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  • Differentiate between: Open and closed circulatory system

Differentiate between:
a. Open and closed circulatory system
b. Oviparity and viviparity
c. Direct and indirect development
d. Acoelomate and pseudocoelomate
e. Notochord and nerve cord
f. Polyp and medusa

Answers (1)

a) In the open circulatory system, blood is pumped out of the heart, and the cells and tissues are directly bathed whereas, in the closed circulatory system, the blood circulates throughout the body with the assistance of a series of vessels.
b) Oviparous refers to the Laying of fertilized and unfertilized eggs whereas viviparous refers to giving birth to young ones. Reptiles, birds, and some mammals fall into oviparous whereas Scolidon and most mammals fall into the category of viviparous.
c) Direct development refers to a form when a larval stage is absent in the development of the organism. In simple words, when the young ones resemble the adult, it is direct development. For example- mammals, reptiles, etc. Indirect development refers to when the larval stage is present in the development of the organism which does not resemble the adult. In other words, when the young ones are different than the adults, this is indirect development. For example- frog, cockroach, silkworm.
d) Acoelomates are the animals possessing no coelom whereas Pseudocoelomates are the animals with a body cavity, present in between ectoderm and endoderm. Mesoderm is present as scattered pouches, complete lining is absent.
e) The nerve cord is a strand comprising solid nervous tissue while the notochord is a rod-like structure that is mesodermally derived and is formed on the dorsal side during embryonic development.
f) Polyp is a cylindrical and sessile form like Hydra while the Medusa is a free-swimming umbrella-shaped like jellyfish.

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