Nitrogen is a very important element in biology. What are some of the reasons that organisms need nitrogen?

How do you date a sample of rock that you suspect as being one of the earliest on earth

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

Everything in the universe originated from a single point. how was it possible for everything in the universe to have occupied a single point in space?