Question 1

The rasping feeding organ found in the mouth of most molluscs is the:

Accepted Answer

Radula. The radula is a file-like rasping ribbon used in feeding by most molluscs.

Question 2

Echinoderms possess a unique ______ used in locomotion, feeding and respiration:

Accepted Answer

Water vascular system (with tube feet). The water (ambulacral) vascular system with tube feet is exclusive to echinoderms.

Question 3

Adult echinoderms show ______ symmetry, whereas their larvae show ______ symmetry:

Accepted Answer

Radial; bilateral. Adult echinoderms are radially symmetrical, but their larvae are bilaterally symmetrical — evidence of bilaterian ancestry.

Question 4

The soft body of molluscs is typically covered by a ______ secreted by the ______:

Accepted Answer

Calcareous shell; mantle. The mantle secretes the calcareous shell; the visceral hump lies within it.

Question 5

Echinoderms are placed close to chordates in evolution because they are:

Accepted Answer

Deuterostomes (blastopore forms the anus), like chordates. Echinoderms and chordates are deuterostomes (enterocoelous coelom), indicating a shared lineage distinct from protostomes (annelids/arthropods/molluscs).

Question 6

Which pairing of animal and phylum is CORRECT?

Accepted Answer

Pila (Apple snail) — Mollusca; Asterias (star fish) — Echinodermata. Pila, Octopus, Sepia are molluscs; Asterias, Antedon (feather star), Echinus are echinoderms.

Question 7

The respiratory organs of most aquatic molluscs are the:

Accepted Answer

Ctenidia (gills). Aquatic molluscs respire through feather-like gills called ctenidia located in the mantle cavity.

Question 8

A calcareous endoskeleton made of ossicles embedded in the body wall is a characteristic feature of:

Accepted Answer

Echinodermata. Echinoderms possess an internal skeleton (endoskeleton) of calcareous ossicles, which is why the group is placed among the spiny-skinned deuterostomes.

Question 9

Assertion (A): Echinoderms are exclusively marine animals. Reason (R): They possess a water vascular system with tube feet used in locomotion, feeding and respiration. Choose the correct option.

Accepted Answer

Both A and R are true but R is not the correct explanation of A. Both statements are true, but the water vascular system explains locomotion and feeding, not why echinoderms are exclusively marine, so R does not explain A.

Question 10

Match the echinoderm with its common name — (i) Asterias, (ii) Ophiura, (iii) Echinus, (iv) Antedon:

Accepted Answer

i-star fish, ii-brittle star, iii-sea urchin, iv-feather star. Asterias is the star fish, Ophiura the brittle star, Echinus the sea urchin and Antedon the feather star (sea lily).

Question 11

Which of the following statements about Mollusca is correct?

Accepted Answer

It is the second largest animal phylum with a body divisible into head-foot and visceral hump. Mollusca is the second largest phylum (after Arthropoda); the soft, unsegmented body is typically divided into a head-foot region and a visceral hump covered by a mantle.

Question 12

Which one of the following statements about echinoderms is INCORRECT?

Accepted Answer

They possess a well-developed excretory system. Echinoderms have no specialised excretory organs; excretion occurs by diffusion. Hence the statement claiming a well-developed excretory system is incorrect.

Question 13

This is the second largest animal phylum, its members having a soft, unsegmented body with a muscular foot and a visceral hump usually protected by a calcareous shell. The phylum is:

Accepted Answer

Mollusca. Mollusca is the second largest animal phylum; molluscs have a soft, unsegmented body with a distinct head, muscular foot, visceral hump and a calcareous shell.

Question 14

An unsegmented, bilaterally symmetrical, coelomate animal has a distinct head, a muscular foot and a visceral hump covered by a mantle. It belongs to the phylum:

Accepted Answer

Mollusca. A distinct head, muscular foot and visceral hump covered by a soft, spongy mantle are defining features of Mollusca.

Question 15

In molluscs, the muscular structure used chiefly for locomotion is the:

Accepted Answer

foot. The mollusc body bears a distinct head, a muscular foot for locomotion and a visceral hump. Tube feet occur in echinoderms and parapodia in annelids.

Question 16

The soft, spongy layer of skin that forms a covering over the visceral hump of a mollusc is called the:

Accepted Answer

mantle. In molluscs a soft and spongy layer of skin forms a mantle over the visceral hump.

Question 17

The mollusc Octopus is commonly known as the:

Accepted Answer

devil fish. Octopus is commonly called the devil fish. Sepia is the cuttlefish, Pila the apple snail and Pinctada the pearl oyster.

Question 18

Pila, a common mollusc, is known by the common name:

Accepted Answer

apple snail. Pila is the apple snail. Dentalium is the tusk shell, Aplysia the sea-hare and Chaetopleura the chiton.

Question 19

The mollusc Sepia is commonly called the:

Accepted Answer

cuttlefish. Sepia is the cuttlefish. Loligo is the squid and Octopus the devil fish; the sea urchin (Echinus) is an echinoderm.

Question 20

Loligo, a marine mollusc, is commonly known as the:

Accepted Answer

squid. Loligo is the squid. Sepia is the cuttlefish; the star fish (Asterias) is an echinoderm and Pinctada is the pearl oyster.

Mollusca & Echinodermata — NEET Biology MCQs with Solutions

Questions with solutions