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Describe the evolutionary change in the pattern of heart among the vertebrates. |
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Answer» All vertebrates possess a muscular chambered heart. Fishes have 2 – chambered heart with an atrium and a ventricle. They have single circulation in which heart pumps deoxygenated blood, which is oxygenated by gills and supplied to body parts. Amphibians and reptiles have a 3 – chambered heart with two atria and a single ventricle. They possess incomplete double circulation with oxygenated and deoxygenated blood getting mixed up in a single ventricle. Crocodiles, birds and mammals possess a 4 chambered heart with two atria and two ventricles. Two separate circulatory pathways are present in these organisms and hence have double circulation. |
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