Where/when/why is diffusion important in our lives/bodies? 2 or more paragraphs, need to be strong

in human body, the diffusion of different chemicals and gases is important functions in the body.  useful molecules enter and waster products are removed from body during diffusion. oxygen and carbon dioxide are diffused in the lungs .

Diffusion of water, salts and waste products occur in the kidneys. The waste products also evaporates in the form of sweating. The diffusion does not require much energy which is advantage of it.  

calcium is diffused in to the cells from the food across the intestinal mucosa.  when there is need of calcium, it get released from the bones and small intestine will then start absorbing calcium.

Studies have shown that the movement of calcium into intestinal cells is both passive diffusion.

because they are eaten by the frog and the frog getseaten by the snake and the snake by the eagle

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.