SCIENCE
ZOOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Annelida
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Cnidaria
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Nematoda
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Platyhelminthes
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Detailed explanation-1: -The closed circulatory system is present in Annelids and Chordates.
Detailed explanation-2: -Annelida is the first phylum to have closed circulatory system. Closed circulatory system has two advantages: Mixing of pure and impure blood does not occur as they flow in different vessels. Efficiency of blood flow is increased as the blood pressure is higher in closed vessels.
Detailed explanation-3: -Solution: A closed circulatory system first appeared in the phylum Annelida.
Detailed explanation-4: -Blood glands are present on fourth, fifth and sixth segments in annelids. Blood glands produce blood cells and hemoglobin which is dissolved in plasma. Annelids possess a closed circulatory system.
Detailed explanation-5: -Circulatory system is firstly completed in phylum annelida.