The digestive enzyme pepsin works with hydrochloric acid to break down proteins in the stomach. pepsin probably works best at a ph of

Which of the following systems in absorbing oxygen and releases carbon dioxide

The diagram shows a fossil of an ancient whale skull and a skull of a present-day whale. the ancient whale is extinct and is believed to be an ancestor of the present-day whale. what do these skulls most likely show that supports darwin’s theory of evolution? all populations can adapt and survive. only some organisms have a common ancestor. populations change slowly over time. populations rapidly become extinct.

How does friction with the atmosphere affect the speed of an artificial satellite