One of the major functions of blood in animals is to maintain a(n) internal environment.

The diagram illustrates the activity of vesicles during a cellular process.

The cretaceous period spanned the time interval between and 65 million years ago. 250 million 144 million 75 million 200 million

Abird flies by moving its wings up and down. which two systems are most directly responsible for the movement of a bird's wings? a. skeletal and muscular systems b. respiratory and muscular systems c. skeletal and digestive systems d. respiratory and digestive systems