Cellular respiration is a: ) a spontaneous reaction that assembles smaller molecules into bigger molecules. b: ) a spontaneous reaction that breaks down larger molecules into smaller molecules. c: ) a nonspontaneous reaction that assembles smaller molecules into bigger molecules. d: ) a nonspontaneous reaction that breaks down larger molecules into smaller molecules.

B:) a spontaneous reaction that breaks down larger molecules into smaller molecules.

Explanation:

Cellular respiration is a spontaneous reaction this is because of the fact that it does not require energy to do carry out the process, instead it produces energy in the form of ATP. In the process of cellular respiration the oxygen is inhaled and combined with the food stuff. This causes oxidation of foodstuff  (large molecules) so that it get broken into simple digestible substances in the form of small molecules, along with the release of waste products like carbon dioxide and excess water.

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.

the median of the data is 4.5.