Answer:
Photosynthesis and cellular respiration allow the carbon and oxygen that organisms consume and produce to be cycled through the ecosystem. They work together so that what is made from one process is used in the other. Without them the ecosystem would run out of carbon dioxide and oxygen, and everything would die.
Answer:
Option A, by having a constant supply of blood
Explanation:
Blood that flows to the muscles bring oxygen from the atmosphere to the contracting muscles where it gets consumed. During large muscle exercise, two physiological needs arise – a) high and prolonged muscle blood flow and b) regulation of blood pressure so that there is adequate perfusion of pressure to all organs. In order to meet both the requirements, the blood flow increases so that the vasoligating muscles do not outstrip the cardiac output.
Hence, option A is correct