Because of underdeveloped lungs the frog has to breathe through moist skin. Therefore for exchange of gases the skin is thin and moist
Into the human digestive system, mucus is used as a lubricant for materials that must passover membranes e.g, food passing down the esophagus. A layer of mucus around the inner walls of stomach is vital to protect the cell things of that organ from the highly acidic environment with in it.
Answer:
<em><u>A</u></em><em><u> hormone that tells cells in your liver and muscles to convert glycogen into glucose and release it into your blood so your cells can use it for energy</u></em><em><u>.</u></em>
D: Rh- can only receive Rh-
Proteins function as builders and give energy repair and reproduce muscle etc ...