What percentage of oxygen is carried by red blood cells?

Match the examples to the correct level of organization. 1. system level roses, snakes, puppies 2. organism level roots, stamens, leaves 3. tissue level bone, cartilage, blood 4. organ level heart, veins, arteries

What causes darkening of the skin as melanin production increases

Awave has a wavelength of 15 mm and a frequency of 6 hertz. what is its speed?