardiovascular, resistance, and flexibility) and list what modifications, if any, you may need to make in your exercise routine.

Some bacteria injure cells by giving off poisons called pathogens antibodies phagocytes toxins