Animal Diversity and Structural Organisation — Practice

Question 1

The presence of a notochord (at some stage) is the defining feature of the phylum:
(a) Chordata (b) Annelida (c) Arthropoda (d) Mollusca

Accepted Answer

(a) Chordata.

Chordates possess a notochord, a dorsal hollow nerve cord, pharyngeal gill slits and a post-anal tail at some stage of life; the notochord is absent in all non-chordates.

Question 2

Which phylum is diploblastic?
(a) Coelenterata (b) Platyhelminthes (c) Annelida (d) Arthropoda

Accepted Answer

(a) Coelenterata.

Coelenterata (Cnidaria) are diploblastic, with only ectoderm and endoderm. From Platyhelminthes onward animals are triploblastic (mesoderm added).

Question 3

Roundworms (Aschelminthes) are:
(a) pseudocoelomate (b) acoelomate (c) coelomate (d) diploblastic

Accepted Answer

(a) pseudocoelomate.

Aschelminthes (nematodes like Ascaris) have a false body cavity that is not fully lined by mesoderm — a pseudocoelom. Flatworms are acoelomate; annelids onward are coelomate.

Question 4

True metameric segmentation first appears in the phylum:
(a) Annelida (b) Platyhelminthes (c) Coelenterata (d) Porifera

Accepted Answer

(a) Annelida.

Annelids (earthworm, leech) show true metameric segmentation — the body divided into repeating segments — and are also the first truly coelomate phylum.

Question 5

The largest phylum in the animal kingdom is:
(a) Arthropoda (b) Mollusca (c) Chordata (d) Annelida

Accepted Answer

(a) Arthropoda.

Arthropoda (insects, spiders, crustaceans) is the largest animal phylum by number of species, with jointed appendages and a chitinous exoskeleton. Mollusca is the second largest.

Question 6

The water-vascular system is a characteristic feature of the phylum:
(a) Echinodermata (b) Mollusca (c) Arthropoda (d) Annelida

Accepted Answer

(a) Echinodermata.

Echinoderms (starfish, sea urchins) have a unique water-vascular system that operates their tube feet; adults are radially symmetrical but larvae are bilateral.

Question 7

Stinging cells called cnidoblasts are characteristic of:
(a) Coelenterata (b) Porifera (c) Ctenophora (d) Platyhelminthes

Accepted Answer

(a) Coelenterata.

Coelenterata (Cnidaria) such as Hydra and jellyfish have cnidoblasts (stinging cells) used for defence and prey capture — the source of the name Cnidaria.

Question 8

In which subphylum is the notochord present only in the larval tail?
(a) Urochordata (b) Cephalochordata (c) Vertebrata (d) Hemichordata

Accepted Answer

(a) Urochordata.

In Urochordata (tunicates like Ascidia) the notochord is confined to the larval tail. In Cephalochordata it runs the whole body length; in Vertebrata it is replaced by a vertebral column.

Question 9

Which of the following groups are warm-blooded (homeothermic)?
(a) birds and mammals (b) reptiles and birds (c) fish and amphibians (d) amphibians and reptiles

Accepted Answer

(a) birds and mammals.

Only birds (Aves) and mammals maintain a constant body temperature (warm-blooded). Fish, amphibians and reptiles are cold-blooded.

Question 10

Among reptiles, a four-chambered heart is found in the:
(a) crocodile (b) lizard (c) snake (d) turtle

Accepted Answer

(a) crocodile.

Most reptiles have a three-chambered heart, but the crocodile has a four-chambered heart. Four chambers occur in birds, mammals and crocodiles.

Question 11

Cartilaginous fish such as sharks belong to the class:
(a) Chondrichthyes (b) Osteichthyes (c) Cyclostomata (d) Amphibia

Accepted Answer

(a) Chondrichthyes.

Chondrichthyes are cartilaginous fish (sharks, rays) with placoid scales. Osteichthyes are bony fish with an air bladder.

Question 12

The lining of the alveoli of the lungs, adapted for gas exchange, is made of:
(a) simple squamous epithelium (b) columnar epithelium (c) cuboidal epithelium (d) stratified epithelium

Accepted Answer

(a) simple squamous epithelium.

The thin, flat cells of simple squamous epithelium line the alveoli, allowing rapid diffusion of gases across the short distance.

Question 13

Which structure connects muscle to bone?
(a) tendon (b) ligament (c) cartilage (d) areolar tissue

Accepted Answer

(a) tendon.

A tendon (dense regular connective tissue) attaches muscle to bone, while a ligament connects bone to bone.

Question 14

Cardiac muscle is:
(a) striated and involuntary (b) striated and voluntary (c) smooth and involuntary (d) smooth and voluntary

Accepted Answer

(a) striated and involuntary.

Cardiac muscle (heart) is striated like skeletal muscle but involuntary like smooth muscle, and its branched fibres are joined by intercalated discs.

Question 15

Blood is classified as which type of tissue?
(a) connective (b) epithelial (c) muscular (d) nervous

Accepted Answer

(a) connective.

Blood is a fluid connective tissue: cells (RBCs, WBCs, platelets) suspended in a liquid matrix (plasma), the defining feature of connective tissue.

Practice — Animal Diversity and Structural Organisation

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