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Expiration is a passive process. It happens due to relaxation, not contraction, of the muscles of the chest. As well as the elastic recoil of the lungs. Both of these processes do not require energy and h...

Active Transport 

• Normally soil ion concentrations will be low, and high in the root cells. The ions have to move up a concentration gradient and therefore requires an energy-using process to...

Archaea 

Bacteria

Eukaryota

During diastole the atria and ventricles are relaxed. The atrioventricular valves are open and the semilunar valves are closed. Deoxygenated blood enters the right atrium from the venae cavae and oxygenat...

Electrical impulses from the SAN (sinoatrial node) spread across the atria walls to cause contraction. The impulses then pass to the ventricles via the AVN (atrioventricular node) after a short delay to a...