a system of interlocking and interdependent food chains.
Upwelling is important to mix the nutrients that are present deep inside the water.Updewelling is a phenomenon in which the deeper water rises and gets mixed to the surface water to promote the growth of phytoplanktons and seaweeds as the water that is present deep inside is rich in nutrients.These phytoplanktons serve as as source of energy for large fishes and other aquatic animals. As these large animals are higher in population and are an important part of food chain and they also provide food to different marine mammals ,sea birds.The deep water infuses with costal water so to serve as a fuel for high productivity of marine ecosystem.
The correct answer is:
A. carry out photosynthesis
Answer:
Venous return (VR) is the flow of blood back to the heart.
Venous return to the right atrium is the most important factor determining cardiac output, provided both ventricles and the pulmonary circulation are normal.
Explanation:
Venous return refers to the flow of blood from the periphery back to the right atrium, and except for periods of a few seconds, it is equal to cardiac output.
Venous return is facilitated by a number of factors, including inspiration, increased total blood volume, increased venomotor tone, the cardiac suction effect, the presence of venous valves and the skeletal muscle pump.
Contraction of the skeletal muscles surrounding veins increases the pressure within the veins, pushing open the proximal valve and forcing blood toward the heart. For example, when calf muscles contract during exercise, blood is forced toward the heart, thus increasing venous return.
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