<span>The abundance and variety of fossils in Phanerozoic rocks have allowed geologists to decipher in considerable detail the past 600 million years or so of the Earth’s history. In Precambrian rocks, however, fossils are rare; thus, the geologic record of this important part of the Earth’s history has been especially difficult to decipher. Nonetheless, stratigraphy and radiometric dating of Precambrian rocks have clearly demonstrated that the history of the Earth extends billions of years into the past.</span>
The transfer of food through a series of organisms by eating and being eaten is called a food chain.
Cellular Respiration and Photosynthesis<span> are </span>almost opposite processes<span> because </span>photosynthesis<span> removes carbon dioxide from the atmosphere while </span>cellular respiration<span> puts back carbon dioxide. </span>Cellular respiration<span> uses oxygen and has its waste product of carbon dioxide (CO2).</span>
Answer:
The two circuits of the cardiovascular system are: Pulmonary Circuit and Systematic Circuit. The pulmonary circuit is shorter than the systemic and is responsible for carrying deoxygenated blood to the lungs from the right atrium, for oxygenation. The systemic circuit is longer and leaves the aortic artery, carrying oxygenated blood throughout the body and nutrients for survival. If less blood were pumped into the systemic circuit, this amount would not be sufficient to compensate for the organism's needs, with the corresponding consequences that this would entail.
It is said that the cardiovascular system is a closed system because blood travels inside a network of blood vessels without leaving them.
