Help please Veins have to ensure that blood under low pressure can return to the heart.
The circuit of circulation that goes from the heart to the body cells and back to the heart is called circulation.
he oxygenated and deoxygenated blood are kept separate in the mammalian heart by the .

What would happen to the nutrients in an ecosystem if decomposers, such as bacteria, didn’t exist there?

The fish shown above is a tarpon. it is a fast-swimming and powerful open-water fish. its closest relatives, oddly, are burrow-dwelling conger eels that stay on the bottom. both eels and tarpon developed from snake-like larvae that float in the plankton during the first stages of life. once they mature, tarpon and eels are not found near one another in the ocean. the tarpon and the eel illustrate all of the following except

The carbon cycle is best defined as a process in which a. carbon changes from inorganic forms to organic forms and back b. carbon is changed into other elements such as oxygen or nitrogen c. carbon is continually created from the sun’s energy by plants d. carbon is consumed and regenerated from other elements such as oxygen and nitrogen