There are so many of us you will probably have a hard time seeing just one of us. I am small but I have a big job. I make compounds that build your muscles, fight disease, transports oxygen, and speed up your metabolism. What am I?

In what for do plants utilize nitrogen? why do they need nitrogen?

2. given that most biochemical (other than coal) rocks react with hydrochloric acid, what does that tell you about organisms?

Which statement describes a way in which the digestive and excretory systems work together? a. the nephrons absorb nutrients from food going to the large intestine. b. the excretory system balances blood gases in the small intestine. c. the intestinal villi filter blood and send wastes to the bladder. d. the excretory system balances the salts and water obtained from digested food