The integumentary system (skin) reacts different on different sun intensity (different length exposure to sun).
For example, moderate exposure to the sunlight contributes to the production of melanin and vitamin D by the body. On the other hand, high exposure to sunlight can have negative health effects such as sunburn, which is an inflammatory response to DNA damage caused by UV radiation.
Caverns most commonly form in limestone
Our elbow bends all the time, we bend it when we pick up things, when we eat, when we do mostly everything. Cows on the other hand dont pick up food with there feet, they use there mouths, and they probably only bend when they are walking.
There aren't enough oxygen molecules in the air are higher altitudes
Osmosis is 98% water and 2% salt inside the cell.