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Phylum Mollusca MCQ - Practice Questions with Answers

Edited By admin | Updated on Sep 18, 2023 18:34 AM | #NEET

Quick Facts

Phylum Mollusca and Body Plan of Mollusca is considered one of the most asked concept.
3 Questions around this concept.

In which one of the following the genus name, its two charcters and its phylum are not correctly match, whereas the remaining three are correct

Genus name		Two Characters	Phylum

Pila	(a)	Body Semented	Mollusca
	(b)	Mouth with Radual

Asterias	(a)	Spiny skinned	Echinodermata
	(b)	Water vascular system

Sycon	(a)	Pore bearing	Porifera
	(b)	Canal system

Periplaneta	(a)	Jointed appendages	Arthropoda
	(b)	Chitinous exoskeleton

Phylum Mollusca and Body Plan of Mollusca

The term ‘Mollusca’ is obtained from the Latin word molluscus that means soft-bodied. The phylum contains soft-bodied animals
It is the second largest phylum of Kingdom Animalia with 60,000 species documented.
They are mostly marine. However, they are also found in freshwater and on land
They have organ system level of organization
They have a true coelom but the coelom is greatly reduced. They are triploblastic
They are bilaterally symmetrical
Examples: Pila (Apple snail), Pinctada (Pearl oyster), Sepia (Cuttlefish), Loligo (Squid), Octopus (Devil fish), Aplysia (Seahare), Dentalium (Tusk shell) and Chaetopleura (Chiton).

Body Plan of Mollusca:

Molluscs are unsegmented animals.
The body may have a covering of hard calcareous shell. The body can be distinguished into three different parts as:
Head - sensory organs and mouth are present here
Muscular foot - used for locomotion
Visceral hump - dorsally placed and contains digestive system, excretory system and heart.
There is a soft and spongy layer of skin over the visceral hump called mantle.
This mantle secretes calcium carbonate shell on its outer surface.
The space between the visceral hump and mantle is called mantle cavity. Gills are present in this cavity.These help in Respiration and Excretion
The general body plan of molluscs can be shown as follows: