Why is the skin a good defense mechanism for the immune system?

Charlie is easily winded during soccer practice and wants to improve his cardiorespiratory fitness. which activity would be best for him to choose? lifting weights walking from one class to another running in a 5k race riding a bike at a leisurely pace

A 22-year-old female patient slipped running down stairs and has injured her right tibia and fibula. you have used an air splint to splint the injury. to test the splint, you can:

What happens in the process of photosynthesis