question_answer 29)

  Which among the following have open circulatory system? (i) Arthropoda                   (ii) Mollusca                        (iii) Annelida                     (iv) Coelenterata (a) (i) and (ii)                      (b) (iii) and (iv)                  (c) (i) and (iii)                     (d) (ii) and (iv)

Answer:

    (a) Blood vascular system is of two types open system and closed system

Open System	Closed System
Low pressure system Blood is conveyed directly to organs without formation of capillaries Distribution of blood is not well regulated Found in leeches, most arthropods and molluscs.	High pressure system Blood is conveyed directly to the organs through capillaries. Distribution of blood is well regulated and controlled Found in annelidas a except leeches cephalopods and vertebrates.