State reasons for the following:
a) Nematodes have pseudocoelom.
b) arthoropodes have open circulatory system.
c) Echinodermates are called so.

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Solution

Nematodes have body cavity that is not lined by middle layer or mesoderm. That’s why they are called as pseudocoelomates because of the presence of this pseudocoelum (false body cavity).

Arthropodes have open circulatory system as they lack blood vessels (veins and arteries) and heart pumps blood directly into body cavity in which organs are bathed.

Echinoderms are called so because of their hedgehog (Echinos in Greek) like skin (derma).

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Question 47
Give examples for the following
(a) Bilateral, dorsiventral symmetry is found in___.
(b) Worms causing disease elephantiasis is ___.
(c) Open circulatory system is found in ___ where coelomic cavity is filled with blood.
(d) ___are known to have pseudocoelom.

Q. Open circulatory system is present in
(A) Arthropods (B) Annelids
(C) Chordates (D) Molluscs

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State reasons for the following:a) Nematodes have pseudocoelom.b) arthoropodes have open circulatory system.c) Echinodermates are called so.

State reasons for the following:
a) Nematodes have pseudocoelom.
b) arthoropodes have open circulatory system.
c) Echinodermates are called so.